Papers by Author: Li Bo Pan

Abstract: Strain paths during sheet metal forming are always complex and nonlinear. Forming limit diagram (FLD) is a common method to determine failure in the past decades. However, it is only suitable for linear strain path condition. Regarding dual phase steel DP780, a special experiment was designed and carried out on Zwick Cupping equipment to get nonlinear strain paths. And the strain status was analyzed in FLD. It was found that FLD cannot predict failure precisely in this case. A new approach proposed by Stoughton and Yoon which based on polar effective plastic strain was introduced to analyze this nonlinear strain paths condition, the result is in good agreement with experiment, which indicated that Polar Effective Plastic Strain Diagram was an effective and precise tool to determine failure especially for complex nonlinear strain paths forming.

Abstract: Traditional IF steel is Ti-IF steel for low cost. Some car producer require IF steel to have good mechanical properties with low delta r (plastic stain ratio) value (△r) as well as high performance after welding. A new IF steel was developed by adjusting amount of Nb and Ti based on Ti-IF steel and employing suitable parameters in manufacturing processes. Annealing experiments were made to decide reasonable annealing temperature. The final products exhibit good isotropy with △r ≤0.3. This new type IF steel also had good performances after welding by analyzing results of some key parameters, which can totally meet requirement of car producer.

Abstract: An effective method was proposed to simulate and control the motion track of guide roller during radial-axial ring rolling in FE simulation. The 3-D finite element model was constructed according to the principle and feature of rolling technology. The rolling process was simulated and analyzed by using dynamic explicit finite element technology. The different rolling processes with different technology parameter were simulated. The width spreads and rolling forces under different parameters are compared and analyzed. The results indicated that high quality ring product could be obtained when rational parameters in radial and axial were assigned.