Improving the performance of a lamb wave sensing array via relaxor ferroelectric single crystal transduction

Abstract

Abstract. This paper reports on the potential use of relaxor ferroelectric single crystal (RFSC) transduction to improve the sensitivity of the thin film multi-element Lamb wave sensor called LAMDA (linear array for modal decomposition and analysis). The previously reported LAMDA sensor was created using a high-density multi-element polyvinylidene fluoride (PVDF) electro-polymer sensing array. The electromechanical coupling factor k=d⁄√(ε^T*s^E ), which is proportional to the piezoelectric coefficient d, is considered important for an ultrasonic receiver such as LAMDA. Comparing the PVDF piezoelectric coefficient d31 ≈ 14 pC/N with that of a recent RFSC [011] Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3 (or Mn-PMN-PZT) having d32 ≈ -1100 pC/N, suggests the replacement of the PVDF array with a RFSC array could lead to a significant improvement in the sensitivity of the LAMDA sensor and consequently broaden the scope of its potential application to structural health monitoring. To this end, multiphysics modelling has been performed which indicates a five-fold increase in signal voltage output from a Mn-PMN-PZT based RFSC LAMDA compared with the original PVDF LAMDA. Model predictions for both RFSC LAMDA and PVDF LAMDA sensors will be reported, compared, and discussed.