Application of commingled thermoplastic composites on an airline seat backrest

[摘要] ENGLISH ABSTRACT: Thermoplastic composites (TPCs) have shown significant advantages over thermosettingcomposites. They have only been put into use recently and global knowledge in TPCs isoften proprietary, therefore a study into the application, processing and properties is ofimportance. The aim of the study is to contribute knowledge in TPCs for South Africanindustry and academic institutions.This thesis studies continuous fibre reinforced thermoplastics (CFRTPs), focussing on theautoclave processing of commingled CFRTPs. A literature study provided backgroundknowledge to CFRTPs regarding processing techniques and mechanics.Flexural testing and impact testing were performed on a variety of CFRTPs andthermosetting composites (TSCs). These tests were performed to further understandCFRTPs as well as to compare CFRTPs and TSCs. The flexural testing revealed thatCFRTPs have comparable strength and stiffness to the TSCs that were tested. They alsorevealed that pre-consolidated sheets showed better and more consistent properties thansheets made from commingled fabric. The impact testing revealed that the tested CFRTPsand TSCs had similar impact resistance even though thermoplastic composites aresupposed to be more impact resistant. The tests also showed that thick unreinforcedthermoplastics had much higher impact resistance than the reinforced materials.Manufacturing experiments were performed to establish sound processing methods ofCFRTPs. It was realised here that the high temperatures required to process the materialsrequire specific processing consumables and tooling. The experiments began byprocessing flat panels in a convection oven with vacuum bagging techniques. They thenprogressed to autoclave processing of parts with complex geometry.An airline seat backrest was chosen as the case study in the application of CFRTPs. Thisapplication requires structural strength and stiffness and also has strict fire, smoke, toxicityand heat release (FSTH) requirements. Its geometry was sufficiently complex todemonstrate the use of commingled CFRTP material. Backrests were made from bothCFRTPs and TSCs so that a comparison could be made between the two types.The backrest was modelled using finite element methods (FEM) to determine an adequatelay-up. This lay-up was then used for both the CFRTP and TSC backrests to ensuresimilarity between the backrests of both materials. LPET (modified polyethyleneterephthalate) was the chosen thermoplastic matrix as it was more attainable than PPS(polyphenylene sulphide) CFRTPs. The backrests of both materials were manufactured inan autoclave with a vacuum bag method and then assembled using adhesives and bondingjigs. Testing revealed that the stiffness and mass of the CFRTP backrests were very similarto the epoxy backrests. This implies that commingled CFRTPs can replace the use ofTSCs in similar applications.A basic cost comparison was also performed to compare the manufacture of CFRTPbackrests to TSC backrests.Further work is needed to optimise processing time of these materials to make them morecompetitive with TSCs. The processing time of commingled materials will probably neverbe as quick as that of press formed pre-consolidated sheets. Their ability to be formed intomore complex parts does however make their use advantageous.

[发布机构] Stellenbosch University