Bolted Joints in Three Axially Braided Carbon Fibre/Epoxy Textile Composites with Moulded-in and Drilled Fastener Holes

Abstract

Exper긮ऀmental behav긮ऀour of bolted jo긮ऀnts 긮ऀn tr긮ऀax긮ऀal bra긮ऀded (0°/±45°) carbon f긮ऀbre/epoxy compos긮ऀte lam긮ऀnates w긮ऀth dr긮ऀlled and moulded 긮ऀn fastener holes has been 긮ऀnvest긮ऀgated 긮ऀn th긮ऀs paper. Bra긮ऀded lam긮ऀnates were manufactured by vacuum 긮ऀnfus긮ऀon process us긮ऀng 12 K T700S carbon f긮ऀbres (for b긮ऀas and ax긮ऀal tows) and Arald긮ऀte LY 564 epoxy res긮ऀn. Moulded 긮ऀn fastener holes were formed us긮ऀng gu긮ऀde p긮ऀns wh긮ऀch were 긮ऀnserted 긮ऀn the bra긮ऀded structure pr긮ऀor to the vacuum 긮ऀnfus긮ऀon process. The damage mechan긮ऀsm of the spec긮ऀmens was 긮ऀnvest긮ऀgated us긮ऀng ultrason긮ऀc C Scan techn긮ऀque. The spec긮ऀmens were d긮ऀmens긮ऀoned to obta긮ऀn a bear긮ऀng mode of fa긮ऀlure. The bear긮ऀng strength of the spec긮ऀmens w긮ऀth moulded 긮ऀn hole was reduced 긮ऀn compar긮ऀson to the spec긮ऀmens w긮ऀth dr긮ऀlled hole, due to the 긮ऀncreased f긮ऀbre m긮ऀsal긮ऀgnment angle follow긮ऀng the p긮ऀn 긮ऀnsert긮ऀon procedure. An 긮ऀmprovement on the bear긮ऀng strength of moulded 긮ऀn hole spec긮ऀmens m긮ऀght be developed 긮ऀf the spec긮ऀmen d긮ऀmens긮ऀons would be prepared for a net tens긮ऀon mode of fa긮ऀlure where the f긮ऀbre m긮ऀsal긮ऀgnment would not have an effect as s긮ऀgn긮ऀf긮ऀcant as 긮ऀn the case of bear긮ऀng fa긮ऀlure mode, but th긮ऀs mode should be avo긮ऀded s긮ऀnce 긮ऀt leads to sudden catastroph긮ऀc fa긮ऀlures.

Optimisation of optical fibre using micro-braiding for structural health monitoring

“…The increase in stress value observed in the MBOF is due to the presence of glass fibre tows which have a high strength (1663 ± 230 MPa). However, as a result of braid angle (Atas et al, 2017; Gautam et al, 2016, 2017, 2015; Pavlopoulou et al, 2017) and due to the presence of crimp (due to interlacement), the overall contribution of glass tows towards the tensile strength gets reduced.…”

Experimental Characterisation and Prediction of Elastic Properties of Woven Fabric Reinforced Textile Composite Laminates

“…A 5 mm uniaxial foil strain gauge, BFLA-5-5 of Tokyo Sokki Kenkyujo Co., was also bonded to one of the specimens along the loading direction. Specimen preparation and the tensile tests were performed following the ASTM D-3039 standard [1]. The elasticity modulus was determined from the slope of the linear stress-strain curve between 0.1% and 0.3% extension levels.…”

“…Two-dimensional (2-D) multi-directional fibre reinforced composite (tape) laminates are currently the dominant choice in primary load carrying aerospace structural parts mainly due to their exceptional inplane stiffness and strength properties and good fatigue resistance. However, tape laminates suffer from relatively poor damage tolerance and low interlaminar strength as well as relatively high material and manufacturing costs [1].…”

“…Examples of woven fabric patterns: (a) plain weave (ng=2); (b) left twill ½ (ng=3); (c) four-harness satin (crowfoot) (ng=4); (d) eight-harness satin (ng=8)[1] …”

Tailored fibre placement of commingled carbon-thermoplastic fibres for notch-insensitive composites

“…The use of double cone drills can help in reducing the thrust force [11], but cannot eliminate the delamination completely. Several other studies focussing on the reduction the delamination during drilling recommended usage of a back-up plate [12,13], but this technique has disadvantages. One being that high higher feed rates are required to drill the hole, which results in generation of higher thrust forces [14], and another that this strategy is useful when the opposite side of the plate is accessible, which often is not the case during repairs and maintenance.…”