Co-authors​ :

 Sudip BOSE (FRANCE), Philip WITHERS (UNITED KINGDOM), Prasad POTLURI , Andy BARNES , Jens ANDREASEN  

Wider adoption of lightweight materials e.g., Fibre Reinforced Composite is seen as one of the crucial levers to decarbonise multiple sectors i.e., transportation, aerospace & defence, and industrial applications. Emerging economies as well as developed countries are unable to integrate CFRP on a mass scale in these sectors due to the higher cost and uncertainty related to failure, respectively. Insights generated from real time imaging aids in enhancing the yield significantly thereby ultimately reducing cost of production. A composites laminate being a heterogeneous structure with different ply-sequences, it is difficult to establish a straightforward failure mechanism and hence there remains uncertainty regarding the safety of the products made from CFRP. Real-time imaging enhances in-service health monitoring protocol of CFRP parts too. Different imaging techniques e.g., X-ray micro-CT, Phase contrast imaging, Tomosynthesis and Synchrotron sources are used to understand defects as well as failure mechanisms by studying fibre orientation, defect origin and propagation for Carbon fibre/epoxy composites of different form factor: hollow braided cylinder, circular disc with indentation at the centre and open-hole (notched) CFRP laminates. In-situ synchrotron imaging of the CFRP cylinders was done under torsional load. Inter-tow crack and debonding were observed. Use of these high energy beams revealed barely visible impact damages too thereby providing with critical inputs for failure prediction and prevention of catastrophic failure. Avizo software suit was used to reconstruct 3D images from 2D radiographs whereas Abaqus was used for FE damage model. These tools helped in identifying intra- and inter-laminar defects e.g., delamination, matrix cracking, fibre pull-out. These experiments helped in establishing structure-property relationship vis-à-vis manufacturing process parameter. The obtained results were validated by comparing with that from ultrasonic scan and FE-simulation. The pros and cons of different techniques could also be established to guide the user in the choice of appropriate imaging technique for a particular type of defect/microstructure. Tomosynthesis on the other hand allows the fast movement of the source and provides high quality images quickly. Development of techniques and instruments through collaboration with a commercial equipment manufacturer helped to build-in the requirement of the industry i.e., faster image acquisition and processing. Initial set of data encourage us to integrate mini FRP-composite manufacturing rig into a CT equipment thus paving the way for faster adoption and implementation by the composite manufacturers.