Academic literature on the topic 'Shear (Mechanics) – Mathematical models'

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Journal articles on the topic "Shear (Mechanics) – Mathematical models"

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Babichev, A. V., V. V. Reverdatto, O. P. Polyansky, I. I. Likhanov, and A. N. Semenov. "Heat generation due to friction in the shear crust zones as a factor of metamorphism and anatexis: the results of numerical simulation." Доклады Академии наук 486, no. 6 (June 28, 2019): 704–8. http://dx.doi.org/10.31857/s0869-56524866704-708.

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The heat release effect was estimated due to friction in faults under shear and thrust conditions by mathematical modeling, 3D and 2D thermomechanical numerical models were developed. The equations of solid mechanics in a coupled formulation were solved: the equations of mechanical equilibrium and the equation of heat transfer. The model of an elastic-plastic material with the Drucker-Prager and Huber-Mises yield function is used. For the 3D shear model, the heating was 100-110 °C for the value of the friction coefficient 0.3, 180-190 °C for 0.5, about 300 °C for 0.65. In models of horizontal thrust, the heating in the contact zone was 120-130 °C with a depth of shear plane of 20 km and 150-160 °C with a depth of shear plane of 30 km for a friction coefficient of 0.3. The results obtained can be considered as a lower estimate of the heating in the Yenisei collision-shear zone.
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Ferreira, Rui M. L., Mário J. Franca, João G. A. B. Leal, and António H. Cardoso. "Mathematical modelling of shallow flows: Closure models drawn from grain-scale mechanics of sediment transport and flow hydrodynamicsThis paper is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007)." Canadian Journal of Civil Engineering 36, no. 10 (October 2009): 1605–21. http://dx.doi.org/10.1139/l09-033.

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Mathematical modelling of river processes is, nowadays, a key element in river engineering and planning. River modelling tools should rest on conceptual models drawn from mechanics of sediment transport, river mechanics, and river hydrodynamics. The objectives of the present work are (i) to describe conceptual models of sediment transport, deduced from grain-scale mechanics of sediment transport and turbulent flow hydrodynamics, and (ii) to present solutions to specific river morphology problems. The conceptual models described are applicable to the morphologic evolution of rivers subjected to the transport of poorly sorted sediment mixtures at low shear stresses and to geomorphic flows featuring intense sediment transport at high shear stresses. In common, these applications share the fact that sediment transport and flow resistance depend, essentially, on grain-scale phenomena. The idealized flow structures are presented and discussed. Numerical solutions for equilibrium and nonequilibrium sediment transport are presented and compared with laboratory and field data.
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Bovendeerd, Peter H. M., Wilco Kroon, and Tammo Delhaas. "Determinants of left ventricular shear strain." American Journal of Physiology-Heart and Circulatory Physiology 297, no. 3 (September 2009): H1058—H1068. http://dx.doi.org/10.1152/ajpheart.01334.2008.

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Mathematical models of cardiac mechanics can potentially be used to relate abnormal cardiac deformation, as measured noninvasively by ultrasound strain rate imaging or magnetic resonance tagging (MRT), to the underlying pathology. However, with current models, the correct prediction of wall shear strain has proven to be difficult, even for the normal healthy heart. Discrepancies between simulated and measured strains have been attributed to 1) inadequate modeling of passive tissue behavior, 2) neglecting active stress development perpendicular to the myofiber direction, or 3) neglecting crossover of myofibers in between subendocardial and subepicardial layers. In this study, we used a finite-element model of left ventricular (LV) mechanics to investigate the sensitivity of midwall circumferential-radial shear strain ( Ecr) to settings of parameters determining passive shear stiffness, cross-fiber active stress development, and transmural crossover of myofibers. Simulated time courses of midwall LV Ecrwere compared with time courses obtained in three healthy volunteers using MRT. Ecras measured in the volunteers during the cardiac cycle was characterized by an amplitude of ∼0.1. In the simulations, a realistic amplitude of the Ecrsignal could be obtained by tuning either of the three model components mentioned above. However, a realistic time course of Ecr, with virtually no change of Ecrduring isovolumic contraction and a correct base-to-apex gradient of Ecrduring ejection, could only be obtained by including transmural crossover of myofibers. Thus, accounting for this crossover seems to be essential for a realistic model of LV wall mechanics.
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Tripp, D. E., J. H. Hemann, and J. P. Gyekenyesi. "A Review of Failure Models for Ceramic Matrix Composite Laminates Under Monotonic Loads." Journal of Engineering for Gas Turbines and Power 112, no. 4 (October 1, 1990): 492–501. http://dx.doi.org/10.1115/1.2906194.

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Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short-term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.
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Molina Herrera, Maritzabel, and Javier Alberto Ortíz Porras. "Behavior of cold-formed thin steel sections (MM) under concentrated loads." Ingeniería e Investigación 26, no. 3 (September 1, 2006): 12–25. http://dx.doi.org/10.15446/ing.investig.v26n3.14744.

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New sections are continually being developed in the cold-formed steel world to improve the performance of existing sections. M-section development provides an example of improving C-sections’ shear resistance and web crippling resistance against C-sections’ concentrated loads. C-sections’ shear nominal strength can be achieved through locating tow web intermediate stiffeners (M-sections) even though web crippling resistance cannot be increased in the same way. Such intermediate stiffeners mean that M-section stresses and deflections cannot be analysed with traditional material mechanics. Concentrated loads cause this behavior to become increased; 4 different models and 3 tests for each of them were thus developed, as well as determining M-sections’ theoretical resistance (based on 1996 AISI). The values obtained corresponded to maximum resistance load, visual identification of any possible type of failure, deflections (at middle span) and deformations (εx, εy, εxy). Mathematical models were also used for comparing the finite element method and simplified mathematical models’ test results for a detailed review of MM-section stress and deformation. These models were calibrated on the test results. After the failure mode was identified for each model, MM-section maximum resistance load was compared to nominal load (according to AISI formulation, also aiding formulating nominal strength calculation). The information obtained from tests and mathematical models was analysed to observe parameter (∆, σ y T) tendencies respecting applied load (P). Cyclic tests under pseudo-static loads were performed to study MM-sections’ hysteretic behavior.
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Solovei, Vladislav, Аnton Karvatskii, Taras Lazarev, Іgor Mikulionok, and Iryna Omelchuk. "Determination of the mechanical properties of 3d-printed polymer products by methods of structural mechanics." Proceedings of the NTUU “Igor Sikorsky KPI”. Series: Chemical engineering, ecology and resource saving, no. 2 (June 28, 2021): 16–32. http://dx.doi.org/10.20535/2617-9741.2.2021.235853.

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Mathematical models of stress-strain state (SSS) for modeling tests of polymer composite samples obtained by fused deposition modeling (FDM) in approximations of isotropic and orthotropic media are formulated. An algorithm for solving the inverse SSS problem to determine the effective mechanical properties in the orthotropic approximation of composite products printed by the FDM method has been developed. Numerical models have been developed to solve inverse SSS problems to determine the effective orthotropic mechanical properties of composite products with different degrees of reinforcement, obtained using additive technologies based on the FDM method. The grid convergence of the developed numerical models by the method of double recalculation is investigated. It is established that the used mesh of geometric models of product samples leads to errors in determining the vector of the modulus of elasticity in the range of 0–3.19%, and the vector of the shear modulus does not exceed 0.05–0.2%. Numerical experiments to determine the effective mechanical properties of samples of composite polymeric materials in the approximation of orthotropic homogeneous medium were performed. The obtained results are compared with the data of calculations by analytical dependences to determine the effective mechanical properties of composite materials. It is shown that the results of numerical studies agree satisfactorily with the corresponding data obtained from analytical dependences in the range of 0.081–5.696%. It is established that all three components of the vectors of modulus of elasticity and shear increase with the degree of reinforcement. The largest increase is observed for the components of vectors and , which is due to the reinforcement in the direction , and the difference between the values ​​of the components of vectors and and and is due to the cross-sectional asymmetry of the strand. Dependences for operative prediction of effective orthotropic mechanical properties of composites based on PLA + KEVLAR 29 within the limits of change in the volume fraction of reinforcing fibers up to 5% are obtained. To develop new composite materials with predetermined properties, it is not necessary to perform multivariate, rather complex and cumbersome numerical experiments in solving the inverse SSS problem.
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Faddeev, Alexander O., Svetlana A. Pavlova, and Tatiana M. Nevdakh. "Mathematical Models and Evaluation Software for Stress-Strain State of the Earth’s Lithosphere." Engineering Technologies and Systems, no. 1 (March 29, 2019): 51–66. http://dx.doi.org/10.15507/2658-4123.029.201901.051-066.

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Introduction. For the purposes of this article, geodeformation processes mean processes associated with deformations arising from the movement of species and blocks of the lithosphere at various depths, including surfaces. The objective is to reconstruct geodynamic stress fields, which cause modern shifts and deformations in the Lithosphere. A mathematical model and software for estimating the stress-strain state of the Earth Lithosphere are considered. Materials and Methods.For mathematical modeling of stresses, isostatically reduced data on abnormal gravitation field were used. The methods of continuum mechanics and methods of the theory of differential equations were used to design a model for estimating the stressstrain state of the Earth Lithosphere. For processing input, intermediate and outcoming data, the Fourier transform method of spectral analysis for constructing grid functions and spectral-temporal method were used. To model for the stress-strain state of the Lithosphere globally, stress calculation was corrected on the basis of sputnik-derived velocity data at the surface of the earth crust. The data on the rates of horizontal and vertical movements at the surface of the Earth crust were processed to obtain a distribution of velocities in the uniform grid embracing longitudes and latitudes. The processing procedure was carried out on the basis of the Kraiging method. The software was developed in Borland Delphi 7.0 programming environment. Results. Based on the data on the abnormal gravitation field in isostatic reduction and information on the distribution of velocities of horizontal motions on the surface of the Earth crust, a mathematical model of the stress-strain state of the Lithosphere was constructed. With the help of the obtained mathematical model and software complex, the stress-strain state of the Lithosphere was calculated at various depth using elastic and elastic-viscous models, and maps of equipotential distribution of shear elastic-viscous deformations in the lithosphere at the depth of 10 km were constructed. Discussion and Conclusion. The presented mathematical model and software allow restoring fields of both elastic and elastic-viscous deformations that is fundamental for quantification of elastic-viscous shear stresses deep in the Earth Lithosphere.
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Theret, D. P., M. J. Levesque, M. Sato, R. M. Nerem, and L. T. Wheeler. "The Application of a Homogeneous Half-Space Model in the Analysis of Endothelial Cell Micropipette Measurements." Journal of Biomechanical Engineering 110, no. 3 (August 1, 1988): 190–99. http://dx.doi.org/10.1115/1.3108430.

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Experimental studies have shown that endothelial cells which have been exposed to shear stress maintain a flattened and elongated shape after detachment. Their mechanical properties, which are studied using the micropipette experiments, are influenced by the level as well as the duration of the shear stress. In the present paper, we analyze these mechanical properties with the aid of two mathematical models suggested by the micropipette technique and by the geometry peculiar to these cells in their detached post-exposure state. The two models differ in their treatment of the contact zone between the cell and the micropipette. The main results are expressions for an effective Young’s modulus for the cells, which are used in conjunction with the micropipette data to determine an effective Young’s modulus for bovine endothelial cells, and to discuss the dependence of this modulus upon exposure to shear stress.
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Burmistrova, Olga, Elena Teterevleva, Igor Grigorev, O. Kunitskaya, Andrey Manukovskiy, Sergey Rudov, and Dmitriy Vostrikov. "BASIS OF MATHEMATICAL INTERACTION MODELS OF WHEEL PROPELLERS OF FORESTRY MACHINES WITH SLIDING SURFACES." Forestry Engineering Journal 10, no. 1 (April 6, 2020): 173–84. http://dx.doi.org/10.34220/issn.2222-7962/2020.1/22.

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The purpose of the research, the results of which are presented in this article, is to analyze the scientific description of the properties of weak bearing movement surfaces of forest machines. The analysis has showed that universal mathematical models of the wheel propeller interaction with soil are based on the provisions of soil mechanics. This approach has been tested in the science of forestry production. It is successfully used by modern domestic and foreign researchers. However, with regard to the development and implementation of a mathematical description of interaction of ultra-low pressure wheeled mover (for example, in all-terrain wheeled vehicle) with supporting surfaces, it is necessary to take into account the ratio of the sides of the mover’s contact spot with the soil, since: mover pressure on the ground is defined as the partial load of a single mover and the area contact spots; the distribution of compressive stress over the depth of the soil mass depends on the ratio of the length and width of the contact spot; the bearing capacity characterizing the resistance to shear of the soil layers depends not only on its physical and mechanical properties, but also on the parameters of the contact spot, which is taken into account by special correction factors, the values of which depend on the aspect ratio of the contact spot. Soil rheology is considered to take into account the number of passes of a wheeled all-terrain vehicle along the route and its speed. One of the characteristics of the impact of the mover is exposure time. Value of the length of the contact spot is also used when determining the impact time of the mover on the soil.
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Burova, Iva, Ivan Wall, and Rebecca J. Shipley. "Mathematical and computational models for bone tissue engineering in bioreactor systems." Journal of Tissue Engineering 10 (January 2019): 204173141982792. http://dx.doi.org/10.1177/2041731419827922.

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Research into cellular engineered bone grafts offers a promising solution to problems associated with the currently used auto- and allografts. Bioreactor systems can facilitate the development of functional cellular bone grafts by augmenting mass transport through media convection and shear flow-induced mechanical stimulation. Developing successful and reproducible protocols for growing bone tissue in vitro is dependent on tuning the bioreactor operating conditions to the specific cell type and graft design. This process, largely reliant on a trial-and-error approach, is challenging, time-consuming and expensive. Modelling can streamline the process by providing further insight into the effect of the bioreactor environment on the cell culture, and by identifying a beneficial range of operational settings to stimulate tissue production. Models can explore the impact of changing flow speeds, scaffold properties, and nutrient and growth factor concentrations. Aiming to act as an introductory reference for bone tissue engineers looking to direct their experimental work, this article presents a comprehensive framework of mathematical models on various aspects of bioreactor bone cultures and overviews modelling case studies from literature.
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Dissertations / Theses on the topic "Shear (Mechanics) – Mathematical models"

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Luo, Sai, and 罗赛. "Fabric evolution of two-dimensional idealized particle assemblage during shear." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B49799721.

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Microstructure or fabric definitely affects macroscopic mechanical behavior of granular material. It is also well-observed that fabric evolves with shearing or plastic deformation. In this study, a series of two-dimensional numerical direct shear tests are carried out with the discrete element method, to study the initial fabric effect on global material responses and their micro-macroscopic relations. Idealized particle assemblages are made up of mono-size elongated particles and are prepared by a “deposition” method. Elongated particle is modeled by the built-in clump logic, in which constitutive balls are joined together without further breakage. In the deposition method, there are three controlling parameters, including, deposited direction, inter-particle friction coefficient and particle number, to prepare specimens with similar initial density but different initial packing or fabric. Three types of fabric of particle assemblages are examined quantitatively and are monitored during shearing, including, particle orientations (PO), contact normal forces (NF), and void spaces (VS). These fabric distributions are described by two parameters―anisotropic degree ( ) and orientation angle ( ), with clear physical implications. An additional parameter ( ) describing the average size of voids, is used to quantify void perimeter. It is found that this parameter has a relation with the assemblage’s volumetric response. C With the systematic and meticulous quantification method, the linkage between the macroscopic and microscopic responses of particle assemblages is discussed quantitatively. The results show that the initial packing affects the shear zone thickness, initial stiffness, peak strength, and dilation rate. In the shear zone, particle orientations do not exhibit a unique state at the final stage of direct shearing. At that state, strong normal forces and strong voids are parallel to the major principal stress direction. It seems that the initial packing does not affect their final distributions. At the end of reverse shearing, strong voids and strong normal forces in the shear zone give an essentially unique state, and their preferential directions are related to the changed loading direction. However, apparent stable particle orientations are still affected by the initial fabric.
published_or_final_version
Civil Engineering
Master
Master of Philosophy
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PRUETT, CHARLES DAVID. "NUMERICAL SIMULATION OF NONLINEAR WAVES IN FREE SHEAR LAYERS (MIXING, COMPUTATIONAL, FLUID DYNAMICS, HYDRODYNAMIC STABILITY, SPATIAL, FLUID FLOW MODEL)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183869.

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A numerical model has been developed which simulates the three-dimensional stability and transition of a periodically forced free shear layer in an incompressible fluid. Unlike previous simulations of temporally evolving shear layers, the current simulations examine spatial stability. The spatial model accommodates features of free shear flow, observed in experiments, which in the temporal model are precluded by the assumption of streamwise periodicity; e.g., divergence of the mean flow and wave dispersion. The Navier-Stokes equations in vorticity-velocity form are integrated using a combination of numerical methods tailored to the physical problem. A spectral method is adopted in the spanwise dimension in which the flow variables, assumed to be periodic, are approximated by finite Fourier series. In complex Fourier space, the governing equations are spatially two-dimensional. Standard central finite differences are exploited in the remaining two spatial dimensions. For computational efficiency, time evolution is accomplished by a combination of implicit and explicit methods. Linear diffusion terms are advanced by an Alternating Direction Implicit/Crank-Nicolson scheme whereas the Adams-Bashforth method is applied to convection terms. Nonlinear terms are evaluated at each new time level by the pseudospectral (collocation) method. Solutions to the velocity equations, which are elliptic, are obtained iteratively by approximate factorization. The spatial model requires that inflow-outflow boundary conditions be prescribed. Inflow conditions are derived from a similarity solution for the mean inflow profile onto which periodic forcing is superimposed. Forcing functions are derived from inviscid linear stability theory. A numerical test case is selected which closely parallels a well-known physical experiment. Many of the aspects of forced shear layer behavior observed in the physical experiment are captured by the spatial simulation. These include initial linear growth of the fundamental, vorticity roll-up, fundamental saturation, eventual domination of the subharmonic, vortex pairing, emergence of streamwise vorticity, and temporary stabilization of the secondary instability. Moreover, the spatial simulation predicts the experimentally observed superlinear growth of harmonics at rates 1.5 times that of the fundamental. Superlinear growth rates suggest nonlinear resonances between fundamental and harmonic modes which are not captured by temporal simulations.
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Amany, Aya Nicole Marie. "Characterization of shear and bending stiffness for optimizing shape and material of lightweight beams." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112553.

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Optimized slender and short-thick beams are used in building, aircraft and machine structures to increase performance at a lower material cost. A previous work proposes an optimum shape, material and size selection model to design lightweight slender beams under pure bending. In short-thick beams, the transverse shear effects are no longer negligible and impact the choice of the optimum shape. This work extends such an optimum selection model to consider both slender and short-thick beams, by formulating the total beam stiffness design requirement as a combination of shear and bending stiffness. Selection charts are developed to show the impact of design variables, such as shape, size, material and slenderness, on the total beam stiffness. The model of total beam stiffness is validated against computational results from finite element analyses of beam models. A case study demonstrates the use of the selection charts to compare the performance of beams at the conceptual design stage.
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Reimnitz, Marc. "Shear-slip induced seismic activity in underground mines : a case study in Western Australia." University of Western Australia. School of Civil and Resource Engineering, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0062.

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Mining induced seismic activity and rockbursting are critical concerns for many underground operations. Seismic activity may arise from the crushing of highly stressed volumes of rock around mine openings or from shear motion on planes of weakness. Shear-slip on major planes of weakness such as faults, shear zones and weak contacts has long been recognized as a dominant mode of failure in underground mines. In certain circumstances, it can generate large seismic events and induce substantial damage to mine openings. The Big Bell Gold mine began experiencing major seismic activity and resultant damage in 1999. Several seismic events were recorded around the second graphitic shear between April 2000 and February 2002. It is likely that the seismic activity occurred as a result of the low strength of the shear structure combined with the high level of mining induced stresses. The stability of the second graphitic shear was examined in order to gain a better understanding of the causes and mechanisms of the seismic activity recorded in the vicinity of the shear structure as mining advanced. The data were derived from the observation of the structure exposures, numerical modelling and seismic monitoring. The numerical modelling predictions and the interpreted seismic monitoring data were subsequently compared in order to identify potential relationships between the two. This thesis proposes the Incremental Work Density (IWD) as a measure to evaluate the relative likelihood of shear-slip induced seismic activity upon major planes of weakness. IWD is readily evaluated using numerical modelling and is calculated as the product of the average driving shear stress and change in inelastic shear deformation during a given mining increment or step. IWD is expected to correlate with shear-slip induced seismic activity in both space and time. In this thesis, IWD was applied to the case study of the second graphitic shear at the Big Bell mine. Exposures of the second graphitic shear yielded information about the physical characteristics of the structure and location within the mine. Numerical modelling was used to examine the influence of mining induced stresses on the overall behaviour of the shear structure. A multi-step model of the mine was created using the three- dimensional boundary element code of Map3D. The shear structure was physically incorporated into the model in order to simulate inelastic shear deformation. An elasto-plastic Mohr-Coulomb material model was used to describe the structure behaviour. The structure plane was divided into several elements in order to allow for the comparison of the numerical modelling predictions and the interpreted seismic data. Stress components, deformation components and IWD values were calculated for each element of the shear structure and each mining step. The seismic activity recorded in the vicinity of the second graphitic shear was back analysed. The seismic data were also gridded and smoothed. Gridding and smoothing of individual seismic moment and seismic energy values resulted in the definition of indicators of seismic activity for each element and mining step. The numerical model predicted inelastic shear deformation upon the second graphitic shear as mining advanced. The distribution of modelled IWD suggested that shear deformation was most likely seismic upon a zone below the stopes and most likely aseismic upon the upper zone of the shear structure. The distribution of seismic activity recorded in the vicinity of the shear structure verified the above predictions. The seismic events predominantly clustered upon the zone below the stopes. The results indicated that the seismic activity recorded in the vicinity of the second graphitic shear was most likely related to both the change in inelastic shear deformation and the level of driving shear stress during mechanical shearing. Time distribution of the seismic events also indicated that shear deformation and accompanying seismic activity were strongly influenced by mining and were time-dependant. Seismic activity in the vicinity of the second graphitic shear occurred as a result of the overall inelastic shear deformation of the shear structure under mining induced stresses. A satisfactory relationship was found between the spatial distribution of modelled IWD upon the shear structure and the spatial distribution of interpreted seismic activity (measured as either smoothed seismic moment or smoothed seismic energy). Seismic activity predominantly clustered around a zone of higher IWD upon the second graphitic shear as mining advanced. However, no significant statistical relationship was found between the modelled IWD and the interpreted seismic activity. The lack of statistical relationship between the modelled and seismic data may be attributed to several factors including the limitations of the techniques employed (e.g. Map3D modelling, seismic monitoring) and the complexity of the process involved.
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Stephens, Max Taylor. "Numerical and Experimental Analysis of Composite Sandwich Links for the LCF System." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/579.

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Shear links are used as fuse elements in lateral load resisting systems to provide ductility and dissipate seismic energy. These links have traditionally been employed in eccentrically braced frames, but have more recently been suggested for use in the innovative linked column frame system (LCF). Current design specifications for shear links require intermediate web stiffeners to provide out-of-plane web stability so ductility requirements can be achieved. This research focused on moving from discrete transverse web stiffening to continuously stiffened webs in built up shear links. Built up links were designed to yield in shear when subjected to severe cyclic loading, however the webs of the links were designed using two metal sheets joined by an elastic core. These composite "sandwich" webs allowed for an increase in web thickness (and inherent flexural rigidity) without increasing the shear strength of the links. Numerical and experimental investigations were conducted to assess the performance of composite sandwich links subjected to severe loading. Numerical results showed improved web behavior in sandwich links in which the core material was assigned an elastic modulus greater than 5000psi. Due to fabrication limitations, experimental specimens were fabricated with a core material elastic modulus of 1000psi. These specimens did not perform as well as unstiffened base case links in terms global hysteretic behavior or ductility.
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To, Chiu-yin, and 杜昭彥. "A unified elasto-plastic model for saturated loosely compacted completely decomposed granite." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203554.

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Wayman, Brian H. "Arterial Response to Local Mechanical Variables: The Effects of Circumferential and Shear Stress." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22611.

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Arteries respond to changes in global mechanical parameters (pressure, flow rate, and longitudinal stretching) by remodeling to restore local parameters (circumferential stress, shear stress, and axial strain) to baseline levels. Because a change in a single global parameter results in changes of multiple local parameters, the effects of individual local parameters on remodeling remain unknown. This study uses a novel approach to study remodeling in organ culture based on independent control of local mechanical parameters. The approach is illustrated by studying the effects of circumferential and shear stress on remodeling-related biological markers. Porcine carotid arteries were cultured for three days at a circumferential stress of 50 kPa or 150 kPa or, in separate experiments, a shear stress of 0.75 Pa or 2.25 Pa. At high circumferential stress, matrix synthesis, smooth muscle cell proliferation, and cell death are significantly greater, but matrix metalloproteinase-2 (MMP-2) and pro-MMP-2 activity are significantly less. In contrast, biological markers measured were unaffected by shear stress. Applications of the proposed approach for improved understanding of remodeling, optimizing mechanical conditioning of tissue engineered arteries, and selection of experimentally motivated growth laws are discussed.
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Evans, T. Matthew. "Microscale Physical and Numerical Investigations of Shear Banding in Granular Soils." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7576.

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Under loading conditions found in many geotechnical structures, it is common to observe failure in zones of high localized strain called shear bands. Existing models predict these localizations, but provide little insight into the micromechanics within the shear bands. This research captures the variation in microstructure inside and outside of shear bands that were formed in laboratory plane strain and two-dimensional discrete element method (DEM) biaxial compression experiments. Plane strain compression tests were conducted on dry specimens of Ottawa 20-30 sand to calibrate the device, assess global response repeatability, and develop a procedure to quantitatively define the onset of localization. A new methodology was employed to quantify and correct for the additional stresses imparted by the confining membrane in the vicinity of the shear band. Unsheared and sheared specimens of varying dilatancy were solidified using a two-stage resin impregnation procedure. DEM tests were performed using an innovative servo-controlled flexible lateral confinement algorithm to provide additional insights into laboratory results. The solidified specimens were sectioned and the resulting surfaces prepared for microstructure observation using bright field microscopy and morphological analysis. Local void ratio distributions and their statistical properties were determined and compared. Microstructural parameters for subregions in a grid pattern and along predefined inclined zones were also calculated. Virtual surfaces parallel to the shear band were identified and their roughnesses assessed. Similar calculations were performed on the DEM simulations at varying strain levels to characterize the evolution of microstructure with increasing strain. The various observations showed that the mean, standard deviation, and entropy of the local void ratio distributions all increased with increasing strain levels, particularly within regions of high local strains. These results indicate that disorder increases within a shear band and that the soil within the shear band does not adhere to the classical concept of critical state, but reaches a terminal void ratio that is largely a function of initial void ratio. Furthermore, there appears to be a transition zone between the far field and the fully formed shear block, as opposed to an abrupt delineation as traditionally inferred.
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Pinilla, Camilo Ernesto. "Numerical simulation of shear instability in shallow shear flows." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115697.

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The instabilities of shallow shear flows are analyzed to study exchanges processes across shear flows in inland and coastal waters, coastal and ocean currents, and winds across the thermal-and-moisture fronts. These shear flows observed in nature are driven by gravity and governed by the shallow water equations (SWE). A highly accurate, and robust, computational scheme has been developed to solve these SWE. Time integration of the SWE was carried out using the fourth-order Runge-Kutta scheme. A third-order upwind bias finite difference approximation known as QUICK (Quadratic Upstream Interpolation of Convective Kinematics) was employed for the spatial discretization. The numerical oscillations were controlled using flux limiters for Total Variation Diminishing (TVD). Direct numerical simulations (DNS) were conducted for the base flow with the TANH velocity profile, and the base flow in the form of a jet with the SECH velocity profile. The depth across the base flows was selected for the' balance of the driving forces. In the rotating flow simulation, the Coriolis force in the lateral direction was perfectly in balance with the pressure gradient across the shear flow during the simulation. The development of instabilities in the shear flows was considered for a range of convective Froude number, friction number, and Rossby number. The DNS of the SWE has produced linear results that are consistent with classical stability analyses based on the normal mode approach, and new results that had not been determined by the classical method. The formation of eddies, and the generation of shocklets subsequent to the linear instabilities were computed as part of the DNS. Without modelling the small scales, the simulation was able to produce the correct turbulent spreading rate in agreement with the experimental observations. The simulations have identified radiation damping, in addition to friction damping, as a primary factor of influence on the instability of the shear flows admissible to waves. A convective Froude number correlated the energy lost due to radiation damping. The friction number determined the energy lost due to friction. A significant fraction of available energy produced by the shear flow is lost due the radiation of waves at high convective Froude number. This radiation of gravity waves in shallow gravity-stratified shear flow, and its dependence on the convective Froude number, is shown to be analogous to the Mach-number effect in compressible flow. Furthermore, and most significantly, is the discovery from the simulation the crucial role of the radiation damping in the development of shear flows in the rotating earth. Rings and eddies were produced by the rotating-flow simulations in a range of Rossby numbers, as they were observed in the Gulf Stream of the Atlantic, Jet Stream in the atmosphere, and various fronts across currents in coastal waters.
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Guvenen, Haldun. "Aerodynamics of bodies in shear flow." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184917.

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This dissertation investigates spanwise periodic shear flow past two-dimensional bodies. The flow is assumed to be inviscid and incompressible. Using singular perturbation techniques, the solution is developed for ε = L/ℓ ≪ 1, where L represents body cross-sectional size, and ℓ the period of the oncoming flow U(z). The singular perturbation analysis involves three regions: the inner, wake and outer regions. The leading order solutions are developed in all regions, and in the inner region higher order terms are obtained. In the inner region near the body, the primary flow (U₀, V₀, P₀) corresponds to potential flow past the body with a local free stream value of U(z). The spanwise variation in U(z) produces a weak O(ε) secondary flow W₁ in the spanwise direction. As the vortex lines of the upstream flow are convected downstream, they wrap around the body, producing significant streamwise vorticity in a wake region of thickness O(L) directly behind the body. This streamwise vorticity induces a net volume flux into the wake. In the outer region far from the body, a nonlifting body appears as a distribution of three-dimensional dipoles, and the wake appears as a sheet of mass sinks. Both singularity structures must be included in describing the leading outer flow. For lifting bodies, the body appears as a lifting line, and the wake appears as a sheet of shed vorticity. The trailing vorticity is found to be equal to the spanwise derivative of the product of the circulation and the oncoming flow. For lifting bodies the first higher order correction to the inner flow is the response of the body to the downwash produced by the trailing vorticity. At large distances from the body, the flow takes on remarkably simple form.
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Books on the topic "Shear (Mechanics) – Mathematical models"

1

A mathematical analysis of bending of plates with transverse shear deformation. Harlow, Essex, England: Longman Scientific & Technical, 1990.

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Obaia, K. H. Inelastic transverse shear capacity of large fabricated steel tubes. Edmonton, Alta., Canada: Dept. of Civil Engineering, University of Alberta, 1991.

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Whyatt, J. K. Numerical exploration of shear-fracture-related rock bursts using a strain-softening constitutive law. Washington: U.S. Dept. of the Interior, Bureau of Mines, 1991.

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Wang, C. M. Shear deformable beams and plates: Relationships with classical solutions. Amsterdam: Elsevier, 2000.

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Hou, Changbao. Rechnerische Untersuchungen zum Querkrafttragverhalten bei verbundlos vorgespannten Betonbalken. Aachen: Verlag Shaker, 1992.

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Reddy, J. N. A refined shear deformation theory for the analysis of laminated plates. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1986.

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Sturm, Terry W. Estimating critical shear stress of bed sediment for improved prediction of bridge contraction scour in Georgia: Final report. Forest Park, Ga.]: Dept. of Transportation, Office of Materials and Research, 2008.

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Priour, D. Genèse des zones de cisaillement: Application de la méthode des éléments finis à la simulation numérique de la déformation des roches. Rennes, France: Centre armoricain d'étude structurale des socles, Université de Rennes I, 1985.

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Andaluzia, Matei, ed. Mathematical models in contact mechanics. New York: Cambridge University Press, 2012.

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Mathematical models in applied mechanics. Oxford: Clarendon Press, 1986.

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Book chapters on the topic "Shear (Mechanics) – Mathematical models"

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Wang, Wei, Ting Hao Lu, and Bin Xiang Sun. "Mathematical Model for Shear Stress-Strain Relationship of Soil-Concrete Interface during Shear Fracture Process." In Advances in Fracture and Damage Mechanics VI, 881–84. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-448-0.881.

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Chapelle, Dominique, and Klaus-Jürgen Bathe. "Shell Mathematical Models." In Computational Fluid and Solid Mechanics, 95–134. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-16408-8_4.

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Chapelle, Dominique, and Klaus-Jürgen Bathe. "Shell Mathematical Models." In Computational Fluid and Solid Mechanics, 81–114. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-05229-7_4.

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Miara, Bernadette. "Mathematical Justifications of Plate Models." In Encyclopedia of Continuum Mechanics, 1–9. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53605-6_138-1.

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Miara, Bernadette. "Mathematical Justifications of Plate Models." In Encyclopedia of Continuum Mechanics, 1514–22. Berlin, Heidelberg: Springer Berlin Heidelberg, 2020. http://dx.doi.org/10.1007/978-3-662-55771-6_138.

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Zin, W. A., and R. F. M. Gomes. "Mathematical Models in Respiratory Mechanics." In Anaesthesia, Pain, Intensive Care and Emergency Medicine — A.P.I.C.E., 391–400. Milano: Springer Milan, 1996. http://dx.doi.org/10.1007/978-88-470-2203-4_34.

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Serovajsky, Simon. "Mathematical models of fluid and gas mechanics." In Mathematical Modelling, 261–78. Boca Raton: Chapman and Hall/CRC, 2021. http://dx.doi.org/10.1201/9781003035602-14.

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Surana, Karan S. "Thermodynamic Relations and Complete Mathematical Models." In Classical Continuum Mechanics, 441–56. 2nd ed. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003105336-15.

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Bellomo, Nicola, Luigi Preziosi, and Antonio Romano. "Models and Mathematical Problems." In Mechanics and Dynamical Systems with Mathematica®, 19–55. Boston, MA: Birkhäuser Boston, 2000. http://dx.doi.org/10.1007/978-1-4612-1338-3_2.

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Petrina, D. Ya. "Exactly Solvable Models." In Mathematical Foundations of Quantum Statistical Mechanics, 307–400. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0185-1_6.

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Conference papers on the topic "Shear (Mechanics) – Mathematical models"

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Yoder, Jonathon H., Heath B. Henninger, Jeffrey A. Weiss, and Dawn M. Elliott. "Annulus Fibrosus Shear Properties Are Consistent With Motion Segment Mechanics When Fibers Are Loaded." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206833.

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The annulus fibrosus (AF) is a highly organized structure made up of concentric lamellae of fibers embedded in a hydrated extrafibrillar matrix; the collagen fibers are oriented at alternating angles in each lamella. The AF undergoes multidirectional loading through combinations of compression, bending, torsion and shear of the motion segment. The composition and structure of the AF leads to mechanical stress-strain nonlinearity and anisotropy. Previous tissue-based studies of shear have tested the AF tissue under compressive simple shear and torsion, producing shear modulus on the order of 0.06–0.4 MPa [1, 2]. However, structural testing and mathematical models of the IVD have reported the shear modulus to be between 3–20 MPa [3–6]. We hypothesize that when the fibers of the AF are loaded the shear modulus will be on the same order as structural tests and mathematical models of the IVD. The objectives of this study are to measure the shear mechanical properties of the bovine outer AF and compare the regional variances between anterior and posterior AF.
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Lortz, Wolfgang, and Radu Pavel. "Fundamental Process Mechanics Common to Machining and Grinding Operations." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8371.

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Abstract All different production processes have one thing in common: in each case a workpiece with characteristic material behavior, stress, strain, self-hardening and temperature will be produced by a tool with special geometry and individual kinematic conditions, with a wide range of energy in a designed machine tool which is working along programmed lines. For the workpiece material, it is not important from which machine the energy is coming. To be able to predict more accurate values of the production process, it will be necessary to focus more on the complex and difficult process mechanics. The result must have a strong physical base and be in good agreement with practical results To solve these problems, we have to uncover all previous simplification assumptions for the existing models. This leads in a first step to a new fundament in process mechanics, which is only based on mathematics, physics and material behavior with friction conditions, and resulting temperatures during metal plastic flow. The new mathematical equations developed for yield shear stress and strain rate will be presented and discussed in this paper. The plastic deformation is the only parameter that will not disappear after completing the operation. Therefore, this will be the base to compare the developed theoretical deformation with the experimental results for two operations: cutting and grinding. In addition, it could be shown that yield shear stress and corresponding strain rate versus temperatures have an interdependent relationship, which creates the opportunity to determine the temperatures during metal plastic flow.
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Tripp, David E., John H. Hemann, and John P. Gyekenyesi. "A Review of Failure Models for Ceramic Matrix Composite Laminates Under Monotonic Loads." In ASME 1989 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/89-gt-153.

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Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.
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Lortz, Wolfgang, and Radu Pavel. "Advanced Modeling of Drilling – Realistic Process Mechanics Leading to Helical Chip Formation." In ASME 2021 16th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/msec2021-63790.

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Abstract There is considerable interest in the “Industry 4.0 project”. Industry hopes that a general solution of the metal removal problem will be found through the use of highly automated manufacturing data. Scientists hope that the computer will provide better models based on artificial intelligence and machine learning. Initial attempts leveraging existing models did not result in satisfactory results yet — largely because of mathematical, physical and metallurgical reasons. This paper presents a new mathematical-physical model to describe the total process mechanics from volume conservation, to friction, to metal plasticity with self-hardening or softening effects and dynamic phenomena during metal plastic flow. The softening effects are created by high energy corresponding to high strain-rate resulting in high temperatures. Furthermore, the developed equations for strain-rate discontinuities as well as yield shear stress with body forces have an interdependent relationship and lead to plastic deformation with dynamic behavior in the total chip formation zone. This plastic deformation is the only parameter that will not disappear after completing the process. This leads to the opportunity to check the theoretically developed grid deformation and compare it with practical results of the same area. In this publication this new theory will be used to analyze the complex contact and friction conditions between the chip and tool edge of a twist drill during operation. It will be shown that the existing conditions are leading to high wear at the corner edge and flank wear at the tool cutting edge. In addition, the existing temperatures can be estimated and compared with practical measurements, and all these complex and difficult conditions create a helical spiral chip, which could be developed as it will be presented in this paper.
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Sambhav, Kumar, Puneet Tandon, Shiv G. Kapoor, and Sanjay G. Dhande. "Mathematical Modeling of Cutting Forces in Micro-Drilling." In ASME 2012 International Manufacturing Science and Engineering Conference collocated with the 40th North American Manufacturing Research Conference and in participation with the International Conference on Tribology Materials and Processing. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/msec2012-7399.

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In drilling, the primary cutting lips and the secondary cutting lips of the drill shear the material while the central portion of the chisel edge indents the workpiece, making the cutting process complex to understand. As we go for micro-drilling, it exhibits an added complexity to the cutting mechanism when the edge radius gets comparable to chip thickness at low feeds. The presented work models the forces by the primary cutting lip of a micro-drill analytically using slip-line field that includes the changes in the effective rake angle and dead metal cap during cutting for cases of shearing as well as ploughing. To study the variation of forces experimentally, the primary cutting lip and chisel edge forces are separated out by drilling through pilot holes of diameter slightly above the drill-web thickness. Finally, the analytical and experimental results have been compared and the model has been calibrated.
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Reckmann, Hanno, Pushkar Jogi, and Christian Herbig. "Using Dynamics Measurements While Drilling to Detect Lithology Changes and to Model Drilling Dynamics." In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29710.

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As a result of bit-rock interaction, downhole weight-on-bit, downhole torque, instantaneous downhole rotational speed and bit motion (acceleration and rate of penetration) are directly affected by the formations being drilled. Since these measurements react differently to different lithologies, and assuming that drilling problems do not effect these measurements, any changes in the measurements in some way will reflect changes in the properties of the lithology. If, based on these measurements, the lithology is assumed to have certain properties, then it is possible to derive models for the interaction between bit, formation and drillstring. With these models it is possible to simulate the dynamic behavior of the system including phenomena like stick-slip. Rate of penetration has long been used as a lithology indicator, and drilling models have been developed using surface measured drilling parameters to infer changes in lithology. With the advent of MWD measurements, significant improvements were made in the mathematical models by involving downhole torque. The model derived parameters were shown to be related to rock strength (drilling and shear strength) and proved to be good indicators of formation changes. Similar expressions in the form of simple bit models can be used in combination with a finite element model of the drillstring to simulate the dynamic behavior of the complete system. A significant improvement in this analysis can be affected by introducing measurements from the dynamics tool, such as instantaneous torque, weight and rotation rate, as well as the bit acceleration. These measurements provide not only static but also dynamic data which can be used to validate simulations and the underlying models. The present analysis explores the use of the dynamic measurements and the application of some drilling models in analyzing formation changes while drilling, and the use of these data and models in simulating drilling dynamics.
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Sisemore, Carl L., Ahmad A. Smaili, and Corinne M. Darvennes. "Experimental Measurement of Compressional Damping in an Elastic-Viscoelastic-Elastic Sandwich Beam." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0202.

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Abstract This article presents the results of an experimental investigation into the compressional vibration in an elastic-viscoelastic-elastic three-layer sandwich beam. The fundamental assumption of most of the current mathematical models is that shear deformation results in the largest energy losses for damping while compressional damping is negligible. In this experiment the relative displacements of the base beam and the constraining layer were measured directly to determine the amount of compression in the viscoelastic core. The experiment showed a maximum difference of 25% between the base beam and constraining layer motions. This suggests that neglecting compressional damping in the mathematical model is an erroneous assumption under most circumstances.
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Tsepelev, I. A., and A. I. Korotkii. "Computational modelling of lava flows in multiphase fluid models with temperature- and shear rate-dependent rheology." In PROCEEDINGS OF THE X ALL-RUSSIAN CONFERENCE “Actual Problems of Applied Mathematics and Mechanics” with International Participation, Dedicated to the Memory of Academician A.F. Sidorov and 100th Anniversary of UrFU: AFSID-2020. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0035525.

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Topcu, Okan, Yigit Tascioglu, and Erhan Ilhan Konukseven. "A Novel Rotary Magneto-Rheological Damper for Haptic Interfaces." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50979.

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Haptic interfaces require lightweight, small actuators with high force capability and low friction. In this paper, based on the structure of conventional shear mode disc and drum type MR fluid dampers, a lightweight continuous rotary MR damper working in valve mode is designed for haptic interfaces. The proposed design is compared to shear mode disc-type and drum-type designs with similar torque–to–mass ratio via computer simulations. Mathematical models for the resistant torques of both the shear mode and the valve mode are derived. Subsequently, the finite element analysis of electromagnetic circuit calculations was carried out by FEMM software to perform an optimization of the dimensions of the parts such as gap size and thickness. It is shown that the proposed continuous rotary valve mode MR damper is a fine candidate that meets the requirements of haptic interfaces.
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Ferry, W., and Y. Altintas. "Virtual Five-Axis Flank Milling of Jet Engine Impellers: Part 1 — Mechanics of Five-Axis Flank Milling." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41351.

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Jet engine impeller blades are flank-milled with tapered, helical, ball-end mills on five-axis machining centers. The impellers are made from difficult-to-cut titanium or nickel alloys, and the blades must be machined within tight tolerances. As a consequence, deflections of the tool and flexible workpiece can jeopardize the precision of the impellers during milling. This work is the first of a two part paper on cutting force prediction and feed optimization for the five-axis flank milling of an impeller. In Part I, a mathematical model for predicting cutting forces is presented for five-axis machining with tapered, helical, ball-end mills with variable pitch and serrated flutes. The cutter is divided axially into a number of differential elements, each with its own feed coordinate system due to five-axis motion. At each element, the total velocity due to translation and rotation is split into horizontal and vertical feed components, which are used to calculate total chip thickness along the cutting edge. The cutting forces for each element are calculated by transforming friction angle, shear stress and shear angle from an orthogonal cutting database to the oblique cutting plane. The distributed cutting load is digitally summed to obtain the total forces acting on the cutter and blade. The model can be used for general five-axis flank milling processes, and supports a variety of cutting tools. Predicted cutting force measurements are shown to be in reasonable agreement with those collected during a roughing operation on a prototype integrally bladed rotor (IBR).
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Reports on the topic "Shear (Mechanics) – Mathematical models"

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Lever, James, Susan Taylor, Arnold Song, Zoe Courville, Ross Lieblappen, and Jason Weale. The mechanics of snow friction as revealed by micro-scale interface observations. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42761.

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The mechanics of snow friction are central to competitive skiing, safe winter driving and efficient polar sleds. For nearly 80 years, prevailing theory has postulated that self-lubrication accounts for low kinetic friction on snow: dry-contact sliding warms snow grains to the melting point, and further sliding produces meltwater layers that lubricate the interface. We sought to verify that self-lubrication occurs at the grain scale and to quantify the evolution of real contact area to aid modeling. We used high-resolution (15 μm) infrared thermography to observe the warming of stationary snow under a rotating polyethylene slider. Surprisingly, we did not observe melting at contacting snow grains despite low friction values. In some cases, slider shear failed inter-granular bonds and produced widespread snow movement with no persistent contacts to melt (μ < 0.03). When the snow grains did not move and persistent contacts evolved, the slider abraded rather than melted the grains at low resistance (μ < 0.05). Optical microscopy revealed that the abraded particles deposited in air pockets between grains and thereby carried heat away from the interface, a process not included in current models. Overall, our results challenge whether self-lubrication is indeed the dominant mechanism underlying low snow kinetic friction.
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Modlo, Yevhenii O., Serhiy O. Semerikov, Stanislav L. Bondarevskyi, Stanislav T. Tolmachev, Oksana M. Markova, and Pavlo P. Nechypurenko. Methods of using mobile Internet devices in the formation of the general scientific component of bachelor in electromechanics competency in modeling of technical objects. [б. в.], February 2020. http://dx.doi.org/10.31812/123456789/3677.

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An analysis of the experience of professional training bachelors of electromechanics in Ukraine and abroad made it possible to determine that one of the leading trends in its modernization is the synergistic integration of various engineering branches (mechanical, electrical, electronic engineering and automation) in mechatronics for the purpose of design, manufacture, operation and maintenance electromechanical equipment. Teaching mechatronics provides for the meaningful integration of various disciplines of professional and practical training bachelors of electromechanics based on the concept of modeling and technological integration of various organizational forms and teaching methods based on the concept of mobility. Within this approach, the leading learning tools of bachelors of electromechanics are mobile Internet devices (MID) – a multimedia mobile devices that provide wireless access to information and communication Internet services for collecting, organizing, storing, processing, transmitting, presenting all kinds of messages and data. The authors reveals the main possibilities of using MID in learning to ensure equal access to education, personalized learning, instant feedback and evaluating learning outcomes, mobile learning, productive use of time spent in classrooms, creating mobile learning communities, support situated learning, development of continuous seamless learning, ensuring the gap between formal and informal learning, minimize educational disruption in conflict and disaster areas, assist learners with disabilities, improve the quality of the communication and the management of institution, and maximize the cost-efficiency. Bachelor of electromechanics competency in modeling of technical objects is a personal and vocational ability, which includes a system of knowledge, skills, experience in learning and research activities on modeling mechatronic systems and a positive value attitude towards it; bachelor of electromechanics should be ready and able to use methods and software/hardware modeling tools for processes analyzes, systems synthesis, evaluating their reliability and effectiveness for solving practical problems in professional field. The competency structure of the bachelor of electromechanics in the modeling of technical objects is reflected in three groups of competencies: general scientific, general professional and specialized professional. The implementation of the technique of using MID in learning bachelors of electromechanics in modeling of technical objects is the appropriate methodic of using, the component of which is partial methods for using MID in the formation of the general scientific component of the bachelor of electromechanics competency in modeling of technical objects, are disclosed by example academic disciplines “Higher mathematics”, “Computers and programming”, “Engineering mechanics”, “Electrical machines”. The leading tools of formation of the general scientific component of bachelor in electromechanics competency in modeling of technical objects are augmented reality mobile tools (to visualize the objects’ structure and modeling results), mobile computer mathematical systems (universal tools used at all stages of modeling learning), cloud based spreadsheets (as modeling tools) and text editors (to make the program description of model), mobile computer-aided design systems (to create and view the physical properties of models of technical objects) and mobile communication tools (to organize a joint activity in modeling).
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