Elastic-plastic Deformation Analysis Research Articles

DEVELOPMENT OF APPROACHES, METHODS AND MODELS OF RESEARCH OF DURABILITY AND LONGEVITY OF TORSION BILLOWS OF THE SUSPENSION SYSTEM THE LIGHT ARMORED VEHICLE

The analysis of materials on approaches, methods and models of research of strength and durability of torsion shafts of systems of suspension of light armored vehicle is carried out. It is concluded that despite the existing significant theoretical developments, the analysis of elastic-plastic deformation of materials of highly loaded structures, including torsion shafts, requires the development and adaptation of appropriate models. The approach to a number of studies on this issue also needs to be developed. As a result of a number of researches, the following model of stress-strain state was performed. The generalized parametric description of the stress-strain state of the torsion shaft contains varied design and technological factors and process parameters. The mathematical model of the stress-strain state of a torsion bar of incremental type has been formulated. It accounts for the contact and elasto-plastic deformation of the material of the torsion bar. At the same time, the stress-strain state depends on the loading history. A parametric model provides advantages in justifying rational technical solutions. This applies to both design and technological solutions. Also, all significant factors at all stages of the life cycle of torsion bars are taken into account. These factors have significant interplay. Ultimately, the determined design, technological and operational parameters satisfy the conditions of the increased strength and durability of torsion bars. The mechanical and physico-mechanical properties of materials used to manufacture the torsion bars are another important factor with regard to these criteria. Accordingly, a complex workflow is established in order to design and improve the torsion bars for the suspension systems of light armored vehicles with increased technical characteristics. Keywords: light armored vehicle; performance characteristics; torsion shaft; suspension systems; stress-strain state; strength; durability; elastic-plastic deformation

Strain energy evolution analysis of elastic-plastic deformation on polycarbonate by infrared radiation characteristics

ABSTRACT In this study, strain energy evolution characteristics of polycarbonate at different loading rates were measured under the tensile loading using infrared thermography. The variation of elastic strain energy, plastic strain energy and infrared radiation were analysed. The experimental results revealed that elastic strain energy and infrared radiation variation have a linear correlation, and the third power correlation between plastic strain energy and infrared radiation variation was obtained. Based on the principle of energy transfer and storage, the elastic strain energy infrared radiation coefficient and the plastic strain energy infrared radiation coefficient were proposed to quantitatively determine the elastic and plastic strain energy via infrared radiation. It is provided a valuable reference to predict and monitor the deformation and failure of polycarbonate based on the infrared thermography.

Elastoplastic analysis of AA7075-O aluminum sheet by hybrid micro-scale representative volume element modeling with really-distributed particles and in-situ SEM experimental testing

• Presents a novel computationally-efficient reconstruction of 3D RVE model of second-phase particle-strengthened AA7075-O sheet with real distribution of particles based on FIB-SEM techniques. • Three types of second-phase particles (i.e., irregularly-shaped iron-rich particle Al 3 Fe, elliptically-shaped particle MgZn 2 , and needle-like particle CuAl 2 ) are determined using SEM-based EDS and EBSD techniques. • Presents a systematic study of the overall elastic-plastic response by developing and applying a hybrid experimental analysis and computational modeling framework. • Good agreement is observed in the comparison of RVE results with that of in-situ SEM tensile tests, indicating that the real 3D microstructure-based RVE models can accurately predict the plastic deformation and interfacial failure evolution in AA7075-O sheet. This paper addresses the challenge of reconstructing randomly distributed second-phase particle-strengthened microstructure of AA7075-O aluminum sheet material for computational analysis. The particle characteristics in 3D space were obtained from focused ion beam and scanning electron microscopy (FIB-SEM) and SEM-based Electron Backscatter Diffraction/Energy Dispersive X-ray Spectrometry (EBSD/EDS) techniques. A theoretical framework for analysis of elastic-plastic deformation of such 3D microstructures is developed. Slip-induced shear band formation, void initiation, growth and linkage at large plastic strains during uniaxial tensile loading were investigated based on reconstructed 3D representative volume element (RVE) models with real-distribution of particles and the results compared with experimental observations. In-situ SEM interrupted tension tests along transverse direction (TD) and rolling direction (RD), employing microscopic-digital image correlation (μ-DIC) technique, were carried out to investigate slip bands, micro-voids formation and obtain microstructural strain maps. The resulting local strain maps were analyzed in relation to the experimentally observed plastic flow localization, failure modes and local stress maps from simulations of RVE models. The influences of particle size, shape, orientation, volume fraction as well as matrix-particle interface properties on local plastic deformation, global stress-strain/strain-hardening curves and interfacial failure mechanisms were studied based on 3D RVE models. When possible, the model results were compared with in-situ tensile test data. In general, good agreement was observed, indicating that the real 3D microstructure-based RVE models can accurately predict the plastic deformation and interfacial failure evolution in AA7075-O aluminum sheet.

A numerical method to predict work-hardening caused by plastic deformation

The hardening layer might form on the machined workpiece surface especially under worn cutting edge, which is caused by plastic deformation. The increased surface hardness affects the using or re-processing performance of workpiece. The finite element method was adopted in most previous works to acquire the elastic-plastic behavior and hardening layer. However, the complexity of meshing is an obvious limitation. To address this, a meshless finite block method with infinite element is developed to conduct elastic-plastic deformation analysis and hardening layer prediction for the first time. The Lagrange interpolation constructs the differential matrices in normalized domain with Chebyshev's distribution of nodes. The infinite element was introduced by a block of quadratic types to reduce the nodes used. The Prandtl–Reuss incremental theory with isotropic hardening was applied. Good agreements on stress and strain predictions were observed between this method and finite element method (ABAQUS), while a higher convergence of this method was demonstrated. The stress and strain results of ABAQUS is more sensitive to node density, which might bring larger error. Finally, the simulated work-hardening layer results show that the traction force plays a more important role than pressure force to cause a larger plastic deformation and a deeper work-hardening layer.

Rebound mechanics of micrometre-scale, spherical particles in high-velocity impacts.

The impact mechanics of micrometre-scale metal particles with flat metal surfaces is investigated for high-velocity impacts ranging from 50 m s-1 to more than 1 km s-1, where impact causes predominantly plastic deformation. A material model that includes high strain rate and temperature effects on the yield stress, heat generation due to plasticity, material damage due to excessive plastic strain and heat transfer is used in the numerical analysis. The coefficient of restitution e is predicted by the classical work using elastic-plastic deformation analysis with quasi-static impact mechanics to be proportional to [Formula: see text] and [Formula: see text] for the low and moderate impact velocities that span the ranges of 0-10 and 10-100 m s-1, respectively. In the elastic-plastic and fully plastic deformation regimes the particle rebound is attributed to the elastic spring-back that initiates at the particle-substrate interface. At higher impact velocities (0.1-1 km s-1) e is shown to be proportional to approximately [Formula: see text]. In this deeply plastic deformation regime various deformation modes that depend on plastic flow of the material including the time lag between the rebound instances of the top and bottom points of particle and the lateral spreading of the particle are identified. In this deformation regime, the elastic spring-back initiates subsurface, in the substrate.

Adhesive Friction Based on Accurate Elastic-Plastic Finite Element Analysis and n-Point Asperity Concept

The present work considers analysis of adhesive friction of rough surfaces using n-point asperity concept for statistical definition of surface roughness features, and accurate finite element analysis of elastic-plastic deformation of single asperity contact. The paper describes theoretical study in which whole range of deformation of an n-point asperity viz. from fully elastic, through elastic-plastic, to fully plastic is considered and the intermediate transition regime is treated analytically as well as numerically. Well defined adhesion index and plasticity index are used to study the prospective contact situations arising out of variation in material properties and surface roughness features. Using practical values of material properties and surface roughness parameters, results are obtained for normally applied load, friction force, and coefficient of friction. It is observed that the surfaces undergoing predominantly plastic type of deformation and having moderate to higher adhesion have constant coefficient of friction.

Adhesive friction based on finite element study and n-point asperity model

The present work considers analysis of adhesive friction of rough surfaces using n- point asperity concept for statistical definition of surface roughness features, and accurate finite element analysis of elastic-plastic deformation of single asperity contact. Well defined adhesion index and plasticity index are used to study the prospective contact situations arising out of variation in material properties and surface roughness features. From the present results it is possible to locate the combinations of adhesion index and plasticity index that may yield very low coefficient of friction. Thus suitable choice of surface and material parameters for the contact of two rough surfaces can be made in order to minimize friction typically at low load and micro scale roughness situations.

Friction analysis at elastic-plastic contact of rough surfaces using n-point asperity model

The paper describes a theoretical study of friction at elastic-plastic contact of rough surfaces in n-point asperity model framework and based on accurate finite element analysis of elastic-plastic deformation of single asperity contact. Plasticity index, a well-defined nondimensional parameter is used to study the prospective situations arising out of variation in material properties and surface roughness. Using practical values of material properties and surface roughness parameters, results are obtained for the behavior of applied load, friction force, and coefficient of friction as a function plasticity index and mean separation of surfaces. It is observed that with increase in amount of plastic deformation, the load required to be applied for maintaining a particular level of separation between contacting surfaces increases while the frictional force decreases. Coefficient of friction is independent of applied load in predominantly plastic domain of deformation but varies nonlinearly in other domains of deformation. Also, for the same applied load the coefficient of friction increases with increase in elastic deformation.

FEM Analysis of Friction for Pressing Dies Controlled by Shot Treatment

AbstractThe finite element method (FEM) analysis of elastic-plastic deformation was applied to examine the effect of surface texture controlling of dies by means of hybrid-shot (double shot by two different kinds of particles) treatment on the galling property applied to high tensile strength steel sheets. The FEM analysis results showed that the apparent friction coefficient, which was calculated from pressing load and the drawing force, increased with each increase in the pressing load. The experimental results from the drawing tests with lubricant oil showed that the friction coefficient of the die after hybrid-shot treatment decreased slightly with the increase of the pressing load. On the other hand, the friction coefficient of the die without shot treatment, (i.e. nearly flat surface), slightly increased with the increase of the pressing load due to the digging effect. These findings reveal that the effect of surface texture of dies was caused not only by the elastic-plastic deformation but also by the oil lubrication condition. The FEM analysis was therefore performed by taking into account the digging effect as well as the micro-oil pool effect. The experimental result in the case of hybrid-shot dies corresponds well to the FEM result by adopting the virtual oil model where the oil segment was defined as an elastic solid body.

The Elastic-plastic Deformation Analysis of the Hydraulic Pipe under Equivalent Static Loads

The finite element model of an aircraft hydraulic pipe was established using the ANSYS APDL command in this paper. The equivalent static pressures as surface loads were applied to the hydraulic pipe based on LS-Dyna software. The pressures were measured in the tire burst test. The stress, strain contours and time course curve of hydraulic pipe were obtained under the dynamic loads. The elastic-plastic deformations of the hydraulic pipe were analyzed by Von Mises yield criterion. The maximum stress is 1090000KPa beyond the yield limit. The hydraulic pipe occurred to plastic deformation. The maximum strain is 0.29168. It is not exceed the elongation of the material. The pipe does not break.

Elastic-Plastic Contact Analysis of a Deformable Sphere and a Rigid Flat with Friction Effect

Elastic-plastic deformation analysis of the deformable sphere and the rigid plane was studied using the finite element software,this paper was focused on the impact of the friction effects on the deformation of the elastic-plastic deformation under considering the material strain stiffening properties,studies have shown that，the strain stiffening feature increases the contact load while reducing the contact area，the friction effect reduce both the contact load and contact area during elastic-plastic deformation process of the deformable sphere with increasing contact interference.

Simulation of Power Transformer Windings Displacement Caused by Multiple Short-Circuit Forces

This research studies the displacement on the windings of transformer due to multiple short-circuit forces. The power transformer winding deformations cumulative impact of multiple short-circuits are studied. the cumulative impact of multiple short-circuit deformation of laminated cylindrical shell with stiffeners model is established, the impact of accumulated deformation of multiple short-circuit of transformer winding is calculated with large deformation elastic-plastic theory , the text introduced by the theoretical formula for power transformer windings of the elastic-plastic deformation analysis of and winding to determine the stability have great significance, To verify the computation results, they are compared with those obtained using ANSYS software simulation.

Influence of Bauschinger effect on springback and residual stresses in plane strain pure bending

A finite deformation elastic plastic analysis of plane strain pure bending of a wide sheet is presented. The general closed-form solution is proposed for a kinematic hardening law assuming that the material is incompressible. The stage of unloading is included in the analysis to investigate the influence of the Bauschinger effect, elastic properties of the material and process parameters on the distribution of residual stresses and springback. A simple example is provided to illustrate the procedure for finding the solution and some quantitative features of the process.

Plane-Strain Bending With Isotropic Strain Hardening at Large Strains

Finite deformation elastic-plastic analysis of plane-strain pure bending of a strain hardening sheet is presented. The general closed-form solution is proposed for an arbitrary isotropic hardening law assuming that the material is incompressible. Explicit relations are given for most popular conventional laws. The stage of unloading is included in the analysis to investigate the distribution of residual stresses and springback. The paper emphasizes the method of solution and the general qualitative features of elastic-plastic solutions rather than the study of the bending process for a specific material. In particular, it is shown that rigid-plastic solutions can be used to predict the bending moment at sufficiently large strains.

2001 メッシュフリー法/粒子法による流体構造連成解析(キーノート講演,OS-20A,OS-20 流体構造連成解析)

2001 メッシュフリー法/粒子法による流体構造連成解析(キーノート講演,OS-20A,OS-20 流体構造連成解析)

924 拘束条件付き移動最小自乗法を用いたSMAC-SPHによる大変形弾塑性解析(OS-9F,OS-9 メッシュフリー/粒子法)

924 拘束条件付き移動最小自乗法を用いたSMAC-SPHによる大変形弾塑性解析(OS-9F,OS-9 メッシュフリー/粒子法)

Elastic-plastic deformation analysis of multi-layer surface coating under sliding contact

The sliding contacts of gradient layer, sandwich layer and ordinary multi-layer coatings subjected to the same surface load have been investigated under elastic-plastic deformation in this paper. The result shows that the positive gradient layer coating, in which the elastic modulus reduced gradually from the top layer to the substrate, can improve the strain and stress fields near the layer-substrate interface greatly and its stress contour in the vertical direction is very smooth. The coating has as well a small stress on the layer-substrate interface and in the substrate. The sandwich layer coating can greatly reduce the maximum shear stress on the interface of the layer-substrate and the stress at the crack tip, but the stress and the strain gradients near the interface are very large. The stress and strain distributions of the ordinary layer have not evidently improved compared to those of single layer. Known from the analysis of the stress and strain distributions and the crack stress fields for the four kinds of coatings, the gradient layer coating has more advantages in these aspects. The results of this paper can provide the reference for the selection and design of coatings.

Large Deformation Elastic-Plastic Analyses of Steel Damper under Cyclic Loading.

A damper made of coiled steel is often used for base isolation systems of buildings. Since large relative displacements occur at the isolation system, large deformation elastic-plastic analysis is necessary in the designing of the damper. In this paper a method of the analysis using the degenerated beam element is presented. A simple uniaxial constitutive equation that can be used in cyclic loadings is proposed. The equation uses a bilinear function for a skeleton curve and the Ramberg-Osgood functions for hysteresis curves. A simple method for the modeling of slips at boundaries of the damper is also proposed. A method for evaluating parameters of the constitutive equation and the model of the slip is shown. With the use of the identified parameters, the results obtained by the analyses agreed well with those of experiments.

ANALYSIS OF CONTACT PROBLEMS IN ELASTIC—PLASTIC METAL SEALS/TAMPRIŲJŲ METALINIŲ SANDARIKLIŲ KONTAKTINĖS SĄVEIKOS TYRIMAS

ANALYSIS OF CONTACT PROBLEMS IN ELASTIC—PLASTIC METAL SEALS/TAMPRIŲJŲ METALINIŲ SANDARIKLIŲ KONTAKTINĖS SĄVEIKOS TYRIMAS

Computational Machining of Titanium Alloy—Finite Element Modeling and a Few Results

A Finite element modeling was developed for the computational machining of titanium alloy Ti-6Al-4V. The chip formation in metal cutting is one of the large deformation problems, thus, in the formulation of the elastic-plastic deformation analysis, geometrical nonlinearity due to the large shape change of the finite elements was taken into account and the over-constraint of incompressibility on the deformation of ordinary finite elements in the plastic range was relaxed to make the elements deformable as a real continuum. A ductile fracture criterion on the basis of strain, strain rate, hydrostatic pressure and temperature was applied to the crack growth during the chip segmentation. The temperature field in the flowing chip and workpiece and the fixed tool was calculated simultaneously by an unsteady state thermal conduction analysis and the remeshing of tool elements. The serrated chips predicted by the computational machining showed striking resemblances in the shape and irregular pitch of those obtained by actual cutting. The mean cutting forces and the amplitude of cutting force vibration in the computational machining were in good agreement with those in the actual machining.