Papers by Keyword: Elastic-Plastic

Abstract: In a previous research by authors, a methodology was developed to derive J-R curves for Hot Mix Asphalt (HMA) mixtures using an elastic-plastic approach where a comprehensive understanding of crack propagation regime could be achieved. In this research, the effect of crumb rubber modification of HMA binder is studied in terms of R-curves and crack propagation at low temperatures. Mode I Single edge notched beam (SE(B)) fracture tests were conducted in temperature levels of 0 °C, -10 °C, and -20 °C. PG58-22 and PG64-22 binders were used in the fabrication of HMA samples. Modified specimens consist of 20% crumb rubber along with the incorporation of 3% warm mix admixture. Crack growth resistance curves were obtained in SE(B) tests by means of image processing and recording of the progressive crack length. Elastic-plastic J-R curves revealed that crumb rubber modified mixtures exhibit higher crack growth resistance for each bitumen performance grade. As well, increased ductility and cohesive energy can be observed according to the R-curves as the mixtures are modified by crumb rubber.

Abstract: Structures are designed based on the seismic precautionary intensity, which is regulated by the government for each county. The basic target is to avoid the structure collapse under rare expected earthquake by the method of FEA and kinds of seismic measures, but buildings may encounter the seismic action with much higher intensity, the structural performance in this situation is researched by numerical methods in this paper. By controlling the parameters of displacement angle, axial compression and so on, the results show that the buildings may possess greater potential than expected.

Abstract: Strain clamp is an important connection device in guy tower. If the quality of the compression splicing position is unsatisfied, strain clamp tends to be damaged which may lead to the final collapse of a guy tower as well as huge economic lost. In this paper, stress distribution on the compressible tube and guy cable is analyzed by FEM, and a large equivalent stress of guy cable is applied to the compression splicing position. During this process, a finite element model of strain clamp is established for guy cables at compression splicing position, problems of elastic-plastic and contracting are studied and the whole compressing process of compressible position is simulated. The guy cable cracks easily at the position of compressible tube’s port, the inner part of the compressible tube has a larger equivalent stress than outside.

Abstract: Using ABAQUS to analyze the response of tall building under expected rare earthquake, usually the gravity field can be derived by the implicit method as the initial condition of simulation for seismic wave executed in the explicit method. In practice of engineering, oscillation of gravity often occurred at the beginning of explicit method which would lowered accuracy and reliability of time-history results. Three main reasons including stress level, constitutive model and the software ABAQUS itself are researched in this paper by numerical examples, and an extra analysis step is proposed for eliminating oscillation before loading the seismic wave.

Abstract: In the nonlinear time-history analysis for high-rise building, different damping models may lead to results with great difference. Limited by the stable time increment, the stiffness proportional damping is usually neglected in Abaqus/Explicit, and only a simplified mass proportional damping is used, which can be derived from the fundamental frequency and the critical damping factor. In this paper, the influence on the results of this method has been researched by numerical examples, the numerical results also show that the stiffness proportional damping cannot be neglected. Based on these comparisons, a more reasonable damping model is presented for improving the results of high frequencies.

Abstract: In order to improve the solution of nonlinear time-history analysis for high-rise buildings, the concrete constitutive relation of Chinese code has been modified by using Najar damage theory, and based on the limitation of stable time increment in explicit dynamic analysis, a simplified Rayleigh damping form with tiny stiffness proportional damping is proposed to decrease the damage induced by those high frequencies, at last, the influence of mesh size on stress and damage is also discussed. The numerical results show that these principles are workable for more accurate results.

Abstract: In this paper, the stability analysis of a single-layer latticed shell structure is presented using ABAQUS, with the geometric nonlinearity considered. The load-displacement curves are calculated according to the elastic and elasto-plastic hypothesis respectively. The ultimate bearing capacity of the structure and its conceivable damage mode are estimated. Finally, the nonlinear stability of this structure is assecced and the further suggstions for improving the structural performance are presented.

Abstract: The design of reinforced concrete structure often used the elastic internal force as the design basis, but the nonlinear behavior of reinforced concrete structures brings about errors in calculation of statically indeterminate structure. By considering the nonlinear properties, the mechanical responses of reinforced concrete structure were investigated, on which an axial force loaded at their middle span section. In a series of analysis on internal force of the reinforced concrete member at all loading stages, through the deformation compatibility equation and the balance equation, the formulas for calculating elastic-plastic internal forces and strains were derived. Comparative examples are provided and the results show a large error between internal forces calculated by the structural mechanics method and those by the elastic-plastic method proposed in this paper, and the maximum error is about 8 times.

Abstract: In order to achieve the work-piece surface quality control, Based on the formation mechanism of surface roughness and generating mechanism of material’s surface, considering the tool parameters and feed per tooth, to modify the maximum residual height’s formula of surface. Based on formation characteristics of machined surface and the elastic-plastic deformation theory of work-piece material, Got a simplified model of the elastic-plastic deformation of the work-piece surface,and according to the molecular-mechanical friction theory ,the calculation method was presented to investigate elastic-plastic deformation of machined surface . By combining the surface residual height calculation formula with the calculation method of elastic-plastic deformation, has built the theoretic model of the milling surface roughness , can forecast to the work-piece surface roughness, as well as provide theory basis for the selection of cutting parameters and optimization.

Abstract: With complex mechanics character and under the action of compression and tension in tri-direction, rock will show coupled plastic-damage mechanism as its basic character. Phenomenological coupled elastic-plastic-damage constitutive model with internal variable is proposed based on thermal mechanics theory, elastic law and macro damage mechanics. Numerical experiments on this model and analyze the model character. The result shows that the coupling model could realize rocks softening behavior brought about by damage and strength enlargement caused by confining pressure increasing.