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1
Guz’, A. N., S. Yu Babich, and V. B. Rudnitsky. "Contact Problems for Elastic Bodies With Initial Stresses: Focus on Ukrainian Research." Applied Mechanics Reviews 51, no. 5 (May 1, 1998): 343–71. http://dx.doi.org/10.1115/1.3099009.
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In the present review article general results concerning problems of contact interaction (contact problems) of pre-stressed bodies with rigid, and elastic punches (facings) are presented. The modern classification of investigations on contact problems for bodies with initial stresses is based on two approaches. The first approach is applicable to bodies with a specific type of elastic potential. The second approach is developed in parallel with the first one. It describes investigations on contact problems for pre-stressed bodies with an arbitrary structure of an elastic potential in a general form for compressible and incompressible materials. In the last case, investigations were carried out in a common form for the theory of large (finite) initial strains and various variants of the theory of small initial strains. The formulation of the problems is given, and methods of solving planar and spatial contact problems for bodies with initial stresses are developed. Procedures of the theory of complex variables and methods of Riemann-Hilbert are used. For planar problems, the authors introduce planar potentials of the linearized static and dynamic problems for elastic compressible and incompressible bodies with initial stresses. In the case of spatial contact problems, various procedures are used: general solutions of spatial static problems for elastic bodies with initial stresses, methods of harmonic potential theory, integral transformations, and integral equations using numerical methods of investigation. The essential numerical results in the form of graphs and tables are presented. These give the quantitative and qualitative analysis of the influence of initial stresses on the main characteristics of contact problems. This review contains 98 references.
2
Xiaoyu, Jiang. "3-D Vibration Analysis of Fiber Reinforced Composite Laminated Cylindrical Shells." Journal of Vibration and Acoustics 119, no. 1 (January 1, 1997): 46–51. http://dx.doi.org/10.1115/1.2889686.
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In this paper, 3-D solutions of free vibrations are presented for isotropic and composite laminated cylindrical shells. The perturbation method and a variational principle are used to obtain the solutions which satisfy the 3-D differential equations of motion, the strain-displacement relations, the stress-strain relations, the boundary conditions and the continuity conditions at layer interfaces. The distributions of displacements and stresses in the shells are shown in figures. The free vibration frequencies are listed in tables. In the thickness direction of the shells, continuous displacements and stresses are obtained. And the importance of transverse shear stresses and transverse normal stress is analyzed.
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Kaczmarczyk, Jarosław, and Adam Grajcar. "Numerical Simulation and Experimental Investigation of Cold-Rolled Steel Cutting." Materials 11, no. 7 (July 23, 2018): 1263. http://dx.doi.org/10.3390/ma11071263.
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The paper presents results of the investigations on numerical computations and experimental verification concerning the influence of selected parameters of the cutting process on the stress state in bundles of cold-rolled steel sheets being cut using a guillotine. The physical model and, corresponding to it, the mathematical model of the analysed steel sheet being cut were elaborated. In this work, the relationship between the cutting depth and the values of reduced Huber–Mises stresses as well as the mechanism of sheet separation were presented. The numerical simulations were conducted by means of the finite element method and the computer system LS-DYNA. The results of numerical computations are juxtaposed as graphs, tables, and contour maps of sheet deformation as well as reduced Huber–Mises strains and stresses for selected time instants. The microscopic tests revealed two distinct zones in the fracture areas. The ductile and brittle zones are separated at the depth of ca. 1/3 thickness of the cut steel sheet.
4
Eryshev, Valeriy A. "Relation between Breaking Stresses in the Strength Calculations of Reinforced Concrete Elements under the Deformation Mode in the Edition of Russian and Foreign Regulatory Documents." Materials Science Forum 974 (December 2019): 653–58. http://dx.doi.org/10.4028/www.scientific.net/msf.974.653.
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Сorrespondence was established between the compressive strength grades of concrete numerically equal to the guaranteed compressive strength of a standard concrete cube and a standard concrete cylinder. Designated concrete resistances are assigned for the limiting states of the first group with a compressive strength grade of concrete. For the corresponding concrete grades, the reduction to unambiguous strains values at the base diagrams points is justified: at the top and at the end of the falling branch of the curvilinear diagrams. In accordance with the regulatory requirements, restrictions are imposed on the stress levels at the end of the falling diagrams branch at the maximum normalized strains values. Mathematical models establishing a uniform format for calculating single-valued strains values at base points of concrete diagrams have been developed taking into account accepted functional relations and the their assignment rules using the requirements documents tables. It is shown that with equal strains values and stresses at base points, analytical expressions describing diagrams recommended by requirement documents, different in their structure, give their identical outlines, the diagrams branches are the same. Relation between design models in the edition of Russian and foreign regulatory documents is correlated by the comparison of integral diagrams parameters and breaking stresses obtained with the calculation of reinforced concrete element under the deformation mode. As integral parameters of concrete deformation diagrams, it is recommended to use the areas bounded by diagrams branches and diagrams fineness coefficient. The diagram area for given values of the element curvature is equivalent to the magnitude of the breaking stress in the compressed concrete zone in the bent and compressed elements, and the stress diagram in outline corresponds to this diagram.
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Banović, Ivan, Jure Radnić, and Nikola Grgić. "Shake Table Study on the Efficiency of Seismic Base Isolation Using Natural Stone Pebbles." Advances in Materials Science and Engineering 2018 (December 20, 2018): 1–20. http://dx.doi.org/10.1155/2018/1012527.
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The results of a shake table study of the efficiency of a seismic base isolation using a layer of natural stone pebbles are presented. Models of stiff and medium-stiff buildings were tested. Case studies were conducted with the foundation of model on the rigid base and on four different layers of pebbles (thin and thick layer with small and large pebbles). Four different horizontal accelerograms were applied, and the characteristic displacements, accelerations, and strains were measured. Strains/stresses of the tested models remained in the elastic area. It was concluded that the effectiveness of the stone pebble layer under the foundation, i.e., the reduction in the seismic forces and stresses in the structure compared to the classical solution of foundation, significantly depends on the type of the applied excitation and depends relatively little on the layer thickness and pebble fraction. The results of the study showed that a layer of pebbles can significantly reduce the peak acceleration and strains/stresses of the model, with acceptable displacements. Further research is expected to confirm the effectiveness of this low-cost and low-tech seismic base isolation and to pave the way to its practical application.
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Parfenov, S. G., and V. Ye Moschenkov. "EXPERIMENTAL STUDY OF CREEP AND SHRINKAGE STRAINS IN FINE- AGGREGATE CONCRETES." Proceedings of the Southwest State University 21, no. 4 (August 28, 2017): 13–20. http://dx.doi.org/10.21869/2223-1560-2017-21-4-13-20.
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The paper studies creep and shrinkage processes running in fine-aggregate concretes with plasto-elastic properties (deformations) under short-time loading are different from those of standard heavy concretes. Experimental studies of creep and shrinkage strains in fine-aggregate concretes that are based on sands with different fineness moduluses permit to compare prestress losses resulting from the creep and shrinkage of concrete. Usually these factors produce an aggregate effect, which makes the study of the processes that run in concrete under long-time influence noticeably complicated. There paper contains analysis results obtained by experimental studies of concrete prisms at different initial strains in the range of , with loading age of t= 14 or 28 days and different properties of concrete mixes. Concrete mix properties were modified by using sands with different fineness modulus. Likewise in order to determine creep and shrinkage deformations due to long-time loads the samples were tested under stress during 14, 73 and 180 days. All experimental data have been systematized in tables and are represented by diagrams. The analysis has helped to investigate the effects of relative stains on the creep deformation in concrete and to define the boundary line between linear and non-linear creep with relation to the stresses in concrete. Analytical description of non-linear deformations was performed with the help of N.H.Arutyunyan’ and I.I.Ulitsky methods. The resultant calculations formed a basis for the recommendations to simplify problem solving methods considering non-linear creep of concrete.
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Varlamov, Andrew, Vladimir Rimshin, and Sergey Tverskoi. "A method for assessing the stress-strain state of reinforced concrete structures." E3S Web of Conferences 91 (2019): 02046. http://dx.doi.org/10.1051/e3sconf/20199102046.
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The article analyses the modern methods of estimation of stress-strain state of reinforced concrete structures. The result of the analysis is a new method for estimating the stress-strain state of reinforced concrete structures. The method is based on extracting a small sample of concrete from the array. The article describes the method of execution of works, the method of calculating the stresses. Previously, the method was investigated under laboratory conditions. The results are presented in graphs and tables. The research was conducted to assess the stress state of existing concrete structures. As the objects of research, two industrial buildings of 1933 and 1941 construction years were taken. An assessment of a stress state of a panel residential building was held. The measurement results were analyzed. The method for determining the stresses in reinforced concrete buildings and structures is recommended.
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Kolchunov, Vladimir I., Aleksej I. Demyanov, and Nikolay V. Naumov. "Theory of “dissolution” and “condensation” of the physical geometric characteristics of an arbitrary cross-section under the action of torsion with bending." Structural Mechanics of Engineering Constructions and Buildings 15, no. 4 (December 15, 2019): 261–70. http://dx.doi.org/10.22363/1815-5235-2019-15-4-261-270.
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Aim of research - to continue the development of methods for determining the stress-strain state of rods during torsion using materials resistance methods. Methods. A new approach for determining tangential torsional stresses for arbitrary cross sectional rods, based on simplified assumptions of material resistance, is proposed. The main feature of this approach is the approximation of rectangular or any complex cross section of reinforced concrete structures by describing a large circle around the cross section and splitting it into small squares with circles inscribed into them. Results. Three theorems have been formulated, the first of which relates the accumulation of tangential stresses (increments) from the edges of a rectangle to the middle of a rectangular section with the formula for determining tangent stresses for round sections. The second theorem allows to establish a connection between the tangential stresses calculated for each of the small squares-circles and the tangent stresses of the large circle through their increments. The third theorem makes it possible to find tangential stresses for each of the small square circles. The proposed approach allows to remove the need to use special tables for the calculation and not only in the elastic stage. It also makes it possible to separate the stress-strain state in the whole set of round cross-sections from the additional field caused by the deplanation of the rectangular cross-section. In addition, the proposed approach makes it possible to take into account the concentration of angular deformations in the incoming angles and other places with changing geometric parameters.
9
Zaripov, R. M., and R. B. Masalimov. "Stress-strain state of an underwater offshore oil pipeline taking into account changes in ground conditions and operating parameters." Multiphase Systems 18, no. 1 (May 2023): 17–26. http://dx.doi.org/10.21662/mfs2023.1.003.
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The article briefly describes the construction of concreted pipes used in recent years in the construction of offshore gas and oil pipelines. In the formulation of the problem of the stress-strain state of an underwater offshore oil pipeline, the calculated section is conditionally divided into three parts: the middle blurred bare part and the underground parts adjacent to it on the left and right. A brief description of the solution of the problem is given. The results of calculations of the main characteristics of the stress-strain state of the underwater section of the offshore oil pipeline are presented in the form of a diagram of the pipeline deflection and bending stresses, as well as in tables through extreme values of deflection and bending stresses from span and support bending moments for various values of operating parameters and soil conditions in adjacent underground parts. By analyzing the stress- strain state of the calculated section of the offshore oil pipeline, the critical values of the operation parameters and the corresponding critical values of the equivalent longitudinal axial force were determined.
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Lekhov, O. S., and A. V. Mikhalev. "Stress-strain state of metal in deformation zone during production of steel section billets on the unit of combined continuous casting and deformation. Report 2." Izvestiya. Ferrous Metallurgy 63, no. 9 (November 16, 2020): 730–34. http://dx.doi.org/10.17073/0368-0797-2020-9-730-734.
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Stress state of metal in deformation zone during introduction of the separating collars of the grooved die into continuously casted steel slab was calculated for production of section billets on the unit of combined continuous casting and deformation. Calculation of axial, tangential and equivalent stresses arising in deformation zone of metal was made in four sections of deformation zone and its results are presented in specific points and lines. View of the section of deformation zone and location of specific points are provided. The stress state of metal in zone of cyclic deformation at formation of three steel section billets from continuously cast slab by separating collars of grooved die on the unit of combined continuous casting and deformation was determined by solving extensive problem of elasticity with the finite element method using the ANSYS package. The results of calculation of axial, tangential and equivalent stresses according to Mises in deformation zone are given in form of graphs and tables for working surfaces in four cross sections. The values and regularities of distribution of these stresses along the length and width of deformation zone were determined. The character of axial stresses distribution by characteristic lines located along the length of deformation zone is shown. Values of the highest compressive and tensile axial stresses arising in deformation zone during introduction of separating collars of grooved were obtained for the unit of combined continuous casting and deformation.
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Ergün, Mustafa, and Şevket Ateş. "The stress analysis of a shear wall with matrix displacement method using rectangular finite element." Journal of Structural Engineering & Applied Mechanics 4, no. 1 (March 30, 2021): 18–27. http://dx.doi.org/10.31462/jseam.2021.01018027.
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The aim in this study is to numerically present some characteristic features of the rectangular finite element using the matrix displacement method and to show the utility of this element in plane stress problems compared to the finite element method. The paper consisted of three parts. In the first part, all of the finite element formulation steps from choosing the convenient coordinate system to creating element stiffness matrix are presented respectively. In the second part of the study, a static finite element analysis of the shear wall is also made by ANSYS Mechanical APDL. In the final part, the results (displacements, strains and stresses) obtained from the previous parts are compared with each other by the help of tables and graphics. The results show that this method is effective and preferable for the stress analysis of shell structures. Further studies should be conducted in order to indicate the efficiency of the matrix displacement method for the solution of different types of plane stress problems using different finite elements.
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Müller, Simon, and Sabine M. Weygand. "Numerical Investigations of Internal and Residual Stresses in Aluminium-Polymer Laminate Foils during Stretch Forming." Key Engineering Materials 742 (July 2017): 697–704. http://dx.doi.org/10.4028/www.scientific.net/kem.742.697.
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Aluminium-polymer laminate foils consisting of the layers PA, Al and PVC are used to manufacture high barrier pharmaceutical packages. These so called cold-formed blister packs are formed by stretch forming at room temperature. As due to the complex material structure the forming process is not yet well understood, the developers of cold-formed blister packaging machines design the punches for forming the cavities bigger than needed for the tablets being packed. Therefore, the aim of this work is to gain insight into the mechanical behavior of the composite during stretch forming. For this, internal and residual stresses in the layers are analyzed with the finite element method. With the help of a micromechanical and a stretch forming model simulations are performed. Furthermore, an analytical solution to calculate the internal and residual stresses during stretch forming the foil is presented. The calculation procedure can be used to determine stresses from surface strains which could be measured in forming experiments.
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Nabika, Toru, Katsumi Ikeda, Kohei Kawakami, Tatsuo Gonda, Yasuo Nara, Junichi Masuda, and Yukio Yamori. "Exaggerated Stress Responses of a Chromosome-1 Congenic Strain Derived from Shrsp/Izm and Wky/Izm." Hypertension 36, suppl_1 (October 2000): 717–18. http://dx.doi.org/10.1161/hyp.36.suppl_1.717-e.
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P136 Background: QTL mapping studies showed that the rat chromosome 1 includes a gene responsible for hypertension in SHR. To understand roles of this putative hypertension gene on the cardiovascular physiology, we studied stress responses of a congenic strain with the chromosome-1 blood pressure (BP) QTL transferred from SHRSP/Izm. Methods: The region between D1Wox29 and D1Rat112 (∼60cM) was introgressed from SHRSP/Izm to WKY/Izm by repeated backcrossing. The established congenic strain (CONG) covered a 100:1 support interval for the BP QTL found in the previous study (Am J Hypert 1999;12:1098). After telemetry probes were implanted, age-matched male CONG and WKY (5-6 month old) were used in the following experiments; 1) Restraint stress: rats were put in small tubes for 1h at room temperature and BP was monitored with radiotelemetry. 2) Cold stress: rats were kept at 4 C for 2h and BP was monitored using telemetry. Results: Without the stresses, BP measured with telemetry was not different between WKY and CONG (Table) although tail-cuff measurement gave a significant difference in BP between the two strains (141±3.5 and 154±8.3mmHg for WKY and CONG, p<0.0001). During the exposure to the restraint stress, CONG showed greater BP increase than did WKY (Table). Similar exaggerated responses in CONG were observed during the cold stress as well. Conclusion: The hypertension gene in the chromosome-1 QTL region may modulate cardiovascular responses to the stresses probably through the sympathetic nervous system.
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Sawicki, Andrzej, Marek Kulczykowski, and Robert Jankowski. "Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table." Archives of Hydro-Engineering and Environmental Mechanics 59, no. 3-4 (December 1, 2012): 101–12. http://dx.doi.org/10.2478/heem-2013-0002.
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Abstract Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.
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M. A. Saber, Azad. "Experimental Stress Analysis for Woven Carbon, Glass, and Kevlar Laminate Shells." DJES 11, no. 4 (December 1, 2018): 60–66. http://dx.doi.org/10.24237/djes.2018.11409.
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Composite shell structures have many applications in aerospace industry in which deal with various loading abundantly. In present paper Strain gauge instrument with rectangular rosette strain gauges were used to detect the maximum stress and strain distributions along the shell composite structure. Also a finite element analysis was done for validation of experimental results. The FEM software used was ANSYS14. Impact test, density measurement, and bending test were performed in order to detect physical and mechanical properties such as toughness, principal stresses, and density, of the three laminated composite shells. In addition, the results between experimental and ANSYS were compared. It was observed that an important discrepancy is found between theoretical and experimental results. It was also found a large difference in modulus of elasticity, toughness, and tensile strength for each composite material. These differences are tabulated in many tables in the last paper.
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Roland, C. M., and K. L. Peng. "Electrical Conductivity in Rubber Double Networks." Rubber Chemistry and Technology 64, no. 5 (November 1, 1991): 790–800. http://dx.doi.org/10.5254/1.3538591.
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Abstract The consequences on electrical conductivity of the various processing steps used to form a double-network rubber are summarized in Table IV. Although the objective was not achieved herein, the potential for using double-network rubbers to attain enhanced conductivity remains. Alternate procedures enabling residual extensions exceeding 100% are suggested for future work. Specific conclusions drawn from this study are as follows: 1. The time dependence of the electrical resistivity after imposition of a tensile strain depends on the magnitude of the strain. The observed behavior is consistent with breakup of carbon-black floc at low strains (with concomitant reduction in conductivity) and with promotion of interparticle contacting at higher strains. The latter engenders enhanced longitudinal conductivity. The enhancement may be due to orientation of the filler phase, but this remains speculative. The effect of deformation on the transverse resistivity could not be reproducibly characterized. 2. The rate dependence of the electrical resistivity was also dependent on the magnitude of the rubber deformation. At the low strains associated with disruption of the filler phase, higher rates (stresses) increase the maximum in the resistivity. At higher elongations for which the resistivity declines, the effect of deformation velocity is less apparent. 3. Subjecting a filled rubber to heating after mixing reduces the electrical resistivity. The irreversible portion of this reduction is attributed to an acceleration in the recovery of an equilibrium level of filler-particle contacts. The resistivity acquires an invariance to temperature after the initial heating that persists for at least several hours. 4. The fact that extension followed by retraction of a carbon-black-reinforced elastomer results in a permanent increase in electrical resistivity negated in this work the possibility of achieving enhanced electrical conductivity via a double-network structure. 5. Consistent with the strain optical properties, orientational crystallization behavior, and stress-strain response previously found for unfilled rubbers containing a double-network structure, carbon-black-reinforced double-network rubbers exhibit electrical resistivities more sensitive to strain than conventionally cured elastomers.
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Eryshev, Vladimir, Nickolay Karpenko, and Artur Zhemchuyev. "INTEGRAL PARAMETERS OF CONCRETE DIAGRAMS FOR CALCULATIONS OF STRENGTH OF REINFORCED CONCRETE ELEMENTS USING THE DEFORMATION MODEL." International Journal for Computational Civil and Structural Engineering 16, no. 1 (March 24, 2020): 25–37. http://dx.doi.org/10.22337/2587-9618-2020-16-1-25-37.
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In accordance with the requirements of regulatory documents, restrictions are introduced on stress levels at the end of the falling branch of the diagrams at the maximum normalized strain values. We have developed mathematical models that establish a uniform sequence for calculating the unambiguous values of deformations at the base points of concrete diagrams, taking into account the accepted functional relationships and the rules for their use according to the tables of normative documents. It was shown that for equal values of deformations and stresses at base points, analytical expressions of diagram recommended by regulatory documents, even if it differs in structure, give identical outlines, diagram branches coincide. The correlation between the calculation models by Russian and foreign regulatory documents was established by comparing the values of the integral parameters of the diagrams and the ultimate forces obtained by calculating the reinforced concrete element according to the deformation model. As integral parameters of concrete deformation diagrams, it was recommended to use areas bounded by diagram branches and diagram completeness coefficients. Analytical modeling of integral parameters allowed us to exclude the procedure for numerically summing stresses along elementary strips in a section and solving nonlinear equations by the method of successive approximations when calculating the strength of an element.
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Markochev, V. M. "The inverse strength problem for evaluation of bending stresses in pipelines during ground movements." Industrial laboratory. Diagnostics of materials 87, no. 9 (September 24, 2021): 68–76. http://dx.doi.org/10.26896/1028-6861-2021-87-9-68-76.
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Three variants of the engineering solution of inverse problems regarding the strength of pipeline sections bent as a result of ground movements or during an earthquake are proposed. The feature of this approach consists in calculation of stresses not by the forces acting on the pipe, but by the displacements or deflections. Therefore, full-scale measurements of the detected deviation of the pipe position from the planned pipeline route should be taken as initial data for estimating the values of additional bending stresses. The first problem considered is the assessment of the risk of pipeline malfunction upon sagging or bulging of the supports of aboveground pipelines. The problem is solved in the beam approximation. The pipeline is considered a statically indeterminate beam, one of the supports of which is forcibly moved to a given distance. For a once statically indeterminate beam, a system of four equations — two equilibrium equations and two integral equations for deflections — was solved numerically. The calculated values of three reactions of the supports and the angle of rotation of the pipe section on the first support are used to calculate bending moments, stresses and deflection lines. The problem for a thrice statically indeterminate beam under strain loading was also solved. The second goal is to model the stress-strain state of the pipeline proceeding from the tables of experimental data on the values of pipe deflections and their coordinates. The problem was also solved numerically, using the procedures of smoothing, linear interpolation and sequential differentiation. It is shown that taking into account the possible ambiguous solution of the inverse problem, we should not rely on the calculated values of transverse forces and distributed loads. It is enough to limit ourselves to the second coordinate derivative of the deflection. The third goal is to prevent accidents at the design stage. It is proposed to create a list of normalized deflection functions for modeling possible emergency situations for pipeline sections placed in difficult ground-geological conditions and seismically dangerous zones. The examples of such functions are given.
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Daniels, Calvin C., P. David Rogers, and Chasity M. Shelton. "A Review of Pneumococcal Vaccines: Current Polysaccharide Vaccine Recommendations and Future Protein Antigens." Journal of Pediatric Pharmacology and Therapeutics 21, no. 1 (January 1, 2016): 27–35. http://dx.doi.org/10.5863/1551-6776-21.1.27.
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This review describes development of currently available pneumococcal vaccines, provides summary tables of current pneumococcal vaccine recommendations in children and adults, and describes new potential vaccine antigens in the pipeline. Streptococcus pneumoniae, the bacteria responsible for pneumonia, otitis media, meningitis and bacteremia, remains a cause of morbidity and mortality in both children and adults. Introductions of unconjugated and conjugated pneumococcal polysaccharide vaccines have each reduced the rate of pneumococcal infections caused by the organism S. pneumoniae. The first vaccine developed, the 23-valent pneumococcal polysaccharide vaccine (PPSV23), protected adults and children older than 2 years of age against invasive disease caused by the 23 capsular serotypes contained in the vaccine. Because PPSV23 did not elicit a protective immune response in children younger than 2 years of age, the 7-valent pneumococcal conjugate vaccine (PCV7) containing seven of the most common serotypes from PPSV23 in pediatric invasive disease was developed for use in children younger than 2 years of age. The last vaccine to be developed, the 13-valent pneumococcal conjugate vaccine (PCV13), contains the seven serotypes in PCV7, five additional serotypes from PPSV23, and a new serotype not contained in PPSV23 or PCV7. Serotype replacement with virulent strains that are not contained in the polysaccharide vaccines has been observed after vaccine implementation and stresses the need for continued research into novel vaccine antigens. We describe eight potential protein antigens that are in the pipeline for new pneumococcal vaccines.
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Korotkin, V. I., and E. M. Kolosova. "THE MAIN PARAMETERS OF THE STRENGTH CALCULATION OF NOVIKOV GEARING WITH STANDARD BASIC RACK PROFILE." Spravochnik. Inzhenernyi zhurnal, no. 291 (June 2021): 3–11. http://dx.doi.org/10.14489/hb.2021.06.pp.003-011.
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The article shows the expediency of using Novikov gearing with standard basic rack profile and with hardened teeth for general purpose gearboxes, also with thermally improved teeth for special purpose gearboxes. It sets out the principled approach for solving the problem definition of basic parameters of the strength calculation of these gears, consisting of two stages: a) definitions of both basic bending, contact stresses and tooth rigidity, and phase taking into account the coefficients of influence of the gear face; b) modeling the process of real multipoint engagement with finding the criterial stress in dangerous sections of the teeth, which determine the load-bearing capacity and service life of the gearbox. Implementing this approach, we obtained generalizing results of solving a spatial problem of the stress-strain state of teeth at any position of the contact area along their length and the way of obtaining partial efforts at the contact area and criterion stresses is indicated. The dependencies, convenient for embedding in the developed computing programs, tables, approximating the power polynomials for determining the basic parameters of the contact were obtained. The completed studies are supposed to be issued in the form allows to offer the method of strength calculation of Novikov gearing with standard basic rack profile domestic machine-building enterprises, producing drives for general engineering and special purpose.
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Viktor Tarasenko and Vera Rykina. "USING OF ELECTRICAL METHODS OF MEASURMENTS FOR TESTING OF BRIDGES AND OTHER STRUCTURES." Bridges and tunnels: Theory, Research, Practice, no. 4 (June 8, 2015): 113–19. http://dx.doi.org/10.15802/bttrp2013/26665.
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Purpose. With the introduction of new designs of bridges and other structures the using of electrical measurement techniques in which the measured deflections, stresses and vibrations, using transmitters, are converted into electrical signals in their testing is of current interest. It is very important to ensure a phase-sensitivity and proportionality between the measured values of mechanical and electrical signals. Methods. For electrical measurements transducers are connected to electrical bridge-type circuits. Calculations of the Wheatstone’s bridge connections forvarious transducers were made on the basis of Kirchhoff's laws for branched electrical networks and using circuitry transformation for which in the original scheme of the Wheatstone’s bridge the group of resistances is replaced by another, equivalent resistances group. Calculations were performed for the cases of presence and absence of internal resistance of the bridge’s power supply with connecting of transducers into one, two and four arms of a Wheatstone’s bridge. Findings. From the calculations the tables and graphs of the functions fi () and f0i () , that determine the change of current in the measuring diagonal of a Wheatstone’s bridge are derived, where is relativechange in resistance of transducers. For one active sensor functions f1() and f01() are characterized by a high non-linearity, but for strain gages at 0,01...0,02 , acceptable linearity and accuracy of the measurements are provided. Originality. Based on the result analyses for calculations conducted, relations of the current in the measuring diagonal of the Wheatstone’s bridge are determined for various connecting circuits of transducers for measurement of the stress-strain state in structural elements during tests. Also the value of the internal resistance of the bridge’s power supply is taken into account. Calculations were performed using Kirchhoff's laws and by equivalenttransformation of branched circuit. Practical value. Obtained plots for functions fi () and f0i () and the above table allow to estimate the conditions for ensuring the linearity of derived dependencies for different transducers’ connections. Bridge-type circuits for insertion of strain gages allow to distinguish stresses in structural elements from the action of normal forces as well as vertical and horizontal bending moments.
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Lekhov, O. S., and A. V. Mikhalev. "Stress-strain state of metal in deformation zone during production of steel section billets on the unit of combined continuous casting and deformation. Report 1." Izvestiya. Ferrous Metallurgy 63, no. 7 (October 5, 2020): 548–53. http://dx.doi.org/10.17073/0368-0797-2020-7-548-553.
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Volumetric problem of determining stress-strain state of metal in deformation zone during forming of three section billets from the slab by separating collars of grooved strikers on the unit of combined continuous casting and deformation was set and solved. The expediency of using such unit was justified for longitudinal division mation are given for St3sp steel. The solid-state finite elements used in calculation of stress-strain state of metal in deformation zone and dimensions of the grid are described. The results of calculation of stress-strain state of metal in deformation zone were obtained by solving the problem of elasticity by the finite element method in volumetric formulation. The results of calculation of displacements and stresses in deformation zone are given in form of graphs and tables by working surfaces in four cross sections and are presented for characteristic points. Values and regularities of distribution of axial displacements in width and length of deformation center were determined during introduction of strikers separating collars into continuously cast slab in production of three section steel billets on the unit of combined continuous casting and deformation.
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Chen, Y. H., and J. J. Han. "Macrocrack-Microcrack Interaction in Piezoelectric Materials, Part II: Numerical Results and Discussions." Journal of Applied Mechanics 66, no. 2 (June 1, 1999): 522–27. http://dx.doi.org/10.1115/1.2791078.
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Numerical results are shown in figures and tables. The major features for the traditional stress intensity factors and the electric displacement intensity factor against the microcrack location angle and the distance of the microcrack center from the macrocrack tip are discussed. It is shown that, unlike single-crack problems, the mechanical loading and the electric loading are coupled together since the microcrack not only releases the near-tip stresses, but also disturbs the near-tip electric field. Furthermore, the influence of the electric loading on the mechanical strain energy release rate (MSERR) at the macrocrack tip is discussed in detail. It is found that the variable nature of the MSERR against the normalized electric loading is monotonic and proportional wherever the parallel microcrack is located near the macrocrack tip. However, the slope of the MSERR's curve considering microcracking diverges far from those without considering microcracking. This finding reveals that, besides the two sources of microcrack shielding discussed by Hutchinson (1987) for brittle solids, the disturbance of the near-tip electric field due to microcracking really provides another source of shielding for piezoelectric solids.
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Abdelali, Hanane Moulay, Mounia El Kadiri, and Rhali Benamar. "A Semi-Analytical Approach for the Geometrically Nonlinear Analysis of Skew Plates." Applied Mechanics and Materials 704 (December 2014): 118–30. http://dx.doi.org/10.4028/www.scientific.net/amm.704.118.
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The present work concerns the nonlinear dynamic behaviour of fully clamped skew plates at large vibration amplitudes. A model based on Hamilton’s principle and spectral analysis has been used to study the large amplitude free vibration problem, reducing the non linear problem to solution of a set of non-linear algebraic equations. Two methods of solution have been adopted, the first method uses an improved version of the Newton-Raphson method, and the second leads to explicit analytical expressions for the higher mode contribution coefficients to the first non-linear mode shape of the skew plate examined. The amplitude dependent fundamental mode shape and the associated non-linear frequencies have been obtained by the two methods and a good convergence has been found. It was found that the non-linear frequencies increase with increasing the amplitude of vibration, which corresponds to the hardening type effect, expected in similar cases, due to the membrane forces induced by the large vibration amplitudes. The non-linear mode exhibits a higher bending stress near to the clamps at large deflections, compared with that predicted by linear theory. Numerical details are presented and the comparison made between the results obtained and previous ones available in the literature shows a satisfactory agreement. Tables of numerical results are given, corresponding to the linear and nonlinear cases for various values of the skew angle θ and various values of the vibration amplitude. These results, similar to those previously published for other plates, are expected to be useful to designers in the need of accurate estimates of the non-linear frequencies, the non linear strains and stresses induced by large vibration amplitudes of skew plates.
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Barsukov, V. G., and T. S. Chikova. "Comparative analysis of rheological properties indicators for thermoplastic melts." Vesnik of Yanka Kupala State University of Grodno. Series 6. Engineering Science 12, no. 1 (September 9, 2022): 65–73. http://dx.doi.org/10.52275/2223-5396-2022-12-1-65-73.
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The introduction analyzes the state of the issue and substantiates the research relevance. The aim of the work is to determine and comparatively analyze the values of physically normalized indicators of rheological properties of typical representatives of thermoplastic melts. In the methodological part of the work, to ensure the comparability of the results, the physically normalized form of the Ostwald-de-Waele power empirical rheological equation proposed by McKelvey is used. The calculation scheme is based on the transition from an approximating power function with rheologically non-deterministic parameters to two dimensionless rheologically determined complexes characterizing the stress-strain state of a nonlinear-viscous medium. The first dimensionless complex is presented in the form as the ratio of the actual shear rate to a unit normalization base value, and the second is in the form as the ratio of shear stresses acting on the deformable medium to the base (reduced) value of these stresses, which are necessary to overcome viscous resistance at a unit normalization shear rate. A technique is described for determining physically normalized indicators of rheological properties using the thermoplastic melts flow curves available in the scientific and technical literature (dependence of shear stresses on shear rate) based on the processing of these graphical dependencies plotted in double logarithmic coordinates. In the main part of the work, the values of physically normalized indicators of rheological parameters (the reduced index of viscous resistance and the indicator of the rheological nonlinearity of the melt) are determined and presented in the form of tables for widely used types of filled and unfilled thermoplastic polymers. A comparative analysis of these indicators has been carried out. Conclusions are given on the work and it is noted that the results of the research can be used in engineering practice, as well as in the educational process when performing rheological calculations of the processes of processing thermoplastic polymeric materials.
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Styranivska, Oksana, Nataliia Kliuchkovska, and Nataliya Mykyyevych. "Comparison of using different bridge prosthetic designs for partial defect restoration through mathematical modeling." European Journal of Dentistry 11, no. 03 (July 2017): 345–51. http://dx.doi.org/10.4103/ejd.ejd_72_17.
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ABSTRACT Objective: To analyze the stress–strain states of bone and abutment teeth during the use of different prosthetic designs of fixed partial dentures with the use of relevant mathematical modeling principles. Materials and Methods: The use of Comsol Multiphysics 3.5 (Comsol AB, Sweden) software during the mathematical modeling of stress–strain states provided numerical data for analytical interpretation in three different clinical scenarios with fixed dentures and different abutment teeth and demountable prosthetic denture with the saddle-shaped intermediate part. Statistical Analysis Used: Microsoft Excel Software (Microsoft Office 2017) helped to evaluate absolute mistakes of stress and strain parameters of each abutment tooth during three modeled scenarios and normal condition and to summarize data into the forms of tables. Results: In comparison with the fixed prosthetic denture supported by the canine, first premolar, and third molar, stresses at the same abutment teeth with the use of demountable denture with the saddle-shaped intermediate part decreased: at the mesial abutment tooth by 2.8 times, at distal crown by 6.1 times, and at the intermediate part by 11.1 times, respectively, the deformation level decreased by 3.1, 1.9, and 1.4 times at each area. Conclusions: The methods of mathematical modeling proved that complications during the use of fixed partial dentures based on the overload effect of the abutment teeth and caused by the deformation process inside the intermediate section of prosthetic construction.
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Bouacha, Nadjet, and Mouloud Belachia. "Elaboration of an Expert System for Sizing, Designing and Verifying Flexible Pavements." Civil and Environmental Engineering Reports 30, no. 3 (September 1, 2020): 94–121. http://dx.doi.org/10.2478/ceer-2020-0035.
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Abstract The use of expert systems in the world of civil engineering, and in particular for roads, has become a necessity for the reason of the particularity, complexity, and diversity of the influencing parameters at the level of the design calculation, the latter of which represents the major source of subsequent degradation. This system consists of proposing a tool for helping the user firstly to size the body of the roadway, with several analytical methods and models (Pre-project, Boussinesq, Westgaard, and Burmister), and secondly, to offer different design possibilities (thickness and type of the material) that make up the layers. Lastly, it is to calculate the stresses and strains in order to compare them with admissible limits. The management of a knowledge base of complex natures (words, sentences, numbers, symbols, tables, calculation methods, equations, conditions, etc.) requires an adequate methodology which goes beyond the simple use of the technology but enables you to imagine the process of regrouping this mass of complex data and classifying the data, which can then be integrated into a database or spreadsheets and external programs designed with code compatible with the expert system generator. Our contribution relates initially to the formulation, organization, and preparation of the algorithms, and then the starting of the programs in order to conceive fully executable programs, the latter of which we can call the expert system. The validation of such a system was made as the work progressed, changes were made in the formulation of the rules, and the order and orientation of the data in the knowledge that the advantage of this type of system is the possibility of permanently reinforcing the database with human expertise in the field, or in books, especially so that we can avoid data loss due to illnesses, retirement, etc.
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Paliichuk, I. I., I. M. Kovbasiuk, O. B. Martsynkiv, and I. I. Vytvytskyi. "Forceful interaction of the casing string with the walls of a curvilinear well." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 4 (August 30, 2022): 45–51. http://dx.doi.org/10.33271/nvngu/2022-4/045.
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Purpose. Developing a method for determining the axial forces and the walls reactions along a casing string, which bend it and make it follow a curved wellbore shape. Methodology. The casing string is represented as a long elastic rod in the curved well. An inhomogeneous system of four differential equations is developed to describe the rods deformations. It was reduced to a first-order differential equation with respect to axial force. Its solution was found by the Bernoulli method. The numerical integration of the differential equation is applied. Findings. The axial force distribution along the casing string was found, taking into account the well curvature and the friction, as well as the reaction forces of the well walls. A method of the tables numerical integration of the wells inclinometric measurements has been developed. The calculating formulas for the reaction forces, axial forces, bending moments and stresses acting in the casing pipes in the well deep are obtained. Originality. The solved problem takes into account the walls reaction and the friction forces that create longitudinal bend during the columns movement. The system of differential equations of equilibrium was supplemented by Eulers kinematic equation. The function of zenith angle, which is known due to the table of the directional survey data, was taken as the integration variable. The inverse problem is solved all unknown internal forces, also such the external distributed reaction, which causes the column to repeat the wells shape, was been determined by the angular deformations of casing string, which are given by the wells shape in the inclinometric table. Practical value. The developed method allows detecting the areas with a significant local increase in the wells curvature, which indicate their obstructed passability. This allows for accurate determination of depth intervals to increase the borehole diameter, which is necessary before lowering the column. According to the analysis results, it is possible to determine the parameters of the stress-strain state of the casing string, which can be used to predict its working capacity and operating life.
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Stetukha, V., and I. Zheleznyak. "Methodology for Calculating the Stability of the Polymer Operating String in Permafrost." Journal of Mining Institute 241 (February 25, 2020): 22. http://dx.doi.org/10.31897/pmi.2020.1.22.
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The goal of this paper is to develop a methodology for calculating the stability of an annular cross-section string casing made of polymer material used for the development of mineral deposits by underground leaching in permafrost formations. The aim was to determine the geometric parameters of the casing and to ensure its operational reliability.The relevance of the research is associated with the peculiarities of external influences on the string, for example, a geotechnological well operating in permafrost formation under conditions of additional exposure to ice pressure during freezing of water in the borehole annulus. This effect is usually accompanied by deformation of the casing due to ice pressure, which can lead to string collapse, abnormal operation and the risk of contamination of the geological environment.The proposed calculation method for a polymer casing is based on simulation of objects using the finite element method. We used the spatial finite elements to model the interaction of key elements of the geotechnological natural-technogenic complex: a polymer casing, ice in the annulus space and homogeneous or heterogeneous rock masses adjacent to the well.The results of the study are presented in the form of tables and patterns of displacements, which reflect stresses and strains in the elements of the calculation scheme. The analysis of the obtained results confirms the possibility of using polymer casings of different technological purposes in various conditions of permafrost formation, including extreme ones. The results of the redistribution of pressure created by ice during the freezing of water in the borehole annulus to the rock mass and the string are evaluated. Interdependent deformations of the rock mass and operating string during freezing of water in the borehole annulus are determined. The necessity of considering the properties of the rock mass in determining the pressure on the string is established. The conditions for the collapse of the string with a different combination of its parameters are revealed.
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Mirnyy, A. Yu. "DISPERSE SOILS DILATANCY STUDIES AND THE METHODS OF ITS QUANTITATIVE ASSESSMENT." Engineering Geology World 14, no. 2 (September 3, 2019): 34–43. http://dx.doi.org/10.25296/1993-5056-2019-14-2-34-43.
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The phenomenon of dilatancy is a unique property of dispersed media, and in the case of soils can have a significant impact on the shear resistance and the stress-strain state change during loading. In the conditions of free boundaries dilatancy leads to volume increase, and in the presence of volume expansion restrictions to the growth of average stresses. Thus, dilatancy leads to an increase in shear resistance, which makes it possible to increase the degree of use of the bearing capacity of the base. Many modern mechanical models of soil allow dilatancy calculation, most often on the basis of the Rowe’s theory, according to which the angle of internal friction changes during loading, and to calculate the base taking into account its hardening. In addition, the introduction of the plastic potential into the strength conditions allows the calculation of the final plastic strains. This is very important in case of complex loading trajectories, often implemented in soil foundations. The article provides an overview of dilatancy phenomenon studies in our country and abroad with main analytical dependencies given. Four main methods for determining the dilatancy angle are considered: the method of direct simple shear (DSS) and multiplane direct shear (MDS), triaxial compression and torsion shear, their main advantages and disadvantages are highlighted in a form of a table. It is shown that determination of the dilatancy angle does not present significant difficulties and does not require specialized equipment, at the same time, the effective use of this parameter in the design leads to economic effect, primarily in the case of sandy and coarse soils.
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Melnikov, Denis A., and Tatyana L. Dmitrieva. "Validation of the load-bearing capacity of the frame assembly of metal structures on the standard 2.440 series using IDEA StatiCa." Journal «Izvestiya vuzov. Investitsiyi. Stroyitelstvo. Nedvizhimost» 10, no. 3 (2020): 406–19. http://dx.doi.org/10.21285/2227-2917-2020-3-406-419.
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The paper aims to study the actual operation of a rigid frame unit for coupling a crossbar with a column on high-strength bolts according to the standard 2.440-2 series using modern software systems of the component finite element method. Special attention was paid to the operation of nodal elements, as well as their stress-strain state. Based on the results of static calculations, the cross-sections of the elements under consideration, as well as the components of the node (plates, bolts, seams, etc.) were selected from the tables of the standard series. Subsequently, using the component finite element method serving as the basis of the IDEA StatiСa software, all the components of the node were mod-elled with respect to acting forces. The conducted calculations confirmed the suitability of the obtained node model for identifying inconsistencies in the series and modern standards. Using stresses on plates, bolt and welding forces, as well as several forms of vibration to assess the stability of compo-nents, the applicability of the node in question in the proposed configuration was evaluated. It turned out that the node failed to meet modern standards in terms of design conditions. Moreover, the serial bolts were overloaded by almost 38%, and some welds approached the limit state. When used in real conditions, this can lead to serious losses, including human lives. Recommendations are given for changing the specific configuration of the node in order to protect it from the destruction of any nature, including local buckling failure.
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Ferdosi, Behnam, Michael James, and Michel Aubertin. "Numerical simulations of seismic and post-seismic behavior of tailings." Canadian Geotechnical Journal 53, no. 1 (January 2016): 85–92. http://dx.doi.org/10.1139/cgj-2014-0345.
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Several tailings impoundments have failed as a result of earthquakes in the last few decades. A majority of these failures were due to direct seismic loading, tailings liquefaction during shaking, or the post-seismic behavior of the tailings as it relates to the dissipation of excess pore-water pressures that were generated during shaking. Previous work has indicated that the UBCSAND model developed by Byrne et al. in 1995 is capable of simulating the cyclic simple shear testing response of low-plasticity tailings over a range of consolidation stresses and cyclic shear ratios. However, the ability of the model to simulate the dynamic and subsequent behavior of such tailings for other conditions, such those induced by shaking table tests, has not yet been evaluated. In this regard, previous work has shown that the main components of the UBCSAND model cannot realistically simulate some specific responses, including the post-seismic volumetric strains related to excess pore-water pressure dissipation. This paper presents numerical modeling results of the dynamic behavior of tailings from hard rock mines. It introduces a method for simulating their post-seismic behavior by including an updating scheme for the elastic moduli into the UBCSAND model. The results of cyclic simple shear testing, seismic table testing, and complementary experimental relationships were used to calibrate and validate the model with its new component. The simulated response of tailings during cyclic simple shear testing and for a complete seismic table test shows that the proposed approach simulates the experimental observations well. Level-ground, seismically induced liquefaction and post-seismic behavior of a 15 m thick tailings deposit are also simulated, leading to post-liquefaction settlements that are in agreement with empirical relationships.
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Miner, Valerie, and Carol Anshaw. "Stresses and Strains." Women's Review of Books 19, no. 9 (June 2002): 14. http://dx.doi.org/10.2307/4023935.
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Greenhalf, Jim. "Stresses and strains in city hall." Local Government Studies 11, no. 2 (March 1985): 1–7. http://dx.doi.org/10.1080/03003938508433189.
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Nowacki, Jerzy, and Michał Kawiak. "Stresses and strains in soldered joints." Welding International 27, no. 1 (January 2013): 42–47. http://dx.doi.org/10.1080/09507116.2011.600025.
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Comba, Peter. "Strains and stresses in coordination compounds." Coordination Chemistry Reviews 182, no. 1 (February 1999): 343–71. http://dx.doi.org/10.1016/s0010-8545(98)00199-4.
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Nichols, T. Richard. "The Stresses and Strains of Tensegrity." Journal of Motor Behavior 46, no. 3 (March 14, 2014): 197–98. http://dx.doi.org/10.1080/00222895.2014.880308.
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Nicholson, D. W. "On stresses conjugate to Eulerian strains." Acta Mechanica 165, no. 1-2 (October 1, 2003): 87–98. http://dx.doi.org/10.1007/s00707-003-0037-2.
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Ghasemi Nejhad, Mehrdad N., Chiling Pan, and Hongwei Feng. "Intrinsic Strain Modeling and Residual Stress Analysis for Thin-Film Processing of Layered Structures." Journal of Electronic Packaging 125, no. 1 (March 1, 2003): 4–17. http://dx.doi.org/10.1115/1.1512295.
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Residual stresses develop due to intrinsic and extrinsic strains that form during the processing. Extrinsic strains can be determined using coefficient of thermal expansion, material properties, and processing conditions. An “Equivalent Reference Temperature (ERT)” technique is described and used to model and evaluate the intrinsic strains. piezoelectric microelectromechanical systems (P-MEMS) are considered in this work. Laminate theory with three-dimensional state of stress and strain is used to evaluate residual stresses using the ERT model. In finite element analysis (FEA), the residual stresses and strains of multi-layer P-MEMS structures deposited layer-by-layer during processing, are simulated using the “element birth-and-death” approach. The evaluated residual stresses for a simplified geometry using ANSYS three-dimensional FEA and analytical analysis employing three-dimensional laminate theory are presented along with their corresponding experimental results. A user-friendly software based on the 3-D laminate theory is developed and installed on the Internet. The “equivalent reference temperature” as well as residual stresses and strains can be determined using this software. The level of residual stresses and strains of P-MEMS depend upon various factors such as geometrical design, material selection, and process conditions.
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Yao, Ye, and Wai-Meng Quach. "Numerical Study on Residual Stresses and Plastic Strains in Cold-Formed High-Strength Steel Circular Hollow Sections." Materials 16, no. 18 (September 21, 2023): 6337. http://dx.doi.org/10.3390/ma16186337.
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This paper presents a numerical investigation on the residual stresses and co-existent equivalent plastic strains in cold-formed high-strength steel (CFHSS) circular hollow sections (CHS) by using an advanced finite element (FE)-based method. In this method, the entire manufacturing process of the CFHSS CHS was modeled numerically. The accuracy of the numerical predictions of equivalent plastic strains and residual stresses in the CFHSS CHS was verified by comparing the predictions with the existing test results of both the residual stress measurement and load-end shortening response of the stub column. By using the FE-based method, the effects of high-frequency electric resistance welding on the residual stresses and the stub column response were investigated. The through-thickness variations of both the equivalent plastic strains and residual stresses in CFHSS CHS, which are difficult to measure in the laboratory, were explored numerically. Finally, the effect of cold work (which is quantified by the equivalent plastic strains and residual stresses) on the stub column response of CFHSS CHS tubes was evaluated. It can be found that the equivalent plastic strains and longitudinal residual stresses are generally uniform around the cross-section of CFHSS CHS. The transverse and longitudinal residual stresses are generally uniform across each half-thickness, with the inner half-thickness under compression and the outer half-thickness under tension. The results also demonstrate that both the plastic strains and residual stresses may significantly affect the cross-section capacities of CFHSS CHS.
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D. D’Lima, Darryl, Peter C. Chen, and Clifford W. Colwell Jr. "Osteochondral Grafting: Effect of Graft Alignment, Material Properties, and Articular Geometry." Open Orthopaedics Journal 3, no. 1 (August 6, 2009): 61–68. http://dx.doi.org/10.2174/1874325000903010061.
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Osteochondral grafting for cartilage lesions is an attractive surgical procedure; however, the clinical results have not always been successful. Surgical recommendations differ with respect to donor site and graft placement technique. No clear biomechanical analysis of these surgical options has been reported. We hypothesized that differences in graft placement, graft biomechanical properties, and graft topography affect cartilage stresses and strains. A finite element model of articular cartilage and meniscus in a normal knee was constructed. The model was used to analyze the magnitude and the distribution of contact stresses, von Mises stresses, and compressive strains in the intact knee, after creation of an 8-mm diameter osteochondral defect, and after osteochondral grafting of the defect. The effects of graft placement, articular surface topography, and biomechanical properties were evaluated. The osteochondral defect generated minimal changes in peak contact stress (3.6 MPa) relative to the intact condition (3.4 MPa) but significantly increased peak von Mises stress (by 110%) and peak compressive strain (by 63%). A perfectly matched graft restored stresses and strains to near intact conditions. Leaving the graft proud by 0.5 mm generated the greatest increase in local stresses (peak contact stresses = 6.7 MPa). Reducing graft stiffness and curvature of articular surface had lesser effects on local stresses. Graft alignment, graft biomechanical properties, and graft topography all affected cartilage stresses and strains. Contact stresses, von Mises stresses, and compressive strains are biomechanical markers for potential tissue damage and cell death. Leaving the graft proud tends to jeopardize the graft by increasing the stresses and strains on the graft. From a biomechanical perspective, the ideal surgical procedure is a perfectly aligned graft with reasonably matched articular cartilage surface from a lower load-bearing region of the knee.
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Ezendiokwere, Nnamdi E., Victor J. Aimikhe, Adewale Dosunmu, and Ogbonna F. Joel. "Influence of depth on induced geo-mechanical, chemical, and thermal poromechanical effects." Journal of Petroleum Exploration and Production Technology 11, no. 7 (May 14, 2021): 2917–30. http://dx.doi.org/10.1007/s13202-021-01174-6.
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AbstractDelivering efficient and cost-effective drilled and excavated holes require effective prediction of instability along the hole profile. Most drilled and excavated hole stability analyses in the literature are performed for a given zone without considering the influence of depth. This study focused on determining the influence of depth on induced geo-mechanical, chemical, and thermal stresses and strains in drilled or excavated holes. To this end, a new porochemothermoelastic model was developed based on extended poroelastic theory, and the developed model was employed in determining induced strains and stresses for an oil and gas well case study, using data from the literature. The study delineated the different significance levels of geo-thermal-, chemical-, and thermal-induced strains and stresses as depth increased. From the results obtained, it was clear that at shallow depths, chemically induced strains and stress were the most significant formation perturbations responsible for instability of drilled and excavated holes. On the other hand, at deeper depths, geo-mechanical-induced strains and stress were the most predominant. Comparatively, thermally induced strains and stresses were found to be the least significant formation perturbations responsible for instability of drilled and excavated holes. For this case study, the results indicated that chemical strains and stresses were more prominent at depths below 170 m, accounting for more than 50% of the total stresses and strains. At 170 m, both chemical and geo-mechanical stress and strain had equal contributions to the overall stress and strain. However, as depth increased, the percentage contribution of the geo-mechanical component increased and accounted for about 80% of the total strains and stresses at 1000 m, which increased to 98.48% at depths of 6000 m and beyond. The findings of this study will provide guide for future studies on the application of extended poroelasticity theory in solving instability problems of drilled and excavated holes.
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CHAUDHRY, H. R., B. BUKIET, T. FINDLEY, and A. B. RITTER. "STRESSES AND STRAINS IN THE PASSIVE LEFT VENTRICLE." Journal of Biological Systems 04, no. 04 (December 1996): 535–54. http://dx.doi.org/10.1142/s021833909600034x.
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In this paper, we estimate the stresses and strains from the equatorial region down to the apex of the heart by modeling the passive left ventricle as a frustrum of a thick hollow cone. Large deformation theory has been employed in this analysis. Furthermore, the effects of residual stresses and the anisotropy due to muscle fiber orientation have been included. It is observed that circumferential stress, which is the most important physiologically, decreases considerably at the endocardium and is more evenly distributed through the wall when residual stresses are taken into account. The stresses also decrease as we go from the equatorial region to the apex. Because heart muscles physically have residual stresses, the consequent lower stress gradient through the wall enhances the diastolic function of the left ventricle.
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Xing, Yufeng, Lingyu Meng, Zhiwei Huang, and Yahe Gao. "A Novel Efficient Prediction Method for Microscopic Stresses of Periodic Beam-like Structures." Aerospace 9, no. 10 (September 26, 2022): 553. http://dx.doi.org/10.3390/aerospace9100553.
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This paper presents a novel superposition method for effectively predicting the microscopic stresses of heterogeneous periodic beam-like structures. The efficiency is attributed to using the microscopic stresses of the unit cell problem under six generalized strain states to construct the structural microscopic stresses. The six generalized strain states include one unit tension strain, two unit bending strains, one unit torsion strain, and two linear curvature strains of a Timoshenko beam. The six microscopic stress solutions of the unit cell problem under these six strain states have previously been used for the homogenization of composite beams to equivalent Timoshenko beams (Acta. Mech. Sin. 2022, 38, 421520), and they are employed in this work. In the first step of achieving structural stresses, two stress solutions concerning linear curvatures are transformed into two stress solutions concerning unit shear strains by linearly combining the stresses under two unit bending strains. Then, the six stress solutions corresponding to six generalized unit beam strains are combined together to predict the structural microscopic stresses, in which the six stress solutions serve as basic stresses. The last step is to determine the coefficients of these six basic stress solutions by the principle of the internal work equivalence. It is found that the six coefficients, in terms of the product of the inverse of the effective stiffness matrix and the macroscopic internal force column vector, are the actual generalized strains of the equivalent beam under real loads. The obtained coefficients are physically reasonable because the basic stress solutions are produced by the generalized unit strains. Several numerical examples show that the present method, combining the solutions of the microscopic unit cell problem with the solutions of the macroscopic equivalent beam problem, can accurately and effectively predict the microscopic stresses of whole composite beams. The present method is applicable to composite beams with arbitrary periodic microstructures and load conditions.
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PAVLOVA, I. P., and I. V. BELKINA. "PARAMETRIC RESEARCH OF RESTRAINED STRAINS AND STRESSES OF SELF-STRESSED FIBER-REINFORCED CONCRETE AT THE STAGE OF EXPANSION." Building and reconstruction 108, no. 4 (2023): 81–92. http://dx.doi.org/10.33979/2073-7416-2023-108-4-81-92.
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One of the main advantages of self-stressed concrete is its ability to compensate for one of the main disadvantages inherent in mineral binders – shrinkage strains. However, approaches to predicting the properties of self-stressed concrete are not universal, since they are based mainly on phenomenological approaches and empirical dependencies. The main approaches to predicting strains and stresses arising in expansive concrete are energy- and deformation approaches. A number of researchers confirm the effectiveness of applying the deformation approach to determine intrinsic strains and stresses. Modification of the model for determining its own stresses and strains made it possible to move from the case of uniaxial bar reinforcement to two- and three-axis-limited elements. Based on the provisions of the deformation approach, a deformation model was proposed to determine the intrinsic strains and stresses of self-stressed fiber-reinforced concrete. The main prerequisites and assumptions of the proposed model are formulated. A block diagram of the algorithm of the iterative procedure is given, which makes it possible to calculate the intrinsic strains and stresses of self-stressed fiber-reinforced concrete. Parametric studies of self-strains and stresses of self-stressed fiber-reinforced concrete at the stage of expansion were carried out. The normalized dependences of the bounded strains on the varied parameters are presented. The area of effective use of steel fibers to achieve "binding" effect of free expansion in self-stressed concrete of different energy-activity has been determined. Influence of change of introduced fiber amount on development of bound strains of self-stressed concrete at different time intervals has been determined. The obtained results can be used in design, educational and research institutions.
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Hyde, T. H., R. Sabesan, and S. B. Leen. "Approximate Prediction Methods For Multiaxial Notch Stresses and Strains Under Elastic-Plastic and Creep Conditions." Journal of Strain Analysis for Engineering Design 40, no. 6 (August 1, 2005): 535–48. http://dx.doi.org/10.1243/030932405x16016.
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This paper describes general techniques for predicting multiaxial notch stresses and strains under elastic-plastic and creep conditions. The Neuber method, which is often used in elastic-plastic analysis, has been adapted and extended for predicting creep equivalent notch stresses and strains, based on a time-stepping integration scheme. A linear interpolation method, often used in creep analysis, is adapted and extended for predicting elastic-plastic equivalent stresses and strains. Then notch principal stresses and strains are obtained by applying plasticity theory in combination with assumptions concerning the ratios of the stress or strain components. The accuracy of the predicted equivalent and principal stress and strain values are assessed by comparing predictions based on them with results obtained from finite element analyses.
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BONIFAZ, E. A., and N. L. RICHARDS. "STRESS–STRAIN EVOLUTION IN CAST IN-738 SUPERALLOY SINGLE FUSION WELDS." International Journal of Applied Mechanics 02, no. 04 (December 2010): 807–26. http://dx.doi.org/10.1142/s1758825110000767.
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A three-dimensional finite element elastic–plastic model was developed to study localized plastic strains and residual stresses that exist in a body that has previously been subjected to nonuniform temperature changes. The mechanical model was used to compute the evolution of plastic strains and residual stresses of welded material. The thermal gradient histories calculated during the GTA welding of cast IN-738LC alloys were imposed as load conditions on structural calculations. It can be clearly seen that at constant heat input, the level of plastic strains and the level of residual (Mises) stresses increase with welding speed. The model predicts highest residual stresses in regions of highest elastic strains, in agreement with conventional phenomenological material models where the macroscopic residual stress is always directly related to the macroscopic elastic strain. The highest residual stresses are located at the fusion line (where coarser dendrite secondary arm spacing exist); and the highest plastic strains are located at centerline (where finer dendrite secondary arm spacing exist). The calculations were performed using ABAQUS® FE code on the basis of a time-increment Lagrangian formulation.
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Shoykhet, B., M. A. Grinfeld, and P. M. Hazzledine. "Internal stresses and strains in coherent multilayers." Acta Materialia 46, no. 11 (July 1998): 3761–66. http://dx.doi.org/10.1016/s1359-6454(97)00244-9.
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Laforte, Caroline, and Jean-Louis Laforte. "Deicing Strains and Stresses of Iced Substrates." Journal of Adhesion Science and Technology 26, no. 4-5 (March 1, 2012): 603–20. http://dx.doi.org/10.1163/016942411x574790.
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Chen, Youping, James Lee, and Liming Xiong. "Stresses and strains at nano/micro scales." Journal of Mechanics of Materials and Structures 1, no. 4 (August 1, 2006): 705–23. http://dx.doi.org/10.2140/jomms.2006.1.705.
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