Suppression of Delamination at Ply Drops in Tapered Composites by Ply Chamfering

Abstract

The design of structures is often optimized by gradually decreasing the thickness as the load carrying requirement on the components decreases. Such structures in composites are made of tapered laminates involving dropping of plies. However, these structures are often prone to early delamination initiation, which leads to premature failure of the component and therefore limits its useful life. In the past, many routes to circumvent this problem have been evolved, such as the use of adhesive film layers or interleaving the dropped plies between continuous ones. In this work, a novel technique of ply edge chamfering has been developed and employed in the specimen fabrication. Comparisons have been drawn between similarly configured specimens, with and without chamfered ply drops. Static and fatigue test results have shown remarkable improvements, both in terms of complete suppression of delamination around ply drops and in realizing 14.5-77.6% higher strength levels in tapered composite test coupons. The experimental data along with their comparative cases are presented.

Manufacturing defects as a cause of failure in polymer matrix composites

“…It would normally be assumed that the reduction in strength due to premature failure initiated by delaminations at ply drops would have to be accepted as a feature of the design (so long as no additional wrinkling was present). In the case reported above, the tensile strength with unchamfered plies was 1090 MPa and was 1400 MPa with chamfered plies [13]. the compressive strength with unchamfered plies was 636 MPa and with chamfered plies was 1130 MPa.…”

Tensile properties of ply splice fiber reinforced composite laminates

“…Many studies have shown that the end part geometry of jointed parts is a key factor affecting the stress distribution in an adhesive joint, and contributes to the overall material strength. 14,15 Additionally, the stacking sequence and orientation angles are other important factors. [16][17][18][19] According to these results, it can be deduced that for the mechanical analysis of a ply splice structure, the junction geometry and the ply angle should also be paid close attention to.…”

Fatigue damage simulation of tension-tension loaded glass/polyester fiber composites with thickness tapering effects

“…Majority of studies about delamination in tapered areas are considered under quasi-static loadings. 9,10 However, low stress-level fatigue failure analyses are still inaccurate and subjected to uncertainties, because unlike quasi-static tests, slight changes in the fatigue-loading history can significantly change the failure process. 11,12 This haphazardness makes each fatigue failure incident a unique case to be verified experimentally.…”