中文摘要：

针对处于拉伸载荷作用下的平板结构表面裂纹，提出一种利用PVDF（polyvinylidenefluoride）压电薄膜测量结构表面裂纹深度的实验方法。首先，从无限体埋藏裂纹表面法向位移间断的解析解人手，推导结构表面裂纹张开位移和深度之间的关系表达式，并通过三维有限元数值分析对表达式进行验证。其次，将PVDF压电薄膜直接粘贴在表面裂纹上，采用非接触式静电电压表测量薄膜表面因裂纹张开位移产生的感应电压，从而反推出裂纹张开位移量，并进一步根据已建立的关系表达式计算表面裂纹深度。最后制作一个表面半椭圆片状裂纹模型，通过实验对提出的测量方法的可行性及精度进行验证。文中提出的方法同前只能应用于平板结构表面裂纹在均匀拉伸状态下的深度测量，因为该方法的理论基础是基于均匀拉伸载荷作用下的埋藏裂纹表面法向位移间断的解析解，并只对平板结构形式的边界效应系数进行研究。

英文摘要：

An experimental method for measuring surface crack depth of plate structures under tension using polyvinylidene fluoride （PVDF） films is developed. First, the relationship between the surface crack opening displacement and the crack depth of the plate structure was deduced, based on the analytical solution of the displacement jumps across a crack surface embedded into the infinite threedimensional homogeneous elastic solid. Finite element analysis for some cracked models was also performed to cheek the relationship, in which the numerical solution of the crack opening displacement was used to estimate the crack depth. Then, an experimental method for measuring the surface crack opening displacement by the use of PVDF fihns and an electrostatic voltmeter of non-contact type is proposed. In this method, a piece of PVDF film is adhered onto the surface crack directly. The surface crack opening displacement can be calculated by the measured electric potential on the polarized PVDF film, when the film has deformation caused by the opening displacement. Experiments were carried out on a plate specimen with a surface semi-elliptical crack in order to verify the feasibility and accuracy of the proposed experimental method. The proposed method is suitable for only the surface crack depth measurement of plate structures under tension, because it originates from the analytical solution of the displacement jumps across a crack surface under uniform tension and considers only boundary effect coefficients for the plate structure.