Papers by Author: Jian Pin Lin

Abstract: To improve the formability of aluminum alloy, a new forming technique-the preform annealing process is proposed. Based on the mechanical properties of the original aluminum alloy AA5182-O with two experienced preforming annealing treatment, and preforming annealing process of a complex geometric shape aluminum door inner panel was numerical simulated by using LS-DYNA software. As a result, the effects of annealing time at 365°C on stamping height of the panel and the optimum annealing time were obtained. The results showed that the preform annealing process was feasible in the door inner panel. At 365°C, the smooth forming of the door inner panel was achieved after annealing for 20s with the pre-deformation amount 97mm, Which are the most suitable parameters.

Abstract: With the development of the auotomobile industry, the body-in-white has to meet the dual requirements of lightweight and NVH performance. This study put forward a new lightweight design method considering NVH performance. An example of lightweighting a non-load-bearing body-in-white was given to illustrate the design flow of this method and certificate the effectiveness and applicability. In order to accurately find out the neutral contribution panels which almost have no influence on the interior acoustic field, a new parameter, the weighted acoustic contribution, was introduced to analyze and evaluate the panel synthetical acoustic contribution to multiple peak frequency at multiple field points. Consequently the whole body-in-white’s weight was reduced by 14.673kg and the interior acoustic field remained basically unchanged.

Abstract: To study the effects of temperature and thickness on forming limits of boron steel 22MnB5, Nakajima tests have been performed for the steels with thickness of 1.0mm and 1.4mm at 600°C and 700°C, respectively. The forming limit curve (FLC) of the steel at 700°C is higher than that at 600°C, and the FLC of the steel with 1.4mm is higher than that of the steel with 1.0mm. With increasing the forming temperature, the strain rate sensitive exponent m increases, and it results in a longer Swift’s diffuse instability phase and greater limit strains. The effect of thickness on yield path is different from the case at room temperature, due to the half angle of pointed Vertex, θ₀, which increases with increasing of the thickness, and then the limit strains increase.

Abstract: The sidewall curl caused by springback widely exists in the U-shape part especially to the advanced high-strength steel. Based on the mechanism of springback and the curl, this paper proposes that the reinforcement is useful to control the U-shaped part’s sidewall curl. The influence law of section parameters such as width, height etc on springback are analyzed. Then a sensitivity analysis was conducted and the prior order of sensitivity factors is given. The result indicates adding the geometric features of reinforcement to part is effective to control the springback and also provides the advice for the springback engineering control in the beginning of part design.

Abstract: Tailor welded blanks (TWBs) offer several notable benefits including decreased part weight, reduced manufacturing costs, increased environmental friendliness, and improved dimensional consistency. To take full advantage of these benefits, however, one needs to overcome the reduced formability of TWBs and be able to accurately predict the failure modes depending on the thickness ratio between the thicker and thinner sheets of a tailor welded blank with similar base materials early in the design process. In this paper, we studied the effect of the thickness ratio on the limit dome height of TWBs by using finite element method and experiments, analyzed the effect of TR on the failure mode of TWBs. A concept of the critical thickness ratio was presented to predict the failure modes of TWBs. The results show that the rapture originates on the weld of TWBs when the thickness ratio is less than the critical thickness ratio and on the thinner side when the thickness ratio exceeds the critical thickness ratio.