高强度双相钢薄板拉弯成形试验及数值模拟

Stretch Bending Limit of Dual Phase Sheet and Its Numerical Simulation

在不同凸模圆角半径下对800MPa级双相钢板进行了拉弯成形试验,观察了不同凸模圆角半径下板材极限拉弯深度及板材的断裂位置和断口形貌,对试验结果进行数值模拟,并分析了采用屈服准则Hill、Barlat和BBC的模拟结果.结果表明:对于较大凸模圆角半径(Rp≥2.5mm)的拉弯试验,在经典成形极限曲线(FLC)判据下,采用Hill准则能够准确预测800MPa级双相钢板的极限拉弯破裂情况;而对于较小凸模圆角半径(Rp=1.0mm)的拉弯试验,在FLC判据下,3种屈服准则都无法准确预测双相钢板的破裂情况.

The stretch bending limit, fracture location and fracture morphology of 800 MPa dual phase （DP） steel sheets under different punch radii was determined through series of U-shape stretching bending tests. The limit bending test was numerically simulated and three yielding models： Hill, Barlat and BBC were compared in the numerical simulation. For those tests with bigger punch radii （Rp≥2.5 mm）, the fracture of limit bending can be predicted using the Hill yielding model, using the traditional forming limit curve （FLC） as fracture criterion. However, the fracture of limit bending can＇t he predicted using the same criterion with smaller punch radius （Rp = 1.0 mm） ; the reason is that the necking based traditional FLC neglects the bending effect with smaller punch radii while the bending of 800 MPa DP steel sheets under this condition shows no obvious necking shear fracture, the actual fracture limit is lower than the traditional FLC.