A Low-Cost Modular Impact-Based Experimental Setup for Evaluation of EMI Based Structural Health Monitoring at High Rates

Abstract

This paper investigates the use of the electromechanical impedance (EMI) method for detecting changes in the dynamic state of structures by presenting a low-cost, modular, instrumented, impact-based experimental setup. This experimental setup consists of a pneumatically actuated moving impacting aluminum bar, which will be launched to collide with a static incident bar at various impact velocities. The system allows for the use of different dimensions and materials for both the impacting bar and the incident bar. The boundary conditions of the incident bar can be changed by configuring the non-impacted side of the bar as clamped or free. The velocity of the impacting bar is measured using an array of two photoelectric sensors. A piezoelectric transducer attached to the incident bar is utilized for detecting the changes in dynamic state at the interface between the two bars by utilizing the EMI method. The impedance data is acquired and processed using a custom made measurement and analysis suite at very high-rate. Preliminary measurement results are presented to demonstrate the capability of the developed system to achieve repeatable and customizable impact events and also monitor the impedance response of the piezoelectric sensor. The long-term goal of this research is the use of this impact-based experimental setup for damage detection in structures operating in highly dynamic environments. This will be done by coupling the setup with a measurement system capable of microsecond data acquisition and processing.