Papers by Keyword: ABAQUS

Abstract: This paper aims to provide a numerical model able to represent the behavior of reinforced concrete slabs subjected to impact loads. The nonlinear finite element analysis adopted by ABAQUS/Explicit Software was used in this study. A parametric study was conducted to provide a comprehensive understanding of the behavior of reinforced concrete slabs subjected to impact load. Two parameters were varied amongst the slabs which classified in to two groups. In the first groups, the thickness of slabs is variable, which was equal to (75, 100, 150 mm). In the second group, the thickness of the slab is constant and the variable was the reinforcement ratio, which ranged from (0.58 to 1%), per layer. In dynamic analysis, the load-time history and deflection-time relation were investigated. For the first group, obviously, as the slab thickness increased, the maximum central deflection of the slabs decreased by (48 – 84 %). Also, the impact force of the slabs increased by (40 – 106%) as the thickness of the slab increased by (33 – 100%). For the second group, the maximum central deflection of the slabs decreased by (6.6 – 8.8 %) as the steel reinforcement increased by (0.58 – 1 %). It was observed in the second group that the change in the value of the impact force was very limited. This lead to a fact that the impact force was not affected by the change of the reinforcement ratio, but mainly affected by the change of the slab thickness.

Abstract: This paper presents a numerical and experimental study of the effect of corrugation pattern on the stiffness of thin plates. A two-dimensionally symmetric pattern of corrugation has been proposed and various parameters affecting the stiffness of corrugated plate were optimized. The numerical analysis was performed using a three-dimensional mechanical software design program SOLID WORKS and the finite element program ABAQUS /standard 6.14 software. The trapezoidal pattern of corrugation was selected for this purpose. Having numerically optimized, the proposed pattern was fabricated and tested for further examination of applicability. Numerical analysis was performed on a [360] mm square steel thin plate of which the number of corrugation cells and its geometric parameters ( like height and angle of inclination ) were optimized; the results have recommended a ( 9 ) cells-[32 mm] height-[70⁰ ] angle combination to have the maximum stiffness. The spacing between cells was then examined for its effect on the stiffness of the proposed pattern. When compared with the existing commercial plates of different patterns of corrugation, the proposed design has been found superior. The manufacture of the proposed corrugated plate has shown some difficulties; A punch and die, 3D printer, and folding techniques were attempted. Close results have been found between the numerical and experimental versions of the design.

Abstract: Effects of laser shock peening on the fatigue properties of 2524 aluminum alloy were investigated by laser shock test, residual stress test and fatigue crack growth test respectively. The results show that the maximum residual stress is -220MPa at a distance of 1.1mm from the spot center after LSP (laser energy of 6.26J). The distribution of residual stress was simulated by Abaqus software, and the numerical simulation results were in good agreement with the experimental results. Compared with the untreated specimens, the fatigue life of the shocked specimens was increased by 32%. Fatigue fracture morphologies of the final rupture zone also show that more dimples of significantly larger depth and size occur. The fatigue life of 2524 aluminum alloy can be effectively extended by laser shock process (LSP).

Abstract: The prediction of a crack initiation and propagation occurring on the microstructural level of heterogeneous materials can be a very demanding problem. According to the results of recent investigations, the emerging phase field approach to fracture has a strong potential in modelling the complex crack behaviour in a simple manner. In this study, recently developed phase field staggered solution scheme with the residual norm stopping criterion has been employed for the fracture analysis of heterogeneous microstructure exhibiting complex crack phenomena. The microstructural geometries based on the metallographic images of the nodular cast iron and the material properties of an academic brittle material have been used in numerical simulations where the graphite nodules have been considered as porosities. Two commonly used energy decomposition models, the spectral decomposition and the spherical-deviatoric split, and their effects on the results of the phase field modelling are investigated. Numerical results show that the proposed algorithm recovers the complicated crack path driven by the complex microstructural topology.

Abstract: In a hybrid coupled wall (HCW), a steel coupling beam with a good shear performance can replace a concrete coupling beam. This is especially applicable for locations in which height restrictions do not permit the use of deep reinforced concrete beams or in which it is not possible to economically develop required capacity, stiffness, or deformation demands with concrete beams. In this study, a new type of connection design with a steel boundary element of hybrid coupled wall (SBE-HCW) was proposed, and a 23-story SBE-HCW structure was analyzed under both gravity and seismic load to examine the seismic performance using ABAQUS. The structural failure process, base shear force, vertex displacement, and damage distribution of core tube were investigated. The analysis results confirmed that the response of specimen exhibited good plastic deformation behavior under seismic, thereby satisfying the demands of seismic ductility design. The connection between the steel coupling beams and the shear walls in the specimen appeared to be intact. The analysis evidence indicated that the proposed connection detailing appeared to be effective.

Abstract: Size effects extremely exist in the metal micro-forming process. When a deformation process scales down to micro scale, the appearances of geometry size and single grain size start to play a major role in deformation. Generally, the size effects are unavoidable in the experimental work and cannot be neglect in the optimization of micro-forming processes. In this paper, size effect on flow stress is investigated in the form of the coupled effect of workpiece geometry (sample thickness) and grain size, (T/D) by the micro tensile test of pure copper foil. Following the previous approaches, a new hybrid material model is projected to describe the hardening behavior of grains in polycrystalline material. Tensile tests performed on the copper foil with constant thickness and width, while to get dissimilar grain sizes, the foil annealed for different times. The ratio of thickness to grain size (T/D) is limited to larger than 1 (T/D˃1). A hybrid material model is proposed and established based on grain heterogeneity and sample thickness. The hybrid material model builds a relationship between the surface layer and sheet interior. The hybrid material model developed by the strain gradient theory in which the dislocation cell structure, cell densities (interior and wall) engaged to define the polycrystalline aggregate and calculated the dislocations in a grain (grain interior and grain wall). The results show that flow stress varies with the different values of T/D, but with an increase of the share of the grains flow stress start to decreases. After applying the hybrid material model of flow stress, the micro-tensile test of copper foil is simulated by finite element method. The simulation outcomes well matched with experimental results.

Abstract: Metal spinning process is widely used because of its low power requirement to producing complex symmetry components. In this paper, a modified 3D finite element(3D-FE) model is developed under the FE software environment based on characteristics of stagger spinning process. Analysis of the multi-pass spinning deformation mechanism and the effects of spinning parameters on spinning deformation is carried out. The results show that, large internal diameter of tube blank and low dimensional accuracy are caused by too little feed rate of spinning roller, especially for thin-walled tube. But if the feed rate is larger than 60mm/min, large spinning forces and instability appear. Strain rate and forming instability increase with the increase of rotational speed of mandrels, on the other hand, more obvious friction leads to bigger strain of surface of tube blank. With the radius of corner of spinning roller getting 13mm, the extensive overlaps lead to the improvement of spinning efficiency, while low forming quality accompanied by the large spinning forces occurs. Cutting phenomena leads to worse surface quality even tends to crack with the radius of corner of spinning roller being smaller than 8mm. An ideal combination of process parameters is obtained: the roller feed rate is 50mm/min, the rotational speed of mandrel is 40rad/min, the radius of corner of spinning roller is 10mm.

Abstract: Calcium leaching degradation could be happened in reinforcement concrete member due to the contact with pure water in underground condition. Thus, it is needed to evaluate the resistance of calcium leaching for concrete mixed with mineral admixtures. So, in this paper, to evaluate the flexural behavior in RC member with mineral admixture under calcium leaching degradation, we investigated the effect of calcium leaching using the non-linear finite-element program. From the results, the load capacity and flexible rigidity of a degraded RC member decrease when the degradation level increases with leaching period. And, regardless of the type of mineral admixtures, finite-element-method analysis effectively showed the characteristics of calcium leaching damaged RC beam.

Abstract: Incremental sheet metal forming, is a non-conventional machining process which offers higher formability, flexibility and low cost of production than the traditional conventional forming process. Punch or tool used in this forming process consecutively forces the sheet to deform locally and ultimately gives the target profile. Various machining parameters, such as type of tool, tool path, tool size, feed rate and mechanical properties of sheet metal, like strength co-efficient, strain hardening index and ultimate tensile strength, effects the forming process and the formability of final product. In this research paper, Single Point Incremental Forming was simulated using Dassault system’s Abaqus 6.12-1 and results are obtained. Results of sheet profile and there change in thickness is investigated. For this paper, we simulated the process in abaqus. The tool diameter and rotational speed is find out for the production of parts through incremental forming. The simulation is done for two type of material with different mechanical properties. Various research papers were used to understand the process of incremental forming and its simulation.

Abstract: The phase field approach to fracture modelling is based on a variational principle of the energy minimization as an extension of the Griffith’s brittle fracture theory. It introduces a scalar damage field, to differentiate between the fractured and intact material state. That way, it regularizes the sharp crack discontinuities and eliminates the need for the explicit tracking of the fracture surfaces. Moreover, the numerical implementation complexity is thus vastly reduced. In this contribution, the staggered phase field algorithm for the modelling of brittle fracture is implemented within the finite element program Abaqus. A common issue of the existing Abaqus implementations of the staggered phase field schemes is the computationally demanding fine incrementation of the loading applied, required to obtain an accurate solution. The computational time is reduced by imposing an appropriate convergence control paired with the Abaqus automatic time incrementation. Therefore, by taking advantage of the Abaqus computational efficiency, an accurate solution can be obtained for a moderate time step. The proposed model is verified on the symmetrically double notched tensile benchmark test. Compared to the existing implementations, it demonstrates an improvement in accuracy and the computational performance. Furthermore, a heterogeneous steel microstructure is analyzed displaying the model’s ability to solve crack nucleation and curvilinear crack paths.