Infrared welding of continuous fibre-reinforced thermoplastics – Investigations on overlapping joints

Continuous fibre-reinforced thermoplastics are offered as impregnated and consolidated semi-finished products that are known as organo sheets. Parts made of organo sheets are processed in presses and formed to half shells. In order to produce larger components, hollow bodies can be produced by joining the half shells. However, current manufacturing technologies allow only cap profile shaped joints, which lead to a deflection of the fibres in the joint plane. Thus, this paper reveals the high potential of overlapping welds in organo sheets that result in a fibre orientation in load direction and lead to weld strengths close to the interlaminar shear strengths of the unwelded materials. The results show that, by using high welding pressures a matrix depletion and a change of the fibre alignment in the weld plane may occur that lead to a decrease in weld strengths. Furthermore, it is demonstrated that these two effects can be hindered by additional polymer matrix on the organo sheets which causes a more ductile fracture behaviour of the welds as well.