Health condition evaluation of carbon fiber–reinforced thermoplastic with a tapping system

Abstract

Carbon fiber–reinforced thermoplastic (CFRTP) composites are gaining popularity in the manufacturing industry of lightweight automobiles. Common composite defects (e.g. voids and delamination) often occur inside CFRTP composites due to their inappropriate manufacturing process and long-term service. In this study, an instrumented tapping system was designed to evaluate the health condition of CFRTP composites by controlling the input force and velocity. The effective mathematical expressions of the contact duration and amplitude of the interactive force were derived to quantify the local stiffness of the tapping area. The amplitude of the interactive force was introduced innovatively as a significant evaluation parameter for a non-closed force–time curve with the time axis due to the influence of constraint condition and coupling effect of the modal shapes excited during tapping. The contact duration of the interactive force over the defective region was longer than that over the sound region. The amplitude of the interactive force applied on the defective area was observed to be lower than that on the sound area. In addition, the applicability and sensitivity of the amplitude of the interactive force was also investigated by changing the dimensions and locations of defects.