金属薄膜弹簧揿压特性仿真研究

随着移动通讯和家电的普及,轻触式按键（Light touch switches)得到广泛的运用。其中关键部件金属薄膜弹簧（Metal diaphragms)是由高强度极薄金属板冲压制成,对其成形特性和工作特性进行仿真研究,可以为优化模具设计,预测产品的疲劳寿命提供依据,本文首先介绍金属薄膜弹簧成形仿真建模的原则,其次,以大变形、小应变弹塑性有限元理论为基础,在单向拉试验的基础上,给出极薄板各向异性指数的计算公式,并采用Hill屈服准则和静力隐式法对金属薄膜弹簧成形进行建模,对成形过程和揿压特性进行仿真研究,预测了冲压成形后的几何形状和揿压过程中的力感特性曲线,最后,比较了仿真结果和试验结果,二者较为符合,验证了建模的正确性。

WORKING BEHAVIORS SIMULATION OF METAL DIAPHRAGMS

Light touch switches are widely used with the development of mobile phones and electrical appliances. The very thin metal diaphragms with high strength are the key component of the switches. The forming capabilities and the working behaviors of diaphragms take a great significance to the design of the dies and the life prediction of the switches. In this paper, first the principles for sheet metal forming are introduced. Second, the diaphragms' geometry after forming is predicted based on the small strain, large deformation elasto plastic FEM theory and the uniaxial tension test results. Also, the formulations of anisotropy parameter for very thin metal sheet forming are provided. In the simulation, Hill criteria and the static implicit method are adopted. The working behaviors of metal diaphragms are simulated considering residual stress after forming. At last, the obtained results are compared with the test results and take rather good agreements with the test results. Also the error is analyzed, and the differences between the isotropic material model and the orthotropic material model are concluded.