Development of a New Testing Method to Capture Progressive Damage in Carbon Fiber Reinforced Polymers Subject to a Simulated Lightning Strike

Abstract

This paper will present a new testing method to simulate lightning strikes and capture the progressive damage that occurs in carbon fiber polymer matrix systems. The simulated lightning strike contains two major components that must occur simultaneously: a normal pressure pulse that impacts the carbon specimen, representative of the impulse shock wave associated with a lightning strike, and a rapid temperature rise, which represents the thermal shock from the lightning strike. The pressure pulse is applied using a shock tube, a device that forms a controlled shock that will impact the sample. The thermal shock is simulated with a capacitive discharging circuit, in which capacitors are charged to a maximum of 400 V and then, due to the relatively low resistance associated with carbon fiber materials, quickly discharged into the sample. The distance between the brass contacts will be varied, ultimately changing the resistance of the sample, in order to achieve the correct timescale and temperature spike. Various discharge voltages and fiber orientations relative to the direction of the current flow will be tested in order to study the effect these parameters have on the response of the sample. Through the use of Digital Image Correlation and an infrared thermal camera, independent measurements of deformation and temperature, respectively, will be found as the damage progresses, and is to be compared to a network of Fiber Bragg gratings (FBG) sensors applied to the sample. The results will help produce a better understanding of the temperature profile and localizations that occur during lightning strike events.