Impedance-Based Structural Health Monitoring of Additive Manufactured Structures with Embedded Piezoelectric Transducers

Abstract

Embedding sensors within Additive Manufactured (AM) structures gives the opportunity to develop smart structures that are capable of monitoring the mechanical health of a system. The main limitation for AM technology is the ability to verify the geometric and material properties of fabricated structures. Over the past several years the impedance-based technique for Structural Health Monitoring (SHM) has been proven to be an effective method for sensing damage in structurers. The general principle is to excite a piezoelectric device, usually Lead Zirconate Titanate (PZT), and measure the corresponding electrical impedance. AM provides an opportunity to embed sensors within the structure during the manufacturing process. Fused deposition modeling (FDM) was used to print the specimen for this feasibility experiment. The specimen were thin beams printed from Poly-Lactic Acid (PLA) with an embedded monolithic piezoelectric ceramic disc. The impedance measurements were taken using a HP 4194-A impedance analyzer with the specimen acting as a cantilever. Damage was simulated in the specimens by adding mass to the tip of the cantilever as well as drilling hole of various sizes and distances from the sensor. Part validation and SHM of components has be accomplished with embedded piezoelectric sensors. A FEM model was created and compared to the experimental results.