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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第30卷    第4期    总第253期    2020年4月

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文章编号:1004-0609(2020)-04-0763-12
高强铝板韧性断裂准则参数求解及其成形极限
陈志伟1,赵长财1,董国疆2,杨卓云1

(1. 燕山大学 先进锻压成形技术与科学教育部重点实验室,秦皇岛 066004;
2. 燕山大学 河北省特种运载装备重点实验室,秦皇岛 066004
)

摘 要: 为确定符合高强铝板变形规律的韧性断裂准则的断裂参数,设计了10种不同形状和缺口的拉伸试样,分别采用积分式方程组法、解析式方程组法和曲面拟合法求解韧性断裂准则的多组断裂参数。通过分析统计理论断裂应变与试验断裂应变之间的相对误差评价了断裂参数的预测精度。结果表明:采用积分式方程组法和解析式方程组法依据误差分析分别筛选出的两组试样组合方案的预测精度均较好(误差均值小于30%),而曲面拟合法由于样本数据较少预测误差较大。根据积分式方程组法、解析式方程组法和曲面拟合法求解的最优断裂参数,应用Lou-Huh 2013准则绘制7075-T6高强铝板成形极限图,并采用半球形刚模胀形试验进行验证。验证结果表明:积分式和解析式方程组法预测7075-T6高强铝板破裂失稳偏于安全,这与参数求解时断裂起始点的选取偏于安全有关。

 

关键词: 韧性断裂准则;断裂参数;误差分析;7075铝合金;成形极限图

Calculation of ductile fracture parameters and forming limit of high-strength aluminum sheet
CHEN Zhi-wei1, ZHAO Chang-cai1, DONG Guo-jiang2, YANG Zhuo-yun1

1. Key Laboratory of Advanced Forging and Stamping Technology and Science, Ministry of Education, Yanshan University, Qinhuangdao 066004, China;
2. Hebei Key Laboratory of Special Delivery Equipment, Yanshan University, Qinhuangdao 066004, China

Abstract:In order to obtain the fracture parameters of the ductile fracture criterion in accordance with the deformation regularity of high-strength aluminum sheet, ten tensile specimens with different shapes and notches were designed, and simultaneously the integral equations method, the analytic equations method and surface fitting method were used to calculate the fracture parameters of the ductile fracture criterion. The prediction error between the theoretical fracture strain and the experimental fracture strain was analyzed to evaluate the prediction accuracy of the fracture parameters. The results show that two specimen options are respectively selected from the integral equations method and the analytical equations method have better prediction accuracy with mean error of less than 30%. The surface fitting method has large prediction error because the data of tensile specimen is less. Based on the optimal fracture parameters, calculated by the integral equations method, the analytical equations method and surface fitting method, the forming limit diagrams of AA7075-T6 sheet are drawn by Lou-Huh 2013 criterion and are verified by punch-sketch test. The verification result shows that it is safe when the integral equations method and analytic equations method were used to predict the fracture problem of AA7075-T6 sheet. This phenomenon is related to the determination of the fracture initiate point during fracture parameters calculation process.

 

Key words: ductile fracture criterion; fracture parameter; error analysis; 7075 aluminum alloy; forming limit diagram

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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