Papers by Keyword: Elasto-Plastic

Abstract: The bucket is a metal entity, linked to a machine called DRAGLINE, used for loading the different sizes of granular materials in large quantities. Each bucket is provided with six teeth which in contact with materials to be discharged, in order to extract the mineral. These teeth are connected to the bucket via a semi-rigid connection. In operation, except for the wear phenomenon "normal", some teeth break after a few hours of operation at the fixed portion in the singularity region (radius of curvature equal to zero). We observed via elastic numerical simulation in quasi-static regime, performed using PATRAN and NASTRAN software, that hot spots are located at the singularity region. We also used this numerical calculation for analyzing the effect of the variation radius of curvature on the stress concentration factor by plotting the variation of this factor vs of said radius. To deepen, we repeated the same study but this time considering the material of the tooth as elastic perfectly plastic for seeking the limit load. For each value of the radius of curvature, was plotted the variation of the elasto-plastic external force according to the displacement of the front end of the tooth, knowing that the other end is fixed.

Abstract: Based on the large geometric deformation and nonlinear of material theories, the seismic responses of a double-layer spherical lattice shells structure were studied. The results show that under multi-dimensional earthquake, the maximum displacement and axial stress, as well as plastic ratio of the structure will be obviously increased than those corresponding to the responses under single-dimensional earthquake. When long-period seismic wave was taken as the input wave, the responses of the structure were the maximum.

Abstract: The mechanics properties of a certain automobile rear axle shell were studied and a large displacement, large strain elastoplastic finite element analysis was carried out. and the followings were obtained: the load-displacement curve at loading point, elastoplastic strain-load curve at the maximum stress point, elastoplastic stress-load curve in dangerous cross-section, and the yielding load at which the dangerous cross-section overall yield. The results show that elastoplastic finite element simulation results are much closer to the experimental corresponding results. Through optimization design in manufacturing system, the weight of the rear axle shell is greatly reduced as compared with the original design. Optimal design not only saves materials and reduces cost, but also greatly reduces the design time. The calculation results provide the necessary data for automobile rear axle design, strength evaluation and fatigue life estimate.

Abstract: For Ramberg-Osgood elasto-plastic material, under the premise that integration path is limited through the Gaussian integration points, the finite element expressions of the J- integral were deduced in detail. Using the method of coordinate transformation, integration was conducted through the plane rs of the shell element local coordinate system rst (t for shell element thickness direction). The integration points on mid-surface of the shell element were considered. Thus the finite element expressions of the J- integral can be applied to shell elements, the J- integral calculation problem of the shell structure with crack can be solved. A lot of standard sample results comparisons show that the calculation precision of the method proposed in this paper meet the requirements of engineering. Finally, the J- integral of a pressure vessel (a cylindrical shell with a hole and unilateral axial crack) was calculated. The obtained results are recognized by a pressure vessel research institution and referenced in the design. In the conventional finite element calculation, users can, at the same time, obtain the J- integral of the component with crack. So the method in the paper has strong practicability and high engineering application value.

Abstract: Solid-gas coupling effect of coal containing gas is studied in order to understand the gas percolation mechanism in coal and rock. On the premise of that porosity and permeability of coal and rock are in dynamic changes and Klinkenberg effect, then seepage mechanics and elastic-plastic mechanics are considered together to established solid-gas coupling model of coal containing gas. With the given fixed solution conditions and parameters, the simulation results of mathematical model is found by the Comsol Multiphysic finite element software. Simulation results are consistent with the stress-strain law, deformation and failure modes of specimen in the experiment. Seepage law obtained in numerical simulation has same trends with experimental data. The elastoplastic solid-gas coupling model of coal containing gas can effectively describe the mechanical percolation characteristics of coal containing gas.

Abstract: An elasto-plastic total stress finite-element computational model is established in two dimensional space to study pile response due to excavation-induced soil movement on the basis of the general-purpose finite element software ABAQUS. And the soil is assumed to be a uniform normally consolidated clay layer. Influences of various parameters including undrained shear strength of soil, excavation depth, strut stiffness and distance from excavation on pile response are investigated. The results indicate that the excavation-induced soil movement is critical for adjacent piles and increasing the undrained shear strength of soil and distance from excavation face would be helpful to control passive pile responses.

Abstract: Bridge jacking technique in the old bridge reconstruction project have broad application prospect, this paper is aim to share the bridge jacking technique and design the steel bracket as the load carrying platform. The finite element calculation is conducted by ANSYS software considering the concrete material nonlinearity with reasonable stress-strain relationship of concrete and element type. Compared with the experimental data, the model reliabilities and the results of two test programs are evaluated. We can conclude that the second structure form of this paper is safer, which can provide the meaningful guidance for similar projects.

Abstract: In two-dimensional space, an elasto-plastic finite element computational model was established to simulate inner support for excavation on the basis of the general-purpose finite element software ABAQUS. The soil was assumed to be a uniform and normally consolidated clay layer and strut was discreted by spring element. Compared with published case study, it can be concluded that FEM software AQAQUS can present one reliable simulation progress of inner support for excavation.

Abstract: According to general crystallographic slip constitutive laws, the stress-strain analysis of nickel based single crystal superalloy (NBSCS) in arbitrary coordinate system were based on material coordinate system (SRCS method). Ignoring the other symmetry of NBSCS, only the symmetry of plane families {001} were considered, which bring considerable errors into the stress-strain analysis. In this paper, the variation regulation of micro-physical systematical property about this alloy in arbitrary directions was investigated. From the arrangement of atoms in different crystal planes, NBSCS has four symmetry plane families, {001}, {110}, {112} and {111}. According to these symmetry planes, three reference orthogonal coordinate systems were established. Based on these coordinate systems and the coordinate rotation method (TRCS method), the stress-strain relationship of crystallographic slip constitutive model in arbitrary coordinate system was established. Meanwhile elastic constants in arbitrary directions were obtained. Comparing the results of the tensile stress-strain curves obtained from TRCS method with that from SRCS method, it is found that by the TRCS method the elastoplastic stress-strain simulation error of the NBSCS could be effectively reduced.

Abstract: The elastoplastic phenomenon of the structures will be advent under the action of the strong earthquakes, the presented research on the vibration control of the ones is chiefly concentrated on fuzzy and neuro-controller with the expense of bigger energy. In the paper, the 3-storey benchmark building is used as research object, the control strategy of vibration system with fractional-order is studied. The control method based on acceleration responses output is emphatically concerned as it is usually adopted in most actual application of active vibration control techniques. The concrete courses include the following three steps: the integer-order approximation of fraction-order, the transfer function reduction in frequency-domain which base on Pade approximation, the controller design and simulation. In the last, an example is used to show the feasibility of proposed method.