Investigation of delamination during hole drilling in Carbon/BMI Laminates

摘要

At Terma Aerostructures A/S, a subsidiary of Terma A/S, a range of production process variations have been investigated in order to clarify their sensitivity towards drillinginduced delamination in carbon/bismaleimide (BMI) laminates. The parameters investigated are drill wear, prepreg remaining life time and debulk rate. The thrust forces produced by the drilling operation have been measured for different levels of drill wear at different feed rates and in materials with prepreg of different remaining life time. Tests uncovering the influence of remaining prepreg lifetime and debulk rate on Mode I interlaminar fracture toughness has been conducted. Also, a test measuring the critical thrust force for multiple hole depths has been made in order to establish an upper limit for the thrust force. The potential for optimizing the feed rate has been investigated and this shows that the feed rate can be increased 18% while using new drills in laminates of fresh prepreg but for increasing levels of drill wear and prepreg age there is a risk of inducing delaminations with the present feed rate.