基于自由振动衰减响应的硬涂层材料力学特性参数辨识

Identification of the mechanical parameters of hard coating based on free vibration decay response

获得硬涂层材料的储能模量和损耗因子等力学特性参数是硬涂层复合结构建模及减振优化设计的基础。现有的关于硬涂层材料参数辨识研究通常是基于梁形试件和复杂的实验过程。而这里面向悬臂板结构,提出一种仅需测得涂层前后悬臂板的时域共振自由振动衰减响应,来辨识硬涂层材料力学特性参数的方法。首先,确定了由自由振动衰减响应辨识硬涂层储能模量及损耗因子的原理。进一步,给出了获得上述硬涂层材料参数所需的关键参数(包括响应包络线、即时共振频率和阻尼)的辨识方法。再则,描述了硬涂层板有限元建模以及共振频率、模态应变能和参考应变的求解方法。最后以涂敷NiCoCrAlY+YSZ硬涂层的悬臂薄板为例进行了实例研究,获得了该混合涂层的储能模量及损耗因子。进一步,将获得的硬涂层材料参数代入到有限元分析模型,通过对比试验与有限元计算获得的硬涂层板前6阶共振频率,证明了所辨识的材料参数的合理性。经比较发现,辨识获得的硬涂层储能模量及损耗因子随参考应变的变化规律同其他文献基本一致,但该结果可直接用于硬涂层板形结构的建模。

Obtaining the mechanical parameters of hard coating is the premise of modeling and damping design of a hard-coating composite structure. Most studies about identifying the mechanical parameters of hard coating are based on beam specimen and a complex test procedure. Here,a cantilever thin plate structure was considered. A new identification method was presented,which only needed to test the free vibration decay responses from resonance status for the uncoated and coated plate. Firstly,based on the free vibration decay responses,the principles of identifying storage modulus and loss factor of hard coating were proposed. Then,to effectively obtain the mechanical parameters of hard coating,the method of identifying some key parameters（ such as envelop of response,instant resonance frequency and damping） was given. Next,the FEM modeling of hard-coating plate and solution of resonance frequency,modal strain energy and reference strain were described. Finally,the cantilever thin plate coated NiCoCrAlY ＋ YSZ hard coating was chosen to demonstrate the proposed method. The storage and loss factor of this mixing coating were identified. Furthermore,the obtained material parameters were inputted into the created FEM model and the rationality of identified parameters was proved by comparing the first 6 orders resonance frequency obtained by measurement and FEM calculation respectively.The identification results show the change rules of storage modulus and loss factor of hard coating with the strain amplitude are consistent with the results listed in other similar references. However,the results herein can more directly serve for the dynamic modeling of hard-coating plate-shape composite structures.