具有温度依赖性的纤维增强复合薄板的非线性阻尼特性分析

Analysis of nonlinear damping characteristics of fiber-reinforced composite thin plates with temperature dependence

基于复指数法分析了具有温度依赖性的纤维增强复合薄板的非线性阻尼问题。首先,考虑热环境对纤维增强复合材料弹性模量的非线性影响,使用复指数法建立了复合薄板的阻尼模型,并实现了非线性阻尼和固有频率的理论求解。然后,结合不同温度下的实验测试结果,构造了各阶固有频率的相对误差函数,并基于迭代和拟合技术,描述了模型中拟合系数的确定方法。最后,以TC500碳纤维/YD127环氧树脂基复合薄板为研究对象,开展了实例测试和验证研究。结果表明,基于复指数法分析获得的复合薄板在20,50和150℃三个温度下的前6阶模态阻尼比和固有频率的最大计算误差不超过9.33%,从而验证了该分析方法的正确性。另外,研究发现该类型复合结构的阻尼比随着温度的升高呈现增大的趋势,但随着模态阶次的升高,其高阶阻尼比对温度的敏感性降低。

In this paper,a complex exponential method is proposed to analyze the nonlinear damping issue of temperature-dependent fiber-reinforced composite thin plates.First of all,by considering the nonlinear effects of thermal environment on the elastic modulus of fiber-reinforced composite materials,this method is employed to establish the damping model of the compsite thin plates,and the nonlinear damping and natural frequency in this model are solved theoretically.Then,the relative error function of the natural frequencies is constructed according to the experimental results under different temperatures,and the determining method of fitting coefficient in the model is explained in detail based on the iterative and fitting techniques.Finally,a case study on test and verification is carried out by taking the TC500 carbon fiber/YD127 epoxy resin composite thin plate as a research object.The results show that the maximum calculation error of the first six modal damping ratios and natural frequencies of composite thin plate obtained by the complex index method at three temperatures,including 20,50 and 150 ℃,does not exceed 9.33%,which verifies the correctness of this analysis method.In addition,it is found that the damping of such a composite structure goes up with the increase of temperature.However,the sensitivity of the high order damping to the temperature is reduced with the increase of the modal order.