Papers by Keyword: Deformation

Abstract: To meet the stringent requirements of heat-resistance products for aerospace applications, an Al-4.0Cu-1.3Mg-0.6Si alloy containing a cubic σ phase (Al₅Cu₆Mg₂) with excellent high temperature stability was developed. Influence of deformation on aging precipitation behavior of the alloy was investigated by transmission electron microscope (TEM) and differential scanning calorimetry (DSC). The results indicated that cold deformation had great effect on aging precipitation behavior in the alloy. When the alloy was processed a pre-stretching deformation before aging, the precipitation of σ phase was restrained while the S′ phase (Al₂CuMg) was promoted. And the nucleation sites played an important role on them.

Abstract: The joint-locking device is an important component used to lock some equipments in the satellite. In this paper, a joint-locking device is designed to lock the deployable equipment in the satellite. The working principle of its locking mechanism is analyzed, exhibiting such characteristics as light weight, small dimensions and strong locking ability. Thermal deformation analysis on the joint-locking device is conducted using finite element method. The simulation results show that the joint-locking device possesses high thermal stability and can meet design requirements.

Abstract: A frame is an automobile parts, narrow, thin wall and bending，This paper mainly analyzes its machining technology andthe key, the difficulty of processing；And studies how to save materials, save the auxiliary tools, improve the machining efficiency.

Abstract: This research aims to develop an aluminum alloy suitable for applications in the nuclear industry, particularly in terms of its hardness. A synthesized AlFeNiMg alloy plate was subjected to deformation in a gradual rolling process at room temperature. A Vickers hardness tester and an optical microscope were employed to analyze the hardness and to observe the microstructure of the aluminum alloy consecutively. Analyses of elements and phase structures were performed by EDS-SEM and X-ray diffraction. The result shows that the hardness of AlFeNiMg alloy increases along with the increase in rolling deformation. The alloy hardness increases from 88 HV to 113 HV, 135 HV, 153 HV and 165 HV at percent cold reduction of 30%, 53%, 65% and 88% consecutively. From the microstructure observation, the grains tend to get more elongated along with increasing rolling deformation. The pattern analysis of X-ray diffraction shows that there are two phases, namely α and θ (FeAl₃).

Abstract: The purpose of this paper is to compare calculation of internal forces and deformations of slabs for two calculation methods: the finite element method and the finite difference method. Two concrete slabs have been analysed. In the case of the finite element method, different element mesh are used, providing, thus, solutions in different variants. The calculation and algorithms is based on a thin slab theory. Variants calculate in program Scia Engineer effects of shearing forces by means of the Midlins theory or thin slab theory. Algorithms for the calculation were developed in Matlab.

Abstract: Considering the material property of the soil body to the earthquake area and the situation that the law of the deformation of surface points in regions of active seismicity will vary before and after the occurrence of an earthquake, the paper discusses the method to erect a model of vertical deformation in regions of active seismicity using spline function. Finally, it verifies the effectiveness of the method using a simulating network. Some beneficial conclusions are obtained.

Abstract: Numerical tests were conducted with six different pillar width to determine the optimal pillar width of the inclined coal seam based on the fracture and deformation characteristics. The results show that, the fracture zone in pillar is consistent when the pillar width is 3m, while the fracture zone is inconsistent when the pillar width is larger than 5m. When the pillar width is 3m, the pillar is completely fractured, and the shear fracture zone in pillar increase gradually with the pillar width ranges from 5m to 10m,. There has the smallest heaving floor when the pillar width is 5m, while the largest heaving floor when the pillar width is 10m. The reasonable pillar width is 5m.

Abstract: The oblique impact of a golf ball with a rigid steel target was studied using a high-speed video camera. The video images during the impact were employed to measure the compressional displacement of the ball normal to the target and to determine the normal velocity and acceleration of the ball as a function of time. The rotation angle of the ball was also measured to evaluate the angular velocity during the impact. The results showed that the angular velocity increased and then decreased during the impact. To study the velocity change, we introduced an analytical model and suggested that the ball deformation can play an important role to understand the friction effect during the impact.

Abstract: The influence of hot deformation on the evolution of size, shape, and fraction of dispersoids has been studied in a simple 3xxx aluminium alloy by means of hot torsion testing. It has been shown that at high strain rates, deformation leads to spheroidization of the dispersoids, an increase in number density, and an increase in volume fraction. The increase in number density and volume fraction are associated with precipitation of new particles. The enhancement of manganese diffusion is a key factor in promoting rapid dispersoid evolution during deformation. A model has been developed to estimate the effect of deformation induced vacancies and dislocations on diffusion. This predicts that an order of magnitude increase in diffusion coefficient between may occur under typical hot deformation conditions, consistent with the rapid microstructural changes measured experimentally.

Abstract: The effect of cooling rate after solution heat treatment and its combination with 1% pre-deformation on precipitation hardening in two Al-Mg-Si alloys is investigated by transmission electron microscopy (TEM), and related to material hardness. Two alloys have been used, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes. A double peak hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. The 1% pre-deformation also made this effect less pronounced, but it led to faster initial hardness evolution and delayed over-aging. Maximum hardness was not influenced by cooling rate and the pre-deformation. Hardness was directly related to precipitate number densities.