Finite element simulation of rotary blanking based on a modified GTN damage model
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摘要: 在GTN模型基礎上,考慮到微孔洞剪切變形對材料劣化的影響,建立適用于壓應力狀態的剪切修正模型.通過用戶子程序接口VUMAT將與損傷耦合的彈塑性本構模型嵌入具有ALE法的有限元軟件Abaqus/Explicit中.利用模擬拉伸與純剪切試驗擬合載荷-位移曲線以確定模型參數.將修正模型應用到輥沖工藝有限元模擬中預測斷面質量,并進行試驗驗證.結果表明:前刃口為小間隙沖裁,塌角較小,光亮帶較大但帶有一定的傾角;后刃口為大間隙沖裁,塌角與斷裂帶較大,光亮帶較小;裂紋會同時在前刃口凸模與凹模側面萌發,而對于后刃口,會首先在凹模側面產生.Abstract: Based on the GTN model,a modified GTN model applicable to compressive stress conditions was established by considering the effect of microvoid shear deformation on the loss of load-carrying capacity. The elastic-plastic constitutive model with the damage model was implemented in finite element software Abaqus/Explicit with ALE description through user subroutine VUMAT.Parameter values of the modified GTN model in simulation were determined by fitting the load-displacement curve in tensile and pure shear tests. Then,the modified GTN model was employed in finite element simulation of rotary blanking processes to predict the sheared edge quality and the simulation results were experimentally verified. The results show that for the leading cutting edge where the clearance is small,the roll-over depth is small and the burnish depth tilting at an angle is large. For the tailing cutting edge where the clearance is large,the roll-over and fracture depths are large and the burnish depth is small. Microcracks will simultaneously initiate near the flanks of the punch and die for the leading cutting edge,while for the tailing cutting edge they will occur firstly near the flank of the die.
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