Experimental Investigation of Impact Localization in Composite Plate Using Newly Developed Imaging Method
Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, SC 29208, USA
Author to whom correspondence should be addressed.
Inventions 2018, 3(3), 59; https://doi.org/10.3390/inventions3030059
Received: 3 August 2018 / Revised: 21 August 2018 / Accepted: 22 August 2018 / Published: 27 August 2018
(This article belongs to the Special Issue Structural Health Monitoring and Their Applications Across Industry)
This paper focuses on impact localization of composite structures, which possess more complexity in the guided wave propagation due to the anisotropic behavior of composite materials. In this work, a composite plate was manufactured by using a compression molding process with proper pressure and temperature cycle. Eight layers of woven composite prepreg were used to manufacture the composite plate. A structural health monitoring (SHM) technique was implemented with piezoelectric wafer active sensors (PWAS) to detect and localize the impact on the plate. There were two types of impact event that were considered in this paper (a) low energy impact event (b) high energy impact event. Two clusters of sensors recorded the guided acoustic waves generated from the impact. The acoustic signals were then analyzed using a wavelet transform based time-frequency analysis. The proposed SHM technique successfully detected and localized the impact event on the plate. The experimentally measured impact locations were compared with the actual impact locations. An immersion ultrasonic scanning method was used to visualize the composite plate before and after the impact event. A high frequency 10 MHz 1-inch focused transducer was used to scan the plate in the immersion tank. Scanning results showed that there was no visible manufacturing damage in the composite plate. However, clear impact damage was observed after the high-energy impact event.