Étude expérimentale et modélisation du procédé de placement de fibres avec chauffe laser

Abstract

Aeronautic industry demonstrates a growing interest in composite materials and development of quick and automated manufacturing processes. Automated Fiber Placement (AFP) process is a certified technology to achieve laminate structure with thermoset composites. Coriolis Composites Company develops robotic cells for fiber placement enabling the laying of continuous fibers in all directions and on complex geometrical surfaces. Thermoplastic (TP) matrix composites are currently a promising alternative for making structures for transport applications. They do not actually require long and expensive curing step in autoclave and would meet the sustainable requirements and expect thermo-mechanical behavior. AFP process bases on high power diode lasers required to melt the TP polymers. The presented work is located at the crossroads of three technologies with a bright future: AFP process, TP matrix composite and diode lasers. It have been carried out within the framework of the IMPALA project with the aim of modeling process by experiments and numerical simulations. APC-2/AS4 from Cytec Engineering Materials is the composite material of the study. It consists of a pre-impregnated composite with carbon fibers and TP PEEK matrix. Three models developed in this study are: (1) an optical model based on a raytracing algorithm to quantify the laser distribution on materials, (2) a thermal model to calculate the thermal field in laminate structure during layup, and (3) a rheological model in order to study the squeezing and bonding of plies. These models base on a characterization of the process, including the laser beam (that heats both fed tows and previous layed plies) and the compaction system (formed by a deformable roller that molds the lay-up surface). Material data like refractive index, emissivity or viscosity are determined by experiments or homogenization method. Experimental measurements are simultaneously realized with thermocouples and infrared cameras to understand thermal phenomena in heating zone and laminate. These measures correlate well with numeric predictions. The optical-thermal model is used to study the influence of process parameters and suggest loops between laser power and lay-up velocity. A FTIR spectroscopic study have finally improved in transient condition for thermal degradation.