螺旋压缩弹簧应力松弛特性试验分析及其应用

本文通过应力松弛试验、理论推导及数值模拟研究了高温下螺旋压缩弹簧的应力松弛规律,并利用加速模型对工况下弹簧应力松弛服役寿命做出预测。首先,根据螺旋压缩弹簧的结构特点搭建了弹簧应力松弛连续动态测试装置,该装置不仅避免了传统测试方法存在的缺陷,而且能够保证试验过程中位移载荷恒定,并实时监测载荷变化。本文以某飞机舱门单锁机构中的螺旋压缩弹簧为试验对象进行了不同温度条件下的应力松弛试验,得到其松弛动力学曲线,并基于Arrhenius模型建立了弹簧在工况下的应力松弛服役寿命预测模型;其次,基于应力松弛和蠕变在本质上的一致性,结合金属材料蠕变规律并根据试验弹簧的受力特点,推导出用于描述试验材料松弛行为的蠕变本构方程,由试验结果获得该本构方程的材料常数;最后,通过该本构方程及材料常数,在ANSYS软件中对试验弹簧的松弛过程进行模拟,结果表明,模拟结果与试验结果误差不大于4%。因此,通过本文方法所建立的蠕变方程对弹簧在不同载荷条件下的应力松弛规律进行仿真分析具有一定的可行性与准确性。

Experimental analysis and application of stress relaxation characteristics of helical compression spring

In this paper, the stress relaxation characteristics of helical compression spring at high temperature are studied by stress relaxation test, theoretical derivation and numerical simulation, and the service life of spring stress relaxation at room temperature is predicted. Firstly, aiming at the defects of traditional spring stress relaxation testing method, a continuous dynamic testing device for spring stress relaxation is set up. The device can ensure that the loading displacement of stress relaxation test is constant, and the load change can be monitored in real time. The stress relaxation tests of a helical compression spring in a single lock mechanism of an aircraft cabin door were carried out under different temperature conditions, and the relaxation dynamic curves were obtained. Based on Arrhenius model, a stress relaxation service life prediction model of the spring at room temperature is established. Secondly, based on the unification of stress relaxation and creep phenomena in mechanism, the creep constitutive equation describing the stress relaxation behavior of spring materials is derived by using the creep theory of metal materials and the stress characteristics of cylindrical helical springs. The material constants of the creep constitutive equation are obtained from the stress relaxation test results. Finally, according to the creep constitutive equation and material constants, the stress relaxation process of spring is simulated by ANSYS software. The errors between the simulation results and the test results are within 4%. Therefore, it is feasible and accurate to simulate the stress relaxation law of spring under different load conditions by using the creep equation obtained from the tests.