能量法理论与数值模拟相结合的方板对角拉伸临界起皱失稳预测

Prediction of Critical Wrinkle Instability of Thin Plates by Combining Energy Method Theory with Numerical Simulation

在薄板塑性成形起皱失稳预测研究领域,由于理论和试验研究方法各自的局限性,有限元模拟成为了不可或缺的研究手段。由于有限元法不包含起皱失稳判据,虽然利用引入初始缺陷等手段能够输出后屈曲形貌,但却无法界定确切的临界起皱时刻,且模拟结果会受到网格参数设置的影响发生波动。针对该问题,以吉田屈曲试验为验证试验,利用能量法理论与数值模拟相结合建立304不锈钢方板对角拉伸临界起皱判定线。探讨不均匀拉伸载荷性质下的临界起皱判定线的形貌及特征,讨论几何条件和边界条件对试件起皱失稳判定线的影响。通过全场应变测量系统VIC-3D拍摄的试验应变云图证实了所建立的起皱判定线的有效性。研究内容为板料起皱失稳极限图的建立提供了研究方法和部分数据支撑。

In the research field of plastic sheet forming wrinkle instability prediction,finite element simulation has become an indispensable research method due to the limitations of theoretical and experimental research methods.Since the finite element method does not contain the wrinkle instability criterion,although the post-buckling morphology can be output by introducing the initial defect,the exact critical wrinkling moment cannot be defined,and the simulation results will fluctuate under the influence of Setting of meshing parameter.Aiming at this problem,the Yoshida buckling test is used as the verification experiment,the use of energy method theory and numerical simulation to establish the critical wrinkle determination line of 304 stainless steel square plate is proposed.The morphology and characteristics of the wrinkle instability determination line under the condition of uneven tensile load are discussed.The influence of geometric conditions and boundary conditions on the determination line of wrinkle instability of the test piece is discussed.The test strain cloud image taken by the full field strain measurement system VIC-3D confirmed the validity of the wrinkle determination line established.The research content provides research methods and some data support for the establishment of the limit diagram of sheet wrinkling instability.