基于各项异性的组合式PVDF应变传感器

在应用压电薄膜测量结构表面应变时,薄膜上的感应电压是其面内两个正交方向应变的函数。要获得结构表面某处一个方向的应变,就必须在该处粘贴和检测两片以上的压电薄膜,这对应用于随机载荷作用下的结构应变测量非常不便。利用压电薄膜材料的各向异性开发了组合式压电薄膜应变传感器,这使检测的感应电压和结构表面单一方向的应变成正比关系。根据压电方程推导了组合式压电薄膜输出电压和被测单向应变间的关系,并通过对一个带有小孔平板试件的应变分布测量试验和有限元数值分析,验证了该组合式应变传感器的可行性及具有很高的测量精度。该法操作简单,对实际工程结构应变测量具有重要的实用价值。

Combined PVDF Strain Sensor Based on Anisotropy of the Material

When the polyvinylidene fluoride(PVDF) film is used for strain measurement of structural surface,the inductive voltage on the film is the function of its in-plane strains which are in two orthogonal directions.Therefore,it is necessary to adhere and detect more than two PVDF films in a position in order to measure the strain in one direction,which is not convenient for the strain measurement of structures under random loading.Based on anisotropy of the film material,we have developed a type of combined PVDF strain sensor to make the detected voltage directly proportional to the structural surface strain in one direction.First,the relationship between the output voltage detected from the combined PVDF film and the measured strain was deduced according to the piezoelectric constitutive law.Then,an experiment for the strain distribution measurement of a holed plate specimen was carried out to verify the feasibility of the combined strain sensor.Numerical analysis for the specimen with the finite element method was also performed for comparison with the experimental results.The results showed that the combined strain sensor had high accuracy of strain measurement.The proposed method is very simple and has practical value for the strain sensing of real engineering structures.