Papers by Author: Tung Sheng Yang

Abstract: The feasibility of forging of AL-1050 alloy of cylindrical heatsink under warm conditions is demonstrated in the present work. The stress-strain curves and friction factor play an important role in the cylindrical heatsink forging. The purpose of forging lubrication is to reduce friction between blank and die, and to decrease resistance of metal flow to die. The stress-strain curves at different temperatures are obtained by compressing tests. The friction factor between 1050 aluminum alloy and die material are determined at different temperatures by ring compression tests with graphite lubricants. The compressing and ring compressing tests are carried out by using the computerized screw universal testing machine. The finite element method is used to investigate the forming characters of the forging process. To verify the prediction of FEM simulation in the cylindrical heatsink forging process, the experimental parameters such as stress-strain curves and fiction factor, are as the input data during analysis. Maximum forging load and effective stress distribution are determined of the heatsink forging, using the finite element analysis. Finally, the cylindrical heatsink parts are formed by the forging machine under the conditions using finite element analysis.

Abstract: Predictive power and final shape are very important in the forging process. This study used a finite element method to analyze the forging force, final shape and stress distribution of the cellphone shell forging at different temperatures. To predict the results of FEM simulation accurately, the stress flow and friction factor play an important role. The AL-6061 stress-strain curve at different temperatures was obtained from the compression test of the universal material testing machine. The friction factor between Al-6061 alloy and die is determined by ring compression test.The stress-strain curve and friction factor are applied to the finite element analysis of cellphone forging. Finite element analysis is used to determine the maximum forging load, effective stress distribution and shape of cellphone shell forging. Then the cellphone shell is forged with the parameters of finite element analysis results. Finally, the forging force and product shape are compared between the experimental data and the simulation results. The dimension of the cellphone shell agree with the initial design and the forming force does not exceed the maximum allowable forging load of the machine.

Abstract: In this paper, the use of the finite element method in conjunction with abductive network is presented to predict the maximum forging force and the volume of billet during near net-shape helical bevel gear forging. The maximum forging load and volume of billet are influenced by the process parameters such as modules, number of teeth, and die temperature. A finite element method is used to investigate the forging of helical bevel gear. In order to verify the prediction of FEM simulation for forging load, the experimental data are compared with the results of current simulation. A finite element analysis is also utilized to investigate the process parameters on forging load and volume of billet. Additionally, the abductive network was applied to synthesize the data sets obtained from the numerical simulation. The prediction models are then established for the maximum forging load and volume of billet of near net-shape helical bevel gear forging under a suitable range of process parameters. After the predictions of the maximum forging force and the volume of billet, the optimum of the power of forging machine and the dimensions of billet are determined.

Abstract: Aimed at AISI-1010 low carbon steel pulley components, a finite element method-based metal forming simulation software of DEFORM 3D was used to simulate and analyze the near net forging process for the low carbon steel pulley, and to design forging molds. This technology was used in the pulley tooth forging in conjunction with the servo press-based servo motion curve technology. First, the cold forging process of the pulley preform forging and the near net forging were simulated. Also, the applications of the pulse wave servo motion curve in the pulley tooth forging was simulated, which was compared with the traditional motion curve-based forging forming, where the comparisons focused on the maximum forming force and maximum equivalent stress. The results indicated that the maximum forming force and the maximum equivalent stress of the punch caused by the pulse wave servo motion curve was smaller than caused by the traditional motion curve.

Abstract: The friction factor between 6061 aluminum alloy and die material (SKD61) are determined at different temperatures by using ring compression test which are carried out on a material testing machine. Mechanical properties and fiction factor are then applied to the finite element analysis of the wheel forging for different elevated temperature. Maximum forging load, effective stress and temperature distribution are determined of the wheel forging, using the finie element analysis. Finally, the wheel parts are formed by the forging machine under the conditions using finite element analysis.

Abstract: The mechanical properties such as stress-strain curves and anisotropic parameters at different elevated temperatures are obtained by the computerized screw universal testing machine. The friction testing machine is used to determine the friction coefficient between die and AZ31 sheets at different elevated temperatures. The finite element method is used to investigate the earing of the deep drawing process. In order to verify the prediction of FEM simulation of the earing in the cylindrical cup drawing process, the experimental parameters such as stress-strain curves, anisotropic parameters, fiction coefficient and blank holder force, are as the input data during analysis. The experimental cup height compared with the current simulation result of cylindrical deep drawing process at different elevated temperature.

Abstract: This study uses the finite element method (FEM) to predict the workpiece surface parameters, including contact area ratio and surface roughness, of asperity flattening in indentation and sliding contact for magnesium alloys sheet during warm isothermal forming. Contact area ratio and surface roughness are investigated for different process and material parameters, such as sliding distance, temperature, normal pressure and bulk strain rate by finite element analysis. The predicted results of the surface parameters from the finite element analysis are in good agreement with the results obtained from experiments.

Abstract: This study applies the finite element method (FEM) to predict maximum forging load, billet volume and effective strain in near net-shaped helical-bevel gear forging. Finite element analysis is also applied when designing the near net-shape of a helical-bevel gear, a reverse forming approach to acquire the initial dimensions of the billet based on the forward forging of the helical-bevel gear. Maximum forging load, billet volume and effective strain are determined for different process parameters, such as modules, number of teeth, helix angle and workpiece temperature of the helical bevel gear forging, using the FEM. Finally, the prediction of the power requirement and billet dimensions for the helical-bevel gear warm forging are determined.

Abstract: This study applies the finite element method (FEM) in conjunction with an nanoindentation test to predict the loading curve and stress distribution of thin hard coatings. To verify the prediction of FEM simulation for loading and unloading process, the experimental data are compared with the results of current simulation. Loading curve is investigated for different material parameters, such as elastic modulus E, yield stress Y₀ and tangent modulus ET of nanoindentation process, by finite element analysis. The effects of material properties of thin film on the stress distribution for loading and unloading in the nanoindentation are also investigated. Therefore, the loading curve and stress distribution will be prediction for the different material parameters of nanoindentation process.

Abstract: This study applies the finite element method (FEM) to predict maximum forging load and effective strain in internal helical gear forging. Maximum forging load and effective strain are determined for different process parameters, such as modules, number of teeth, and die temperature of the internal helical gear forging, using the FEM. Finally, the prediction of the power requirement for the internal helical gear warm forging is determined. Therefore, the maximum forming force and strain distribution will be prediction for the different parameters of helical gear worm forging.