材料的双轴拉伸的规律的研究

Experimental Study of Spring-back Emulation System with High Precision

汽车车身覆盖件是冲压成型的,其覆盖件的高精度回弹量计算非常困难,并少见有研究和报道。由于冲压成型过程是一个大应变和塑性屈服,常规的拉伸试验机无法测出其应力应变曲线,而目前汽车工业领域还没有建立用于修正回弹量的数据库,所以必须通过数值模拟和实验的方法对汽车车身覆盖件进行弹性模量、屈服强度和硬化规律进行研究。本实验研究的目的是通过对规定材料的双轴拉伸试验,应用数字图像处理的光测方法,确定材料屈服强化阶段复杂本构模型的材料特性常数,以达到正确合理描述复杂材料的硬化行为。试验中采用机械式拉伸试验机实现材料的双轴拉伸行为,利用数字相关光测方法获得拉伸材料屈服面屈服过程中大应变全场的数据,通过数字图像相关处理,得到材料在屈服强化阶段复杂本构模型的特性参数。实验研究的设备和仪器包括(1)双轴拉伸试验机;(2)计算机,高分辨率CCD和摄像头,图像卡,图像处理软件;(3)其它辅助设备等。实验研究设备的规范标准根据国家现行实验规范标准对本实验研究设备进行标定和计量审核。

The covering parts are manufactured by pressing process. It is very difficult to calculate the high precision rebound amount of the parts, it is rarely reported. Large strain and plastic yielding are presented in the pressing process so that the conventional machine can＇t get the curve between stress and strain. Because of the unavailability of the database in the current automobile manufacturing field which can be used to modify the rebound amount, we can only rely on experiments to research automobile＇s covering parts for the elastic modulus, yielding strength and hardening law. The purpose of the present experiments together with the digital correlation method is to define characteristic constants of the complicated module＇s material, which can be used to correctly describe the hardening process of complex materials. During the experiments mechanical tension machine is used to realize the double-axis stretching test, and then the data of material characteristic is obtained with the digital correlation method. Experimental equipments include. （1） double -axis static-dynamic test machine, （2） soft of the Digital correlation method computer, graphic card, CCD camera, software and （3） other equipments. The experiments are technically accorded with the normal standards for stretching test.