Journal articles on the topic 'Stresses and deformations condition'
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1
Zabaras, Nicholas, Yimin Ruan, and Owen Richmond. "On the Calculation of Deformations and Stresses During Axially Symmetric Solidification." Journal of Applied Mechanics 58, no. 4 (December 1, 1991): 865–71. http://dx.doi.org/10.1115/1.2897699.
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In this paper finite element modeling of the deformation and stress development in solidifying bodies is presented. Emphasis is given to axially symmetric problems and especially to the accurate implementation of thermal and mechanical phenomena occurring at the freezing front. More specifically, the interface velocity and location are treated as primary variables of the heat transfer analysis, and the isostatic stress condition at the front is utilized as an initial condition in the stress analysis. A hypoelastic-viscoplastic constitutive model and a rate form of the principle of virtual work are involved to model the stresses and deformation. The mechanical and thermal properties are allowed to vary with temperature and strain rate in a realistic manner. Several examples of calculated residual stresses are shown for pure aluminum under axially symmetric geometries and realistic boundary conditions. The effects on the evolving deformations and stresses of the melt pressure, geometry, and cooling conditions are examined and reported.
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Nurul Misbah, Muhammad, Septia Hardy Sujiatanti, Dony Setyawan, Rizky Chandra Ariesta, and Satriyo Rahmadianto. "Structural Analysis on the Block Lifting in Shipbuilding Construction Process." MATEC Web of Conferences 177 (2018): 01027. http://dx.doi.org/10.1051/matecconf/201817701027.
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Deformation is unavoidable in some stages of the ship production process. Deformation occurs when the blocks are lifted in an erroneous eye pad position. The aim of this study was to determine behaviour of the ship structures during assembly and lifting process. A typical tanker was used as the basic structural shape. The bottom structures was modeled to be analyzed. In this study, deformations and stresses on the bottom structures during the block lifting are investigated using the finite element method. The deformations and stresses are evaluated and critical condition detected. The preferable block lifting method with the minimum distortion on the bottom structures of tanker is proposed.
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Shrestha, Pawan Kumar, and Krishna Kanta Panthi. "Estimating Tunnel Strain in Weak and Schistose Rock Mass under a State of in-situ Stress Anisotropy." Hydro Nepal: Journal of Water, Energy and Environment 16 (February 28, 2015): 7–13. http://dx.doi.org/10.3126/hn.v16i0.12212.
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Tunnels excavated in weak and schistose rock mass below high overburden (rock cover) are prone to instability in the form of tunnel deformation. The deformation in the tunnel takes place to such an extent that it is irreversible and of significant magnitude, which is often known as tunnel squeezing. In order to limit such plastic deformation in tunnels, it is desirable that the response of the rock mass to induced stresses is known so that requirement of rock support can be estimated. Contrary to the assumption of uniform in-situ stresses made in analytical solutions for elasto-plastic analyses, large degree of stress anisotropy condition prevails in most tunnelling conditions. The effect of such anisotropic stress condition leads to varying degrees of deformations around the tunnel contour. Therefore, stress anisotropy is also an important factor that needs to be addressed to ensure a proper support design for tunnels. This paper discusses the inter-relationship among rock mass property, in-situ stresses including horizontal to vertical stress ratio, tunnel support pressure and deformation. The study is based on the tunnel cases from the Nepal Himalaya. Three completed tunnel projects were selected, where moderate to large tunnel deformations had been recorded. Long term deformation records were analyzed to assess time independent and time dependent deformations. Results of the analyses of the tunnels in weak and schistose rock mass at stress anisotropy states show that a good correlation among tunnel strain, rock mass shear modulus, support pressure, vertical stress and stress ratio of horizontal to vertical stresses exists. Moreover, the study also shows that significant amount of time dependent deformation can occur in such weak rock mass. Such deformation was found to be high in schist and micaceous phyllite, moderate in graphitic phyllite and low in siliceous phyllite. The suggested relationships can be used as a basis for an early estimate of instantaneous and final deformations and the corresponding requirement of support pressures in tunnel walls in weak and schistose rock mass.DOI: http://dx.doi.org/10.3126/hn.v16i0.12212HYDRO Nepal Journal of Water Energy and EnvironmentIssue. 16, 2015 January Page: 7-13 Upload date: March 1, 2015
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Eremeev, V. V. "ON THE LOSS OF STABILITY OF A TWO-LAYERED PLATE MADE OF A FUNCTIONAL-GRADIENT MATERIAL WITH A NON-UNIFORM FIELD OF PRE-STRESSES." Problems of strenght and plasticity 81, no. 4 (2019): 512–18. http://dx.doi.org/10.32326/1814-9146-2019-81-4-512-518.
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In the framework of three-dimensional nonlinear elasticity we consider linear instability of a composite plate made of functionally graded material and having initial stresses. The plae consists of two layers which were obtained as a result of flattening of an annual sector of an elastic cylinder. This deformation results in appearance of internal stresses. Thus, the plate becomes initially stressed. The initial stresses depend on the thickness coordinate, so we get inhomogeneous stress field. We have two types of inhomogeneities, the first is the inhomogeneity of the initial stresses whereas the second is the material inhomogeneity.We use the incompressible neo-Hookean material model as a constitutive relation. Despite of relatively simple form this model describes properly severe deformations of some rubber-like materials. For incompressible materials the flattening constitutes one of the so-called universal deformations, that is such deformation which is independent on the choice of constitutive relation. The material inhomogeneity is described through a dependence of the shear modulus on the thickness coordinate. Such inhomogeneity could be related to the manufacturing of the material or to further treatment. The stability was analysed using the linearization approach. We superimpose infinitesimal deformations on the finite initial one. The linearized boundary-value problem was derived and its nontrivial solutions were obtained. The solution was obtained in series of trigonometric functions. This helps to automatically satisfy a part of boundary conditions. We consider the influence of the inhomogeneity and initial stresses. We show that the initial stresses may significantly change critical deformations. For example, the loss of stability is possible due to initial stresses only.
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Eremeev, V. V. "ON THE LOSS OF STABILITY OF A TWO-LAYERED PLATE MADE OF A FUNCTIONAL-GRADIENT MATERIAL WITH A NON-UNIFORM FIELD OF PRE-STRESSES." Problems of strenght and plasticity 81, no. 4 (2019): 513–20. http://dx.doi.org/10.32326/1814-9146-2019-81-4-513-520.
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In the framework of three-dimensional nonlinear elasticity we consider linear instability of a composite plate made of functionally graded material and having initial stresses. The plae consists of two layers which were obtained as a result of flattening of an annual sector of an elastic cylinder. This deformation results in appearance of internal stresses. Thus, the plate becomes initially stressed. The initial stresses depend on the thickness coordinate, so we get inhomogeneous stress field. We have two types of inhomogeneities, the first is the inhomogeneity of the initial stresses whereas the second is the material inhomogeneity.We use the incompressible neo-Hookean material model as a constitutive relation. Despite of relatively simple form this model describes properly severe deformations of some rubber-like materials. For incompressible materials the flattening constitutes one of the so-called universal deformations, that is such deformation which is independent on the choice of constitutive relation. The material inhomogeneity is described through a dependence of the shear modulus on the thickness coordinate. Such inhomogeneity could be related to the manufacturing of the material or to further treatment. The stability was analysed using the linearization approach. We superimpose infinitesimal deformations on the finite initial one. The linearized boundary-value problem was derived and its nontrivial solutions were obtained. The solution was obtained in series of trigonometric functions. This helps to automatically satisfy a part of boundary conditions. We consider the influence of the inhomogeneity and initial stresses. We show that the initial stresses may significantly change critical deformations. For example, the loss of stability is possible due to initial stresses only.
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Ayoub, Mai, Mohamed EL-Anwar, and Mazen I. Negm. "Arthroscopic Suture Anchor Design Finite Element Study." Open Access Macedonian Journal of Medical Sciences 9, A (July 22, 2021): 562–66. http://dx.doi.org/10.3889/oamjms.2021.6409.
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AIM: This in-vitro study investigated arthroscopic suture anchors’ main design parameters effect on surrounding bone. METHODS: Thirty-dimensional arthroscopic suture anchor designs’ models were created on engineering CAD software by changing thread profile, pitch, and anchor tip profile as design parameters. These models were imported into ANSYS Workbench for finite element analysis. Bone was simplified and modeled as two coaxial cylinders. Tensile vertical load of 300 N, and oblique at 45º to the vertical axis, were applied to each model as two loading conditions while the simplified bone base was fixed in place as a boundary condition. RESULTS: The finite element analyses on all models under both loading conditions showed stresses within physiological limits on bone. Trapezoidal teeth and inclined cut teeth designs showed the lowest values of stresses and deformations respectively on the bone under oblique loads, while curved tooth and square tooth designs showed the lowest values of stresses and deformations respectively on the bone under vertical loads. General ascending or descending trend was recorded by increasing pitch from 1.2 to 1.5 to 1.8 mm on the total deformation and maximum Von Mises stress on bone and anchor body. Tapered tip slightly increased bone and anchor stresses. CONCLUSION: Arthroscopic anchors thread profile has minor affect on cortical bone behavior. Trapezoidal teeth, square tooth, and inclined cut teeth profiles showed the lowest values of stresses and deformations on cortical bone. Increasing thread pitch of arthroscopic suture anchors increases or decreases stress on the bone, and anchor body according to thread profile edges. Anchor tip profile negligibly affects both deformations and stresses on bone and anchor body.
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Savaş, Atilla. "SELECTION OF WELDING CONDITIONS FOR MINIMIZING THE RESIDUAL STRESSES AND DEFORMATIONS DURING HARD-FACING OF MILD STEEL." Brodogradnja 72, no. 1 (March 1, 2020): 1–18. http://dx.doi.org/10.21278/brod72101.
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Hard-facing process is widely used for improving the wear resistance of mild steel. During the application of hard-facing, due to high temperatures, residual stresses and deformations may occur. The tensile residual stresses may cause crack propagation on the hard-faced part. The purpose of this study is to utilise minimum computer work for minimizing these residual stresses and deformations during the hard-facing of mild steel. The fully coupled transient heat transfer and structural analysis was performed for calculations. The double-ellipsoidal moving heat source was utilised to simulate the heat input from the gas metal arc welding (GMAW). Only eight numerical simulations were performed to minimize the computer work; the grey relational analysis was used for minimizing both the residual stresses and deformations. Welding speed, welding current, and welding pattern were considered as changing parameters. At the end of the numerical and statistical solutions, it is observed that heat input should be kept minimum to minimize the stresses and deformations. But it is obvious that the heat input must provide a temperature greater than the melding point. Straight patterns always produce better results for minimizing stresses and deformations. Transverse stress at the beginning and end of the longitudinal path gets higher significantly after cooling. Cooling does not affect the total deformation.
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Bondar, Ivan, Mikhail Kvashnin, Dinara Aldekeyeva, Saule Bekzhanova, Aliya Izbairova, and Assem Akbayeva. "Influence of the deformed state of a road bridge on operational safety." Eastern-European Journal of Enterprise Technologies 2, no. 7 (116) (April 28, 2022): 29–34. http://dx.doi.org/10.15587/1729-4061.2022.255275.
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The article deals with the issues of vehicle traffic safety on artificial constructions. Ensuring safety in the field of rail transport is an essential element in the activities of all subjects of the market of railway services, including passenger carriers. To fully study the issues of the deformed state of beam superstructures, it is necessary to conduct static and dynamic tests. Before the start of the tests, it is mandatory to check the technical condition of the artificial structure: 1) visual inspection, special checks with verification of necessary parameters; 2) carrying out control linear measurements; 3) selective determination of concrete strength by non-destructive methods. First, the static tests is conducted to determine the total deformations of each beam of the superstructure at the control point with maximum deformations of ½ L. Then dynamic tests with determination of periods of natural oscillations and deformations (stresses). Processing of the results of surveys and tests of the overpass with an assessment of the possibility of passing design loads on the road bridge, after which a dynamic passport of the transport structure is compiled. The study of the stressed state of vehicles gives a clear idea of the causes of deformations in the structural elements when analyzing the work of the span of the automobile bridge in conditions of increasing axial loads and traffic flow speeds. Deformation processes lead to defects, structural failures and accidents on the vehicle, which leads to premature wear, material damage and environmental damage. Periodic measurements of deformations (stresses) of the superstructure structure over several years will make it possible to predict changes in its condition over time and determine the remaining resource in terms of load-bearing capacity and load capacity. As a result of experimental studies, it was proved that the presented technique, developed in the classical version for detecting structural defects between a single-layer coating and a base of various types, can also work effectively in the case of non-destructive testing of multilayer structures
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Kassem, Abdelraouf Tawfik. "Deformations of R.C.Circular Slabs in Fire Condition." Civil Engineering Journal 4, no. 4 (May 3, 2018): 712. http://dx.doi.org/10.28991/cej-0309126.
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Reinforced concrete slabs are elements in direct contact with superimposed loads, having high surface area and small thickness. Such a condition makes slabs highly vulnerable to fire conditions. Fire results in exaggerated deformations in reinforced concrete slabs, as a result of material deterioration and thermal induced stresses. The main objective of this paper is to deeply investigate how circular R.C. slabs, of different configurations, behave in fire condition. That objective has been achieved through finite element modelling. Thermal-structural finite element models have been prepared, using "Ansys". Finite element models used solid elements to model both thermal and structural slab behaviour. Structural loads had been applied, representing slab operational loads, then thermal loads were applied in accordance with ISO 843 fire curve. Outputs in the form of deflection profile and edge rotation have been extracted out of the models to present slab deformations. A parametric study has been conducted to figure out the significance of various parameters such as; slab depth, slenderness ratio, load ratio, and opening size; regarding slab deformations. It was found that deformational behaviour differs significantly for slabs of thickness equal or below 100 mm, than slabs of thickness equal or above 200 mm. On the other hand considerable changes in slabs behaviour take place after 30 minutes of fire exposure for slabs of thickness equals or below 100 mm, while such changes delay till 60 minutes for slabs of thickness equals or above 200 mm.
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Rutman, J., and V. Ulitin. "Limit Dependences in Stability Calculations With Account for Physical Nonlinearity." Journal of Mechanics 33, no. 2 (September 13, 2016): 157–60. http://dx.doi.org/10.1017/jmech.2016.72.
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AbstractStability of bars, plates, shells, and other thin-walled structures in conditions of small physical nonlinearity is considered, when stresses exceed the proportionality limit, the amount of deformations being limited. Shanley's concept is used. The critical state is determined by means of some limit dependences. In a large number of cases, when creating efficient highly-stressed constructions, limited plastic deformations are allowed in them. When analysing stability in the critical state, the calculated stresses turn out to exceed the proportionality limit and the Young's modulus of elasticity turns out to be greater than the tangent modulus corresponding to the calculated stress on the diagram “deformation-stress”. The objective of this work is to show that stability calculation beyond the proportionality limit is reduced to the analysis of some limit dependences as well as to develop a general solution algorithm for similar problems.
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You, L. H., J. J. Zhang, H. B. Wu, and R. B. Sun. "Regular papers / Articles ordinaires A numerical approach for the static analysis of the body of pressurized dry gas holders." Canadian Journal of Civil Engineering 30, no. 2 (April 1, 2003): 381–90. http://dx.doi.org/10.1139/l02-095.
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In this paper, a numerical method is developed to calculate deformations and stresses of the body of dry gas holders under gas pressure. The deformations of the wall plates are decomposed into out-of-plane bending and in-plane deformation. The out-of-plane bending of the wall plates is described by the theory of orthotropic plates and the in-plane deformation by the biharmonic equation of flat plates under plane stress. The theories of beam columns and beams are employed to analyze the columns and corridors, respectively. By considering compatibility conditions between the members and boundary conditions, equations for the determination of deformations and stresses of dry gas holders under gas pressure are obtained. Both the proposed approach and the finite element method are used to investigate the deformations and stresses of the body of a dry gas holder under gas pressure. The results from the proposed method agree with those from the finite element method. Because far fewer unknowns are involved, the proposed method is computationally more efficient than both the finite element method and the series method developed from the theory of stiffened plates.Key words: numerical approach, body of dry gas holders, gas pressure.
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Elad, D., A. Foux, and Y. Kivity. "A Model for the Nonlinear Elastic Response of Large Arteries." Journal of Biomechanical Engineering 110, no. 3 (August 1, 1988): 185–89. http://dx.doi.org/10.1115/1.3108429.
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The nonlinear elastic response of large arteries subjected to finite deformations due to action of biaxial principal stresses, is described by simple constitutive equations. Generalized measures of strain and stress are introduced to account for material nonlinearity. This also ensures the existence of a strain energy density function. The orthotropic elastic response is described via quasi-linear relations between strains and stresses. One nonlinear parameter which defines the measures of strain and stress, and three elastic moduli are assumed to be constants. The lateral strain parameters (equivalent to Poisson’s ratios in infinitesimal deformations) are deformation dependent. This dependence is defined by empirical relations developed via the incompressibility condition, and by the introduction of a fifth material parameter. The resulting constitutive model compares well with biaxial experimental data of canine carotid arteries.
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Al wazir, Ali hammoudi Abdul-Kareem. "Analysis of the natural composite material layers influence on the cantilever’s structural performance." Eastern-European Journal of Enterprise Technologies 2, no. 1 (116) (April 28, 2022): 16–23. http://dx.doi.org/10.15587/1729-4061.2022.253990.
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In this study, with their high strength-to-weight ratio, adaptability, and lack of corrosion, composite materials are widely used in aircraft construction and can be considered an acceptable metal substitute by all parties involved. Static load tests have been performed under identical conditions and stresses, but the layer sequence was changed. The Ansys workbench ACP-pre is utilized to analyze the data. Various deformations were found as a result of this. There are values of 14.265 and 0.1335 for the smallest z-direction deformation and for the overall strain in the composite 3 examples. Boundary conditions have been confirmed with 1,500 N as a resultant force with the static condition. The simulation results have been analyzed as a static condition. Four materials have been employed in different order to be investigated and these materials are Sisal, Pineapple, Jute, and Kenaf. The numerical results have been undertaken using the static structure of Ansys 16.1 Version tool. Geometry has been modeled and meshed using Ansys workbench. The model has been verified using convergence test. As the output, total deformation and von Mises stresses were investigated and explained accordingly. Numerical results stated that the maximum deformation due applied load was at the Z-axis. The maximum total deformation value is 1.254 mm and the minimum is 2.5 mm. Furthermore, von Mises stresses of the entire body have been calculated. The numerical results have shown the maximum result due to 1,500 N is 1.1 mPa. Eventually, the main aim has been achieved by employing total deformation and von Mises stresses accordingly
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Delyová, Ingrid, Peter Sivák, Darina Hroncová, and Ladislav Jakab. "Analysis of Stresses and Deformations in Container with Flat Bottom." Applied Mechanics and Materials 816 (November 2015): 255–60. http://dx.doi.org/10.4028/www.scientific.net/amm.816.255.
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There is a general condition of the stress created by superficial forces in praxis. It can be also simplified when the shifting the forces and bending torques are equal to zero, or we can ignore them because they are too low. In term of draft it is just a condition which has the best result when the material for the construction is exploited. The edge of the cylindrical container failures are the differential base for the axisymmetric shell within an internal pressure. That main point of that contribution is the effect of the internal load and the bending effects to joining pressure of the slice cylindrical part and the plate bottom.
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Wen, Z. F., and X. S. Jin. "Elastic-Plastic Finite-Element Analysis of Repeated, Two-Dimensional Wheel-Rail Rolling Contact under Time-Dependent Load." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, no. 5 (May 1, 2006): 603–13. http://dx.doi.org/10.1243/09544062jmes201.
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A study was performed using a finite-element model to obtain stresses, strains, and deformations for repeated, two-dimensional rolling contact of a locomotive driving wheel and a rail under time-dependent load. An advanced cyclic plasticity model was used with a commercial finite element code via a material subroutine. The time-dependent load was considered a harmonic variation of the wheel-rail normal contact force. The normal contact pressure was assumed to follow the Hertzian distribution and the tangential force followed the Carter distribution. A wavy profile is formed on the running surface of the rail subjected to the harmonic variation of the normal (vertical) contact force. The developed wavelength of the profile corresponds to the frequency of the normal contact force for the actual train speed. The creepage or rolling-sliding condition plays an important role in the residual strains and deformations, but its influence on the residual stresses is insignificant. The residual stresses at the surface decrease with increasing rolling passes and gradually tend to stabilize. The residual strains and surface displacements increase with increasing rolling cycle, but the increases in residual strain and surface displacement per rolling pass (ratchetting rate) decay. The residual stresses, strains, and deformations near the wave trough of the residual wavy deformation are larger than those near the wave crest. For any given creepage including zero value, when the number of rolling passes increases, the surface depth of the wavy-deformed surface increases but the ratchetting rate decays. The results are useful in investigating the influence of plastic deformation on rail corrugation.
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Schlicht, Hans, and Hermann Vetters. "Residual Stresses in Roller Bearing Components." Materials Science Forum 768-769 (September 2013): 755–61. http://dx.doi.org/10.4028/www.scientific.net/msf.768-769.755.
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Rolling contact fatigue is a very complex process. The mechanism can only be described by speculative considerations. Because the loading conditions during the elastic- hydro- dynamical contact are not clearly described. The loading cycle runs within extremely short rates and structural alterations occur under high hydrostatic pressure. Widely unknown is therefore, how the materials conditions are influenced by these processes. But by means of simplified considerations an approach to the rolling contact fatigue process can be obtained. Following these conceptions simplifying quasi-static conditions are drawn. A lubricant film inhibits the metallic contact of the revolved bearing components. A HERTZian load stress will be accumulated over an elliptical contact area and within and beneath this contact area three dimensional stresses are acting. The materials strengthening can be described by the hypothesis of alteration of shape. During the fatigue period, the microstructure will be changed by micro- and macro- plastically deformation. By this residual stresses occur. These are superimposed to the operational -loading –stresses which change the distressing conditions of the material. The progressive plastically deformations accompanying the growing fatigue procedure cause perpetually alterations in the distress- conditions of the material. Structural alterations of the rolling contact fatigue process are shown by means of metallography as followed: by dark etching areas (DEA), and by white etching areas (WEA) showing bands, which are positioned beneath the contact area at an angle of 30° (30°WEB) and for instance at 80° (80°WEB), and furthermore by so called butterfly structures (butterflies with “white etched” flanks). All these white etching areas, regarding their morphological structure and the etching conditions, are commonly originated by two axial distressing. The three dimensional materials distressing within the roller-bearing component on the one hand and the two dimensionally originating of the WEA on the other seem to be an antagonism. But when the changes of residual stresses during the contact rolling fatigue process are to be analyzed, it is clear that this antagonism rises only virtually because there exists a real tri-axial stress condition, which tolerates a two axial distressing of the material. By the concept, that the growing plastically deformations cause residual stresses superposing the operational load stresses, the temporary cycle of the structural alterations and the local and angular positions of the 30° WEB can be explained.
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Wang, Kelin, Wei Zhang, Yihua Dou, Xiaozeng Wang, and Yinping Cao. "Stresses and deformations of an eccentric cylindrical cam during hydro-joining." MATEC Web of Conferences 353 (2021): 01025. http://dx.doi.org/10.1051/matecconf/202135301025.
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The stresses and deformations of an eccentric cylindrical cam during the process of hydro-joining have been calculated in orthogonal curvilinear coordinates according to the mechanical model of the cam and governing equations in terms of appropriate complex potentials with suitable boundary conditions. The radial and shearing stress coefficients determined for an example cam are far less than that of the tangential stress during hydro-joining. The tangential stress coefficient of the outer surface of the cam is greater than that of the internal surface when the polar angle exceeds a particular value. The position of the maximum value of the radial stress coefficient is located on the internal surface of the cam, and the maximum shear stress coefficient is located between the inside and outside surfaces of the cam. The cam deformations on the internal and external surfaces under internal pressure respectively attain maximum values at particular angles. The maximum values of the radial and y-directional deformations are located at the position of the minimum wall thickness. The radial deformations determined for an example cam are far larger that the tangential deformations during hydro-joining. The errors between the theoretical and numerical solutions for the tangential stress and the y-directional deformation are both very small.
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Alegre, Jesus Manuel, Andrés Díaz, Isidoro Ivan Cuesta, and Juan Manuel Manso. "Application of the hole-drilling method for the evaluation of residual stresses near rounded ends." Journal of Strain Analysis for Engineering Design 54, no. 7-8 (March 7, 2019): 424–30. http://dx.doi.org/10.1177/0309324719833227.
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The experimental measurement of residual stresses by the hole-drilling method is a versatile technique due to its great simplicity. The technique consists of drilling on a material surface and measuring the relieved deformation on the surface by means of strain gauge rosettes. The most widespread method to obtain residual stresses from relieved deformation is the integral method and is found in the ASTM E837-13a standard. The procedure is standardised for very specific conditions, which are based on the application of the technique on a large flat-plate. To apply this technique to situations outside the standard scope, it is necessary to perform studies that validate its applicability. One of these situations is to evaluate the stresses introduced in hot- or cold-rolled profiles, where the residual stresses are concentrated on the rounded corners generated by rolling operations. In this study, a numerical simulation by finite elements has been carried out to obtain the relieved deformations for the case of drilling near rounded ends. The results show that the hole-drilling technique is applicable for the case of rounded ends; however, there is a significant deviation from the flat-plate condition which can be minimised by considering new matrices for the specific rounding radius and thickness of the analysed workpiece.
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Nejad, M. Z., Z. Hoseini, A. Niknejad, and M. Ghannad. "Steady-State Creep Deformations and Stresses in FGM Rotating Thick Cylindrical Pressure Vessels." Journal of Mechanics 31, no. 1 (October 21, 2014): 1–6. http://dx.doi.org/10.1017/jmech.2014.70.
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AbstractIn the present study, a closed-form analytical solution for the steady-state creep stresses of rotating thick cylindrical pressure vessels made of functionally graded materials (FGMs) is carried out. Norton's law governs the creep response of the material. Exact solutions for stresses and strain rate are obtained under the plane strain condition. How different material parameters involved in Norton's law affect radial and circumferential stresses together with the equivalent strain rate in rotating thick-walled cylindrical vessels under internal pressure is investigated. The result obtained shows that the property of FGMs has a significant influence on the equivalent creep strain rate and stresses distributions along the radial direction.
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Nardinocchi, Paola, and Luciano Teresi. "The Influence of Initial Stresses on Blood Vessel Mechanics." Journal of Mechanics in Medicine and Biology 03, no. 02 (June 2003): 215–29. http://dx.doi.org/10.1142/s0219519403000739.
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In order to account for the in vivo conditions of blood vessels, we investigate the mechanical behavior of a stressed tube-like membrane when small deformations are superimposed on large deformations: the latter simulate the stretches present in the in vivo arteries while the superimposed deformations account for the small — but essential for the blood propagation — deformations due to the pulsatile nature of the blood flow. Our aim is to discuss how a stress state influence the response of the vessel-blood system.
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Burenin, A. A., and A. V. Tkacheva. "Evolution of temperature stresses in the Gadolin problem of assembling a two-layer elastoplastic pipe." PNRPU Mechanics Bulletin, no. 3 (December 15, 2020): 20–31. http://dx.doi.org/10.15593/perm.mech/2020.3.03.
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The work aims at solving the problem of the theory of unsteady thermal stresses simulating the assembling of the two-layer elastoplastic pipe using the shrink fit (Gadolin problem). The plastic flow condition is taken in the form of a piecewise linear condition of maximum reduced stresses (the Ishlinsky - Ivlev condition) with a parabolic yield point depending on temperature. It is shown that when solving the mechanical part of a disconnected problem of the theory of temperature stresses, the calculations of reversible and irreversible deformations and stresses can be carried out numerically, i.e. analytically without resorting to approximate calculation procedures and, therefore, without discretizing the computational domains. We present a diagram of the emergence and disappearance of plastic flow regions under the assembly conditions and its subsequent cooling. With a different choice of problem parameters, some plastic regions may not appear. However, it is impossible to obtain other areas of plastic flow by changing the geometry of the problem, properties of assembly materials, and the level of heating. This is the adequacy of the calculations. Only those plastic areas that are shown in the diagram appear and disappear. In contrast to the classical case of uniform heating of the outer pipe, this article deals with a widely used case of an uneven heating of the outer pipe from the inner surface. In this case, irreversible deformations are calculated, and then taken into account, which originated in the pipe material before the moment of landing. A comparison of the distribution of residual stresses obtained during the uniform and non-uniform heating of the outer pipe is given. As a result, the interference with the uniform heating exceeds the interference formed with the non-uniform heating of the pipe.
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Prokopenko, Mykola. "GENERAL ANALYSIS OF STRESS AND DEFORMATION OF PARTS MOVING WITH HIGH VELOCITY IN A LIQUID OR GAS (REVIEW ARTICLE)." Bulletin of the National Technical University «KhPI» Series: Engineering and CAD, no. 2 (December 30, 2021): 71–76. http://dx.doi.org/10.20998/2079-0775.2021.2.10.
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The article provides an analytical review and analysis of stresses and deformations of parts moving at high speeds in a liquid or gas. The working conditions of materials and parts of turbines (blades, rotor and casing) operating at high temperatures and loads are analyzed. The main ways of solving the problem of ensuring the strength of such parts are presented. The main ways to solve the problem of reliability of parts or the product as a whole are given: mathematical modeling (calculated determination of strength, durability and reliability); physical modeling (model testing); testing of full-scale products in reproducible real or operational conditions.It is impossible to speak about the strength of a part only from the calculation of deformations and stresses, even taking into account their change over time, so it is necessary to have strength criteria that establish the relationship between the strength parameters. It is emphasized that in the general case, the criterion of strength should answer the question: will the part collapse or not with the known laws of change in time of stresses, strains and temperatures It is shown that the considered standard characteristics of creep and long-term strength can be directly used in calculations only for those parts in which the uniaxial stress state at constant stresses and temperature is realized, when the working conditions of the material fully meet the test conditions of materials.An analytical view of deformation diagrams is considered as the main means of carrying out practical calculations of material strength. It is shown that in order to determine the stresses and strains in parts that move at high speeds in a liquid or gas, it is necessary to take into account the model of parts exploitation, the processes of creep and thermal fatigue of the material, and the unsteadiness of load processes. Keywords: stresses and deformations of turbine parts; deformation diagram; operating model of turbine parts; creep and thermal fatigue; nonstationarity of loading processes
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Karmarkar, Aditya P., Xiaopeng Xu, and Karim El-Sayed. "Temperature and Process Dependent Material Characterization and Multiscale Stress Evolution Analysis for Performance and Reliability Management under Chip Package Interaction." International Symposium on Microelectronics 2017, no. 1 (October 1, 2017): 000013–24. http://dx.doi.org/10.4071/isom-2017-tp13_051.
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Abstract Distinct temperature and process dependent deformation behaviors under packaging temperature cycles are characterized for various packaging materials. Substrate and underfill deformations are described using Maxwell viscoelasticity model. Solder bump deformation is represented by incremental plasticity model. Anisotropic deformation in silicon and orthotropic deformation in substrate are also considered. The material deformation effects on stress evolutions during fabrication and under chip package interaction (CPI) are analyzed for a large package structure. Complex geometries spread over a large range of length scales are simulated using multi-level and multiscale sequential submodeling technique. Global package simulations show that substrate orthotropy has a significant impact on the package warpage during the assembly process. Sequential package assembly simulations are performed to examine the residual stresses at package, bump and interconnect scales. The results show that the package material behaviors during the assembly process affect not only the residual stresses in the large package structure but also in the local bump regions and the interconnect structures. The temperature dependent material non-linear behaviors under operating conditions also affect residual stresses and carrier mobility. This work demonstrates that developing performance and reliability management strategies under CPI should consider temperature and process dependent material deformations during fabrication and packaging.
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Medved, Ivan, Volodymyr Kovregin, Oksana Myrgorod, and Andrii Lysenko. "Planning an Experiment for Low-Cycle Fatigue under Conditions Deep Cooling." Materials Science Forum 1038 (July 13, 2021): 9–14. http://dx.doi.org/10.4028/www.scientific.net/msf.1038.9.
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In the elements of structures with a limited resource during operation, significant cyclic stresses can occur, reaching and exceeding the yield strength; the results of an experimental study of the effect of the magnitude of preliminary plastic deformations on the strength and durability of structural alloys under low-cycle loading can be of undoubted interest for practice. The use of experimental planning methods in the study of the influence of the maximum cycle stresses and the magnitude of the preliminary permanent deformation on the low-cycle fatigue of 03Kh13AG19 chromium-manganese steel at T = 4.2 K under pulsating tension showed that these methods can be successfully used.
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Eryshev, V. A. "Methodology of studying the mechanical properties of composite materials (reinforced concrete)." Industrial laboratory. Diagnostics of materials 84, no. 12 (December 20, 2018): 61–67. http://dx.doi.org/10.26896/1028-6861-2018-84-12-61-67.
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The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.
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Sigaeva, Taisiya, Gerhard Sommer, Gerhard A. Holzapfel, and Elena S. Di Martino. "Anisotropic residual stresses in arteries." Journal of The Royal Society Interface 16, no. 151 (February 2019): 20190029. http://dx.doi.org/10.1098/rsif.2019.0029.
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The paper provides a deepened insight into the role of anisotropy in the analysis of residual stresses in arteries. Residual deformations are modelled following Holzapfel and Ogden (Holzapfel and Ogden 2010, J. R. Soc. Interface 7 , 787–799. ( doi:10.1098/rsif.2009.0357 )), which is based on extensive experimental data on human abdominal aortas (Holzapfel et al. 2007, Ann. Biomed. Eng. 35 , 530–545. ( doi:10.1007/s10439-006-9252-z )) and accounts for both circumferential and axial residual deformations of the individual layers of arteries—intima, media and adventitia. Each layer exhibits distinctive nonlinear and anisotropic mechanical behaviour originating from its unique microstructure; therefore, we use the most general form of strain-energy function (Holzapfel et al. 2015, J. R. Soc. Interface 12 , 20150188. ( doi:10.1098/rsif.2015.0188 )) to derive residual stresses for each layer individually. Finally, the systematic experimental data (Niestrawska et al. 2016, J. R. Soc. Interface 13 , 20160620. ( doi:10.1098/rsif.2016.0620 )) on both mechanical and structural properties of the different layers of the human abdominal aorta facilitate our discussion on (i) the importance of anisotropy in modelling residual stresses; (ii) the variability of residual stresses within the same class of tissue, the abdominal aorta; (iii) the limitations of conventional opening angle method to account for complex residual deformations; and (iv) the effect of residual stresses on the loaded configuration of the aorta mimicking in vivo conditions.
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Gadenin, M. M. "Features of the kinetics of cyclic elastoplastic deformation diagrams at dwells in cycles and superimposition of variable stresses on them." Industrial laboratory. Diagnostics of materials 86, no. 12 (December 17, 2020): 46–53. http://dx.doi.org/10.26896/1028-6861-2020-86-12-46-53.
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The goal of the study is determination of the regularities of changes in cyclic strains and related deformation diagrams attributed to the existence of time dwells in the loading modes and imposition of additional variable stresses on them. Analysis of the obtained experimental data on the kinetics of cyclic elastoplastic deformation diagrams and their parameters revealed that in contrast to regular cyclic loading (equal in stresses), additional deformations of static and dynamic creep are developed. The results of the studys are especially relevant for assessing the cyclic strength of unique extremely loaded objects of technology, including nuclear power equipment, units of aviation and space systems, etc. The experiments were carried out on the samples of austenitic stainless steel under low-cycle loading and high temperatures of testing. Static and dynamic creep deformations arising under those loading conditions promote an increase in the range of cyclic plastic strain in each loading cycle and also stimulate an increase in the range of elastoplastic strain due to active cyclic deformation. At the same time the existence of dwells on extrema of stresses in cycles without imposition of additional variable stresses on them most strongly affects the growth of plastic strain ranges in cycles. Imposition of additional variable stresses on dwells also results in the development of creep strains, but their growth turns out to be somewhat less than in the presence of dwells without stresses imposed. The diagrams of cyclic deformation obtained in the experiments are approximated by power dependences, their kinetics being described in terms of the number of loading cycles using corresponding temperature-time functions. At the same time, it is shown that increase in the cyclic plastic deformation for cycles with dwells and imposition of additional variable stresses on them decreases low cycle fatigue life compared to regular loading without dwells at the same stress amplitudes, moreover, the higher the values of static and dynamic creep, the greater decrease in low-cycle fatigue life. This conclusion results from experimental data and analysis of conditions of damage accumulation for the considered forms of the loading cycle using the deformation criterion of reaching the limit state leading to fracture.
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Orgill, G., and J. F. Wilson. "Finite Deformations of Nonlinear, Orthotropic Cylindrical Shells." Journal of Applied Mechanics 53, no. 2 (June 1, 1986): 257–65. http://dx.doi.org/10.1115/1.3171749.
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The nonbuckling finite deformations of an orthotropic, thin wall cylinder are investigated. The cylinder is made of a nonlinear material and subjected to internal pressure, end load and torque. Initially the stresses and strains in the cylinder are assumed to be axially homogeneous. The model is then extended to include axially nonhomogeneous stresses and strains that may arise due to particular displacement boundary conditions such as radial confinement at the edges. The loads are applied to the cylinder incrementally, the finite strains are computed, and adjustments are made in cylinder dimensions and the constitutive law to account for geometric and material nonlinearities. Parametric studies show how the deformation behavior is influenced by the orientation of the angle of material orthotropy. Results may be applied to the design of pressure controlled robotic actuators and manipulators.
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Riccobelli, Davide, and Pasquale Ciarletta. "Shape transitions in a soft incompressible sphere with residual stresses." Mathematics and Mechanics of Solids 23, no. 12 (December 28, 2017): 1507–24. http://dx.doi.org/10.1177/1081286517747669.
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Residual stresses may appear in elastic bodies, owing to the formation of misfits in the microstructure, driven by plastic deformations or thermal or growth processes. They are especially widespread in living matter, resulting from dynamic remodelling processes aimed at optimizing the overall structural response to environmental physical forces. From a mechanical viewpoint, residual stresses are classically modelled through the introduction of a virtual incompatible state that collects the local relaxed states around each material point. In this work, we employ an alternative approach based on a strain energy function that constitutively depends only on the deformation gradient and the residual stress tensor. In particular, our objective is to study the morphological stability of an incompressible sphere, made of a neo-Hookean material, and subjected to given distributions of residual stresses. The boundary value elastic problem is studied with analytic and numerical tools. Firstly, we perform a linear stability analysis on the prestressed solid sphere using the method of incremental deformations. The marginal stability conditions are given as a function of a control parameter, which is the dimensionless variable that represents the characteristic intensity of the residual stresses. Secondly, we perform finite-element simulations using a mixed formulation in order to investigate the postbuckling morphology in the fully nonlinear regime. Considering different initial distributions of the residual stresses, we find that different morphological transitions occur around the material domain, where the hoop residual stress reaches its maximum compressive value. The loss of spherical symmetry is found to be controlled by the mechanical and geometrical properties of the sphere, as well as the spatial distribution of the residual stress. The results provide useful guidelines for designing morphable soft spheres, for example by controlling residual stresses through active deformations. They finally suggest a viable solution for the nondestructive characterization of residual stresses in soft tissues, such as solid tumours.
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Ogarkov, Vyacheslav, Aleksei Aksenov, Sergei Malyukov, and Margarita Malyukova. "CALCULATION OF STRESS-DEFORMED STATE OF ELASTIC CYLINDERS UNDER TEMPERATURE AND HUMIDITY IMPACT." Voronezh Scientific-Technical Bulletin 3, no. 3 (November 11, 2020): 94–112. http://dx.doi.org/10.34220/2311-8873-2020-3-3-94-112.
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The actual scientific and practical problem of plane deformation of an elastic cylinder under conditions of temperature and humidity is considered. Various pipes, shafts, plain bearings, bushings from natural and modified wood, etc. have a cylindrical shape. An exact analytical solution of this problem is given for an isotropic cylinder in the case of stationary temperature and humidity exposure. All formulas for stresses and strains and stresses contain mechanical and thermophysical constants, which corresponds to the physical meaning. It is proved that the use of classical methods for solving this problem through the potentials of stresses and displacements leads to an undesirable result in which stresses or deformations do not depend on the thermophysical constant C_2, which contradicts the physical meaning.
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Li, Lijia, Xingdong Sun, Yue Guo, Dan Zhao, Xiancheng Du, Hongwei Zhao, and Zhichao Ma. "Nanoindentation response of monocrystalline copper under various tensile pre-deformations via molecular dynamic simulations." Advances in Mechanical Engineering 10, no. 12 (December 2018): 168781401881687. http://dx.doi.org/10.1177/1687814018816874.
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The mechanical properties of a material can be positively or negatively affected by its applied or residual stress. In this article, a series of molecular dynamic simulations were adopted to investigate the nanoindentation response of monocrystalline copper under tensile pre-deformation. Nanoindentation simulation under stress-free condition was compared with those under pre-tension strain values of 1.2%, 2.4% and 3.6%. Load–displacement curves with hardness value and recovery rates of total work for nanoindentation based on various tensile pre-deformations were obtained and discussed. It indicated that tensile pre-deformations resulted in a higher potential energy in substrate and a lower external energy will be introduced to realize the same elastic or plastic deformation during indentation. Moreover, the evolution of interior defects during indentation was also observed and analysed. The results showed that tensile pre-strain can influence dislocation nucleation behaviour of material during indentation. This article proposed a special molecular dynamic simulation method to characterize the mechanical properties of the material under tensile pre-deformations via nanoindentation, which gives an effective approach to characterize residual stresses in micro- and nanoscale and will have promising application in mechanical characterization of Microelectro Mechanical Systems devices and structures. Further analysis based on experiments will be done in our further research work.
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Ogarkov, Vyacheslav, Aleksei Aksenov, and Sergei Malyukov. "POLAR-SYMMETRIC DEFORMATION OF AN ELASTIC CYLINDER UNDER TEMPERATURE-HUMIDITY EXPOSURE." Voronezh Scientific-Technical Bulletin 3, no. 3 (November 11, 2020): 81–93. http://dx.doi.org/10.34220/2311-8873-2020-3-3-81-93.
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The actual scientific and technical problem of polar-symmetric deformation of an elastic cylinder under conditions of temperature and humidity influences is considered. An exact analytical solution to this problem is obtained with the determination of unambiguous expressions for stresses, deformations and radial displacement. The obtained solution allows solving this problem for an incompressible material with μ = 1/2 as a special case.
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Jia, Fan Xin, De Wei Chen, and Yang Yang Wu. "Fine-Analysis for the Concrete Upper Rotation Table and Pier of a Bridge Using Rotation Construction Method." Applied Mechanics and Materials 638-640 (September 2014): 1099–102. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1099.
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This paper focuses mainly on the case of a three-span prestressed concrete continuous girder bridge. A solid element model of the concrete upper rotation table and pier was established adopting the Midas/Civil Software, considering four unfavorable conditions including eccentric load effects. Then a strict inspection was given on the stresses and deformations of the model in each condition to check the safety of the structures during both processes of girder casting and bridge rotation. The results are positive and satisfactory.
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Avhad, Pravin V., and Atteshamuddin S. Sayyad. "On the deformation of laminated composite and sandwich curved beams." Curved and Layered Structures 9, no. 1 (October 18, 2021): 1–12. http://dx.doi.org/10.1515/cls-2022-0001.
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Abstract Plenty of research articles are available on the static deformation analysis of laminated straight beams using refined shear deformation theories. However, research on the deformation of laminated curved beams with simply supported boundary conditions is limited and needs more attention nowadays. With this objective, the present study deals with the static analysis of laminated composite and sandwich beams curved in elevation using a new quasi-3D polynomial type beam theory. The theory considers the effects of both transverse shear and normal strains, i.e. thickness stretching effects. In the present theory, axial displacement has expanded up to the fifth-order polynomial in terms of thickness coordinates to effectively account for the effects of curvature and deformations. The present theory satisfies the zero traction boundary condition on the top and bottom surfaces of the beam. Governing differential equations and associated boundary conditions are established by using the Principal of virtual work. Navier’s solution technique is used to obtain displacements and stresses for simply supported beams curved in elevation and subjected to uniformly distributed load. The present results can be benefited to the upcoming researchers.
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SELYAEV, V. P., P. V. SELYAEV, S. YU GRYAZNOV, and D. R. BABUSHKINA. "VERIFICATION OF DEPENDENCES APPROXIMATING THE DIAGRAMS OF DEFORMATION OF CEMENT AND POLYMER CONCRETE BY THE METHOD OF NORMALIZED INDICATORS." Building and reconstruction 93, no. 1 (2021): 125–33. http://dx.doi.org/10.33979/2073-7416-2021-93-1-125-133.
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The article verifies some approximating power-law and hyperbolic dependences between stresses σ and deformations ε for experimental deformation diagrams of cement concrete and polymer concrete. When analyzing the state and residual life of reinforced concrete structures, one has to solve the problem of determining the relationship between stresses and deformations in various design sections of structures. The traditional approach, based on the selection of the approximating function "σ – ε" from the numerical values of the deformation diagram obtained by testing samples (cubes, prisms, cylinders), is practically impossible. Therefore, an alternative approach is proposed based on the selection of an approximating function according to standardized indicators: ultimate strength (σ_bu); modulus of elasticity (E_b0); ultimate deformation (ε_bu). The numerical values of the normalized indicators can be determined at a given point by analyzing the results of indentation of the indenter into the material of structures. As approximating ones, consider the power functions that are most preferable for materials with a fractal structure. Various boundary conditions are considered for determining the constant coefficients α and β according to the system of normalized indicators. The graphs of changes in tangent modules are analyzed.
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Gainanov, Sharibzan Kh. "Tectonic stresses impact on rock mass structure and properties." Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal 1, no. 3 (May 14, 2021): 71–78. http://dx.doi.org/10.21440/0536-1028-2021-3-71-78.
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Introduction. By the example of the local structures formed by the rock of terrigenous red bed, the present work illustrates the impact made by tectonic fracturing on their properties development. Rock microstructure and strength changes were the results of tectonic stresses during the rock mass formation. The detected zones of increased fracturing are clearly correlated with both the indices of crystal lattice deformation and rock strength properties. Research aim is to assess the impact made by the local structures formation on rock properties and the development of various tectonic stresses. The methodology included rock sampling, fracture survey within the local structure, condition of the mineralogical composition of the samples, determination of the samples strength by uniaxial compression, the rock-forming mineral crystal lattice study using X-ray diffraction analysis, and subsequent analysis and comparison of the obtained materials. Results. A study area fracturing map was compiled and the information on the crystal lattice structure and rock strength was obtained. Correlation between crystal lattice deformations, strength properties of selected samples, and rock fracturing in the rock mass under study was performed. Conclusions. The presented research results explain a wide range of values of strength properties by crystals microstructure imperfection, which, in turn, is closely related to the rock mass destruction.
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Eryshev, Valeriy A. "The Concrete Diagrams Integral Parameters in the Calculations of Reinforced Concrete Elements by Limiting States." Materials Science Forum 974 (December 2019): 698–703. http://dx.doi.org/10.4028/www.scientific.net/msf.974.698.
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The paper proposes a method for calculating the reinforced concrete elements strength according to the deformation model using the deformation diagrams of concrete and reinforcing steel materials, which eliminates the complicated procedure of numerical integration of stresses in the element section during the transition to generalized internal forces. Integral parameters of diagrams are introduced into the energy model for calculating the strength of reinforced concrete elements along with the deformations and stresses normalized values at the base diagrams’ points. The integral parameters are calculated for the element cross section, the strain at the stress diagram gravity center in the compressed concrete zone and the coordinates of force in the concrete and reinforcement are relative to the neutral axis from the condition of the stress profile shape compliance in the element compressed zone, and the concrete diagram is used in the calculations. The integral parameters calculated dependences for the compressive strength concrete classes. The recommendations on the concrete diagrams integral parameters values rationing and their use in the complex sections and statically indeterminable systems calculations are given.
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Lazăr, Ştefan Marian, and Elena Diaconu. "Influence of the interface conditions on flexible pavement structures life." Romanian Journal of Transport Infrastructure 5, no. 1 (July 1, 2016): 30–37. http://dx.doi.org/10.1515/rjti-2016-0040.
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Abstract This paper aims to establish the interface conditions influence on the flexible pavement structures life. The methodology consists in using the interface constitutive model available in the Alizé calculation program to calculate the stresses and strains in the flexible pavement structures. The design criteria related to limiting fatigue cracking of asphalt layers and permanent deformations at the subgrade level from the road bed are used to estimate the flexible pavement structures lifetime. When calculating the critical stresses and strains, most mechanical design methods of the flexible pavement structures considers that the road layers at interfaces are perfect bonded or total unbonded. Proper modeling of the interface binding condition is an important aspect in understanding the real behaviour of in-service flexible pavement structures.
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Yaguchi, Masatsugu, Masato Yamamoto, Takashi Ogata, and Nobutada Ohno. "An Anisotropic Constitutive Model for a Directionally Solidified Superalloy." Key Engineering Materials 340-341 (June 2007): 901–6. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.901.
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The monotonic tensile and creep deformations of a directionally solidified (DS) superalloy are investigated for several loading directions. The material exhibits remarkable anisotropy under elastic and creep loading conditions, whereas it shows isotropy under loading conditions of high strain rates. Tension-torsion creep tests are also conducted to investigate the deformation under multiaxial stress conditions. Referring to the observed behavior, a unified constitutive model, which has two features, is developed for the DS superalloy. One is a static recovery term of back stresses that is prescribed as a transversely isotropic property, which is supposed to have an effect on the deformation behavior under creep loading conditions. The other is the division of inelastic strain into two components, which represent octahedral and cubic slip system deformations, so as to describe multiaxial creep deformation. Calculation results obtained using the constitutive model are compared with the uniaxial and multiaxial experimental results to evaluate the validity of the model.
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Balek, Alexander, and Anatoly Sashourin. "In-situ rock mass stress-state measurements in scales of mineral deposits: problem-solving." E3S Web of Conferences 56 (2018): 02004. http://dx.doi.org/10.1051/e3sconf/20185602004.
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This paper describes the new method for in-situ measurements of the most large-scale stress fields that are comparable to dimensions of deposits and mining leases. The method considers open cast mines and collapse zones of underground mining as disturbing cavities. The calculation of stresses is carried out thru measured deformations for the conditions of plane stressed state from the measured displacements of survey marks on the earth surface. GPS or GLONASS technology is used for the measuring. The results of in-situ study deformations of pit edges Pipe Udachnaya Mine (Sakha Republic, Russia) have been presented as an example of practical application of the method.
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Kuzmych, L. "Synthesis of Measurement Method of Stressed — Deformed Condition of Complex Structures." Metrology and instruments, no. 3 (July 3, 2019): 12–18. http://dx.doi.org/10.33955/2307-2180(3)2019.12-18.
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Nowadays the most common instruments of measuring the stress-strain state of complex structures are strain gauges. As a rule, strain gages are connected to the measuring system according to the bridge scheme, it provides elimination of systematic errors of measurement and compensation of temperature deformations. The principles of constructing, designing and mathematical modeling of deformation and stresses of complex technical constructions with the help of strain gauges taking into account destabilizing factors are developed, which allows to significantly reduce the level of errors in relation to existing methods of measurement and known analogues.
The analysis of the main destabilizing factors that limit the accuracy of measurement using strain gauge is carried out, are (Fig. 1—4):
the random processes (noises, obstacles, etc.);
the time changes of parameters of measuring transducers due to aging and physical degradation;
the influence of external climatic and mechanical factors (temperature, humidity, etc.).
The temperature error values are set for the most common alloys used for the manufacture of strain gauges, namely: constantan and karma.
This work is aimed at finding ways to improve the accuracy of remote measurements and impedance of measuring devices of the stress — strain state, in particular strain gauges and strain gauges, by introducing improved theoretical calculations taking into account destabilizing factors, which makes it possible to reduce the level of errors with respect to known analogs in dozens of times.
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Belyaev, A. K., V. A. Polyanskiy, and D. A. Tretyakov. "Estimating of mechanical stresses, plastic deformations and damage by means of acoustic anisotropy." PNRPU Mechanics Bulletin, no. 4 (December 15, 2020): 130–51. http://dx.doi.org/10.15593/perm.mech/2020.4.12.
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Acoustic anisotropy is a consequence of anisotropy of the mechanical characteristics of a solid. In metals, it is associated with microstructural anisotropy of mechanical characteristics, internal mechanical stresses and strains, including residual stresses and plastic deformations. Sensors measuring acoustic anisotropy do not require complex preparations of a metal surface, therefore it is easy to measure which makes it possible for measurement results to be used to quantify stresses and strains in metals based on the magnitude of phase shifts of the shear wave velocities of the orthogonal polarization. Acoustic anisotropy is one of the manifestations of the phenomenon of changes in the elastic properties of an acoustic medium caused by mechanical stresses and deformation (acoustoelastic effect). This makes it possible to use the effect of acoustic anisotropy for the development of quantitative methods of acoustic tensometric measurements, as well as methods of non-destructive testing, which enables effective quality controls and diagnostics of the residual life of structures and machine parts. The article describes the history of the discovery and theoretical substantiation of the acoustoelastic effect and the quantitative relationship of acoustic anisotropy with stresses and deformations, starting with the pioneering works of the twentieth century. The way of forming the theory based on nonlinear mechanics of continuous media is shown. The third part of the article is concerned with an overview of the current state of research. An analysis is presented of experimental works on the measurement of acoustic anisotropy in low- and high-carbon steels, aluminum alloys, as well as in composites and other structural materials. Special attention is paid to a review of studies on the relationship between acoustic anisotropy and plastic deformations and the applicability limitations of the acoustic method. It also provides a list of the main applied results related to the measurement and use of acoustic anisotropy to control the blades of compressors and gas turbine engines, pipe steels, welded joints, etc. A review is given of the main publications on system analysis and generalization of theoretical and experimental scientific results obtained by domestic and foreign researchers in the field of studying the acoustic anisotropy of metallic structural materials under conditions of uniaxial and complex stress states, plastic deformation, thermomechanical loading and fatigue fracture is given.
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Bout, D. K., P. S. Bychkov, and S. A. Lychev. "The Theoretical and experimental study of the bending of a thin substrate during electrolytic deposition." PNRPU Mechanics Bulletin, no. 1 (December 15, 2020): 17–31. http://dx.doi.org/10.15593/perm.mech/2020.1.02.
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The present paper is aimed at the theoretical and experimental study of the shape distortion of thin substrates during electrolytic deposition and gaccumulation of residual stresses in them. The theoretical modeling is provided in the framework of the theory of solids with variable material composition. The result of the deposition process is modeled with a continuous family of elastic bodies, which local deformations are incompatible. These deformations act as internal sources for stresses. Formally they are equivalent to the field of distributed defects. Unlike the classical approach adopted in nonlinear elasticity, the elements of the family which present a body with a variable material composition don’t have a global reference natural (free of stresses) form. Instead we used the continuous family being only locally free from stresses. To formulate the boundary value problem, continuous families of reference, intermediate and actual forms and corresponding families of deformations are defined. The deformations, belonging to these families, locally represent implants (local deformations of reference forms into intermediate ones) and deformations that bring intermediate forms into actual ones. Relations for stresses and strains in such bodies are obtained under the assumption that the displacement gradients are small with respect to unity and satisfy the kinematic hypothesis of the technical plate theory. Under these assumptions the equilibrium equations are derived. They include specific terms which determine formal loading that is caused by incompatible deformations. Axisymmetric problems for a circular substrate under various types of fixing and tension on the boundary, which characterize the conditions of the experiment, are obtained. The theoretical distribution for displacements of the substrate surface is formulated upon the obtained solution. They are intended to identify incompatible deformations that cause bending during the deposition process. The experimental measuring setup is constructed according to a holographic scheme of displacement measurements in real time. The deposition process is carried out in a cylindrical chamber with flange fastening of the cathode. The electrochemical process is implemented in sulphate electrolyte. As a result of comparing the theoretically obtained relations for bending surfaces of the substrate with the experimental results, the parameters that characterize the substrate shrinkage and tension are estimated.
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Reznik, V. S., O. V. Ushakov, and O. Y. Gorun. "On the problem of calculating shear deformations in prismatic bars made of polymer materials under tension with torsion." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 3 (2021): 115–18. http://dx.doi.org/10.17721/1812-5409.2021/3.22.
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The process of creep of prismatic rods made of linear-viscoelastic polymeric materials under combined loading is considered. Defining equations that determine the relationship between strains, stresses and time are given in the form of a superposition of shear and bulk strain. The object of study is prismatic bars made of fiberglass ST-1. The area of linearity of the model is substantiated on the basis of the hypothesis of the existence of the creep function, which is built on the yield curves, a single diagram of long-term deformation and the statistical value of the quantile of statistics. The region of linear-elastic deformation is recognized based on the fulfillment of the condition of existence of a single creep function. The defining equations of the model contain a set of functions and coefficients determined from the basic experiments. On the basis of the relations between the kernels of the one-dimensional stress state, the parameters of the kernels under the condition of a complex stress state are determined. The linearity of viscoelastic properties is given by the Boltzmann-Voltaire equations. The fractional-exponential kernels of heredity are chosen as the kernels of heredity. The obtained values of the core parameters are used to calculate the creep deformations of prismatic bars made of ST-1 fiberglass under conditions of simultaneous tensile tension.
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Peyre, Patrice, Neila Hfaiedh, Hongbin Song, Vincent Ji, Vincent Vignal, Wilfrid Seiler, and Stephane Branly. "Laser shock processing with two different laser sources on 2050‐T8 aluminum alloy." International Journal of Structural Integrity 2, no. 1 (March 8, 2011): 87–100. http://dx.doi.org/10.1108/17579861111108644.
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PurposeThe purpose of this paper is to conduct a comparative study of the surface modifications induced by two different lasers on a 2050‐T8 aluminum alloy, with a specific consideration of residual stress and work‐hardening levels.Design/methodology/approachTwo lasers have been used for Laser shock peening (LSP) treatment in water‐confined regime: a Continuum Powerlite Plus laser, operating at 0.532 mm with 9 ns laser pulses, and near 1.5mm spot diameters; a new generation Gaia‐R Thales laser delivering 10 J‐10 ns impacts, with 4‐6mm homogeneous laser spots at 1.06 mm. Surface deformation, work‐hardening levels and residual stresses were analyzed for both LSP conditions. Residual stresses were compared with numerical simulations using a 3D finite element (FE) model, starting with the validation of surface deformations induced by a single laser impact.FindingsSimilar surface deformations and work‐hardening levels, but relatively lower residual stresses were obtained with the new large 4‐6 mm impact configuration. This was attributed to a reduced number of local cyclic loadings (2) compared with the small impact configuration (4). Additionally, more anisotropic stresses were obtained with small impacts. FE simulations using Johnson‐Cook's material' behavior were shown to simulate accurately surface deformations, but to overestimate maximum stress levels.Research limitations/implicationsThis work should provide LSP workers a better understanding of the possible benefits from the different LSP configurations currently co‐existing: using small (<2 mm) impacts at high‐cadency rates or large ones (>4‐5 mm). Moreover, experimental results and simulated data had never been presented on 2050‐T8 Al alloy.Originality/valueAn experimental (and numerical) comparison using two distinct laser sources for LSP, has never been presented before. This preliminary work should help LSP workers to choose adequate sources.
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Huang, Xinbo, Long Zhao, Ziliang Chen, and Cheng Liu. "An online monitoring technology of tower foundation deformation of transmission lines." Structural Health Monitoring 18, no. 3 (May 29, 2018): 949–62. http://dx.doi.org/10.1177/1475921718774578.
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In this article, an online monitoring technology applied to transmission line towers is proposed to overcome the problems that the foundation deformation is difficult to find in the mining area, river, hillside, and other special areas. The measurement of the stress or the strain caused by the tower foundation deformation are rarely issued, though the tower status can be possibly assessed by the stress or the strain. A new online monitoring technology of tower foundation deformation of transmission lines is developed which consists of three parts. In the first part, the stress or the strain of the key elements is effectively analyzed under the different deformations such as foundation settlement, inclination, and side-slip with the tower finite element model built and the wind load and ice load applied on the tower. In the second part, the experimental platform of tower stress tests is set up, and the internal relations between the stress variation and the tower foundation deformation are determined. In the third part, the online monitoring technology of tower foundation deformation of transmission lines is developed based on fiber Bragg grating stress sensor and successfully applied in Jibei power grid in China. The results show that all the monitored stresses fluctuating with the wind speed are small in case that the condition of tower foundation is normal; on the contrary, the corresponding stresses will change greatly.
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Kahraman, Ahmet, and Sandeep Vijayakar. "Effect of Internal Gear Flexibility on the Quasi-Static Behavior of a Planetary Gear Set." Journal of Mechanical Design 123, no. 3 (May 1, 2000): 408–15. http://dx.doi.org/10.1115/1.1371477.
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Effect of flexibility of an internal gear on the quasi-static behavior of a planetary gear set is investigated. A state-of-the-art finite elements/semi-analytical nonlinear contact mechanics formulation is employed to model a typical automotive automatic transmission planetary unit. The model considers each gear as deformable bodies and meshes them to predict loads, stresses and deformations of the gears. Actual support and spline conditions are included in the model. The rim thickness of the internal gear is varied relative to the tooth height and gear deflections and bending stresses are quantified as a function of rim thickness. Influence of rim thickness on the load sharing amongst the planets is also investigated with and without floating sun gear condition. The results are discussed in detail and guidelines regarding the design of a planetary internal gear are presented.
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Zavalis, Robertas, and Bronius Jonaitis. "THE ANALYSIS OF STRESS DEFORMATION STATE PECULIARITIES OF MASONRY UNITS AND BED JOINTS." Engineering Structures and Technologies 3, no. 3 (September 30, 2011): 105–11. http://dx.doi.org/10.3846/skt.2011.12.
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In this paper, the analysis of various effects that have influence to the mechanical properties of masonry is made. Masonry is nonhomogeneous and anisotropic material composed of two materials with different stiffness properties. In order to analyze masonry deformations it is necessary to evaluate all effects that have influence to masonry mechanical properties (Table 1). The analysis of stress-strain state of masonry is presented in this paper. During the analysis of stressstrain state, the mechanical properties of masonry units and mortar were defined from experimental investigation of samples of unit and mortar materials. The following conclusions were reached based on the analysis of experimental data: 1) The deformations and stresses along the height of masonry unit distributes unevenly. The stresses and deformations near the bed joint are higher than in the middle of the unit (4 pav). 2) From experimental data it was determined that the deformation of bed joints mostly depend on contact zone between units and mortar. The contact zone deformation contains about 80…90% of all bed joint deformation. 3) The elastic modulus of mortar inside the composite is different from modulus of mortar specimens cast separately due to different laying and curing conditions. The elastic modulus values performed from composite were 15…25 times less than the values from standard mortar prisms (EN 1015-11). It is advisable to use real (defined from experiments) masonry units and mortar properties when detailed, numerical stress-strain analysis is performed. 4) Experimental analysis showed that bed joints have big influence to vertical deformation of masonry in axial compression. Masonry units have influence to mechanical properties of mortar joints. The experiment was carried out, during which dry and wet masonry units were used. Units were wet out to eliminate there absorption characteristics. Extra wet out units had an effect to the stiffness of bed joints (12 pav).
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Chepak-Gizbrekht, Marija V., and Anna G. Knyazeva. "Diffusion and Mechanical Stresses in a Material with Two-Component Coating at External Heating." Applied Mechanics and Materials 756 (April 2015): 105–10. http://dx.doi.org/10.4028/www.scientific.net/amm.756.105.
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Multilayer materials and materials with coatings are widely used in various applications. In studies of properties of new materials are run into poorly explored occurrences quite often. In such occurrences are among thermal diffusion (Soret effect) in solid materials. At this paper presented the model of formation of diffusion zone between two-component coating and base at the condition of heat flux action. Model completed of mechanical equilibrium problem. It was formulated the analytical solution of problem, which are applicable for concentration redistribution calculations and also for stresses and deformations in diffusion zone.
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Zahalak, G. I., V. de Laborderie, and J. M. Guccione. "The Effects of Cross-Fiber Deformation on Axial Fiber Stress in Myocardium." Journal of Biomechanical Engineering 121, no. 4 (August 1, 1999): 376–85. http://dx.doi.org/10.1115/1.2798334.
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We incorporated a three-dimensional generalization of the Huxley cross-bridge theory in a finite element model of ventricular mechanics to examine the effect of nonaxial deformations on active stress in myocardium. According to this new theory, which assumes that macroscopic tissue deformations are transmitted to the myofilament lattice, lateral myofilament spacing affects the axial fiber stress. We calculated stresses and deformations at end-systole under the assumption of strictly isometric conditions. Our results suggest that at the end of ejection, nonaxial deformations may significantly reduce active axial fiber stress in the inner half of the wall of the normal left ventricle (18–35 percent at endocardium, depending on location with respect to apex and base). Moreover, this effect is greater in the case of a compliant ischemic region produced by occlusion of the left anterior descending or circumflex coronary artery (26–54 percent at endocardium). On the other hand, stiffening of the remote and ischemic regions (in the case of a two-week-old infarct) lessens the effect of nonaxial deformation on active stress at all locations (9–32 percent endocardial reductions). These calculated effects are sufficiently large to suggest that the influence of nonaxial deformation on active fiber stress may be important, and should be considered in future studies of cardiac mechanics.