Liquid Composite Moulding (LCM) processes are commonly used techniques for the manufacture of fibre reinforced plastic components. The range of LCM processes addresses manufacturing scenarios from low to high volume. This study explores the potential of natural fibres as reinforcement for LCM preforms, considering discontinuous fibre mats produced using several novel methods. Modified paper manufacturing techniques were employed to produce two types of wet formed wood fibre mats, the other two being manufactured using dry methods. The natural fibre reinforcements considered in this study have been characterised with regard to permeability and compaction response, such that their application to a wide range of LCM processes can be evaluated. Reinforcement permeability and compaction response data are required to simulate LCM processes. Permeability of all four types of wood fibre mats was measured as a function of fibre volume fraction. The dry compaction response of these mats has been investigated, with the compression loads being measured up to a fibre volume fraction of 0.4. A complex non-elastic compression response was observed which has significant influence on forces generated within moulds. Saturated compaction tests were also carried out, the samples infiltrated with a test fluid (mineral oil). These results were compared to typical glass fibre mats used for LCM processes. It was found that the wood fibre mats have permeability two orders of magnitude lower, and required significantly larger force to compact to at similar fibre volume fractions as compared to glass fibre reinforcements. Model fluids are used extensively for LCM characterisation experiments because of ease of handling and chemical stability. The influence of test fluid type on permeability and compaction response of four manufactured wood fibre mats has been determined using two different test fluids, a water based polar fluid (glucose syrup) and a non polar fluid (mineral oil). It was found that glucose syrup caused fibre softening and swelling which reduced the required compaction loads, and permeability of a wood fibre mat. On the other hand, mineral oil did not cause any fibre softening and swelling. The effect of geometrical parameters such as reinforcing fibre bundle diameter and length on characterisation was also determined. Six different types of flax fibre yarn mats were manufactured. A series of compaction tests were carried out on both dry and saturated samples. Saturated permeability was also measured at a number of fibre volume fraction levels. The fibre bundling reduced compaction forces and increased permeability of a mat. Composite panels were manufactured using an epoxy resin to visualise the penetration of resin into yarns and fibre cells. The reinforcement permeability and compaction response data were used to model two LCM variants, Resin Transfer Moulding (RTM), and Injection Compression Moulding (I/CM). A consolidation model approach was applied to simulate both RTM and I/CM processes, addressing a simple mould geometry. The RTM and I/CM clamping force traces, flow rates, and gate pressures were also measured. The simulation results have been compared with experiments completed for wood and glass fibre reinforcements at three different fibre volume fractions. It was found that at similar fibre volume fractions, the wood fibre mats produced longer mould filling times, and required larger forces to compact.
| Identifer | oai:union.ndltd.org:ADTP/290066 |
| Date | January 2008 |
| Creators | Umer, Rehan |
| Publisher | ResearchSpace@Auckland |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated., http://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm, Copyright: The author |
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