Using dampers to mitigate thrust forces during carbon-fibre reinforced polymer drilling: Experimental and finite element evaluation

The current most favourable material to aerospace industry is the carbon-fibre reinforced polymer composite. Drilling of carbon-fibre reinforced polymer to facilitate holes for component assembly subjects it to myriad of failures with the most severe one being delamination. Thrust force involved during the drilling process has been found to bear a greater responsibility for delamination damage. The elevated forces exceed the interlaminar strength of the composite laminates leading to separation of layers. This work proposes the use of spring dampers as a means of reducing the thrust forces. In order to arrive at a conclusion, two experimental and finite element simulation setups have been done (one with dampers included and the other without). Thrust forces against the drilling depth were recorded for both setups and compared. Scanning electron microscope was used to examine the drilled plates for delamination at entry and exit of the holes. The results show that using dampers does reduce the thrust forces by about 25% and that the forces are higher towards the exit of the hole which explains the elevated push-down delamination. The experimental and finite element simulation results for forces were found to agree reasonably, hence validating the finite element model.