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Gilles Saint-Martin
Abstract
Typological study of structural defects generated in injection moulding of short glass fibre reinforced thermostable polymer composites
Gilles Saint-Martin - 20 march 2003
This PhD study is realised in collaboration with aeronautical companies (Technofan, Microturbo, Liebherr Aerospace) and research laboratories (Ecole des Mines of Albi, Paul Sabatier University of Toulouse). The aim is to control the structural quality of injection moulded short fibre reinforced polyetherimide parts. The first chapter proposes a bibliography study concerning the injection moulding process and the structural defects. Two types of defects are identified as representing the majority of the cases: weldlines and voids. A notable imbalance exists between the scientific knowledge of both defects. Numerical and experimental methods are developed in chapter II. We first describe the calculation methods used in Moldflow software. We also propose an original method used for representing fibre orientation statement in the injection moulded parts. Chapter III deals with weldline defects. We distinguish frontal and adjacent weldlines. The latest has a strong potentiality of optimisation. We particularly study the effect of processing parameters on this type of defect. A weldline reinforcement methodology consisting in a volume deviation is also studied. This work gives us a better understanding of the process-weldline dependence. Chapter IV is related to studies concerning void defects. The aim is to propose prevision and control methodologies for this type of defect in thick injection moulded parts. Experimental studies are also realised in order to have a better understanding of voids morphology and growth. Finally, several applications of these studies are proposed. Moreover, they lead to encouraging scientific prospects.
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