Investigation into the mechanical properties of thermoplastic composites containing holes machined by a thermally-assisted piercing (TAP) process

Abstract

A thermally-assisted piercing (TAP) process has been investigated as an alternative to current methods of machining holes in thermoplastic composites.The spike force/displacement responses during piercing were affected by both the processing temperature and the size of the heated area, as were the resultant microstructure and subsequent mechanical performance. Overall, the results suggest that for advanced manufacturing of thermoplastic composites, good tensile and compressive open-hole properties are produced in the TAP process when using small heated areas and higher temperatures.

On the mechanical properties of continuous fiber reinforced thermoplastic composites realized through vacuum infusion

“…15 Mechanical properties of carbon fiber-reinforced polyetheretherketone composites containing holes machined by a thermally-assisted piercing process were investigated by Brown et al. 16 Experimental investigations on the damage development in open-hole composite specimens subjected to fatigue have also been reported. 17…”

“…Strength prediction of composite laminates loaded in tension containing notches or cracks has already been reported. 14 A finite fracture mechanics model for the prediction of open-hole strength of composite laminates was also reported by Camanho et al 15 Mechanical properties of carbon fiber-reinforced polyetheretherketone composites containing holes machined by a thermally-assisted piercing process were investigated by Brown et al 16 Experimental investigations on the damage development in open-hole composite specimens subjected to fatigue have also been reported. 17 In this work, open-hole compressive (OHC) strength of composites have been determined using a uniaxial compression test of balanced and symmetric laminate with a 6-mm diameter hole at the center.…”

Enhancing the bearing strength of woven carbon fibre thermoplastic composites through additive manufacturing

“…Whilst machining ensures more accurate final part dimensions, mechanical machining can result in damage of the reinforcing fibres and/or matrix material [18], this often leads to the use of bulking to increase mechanical performance, increasing weight. A method that has proven successful in limiting fibre damage around a hole to be placed in a composite, is the use of a large heated spike [24], [25]. This spike is driven into the composite laminate and the heating action helps to part the fibre bundles within the matrix.…”

“…"Tailor Woven" Hole Feature Previous studies on tailored pathing have utilised a thermally assisted Piercing (TAP) or plug method to divert fibre around a hole into a multi-laminate composite sheet [18], [24], [25], in both cases this leads to resin rich region directly above and below the hole. This resin region allowed bolt travel in the Y-axis as the resin is easily compressed without reinforcement.…”

Strength degradation and fractographic analysis of carbon fiber reinforced polymer composite laminates with square / circular hole using scanning electron microscope micrographs

“…A fairly large number of investigations have been done on the tensile 11,12 and compressive 13 performance of the composite material due to the notches, 14 open holes [11][12][13] and cracks. 15 Mechanical performance of the laminated composite components with the geometrical irregularities depends on the shape and size of the irregularity, 10,16,17 stacking sequence, [18][19][20] ply and laminate thickness, 21,22 specimen size, 23 Fiber/matrix system, 24 process of creating geometrical irregularity, [25][26][27][28] volume fraction of the composite. 27 Green et al 21 investigated the effect on the notched tensile strength of Quasi-isotropic laminate of carbon/ epoxy system containing circular hole by considering the hole diameter, ply and laminate thickness as the independent variable.…”