A simple portable low-pressure healant-injection device for repairing damaged composite laminates

Abstract

This article presents the outcomes of an undergraduate design-for-industry team-driven project to develop a portable low-pressure healant-injection device. The developed healant-injection device is intended to use for teaching purpose. The students practice some of the techniques of repairing damaged composite laminates, as part of an engineering composite-related course, which mainly covers the fundamentals and applications of composite laminates. The healant-injection device works by introducing resin into damaged site that can assist the healant to flow through the network of micro-cracks in a low-pressure environment. The device comprises three components: a chamber featuring a (rectangular box) cover made from acrylic that is intended to cover a damaged surface in a low-pressure environment, an injection unit and a vacuum pump unit. Only the vacuum chamber was designed from scratch by the team; the other components were sourced commercially. The repair of composite laminates can be performed using a low viscosity resin, which is made to flow through a hole on the roof of the chamber, assisted by the injection unit (fluid dispenser), from which the resin flows into the damaged (micro-cracks) site; the very low pressure environment (25–29 inHg) in the chamber facilitates the removal of air pockets in the cracks. The composite laminates featured in this project are carbon fibre reinforced composite laminates, which are of great interest to the aerospace industry. Testing and evaluation were carried out by the team to assess the performance of the healant-injection device using impacted carbon fibre reinforced composites. To assist the team to study the effectiveness of the repair, (a) an ultrasonic C-scan equipment for non-destructive testing was used to assess the extent of the healant flow into the crack regions within the damaged carbon fibre reinforced composites and (b) a compression after impact test was carried out to assess the recovery of the compressive strength of the repaired carbon fibre reinforced composites compare to the pristine and damaged samples in different number of carbon-fibre plies (10, 16, 24 and 32).