压电力传感器晶片与电极接触刚度影响研究*

以压电力传感器为核心的多分量测量系统是航空、航天等领域重要的力学测量装置。压电力传感器中晶片与电极结合面接触刚度是基础性能参数，对压电力传感器的分载效应及灵敏度，多分量测量系统的整体刚度及静、动态性能有直接影响。由于尚无对该参数的研究，导致在设计封装压电力传感器过程中缺少相应的理论依据，在使用多分量测量系统时存在标定困难等问题。针对以上问题，研究晶片与电极结合面接触刚度的影响因素，建立基于分形理论的接触刚度模型，优化了晶面表面形貌、压电材料、电极材料、预紧力等参数。在此基础上，研究接触刚度对传感器性能——刚度、灵敏度、固有频率等影响，提出一种以接触刚度为约束的晶片表面形貌优化方法。基于结构函数法，建立分形理论与实际工程测量参数的联系，通过两种压电晶体——石英与硅酸镓镧，四种电极材料——钛合金、不锈钢、黄铜、铝，试验验证了理论模型。试验表明，优化晶片表面分形参数、提高预紧力、选用弹性模量小的电极有助于提高晶片与电极接触刚度，进而提高传感器的整体刚度、灵敏度和固有频率。研究为高性能压电力传感器的设计提供了理论参考。

Effect of Contact Stiffness between Sheets and Electrodes in Piezoelectric Force Sensors

Multicomponent measurement systems centered with piezoelectric force sensors are one of the most significant force measurement equipment's in aerodynamic,aviation etc.The contact stiffness of sheets and electrodes,is a basic performance parameter,not only plays a significant role on load sharing and sensitivity of piezoelectric force sensors,but also affects the stiffness and static/dynamic performance of multicomponent measurement systems.As the contact stiffness has been generally neglected,there are little rules to design and packaging sensors;even it is rather different to calibration in multicomponent measurement systems.To solve these problems,influence factors of contact stiffness between sheets and electrodes is researched.Mathematical model is built based on fractal theory.The parameters such as surface topography of sheets,materials of sheets and electrodes and reload are optimized.Moreover,effect of contact stiffness on performance of sensors such as sensitivity and dynamic are expounded and an optimizing approach to surface roughness of sheets,with contact stiffness as constraint is put forward.Relationship between fractal parameters and measurement data is built using structure function method.The validation tests are performed using two kinds of piezoelectric materials-quartz and Langasite,four kinds of electrodes-TC4,304,copper,aluminum.The results indicate that methods such as optimizing fractal parameters of sheets,increasing the reload and decreasing elasticity modulus of electrodes are significant for piezoelectric force sensors to improve contact stiffness and increase sensitivity even improve natural frequency.The results provide theory reference for high-performance piezoelectric sensors' designing.