Analysis of the vacuum infusion moulding process

This thesis focuses on flow through compliant porous media with applications to the manufacturing of composites by vacuum infusion (VI). The context of this work is the need for reliability in environmentally friendly composite processing methods for composite materials. Commercial reality and the prospective application to low cost structures for the transportation industry dictate that appropriate emphasis should be put on obtaining robust simulations, ensuring reliability and progressing toward efficient means of process control. In this context, the open mould manufacturing processes which have been used to produce large composite structures, and are not conducive to quality nor environmental responsibility, must be replaced. Hence, establishing composites as a viable alternative requires closed moulding techniques, of which VI is the most practical for large structures, but where reliability is required for economic survival. This work addresses many aspects of this problem, by making innovative use of fluid mechanics and developing, implementing and proposing new analysis and modelling tools for VI. Main results include a validated analytical model for flow through compliant media, a study of the compliance of textile reinforcements, a finite element model for VI and novel stochastic techniques for the analysis of reliability in liquid composite moulding processes. The work discussed herein stems from a thorough evaluation of published models and leads to novel flow modelling tools for VI including a unique and general formalism for textile compliance. Using these tools it was possible to study, for the first time, the effect of different parameters on VI manufacturing. The reliability issue was addressed by integrating stochastic models for compliance and permeability, and the ability to model complex geometries was demonstrated by adapting a commercial finite element flow code (LIMS)

Analysis of the vacuum infusion moulding process

This thesis focuses on flow through compliant porous media with applications to the manufacturing of composites by vacuum infusion (VI). The context of this work is the need for reliability in environmentally friendly composite processing methods for composite materials. Commercial reality and the prospective application to low cost structures for the transportation industry dictate that appropriate emphasis should be put on obtaining robust simulations, ensuring reliability and progressing toward efficient means of process control. In this context, the open mould manufacturing processes which have been used to produce large composite structures, and are not conducive to quality nor environmental responsibility, must be replaced. Hence, establishing composites as a viable alternative requires closed moulding techniques, of which VI is the most practical for large structures, but where reliability is required for economic survival. This work addresses many aspects of this problem, by making innovative use of fluid mechanics and developing, implementing and proposing new analysis and modelling tools for VI. Main results include a validated analytical model for flow through compliant media, a study of the compliance of textile reinforcements, a finite element model for VI and novel stochastic techniques for the analysis of reliability in liquid composite moulding processes. The work discussed herein stems from a thorough evaluation of published models and leads to novel flow modelling tools for VI including a unique and general formalism for textile compliance. Using these tools it was possible to study, for the first time, the effect of different parameters on VI manufacturing. The reliability issue was addressed by integrating stochastic models for compliance and permeability, and the ability to model complex geometries was demonstrated by adapting a commercial finite element flow code (LIMS)

Influence of strain rate on the ashby-gibson parameters of sheet diamond lattice structures

Triply periodic minimal surface structures (TPMSs) can be used as a substitute for polymeric foams in applications where is necessary to absorb a large amount of energy with high structural deformation. Diamond TPMS offers higher energy absorption per unit weight. This structure is based on the Ashby-Gibson material model that establishes the main mechanical material properties as functions of the relative density and material properties. However, since TPMSs are used in dynamic applications, it is essential to analyse them under dynamic loads. In this study, we investigate the influence of the strain rate on the Ashby-Gibson parameters of sheet diamond

Analysis of the vacuum infusion moulding process

This thesis focuses on flow through compliant porous media with applications to the manufacturing of composites by vacuum infusion (VI). The context of this work is the need for reliability in environmentally friendly composite processing methods for composite materials. Commercial reality and the prospective application to low cost structures for the transportation industry dictate that appropriate emphasis should be put on obtaining robust simulations, ensuring reliability and progressing toward efficient means of process control. In this context, the open mould manufacturing processes which have been used to produce large composite structures, and are not conducive to quality nor environmental responsibility, must be replaced. Hence, establishing composites as a viable alternative requires closed moulding techniques, of which VI is the most practical for large structures, but where reliability is required for economic survival. This work addresses many aspects of this problem, by making innovative use of fluid mechanics and developing, implementing and proposing new analysis and modelling tools for VI. Main results include a validated analytical model for flow through compliant media, a study of the compliance of textile reinforcements, a finite element model for VI and novel stochastic techniques for the analysis of reliability in liquid composite moulding processes. The work discussed herein stems from a thorough evaluation of published models and leads to novel flow modelling tools for VI including a unique and general formalism for textile compliance. Using these tools it was possible to study, for the first time, the effect of different parameters on VI manufacturing. The reliability issue was addressed by integrating stochastic models for compliance and permeability, and the ability to model complex geometries was demonstrated by adapting a commercial finite element flow code (LIMS).EThOS - Electronic Theses Online ServiceGBUnited Kingdo