Shao Zhutao, Li Nan
Department of Mechanical Engineering, Imperial College London.
Department of Mechanical Engineering, Imperial College London;
J Vis Exp. 2017 Apr 4(122):55524. doi: 10.3791/55524.
The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional experimental approaches, such as out-of-plane and in-plane tests, are not applicable to the determination of forming limits when heating and rapid cooling processes are introduced prior to forming for tests conducted under hot stamping conditions. A novel in-plane biaxial testing system was designed and used for the determination of forming limits of sheet metals at various strain paths, temperatures, and strain rates after heating and cooling processes in a resistance heating uniaxial testing machine. The core part of the biaxial testing system is a biaxial apparatus, which transfers a uniaxial force provided by the uniaxial testing machine to a biaxial force. One type of cruciform specimen was designed and verified for the formability test of aluminum alloy 6082 using the proposed biaxial testing system. The digital image correlation (DIC) system with a high-speed camera was used for taking strain measurements of a specimen during a deformation. The aim of proposing this biaxial testing system is to enable the forming limits of an alloy to be determined at various temperatures and strain rates under hot stamping conditions.
热冲压和冷模淬火工艺越来越多地用于成型复杂形状的金属薄板结构部件。在热冲压条件下进行测试时，若在成型前引入加热和快速冷却工艺，诸如平面外测试和平面内测试等传统实验方法不适用于确定成型极限。设计了一种新型平面内双轴测试系统，并将其用于在电阻加热单轴测试机中经过加热和冷却工艺后，测定各种应变路径、温度和应变速率下金属薄板的成型极限。双轴测试系统的核心部分是一个双轴装置，它将单轴测试机提供的单轴力转换为双轴力。设计了一种十字形试样，并使用所提出的双轴测试系统对6082铝合金的成型性进行了验证。带有高速摄像机的数字图像相关（DIC）系统用于在变形过程中对试样进行应变测量。提出这种双轴测试系统的目的是能够在热冲压条件下，在各种温度和应变速率下确定合金的成型极限。
