Papers by Keyword: Plastic Flow

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Authors: Marina V. Polonik, Egor E. Rogachev
Abstract: Within the linear theory of elastic-plastic body we carried out the modeling of technological process of annealing: slow heating stage, the holding stage under constant temperature and slow cooling step. Holding stage is simulated with consideration of creeping properties of materials. Boundary value problems are examined and patterns responsible for the removal of residual stresses at temperature influence are described. An analytical solution is found. It is proved that the holding stage is essential for describing the process of residual stress relief.
870
Authors: Wen Zhong, Jia Jie Hu, Cai Yun Wang, Peng Shen, Qi Yue Liu
Abstract: The rolling tests of railway rail were performed using a JD-1 wheel/rail simulation facility without any lubricant. The failure behaviour of rail rollers with different materials, was investigated in detail by examining wear volume and wear scar using optical microscopy (OM) and scanning electronic microscopy (SEM). The results indicate that rail material with a high hardness appears less plastic flow after rolling test. When the plastic flow is small, the wear resistance of material appears better. However, the crack propagation is more significant and fatigue damage is more severe. There is a mutual competitive relationship between wear and surface fatigue crack. A high wear rate can reduce rolling contact fatigue damage by removing constantly surface cracks. The analysis shows that U71Mn rail is more suitable for the high-speed railway.
1131
Authors: Zeng Gao, Friedrich Krumphals, Pavel Sherstnev, Norbert Enzinger, Ji Tai Niu, Christof Sommitsch
Abstract: Friction stir spot welding (FSSW) as a variant of the linear friction stir welding is implemented in automotive industry as a partial replacement of resistance spot welding for aluminium. FSSW as a solid state joining technology, primarily takes advantage of severe thermoplastic deformation, to achieve the joining between two parts, which can be from the same material or even dissimilar. In this paper, the coupled thermo-mechanical viscoplastic finite element formulation is presented based on the character of FSSW. The model was calibrated by comparing temperature history obtained from the simulation with experimental data and subsequently used to investigate the effective strain distribution in the weld zone as well as the material flow and the shape of the stir zone.
419
Authors: Qing Liang Zhao, Jun Yun Chen, Jian Luo
Abstract: The swelling effect is an important factor to affect surface generation in SPDT. Face cutting experiments are conducted for copper, aluminum alloy and electroless nickel phosphorus to analyze the swelling effect including the relationship between it and cutting parameters as well as effect of material property. How the material swelling affects surface roughness is also studied in this paper. The results indicate that the swelling effect is influenced by spindle speed and material property more remarkably when compared to feed rate and depth of cut. In addition, a softer and more ductile material will lead to a stronger material recovery, a lower swelling proportion, a lower tool mark height and a smoother machined surface. The result reveals that the swelling effect must be considered when predicting surface roughness in SPDT
984
Authors: Claudio Testani, Antonino Squillace, Livan Fratini
Abstract: Ti6Al4V is probably the best known and studied titanium alloy, not only for aerospace applications. Nevertheless the deformation behavior still represents a challenge if any modification in the deformation process is required or introduced. This work deals with deformation behavior description of Ti6Al4V HIPped powders during high temperature deformation tests carried on in the Beta-region. Laboratory compression and tensile tests have been coupled with relaxation tests in order to achieve robust data about strain rate sensibility m-coefficient and activation energy Q. These results have been fitted for the assessment of a more general exponential deformation law. The final result is a “Dorn model” that takes into account and compare all the results from the three different laboratory techniques: compression, tensile and relaxation with a statistical correlation coefficient Rd2=0,78. The deformation tests have been carried out at temperatures ranging from 1173 K up to 1373 K and strain rate from 0,01 s-1 up to about 1 s-1, trying to describe the high temperature complex shape forging operations. The final results has been used and are in use for modeling the forging precursors and dies-shapes to optimize industrial small scale forging tests.
613
Authors: Yasunori Harada, Makoto Fukunaga, Kenzo Fukaura, Satoru Ujihashi, Yuji Kobayashi
Abstract: The butt joining of dissimilar sheets using a shot peening process was investigated. Shot peening is a surface treatment and improves the performance of engineering components. In shot peening, the substrate undergoes a large plastic deformation near its surface due to a hit with many shots. Thus, plastic flow characterized by a shear droop occurs at the edge of the substrate due to shot peening. When the dissimilar sheets with the edge of the notch geometry are connected without level difference and shot-peened the connection, the sheets can be joined due to the plastic flow generated by the large plastic deformation during shot peening. In the experiment, a compressed-air-type shot peening machine was employed. The influences of processing conditions on the joining of the dissimilar sheets were examined. The joint strength increased with the kinetic energy of shots. It was found that the present method using shot peening process was effective in joining dissimilar sheets.
843
Authors: Yasunori Harada
Abstract: The cold joining of dissimilar metal sheets using a shot peening process was investigated. In shot peening the substrate undergoes large plastic deformation near the surface due to the hit with shots. Consequently, plastic flow areas formed by cold working may form the surface layer. The dissimilar sheets with the concavo-convex edge are connected, and then the contact area is shot-peened. In this joining, the convex edges of the sheet are laid on the other sheet. Namely, in the joining area, the two sheets are superimposed. In the experiment, the shot peening treatment was performed by using an air-type peening machine. The shots used were made of high carbon cast steel. Air pressure was 0.6MPa and peening time was in the range of 30-150s. The peening conditions were controlled in the experiment. The sheets were commercial low-carbon steel, stainless steel, pure aluminum, pure titanium, pure copper, and magnesium alloy. The effects of processing conditions on the joinability were mainly examined. The joint strength increased with the kinetic energy of shots. It was found that the present method was effective for cold joining of dissimilar metal sheets.
1327
Authors: Juan Daniel Muñoz-Andrade
Abstract: The goal of this work is to describe the cosmic micromechanics connection with irreversible deformation processes in spatially extended polycrystalline systems, where the nature of the crystalline structure of the universe in a relativistic framework at Max Plank scale and Edwin Hubble scale play and important role. In this physical construction by applying the theoretical model of Muñoz-Andrade the activation energy for irreversible deformation processes in spatially extended polycrystalline systems is obtained. Consequently, the main results of this work are analyzed in the context of the unified interpretation of Hubble flow, plastic flow and super plastic flow.
1927
Authors: Alexandr A. Mantsybora, Maxim M. Rusanov
Abstract: The problem of shock deforming of elastic-plastic half-space with large deformation was examined. We have obtained that the deformation state can be changed in two types of simple plastic waves and two types of shock elastic waves in the case of self-similar medium motion. The speeds and characteristics of plastic waves were examined. The numerical solution of boundary value problem was found.
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