Analysis Of Stress-strain State Research Articles

Modeling of Stress-Strain State and Coseismic Effects of Epicentral Zone of Tangshan Earthquake (Southeastern China)

The paper presents the results of numerical modeling and analysis of stress-strain state of the epicentral zone of the strong earthquake in the north-east of China, which occurred on 27.07.1976 with Ms=7.8. Many present-day works continue to discuss the reasons for such a strong earthquake, which occurred in tectonic conditions ‒ far from interplate boundaries, inside the Tangshan tectonic block bounded by tectonic faults. However, published new geodynamic, seismological, geophysical and geodetic data provide confidence in the determining role of fault tectonics in this region. Based on the analysis of the results of modeling of the stress-strain state preceding the Tangshan earthquake with coseismic geophysical and geodetic data, we propose a model of earthquake rupture formation. The results of comparison of independent estimates of shear stresses with the results of modeling in the sources of strong earthquakes suggest that the areas of tectonic stress concentration are localized in the interfault rupture of the Tangshan fault, reaching maximum values at the termination of fault ruptures σi ≈ 50 MPa и τxy ≈ 20 MPa. The hypocenter of the main seismic event (taking into account the error of coordinate determination) is located in the region of stress intensity 35‒50 MPa and the ratio of main stresses σxx/σyy ≈ 8–10. It should be expected that these zones are the starting site of rupture, the extent of which depends on the amount of accumulated elastic potential energy of tectonic stresses in the adjacent region. For the Tangshan earthquake, this area corresponds to a high intensity of stresses exceeding 30 MPa in a band with a length more than 30 km and a width reaching 4.5 km.

Analysis of stress-strain state of plates made of crosslaminated timber reinforced with composite tapes

In our time, the construction industry is actively developing in various directions. Constructions with large cross-sections are being replaced by counterparts with reduced cross-sectionsusing various types of reinforcement.Cross-laminated timber (CLT) panels are a massive, multi-layered glued timber construction material. For high-rise building structures and wooden buildings, the use of CLT panels is the primary method for arranging floors and roofs. Layers oftimber are glued together under pressure, forming a virtually ready-made panel. The layers of timber lamellas are laid perpendicular to each other, transversely. The outer layers usually have the same orientation, while the internal layers, perpendicular to the outer ones, may consist of cheaper wood to savecosts. Most often, softwood is used for the production of such panels as the most affordable.However, the production of such panels requires significant material costs. Therefore, research in the field of reinforcement of CLT panels to reduce their cross-section is relevant.Composite materials are leading in structural reinforcement now, as most of them have high resistance to various chemical influences, such as alkalis, acids, chlorides, sulfates, nitrates, and others.This allows them to be used both in industrial and agricultural construction, where there is a significant impact of the external environment on structures reinforced with composite materials, and in residential buildings, without harm to residents.After analyzing the stress-strain state through modeling in the LIRA CAD software package of CLT panels reinforced with composite strips and comparing them with similar panels without reinforcement, we can conclude that such materials canbe excellently combined with cross-laminated timber structures, allowing to increase the load-bearing capacity while reducing their cross-section.

Numerical modelling of the pit wall stability while optimizing its boundaries to ensure the ore mining completeness

Purpose is to assess changes in the stress-strain state of walls along the whole periphery of a super-deep open pit while optimizing its current and final boundaries for the complete ore excavation. Methods. Finite element 3D analysis of stress-strain state (SSS) of the soil and rock mass relies upon the models varying in their scales. Macrolevel model includes the full pit helping perform initial evaluation of its stability depending upon changes in the general wall slope along the pit periphery. Then, the macromodel is separated into sectoral models with smaller scales oriented radially in such a way to include potentially unstable wall areas. The sectoral models make it possible to show the complex bench line in more detail after the peripheries were optimized in terms of economic factor and simulate layered structure of the rock mass. Elastoplastic model of the medium as well as Mohr-Coulomb strength criterion has been implemented using RS3 (Rocscience) program codes. Findings. An indicator of wall strength (safety factor) distribution along the pit periphery has been identified; potential sliding surfaces within each of the separated open pit sectors have been localized based upon the shear strength reduction (SSR) procedure. Influence by the general wall slope as well as by the indicator of the ore excavation completeness on the stripping ratio has been demonstrated. Originality. For the first time, two-level modelling has shown difference in a safety factor depending upon a model scale and a reflection degree of the soil-rock mass structure. In the context of the actual mining and geological conditions of Kacharsky open pit, changes in the safety factor along the pit periphery have been identified depending on the general slope of the wall. Practical implications. Based upon the pit wall stability along the whole periphery, the possibility has been substantiated to optimize its design boundaries for the excavation of those amenable ore reserves, occurred near them, inclusive of ore, occurring in a bottom, which mining is impossible due to inaccessibility.

Підхід до визначення напружено-деформованого стану стрижнів з композиційних матеріалів з урахуванням внутрішнього самоврівноваженого напруженого стану

The subject of this research is methods of stress-strain state analysis of composite structures. The goal is to develop a mechanism to explain the phenomenon of warping of thin-walled composite sections with a non-uniform cross-section under thermal loading and to synthesize a model to determine the forces in the section elements. The objectives of this study are to predict the deformed states of composite sections at the manufacturing stage and to determine the temperature stresses that occur at the manufacturing stage, as well as after the assembly of the structure. The methods used are related to the mechanics of materials and structures. The following results were obtained. The possible deformation forms of composite plates with an asymmetric structure are analyzed and the rationale for the appearance of such deformations is given. A model of the force interaction of elements in a folded section is proposed. The proposed model can be extended to most sections of load-carrying aircraft structures. Based on the analysis of the mechanics of thin-walled folded sections, the mechanism of the occurrence of complex bending-torsional deformation of long-dimensional sections made of composites with a non-uniform cross-section under the action of an internal self-equilibrium stress state caused by a change in temperature or shrinkage of the binder or both is explained. The analysis of this mechanism makes it possible to design composite sections with minimal warping and to propose engineering methods to compensate for unwanted spatial movements in the case of arbitrary loading of section elements. Conclusions. The scientific novelty of the obtained results can be summarized as follows. A mechanism for the deformation of rods made of dissimilar composite materials when the temperature changes (after extraction from the tool or during operation) is proposed considering the difference in Poisson's coefficients. A model for determining the forces acting on the perimeter of section elements was synthesized, and the corresponding formulas were obtained, which form the basis for the theory of off-center compression of rods. The direction of further research in this field is currently being planned.

Method of information technology for calculating the nodal loads in stress strain state analysis of the transport category aircraft wing model

Method of information technology for calculating the nodal loads in stress strain state analysis of the transport category aircraft wing model

Stress-strain State Analysis of Porous Elasto-plastic Size-dependent Plates Subjected to Hygro-Mechanical Loads Using the Variational Iterations Method

Stress-strain State Analysis of Porous Elasto-plastic Size-dependent Plates Subjected to Hygro-Mechanical Loads Using the Variational Iterations Method

Analysis of the pure shear stress-strain state obtained by biaxial tension-compression test

Analysis of the pure shear stress-strain state obtained by biaxial tension-compression test

A methodological approach to assessing the durability of welded structures of screens using SolidWorks Simulation software

Purpose. To develop methodological recommendations for studying the characteristics of screen welded assemblies of ГВЧ-31 С type using specialized tools of the SolidWorks Education Edition software package. Methodology. The methodology for analyzing welds when designing a vibrator fixation system is based on the use of current software tools, in particular SolidWorks Simulation in combination with SolidWorks Motion, as well as the HOT SPOT STRESS technology. To analyze the accuracy of determining the dynamic loads arising during the screen operation, the results of modeling using the SolidWorks Motion program are compared with those obtained by traditional methods using the Lagrange equation of the second kind. The computation discrepancy is within 10 %. Findings. It has been determined that it is rational to analyze welds using the SolidWorks Education Edition software shell, taking into account the least profitable option, namely, when their edges are not finished. Furthermore, during solid-state modeling, the formation of a cavity in the weld is simulated in the form of a gap between the welded elements. The stress-strain state analysis of welded constructions using the Finite Element Method has revealed that when the computational mesh cell size is reduced, the stress value increases significantly, which indicates the result singularity and the need for further application of the HOT SPOT STRESS method. In the course of research, it has been determined that the highest stresses in welds occur on the central rib. The duration of use of welded joints is more than 2·106 cycles. Originality. For the first time, the methodology has been substantiated for determining the service life of welded elements of screen constructions using the latest computer analysis tools. The method makes it possible to calculate the dynamic forces arising in constructions performing oscillatory movements, as well as to analyze the stress-strain state of welds using the HOT SPOT STRESS technology and assess their service life. Practical value. It has become possible to implement the method for calculating the stress-strain state of welds in the design of a vibrator fixation system and assessing their service life, which is important for analyzing and determining the parameters of various vibrating machines. The results derived from the investigation were incorporated by the local entity, Ukrprommineral, to modernize the screens.

Experimental study and simulation of the interface shear deformation behavior in AISI304/Q235 clad plate with thin cladding layer

The mechanical properties and interface damage characteristics of hot-rolled bonded stainless steel/carbon steel (SS/CS) clad plate with thin cladding were investigated. The focus is on mechanical property-microstructure relationships in shear deformation. In detail, the mechanical response of the cladding components and clad plate were characterized. Then a hybrid numerical–experimental identification procedure for the cohesive zone model (CZM) in the simulation of heterogeneous SS/CS interface using finite element (FE) method was developed. A mixed-mode bilinear CZM, considering the anisotropy of the thin cladding was coupled FE model, showing a high accuracy for predicting the shear deformation behavior. The results showed obvious differences in the microstructure and mechanical properties of the SS and CS layers and the formation of an inhomogeneous interfacial layer. Additionally, the bond strength and delamination position of SS/CS clad plate are highly dependent on the interfacial oxide distribution and elemental diffusion behavior. Interestingly, the thin cladding is subjected to bending moments in shear deformation, resulting in delamination of the interface that is not completely dominated by one shear mode. And these abrupt interfacial failures could be clarified via stress-strain state and local damage analysis of the well-reproduced FE model of cladding material.

Finite-Element Analysis of Stress-Strain State of Steel Reinforcement in Stretching–Bending–Rebending (Cold Stretching)

Finite-Element Analysis of Stress-Strain State of Steel Reinforcement in Stretching–Bending–Rebending (Cold Stretching)

Stress-strain state analysis of the polymer insulator adhesive bonding of a railway overhead system with a metal insulation displacement contact under torsion

Based on consideration of a simplified model, an analytical solution to the problem of adhesive bonding stress-strain state estimation of a polymer insulator of the railway overhead system with a metal insulation displacement contact under torsion is presented. The polymer insulator is made of unidirectional epoxy resin-based fibreglass with the ratio of binder and filler 0.3:0.7. The solution is obtained by considering the adhesive bonding incremental element equilibrium. The influence of such parameters as the thickness of the adhesive layer, the adhesive bonding length, and the modulator of shearing of the metal insulation displacement contact on the adhesive bonding stress-strain state change has been investigated. It is shown that the greatest tangential stresses in the adhesive layer occur at the point of entry of the fibreglass rod into the steel termination, and the length of the zone of relatively large tangential stresses in the adhesive layer is a small value compared to the length of the adhesive bonding. During the research of influence of glue layer thickness on the greatest tangential stresses in a glue layer it is received, that at accepted parameters of a glue bonding increase of thickness of a glue layer in ten times leads to reduction of the greatest tangential stresses in a glue layer approximately in three times. An increase in the length of the adhesive bonding, all other things being equal, has little noticeable effect on the greatest tangential stresses in the adhesive layer. The same conclusion can be reached by varying the shear modulus of the metal termination. Thus, replacement of steel insulation displacement contact with copper or aluminium insulation displacement contact practically does not change the value of the greatest tangential stresses in the adhesive layer.

Three-Dimensional Stress-Strain State Analysis of the Bimetallic Launch Vehicle Propellant Tank Shell

Three-Dimensional Stress-Strain State Analysis of the Bimetallic Launch Vehicle Propellant Tank Shell

Analysis of Stress-Strain State of a Cylinder with Variable Elasticity Moduli Based on Three-Dimensional Equations of Elasticity Theory

Introduction. Functionally graded materials are of great use, because heterogeneity of properties enables to control the strength and rigidity of structures. This has caused great interest in the topic in the world scientific literature. The construction of solutions to such problems depends significantly on the type of boundary conditions. In this paper, we consider the equilibrium of a thin-walled circular cylinder whose mechanical properties change along the radius. Homogeneous boundary conditions were set on cylindrical surfaces that had not been considered before, the effect was on the ends. The mathematical formulation of the problem was carried out in the linear theory of elasticity in the framework of axisymmetric deformation. Expressions were constructed for the components of the stress-strain state of the cylinder, in which some coefficients were found from the solution to the resulting system of linear algebraic equations.Materials and Methods. The material of the cylinder was linearly elastic, the elastic modulus of which depended linearly on the radial coordinate. The basic research method was the asymptotic method, in which half the logarithm of the ratio of the outer and inner radii acted as a small parameter. Iterative processes were used to construct the characteristics of the stress-strain state of the cylinder.Results. Homogeneous solutions to the boundary value problem were obtained for a linearly elastic functionally gradient hollow thin-walled cylinder. An analysis of these solutions made it possible to reveal the nature of the stress-strain state in the cylinder wall. For this purpose, an asymptotic analysis of the solutions was carried out, relations for displacements and stresses were obtained. It was determined that those solutions corresponded to the boundary layer, while their first terms determined Saint-Venant edge effect similar to the plate theory.Discussion and Conclusion. The analytical solution to the equilibrium problem of a thin-walled cylinder inhomogeneous in radius constructed by asymptotic expansion can be used for numerical solution to a specific problem. For this, it is required to solve the obtained systems of linear algebraic equations and determine the corresponding coefficients. The resulting asymptotic representations provide analyzing the three-dimensional stress-strain state. The selection of the number of expansion terms makes it possible to calculate displacements and stresses with a given degree of accuracy. This analysis can be useful in assessing the adequacy of applied calculation methods used in engineering practice.

High performance modeling of the stress-strain state of thin-walled shell structures with the use of deep learning

Computer modeling is one of the most common approaches to the analysis of thin-walled shell structures stress-strain state analysis. It requires considerable time costs and high-performance hardware, especially when it is necessary to conduct a comparative analysis of various shell configurations. In this paper, we propose the use of deep learning methods to improve performance of this process. The purpose of work is to develop methods for high-performance computer simulation of thin-walled shell structures using deep neural networks, allowing to take into account geometric and physical properties of the structure as well as the load applied to it. A training approach and deep neural network architecture were developed to perform computer modeling of the stress-strain state of the shell. To form a training dataset, a computational experiment was carried out to simulate 3904 different configurations of doubly curved shallow shells that differ in linear dimensions, curvature radii, and materials used. Based on this dataset, 30 deep neural networks with different architectures were trained. To determine the optimal architecture in terms of modeling accuracy, mean absolute percentage error with clipping near-zero samples was calculated for each of the neural networks based on the test dataset. A network has been developed that allows calculating the stress-strain state of different shell configurations under an arbitrary uniformly distributed load. This is the first solution in the field of shell neural network modeling that allows us to vary the applied load, geometric and physical parameters of the shell and obtain calculation results at an arbitrary point of its middle surface. Performance measurements were carried out which show that the developed neural network allows simulating the stress-strain state of a shell structure 2117 times faster compared to the duration of solving the same problem by classical simulation. The modeling error using the network is at an acceptable level. An original architecture of a neural network for modeling the stress-strain state of shells was proposed which, through minor modifications, can be adapted for high-performance modeling of other building structure types. In accordance with the described architecture, a deep neural network was trained which reduces the computation time by several orders of magnitude. The results obtained are of high practical importance for researchers in the field of thin-walled shells modeling since they allow us to significantly reduce the time costs associated with conducting computational experiments. One of the possible applications for developed solution is prototyping of various shell configurations. Once prototyping is complete, the most efficient shell configurations can be explored in detail using classical computer simulation techniques.

A Dynamic Analysis of the Cycloid Disc Stress-Strain State

The problem of internal forces that occur on the cycloid disc during the cycloid speed reducer operation so far has not been considered in a way that reflects its actual workloads and stresses in the cycloid disc itself. This paper presents a dynamic analysis of the stress-strain state of a cycloid disc by using experimental and numerical methods. The following cases of meshing are presented in the paper: a single-tooth, double-tooth, and triple-tooth meshing of the cycloid disc and the ring gear. The cycloid disc was chosen for this study because it is one of the main elements and the most critical element of the cycloid speed reducer. An experimental physical model of the cycloid disc and the meshing elements of the cycloid speed reducer was made based on a previously performed 3D CAD model. The numerical analysis of the stress-strain state of the cycloid disc was performed with the identically defined external load using the transient stress method. The paper presents a comparative analysis of the experimental and numerical results, which gives a solid insight into what is happening in the cycloid disc during the cycloid speed reducer operation. The experimental and simulation results both give the results with a deviation between 3% and 15%. After the detailed analyses, it is shown that the most critical element of cycloid speed reducer are output rollers, which need further study.

Geomechanical substantiation of parameters for safe completion of mining the coal reserves adjacent to main workings

Purpose. Geomechanical substantiation of the parameters for conducting stope operations, ensuring the operational state of main workings. Methodology. The research is performed using an algorithm which includes the sequential execution of interrelated stages: analysis of mining-geological and mining-technical conditions for maintaining the network of main workings; mine observations of their state with the identification of specifics of rock pressure manifestations and predicting the probable negative consequences of conducting stope operations in the immediate vicinity; preliminary substantiation of possible technological options for mining the coal seam, taking into account the preservation of operational state of main workings. Scientific calculations for determining the most expedient option are based on the development of geomechanical models of the rock mass behavior around the main workings when mining the adjacent extraction site; analysis of the mass stress-strain state with the prediction of probable rock pressure manifestations; development of recommendations for limiting (or completely eliminating) the negative consequences of conducting stope operations near main workings. The above algorithm of actions uses a combination of experimental mine research methods with technologies for performing computational experiments based on the finite element method. Findings. A systematic analysis of the mining-geological and mining-technical conditions for maintaining the network of main workings has been performed, the results of which are used to substantiate ideas about the mechanism for the occurrence of specifics of rock pressure manifestations, recorded during instrumental observations of their state. Three options have been developed for completing the mining of the extraction site adjacent to the mine horizon main workings. For each of them, a geomechanical model has been constructed for calculating the stress-strain state of the adjacent coal-bearing mass. Its analysis makes it possible to formulate a number of recommendations regarding the rational parameters for conducting stope operations, as well as structural and technological solutions to increase the stability of the main workings and maintain the conditions for their safe operation. Originality. New dependences of influence of the extraction sites on the main working network stability depending on the texture and mechanical properties of lithotypes have been obtained based on the research on the stress-strain state of a weakly metamorphosed mass. For the first time, geomechanical models have been developed of the mutual influence of main workings on the parameters for conducting stope operations. Practical value. The presented recommendations simultaneously reduce the loss of coal reserves and preserve the network of main workings in proper operational state.

FREQUENCY RESPONSE AND STRENGTH ANALYSIS OF THE ELBOW ORTHOSIS PLANETARY GEARBOX SHAFT USING FEA

Shafts of various sizes are used in various fields of mechanical engineering, automotive, marine and aerospace industries to transmit torque according to requirements. In this paper, we simulate and analyse the modal and harmonic response of a shaft on which a satellite of a planetary gearbox for an elbow orthosis is mounted. The orthoses are used during the rehabilitation of patients in the postoperative period or during the regeneration of lost limb functions. Steel 45 and PLA polylactide were used in the shaft modelling. The planetary gearbox shaft was analysed for modal and harmonic characteristics at three different torque values, i.e. 1732 N·mm, 3464 N·mm, 5196 N·mm, using ANSYS Workbench. The modal and harmonic analysis of the shaft stress-strain state is calculated, completed comparative analysis, and the vibration characteristics are discussed: shown natural frequencies, mode shapes, and harmonic response. Calculations for shaft durability under a complex stress state were performed, and safety factors were calculated for shafts made of steel 45 and PLA polylactide.

Comparative analysis of stress-strain state of tissues of multi-root teeth restored by root pin tabs made of zirconium dioxide and cobalt-chromium alloy

Comparative analysis of stress-strain state of tissues of multi-root teeth restored by root pin tabs made of zirconium dioxide and cobalt-chromium alloy

Analysis of stress-strain state of bogie frame of PE2U and PE2M industrial traction unit

This article presents the results of the theoretical analysis of the stress-strain state of the industrial traction unit PE2U and PE2M frame. The stress-strain analysis was performed using the finite element method in SolidWorks Simulation software. The analysis results are necessary to estimate the residual resource of the traction units at the end of their service life and extend their service life. According to the requirements of the state standards, to extend the service life of the rolling stock load-bearing constructions, the stress-strain state of these constructions should be studied. A 3D model of the bogie frame was built using SolidWorks software to evaluate the strain-deformation state. Using the SolidWorks Simulation program, the stress-strain state of the bogie frame was evaluated using the finite element method based on the Palmgren–Miner–Mises theory. All static and dynamic loads in use affecting the bogie frame are taken into account.

Probabilistic assessment of slope stability at ore mining with steep layers in deep open pits

Purpose. A methodology development for predicting the geomechanical situation when mining an ore deposit with steep-dipping layers, taking into account the uncertainty in determining the rock properties, which is a consequence of the rock mass heterogeneity. Methods. The assessment of the open-pit wall stability is based on a combination of numerical simulation of the rock stress-strain state (SSS) and probabilistic analysis. The finite element method is used to determine the changes in the SSS that occur at various stages of mining operations due to design changes in the overall open-pit slope angle. The elastic-plastic model of the medium and the Mohr-Coulomb failure criterion are implemented in the codes of the 3D finite element analysis program RS3 (Rocscience). Stochastic simulation is used to assess random risks associated with natural object state variations. Findings. The distribution of maximum shear strains, which localizes the real or potential sliding surfaces in the open-pit wall at various stages of ore mining, has been identified. Based on the Shear Strength Reduction procedure, the open-pit wall Strength Reduction Factor (SRF) has been determined. The probabilities of open-pit wall stability loss, as well as the decrease in the strength reduction factor below the standard level at all stages of the ore body mining, have been revealed. Originality. For the first time, for real mining-geological conditions of a deep ore open pit, the dependence of the strength reduction factor on the overall wall slope angle, which changes during mining of each steep layer, has been determined. For each stage of mining operations, for the first time, the probability of a decrease in the open-pit wall stability below the standard level has been determined based on stochastic simulation. Practical implications. The ratio between the open-pit contour characteristic (overall slope angle) and the probabilistic safety factor is the basis for practical solutions to ensure the efficiency and safety of mining at various stages of friable and hard overburden excavation, ore extraction, as well as for the subsequent optimization of the open-pit design contours.