TWB 이종재의 충돌 해석, 기계적 특성 및 내식성 평가 연구

Abstract

This study was carried out the analysis of dynamic characteristic for laser TWB of different material. Analysis program is Hyper works 10.0 with Solver LS-DYNA v.971. Modeling element is 2D-Shell, Number of element is 35,641, Number of node is 36,561. Impact speed is 10 km/sec. To investigate influence according to height of weld line for upper part and lower part, length of lower part was different from each 300 mm and 400 mm. The obtained results are as follows; In lower part material SPFC980 with length of 300 mm, the deformation was the smallest and absorbed energy of impact force was the biggest. On based the lower part of center pillar, the position of TWB shows the shorter and the better value. That is, the performance was depended upon according to proportion of upper part, high strength steel; SABC1470. Case 1 and 2 of lower part material SPFH590 showed the large deformation. Impact performance was reduced significantly for case 3 and 4 of lower part material SPFC980. Therefore, impact performance of length of lower part material SPFC980, 300 mm, showed the best analysis result. TWB different materials specimen qualified the high strength in SABC1470 material by heat treatment. The tensile properties according to waiting time up to water cooling and the deformation behavior of high speed bending by statically indeterminate condition like center pillar were evaluated. In same temperature, the heat treated TWB specimen shows a decreasing trend the tensile and yield strength according to waiting time up to water cooling. SABC1470 + SPFH590 TWB specimen of 850 ℃ was moderate conditions that can protect passenger by accident. Considering it's safety of passenger by accident, center pillar is safe to use with SABC1470 of top part and SPFH590 of bottom part. In salt spray test, as-received materials, SABC1470 with Al+Si plating had red rust after 18 hours, SPFH590 with Zn plating had rust after 6 hours. But, SPFC980 without plating had red rust in 30 minute. In salt spray test in 72 hours, the corrosion resistance of SABC1470+SPFH590 TWB specimen with heat treatment at 950 ℃ was more excellent than that of 850 ℃. SABC1470+SPFC980 TWB specimen was excellent in 850 ℃.