The use of polyvinylidene fluoride films as sensors for the experimental modal analysis of structures

摘要

This work presents the use of a rectangular shape of PVDF (polyvinylidene fluoride) film adhered on the surface of a cantilever beam and a simply supported plate as the sensor, while the impact hammer is applied as the actuator for the structural modal testing. This work first formulates the frequency response function (FRF) based on the hammer excitation and PVDF sensing. The hammer actuator eigenfunction and the PVDF sensor eigenfunction can be identified as the displacement mode shape and the mode shape of the slope difference between the PVDF edges, respectively. A dual-channel FFT analyzer is used to perforrn the experiments. A row of the FRF matrix can be obtained when the PVDF sensor is roving with the hammer actuator fixed. The MDOF curve-fitting algorithm is used to extract the modal parameters, including natural frequencies, mode shapes and modal damping ratios of the structures. The frequency response functions are shown to agree reasonably well between theoretical and experimental results. Results also show that modal parameters can be properly obtained and physically interpreted with theoretical solutions. This work, therefore, demonstrates the feasibility of using the PVDF sensor in conjunction with the hammer for structural modal testing and can also be extended to other structures.