Effects of laminate sequencing on thermoforming of thermoplastic matrix composites

Continuous fiber-reinforced thermoplastic composites are promising materials for light-weight structural components. Their medium to high processing and temperature-dependent properties, and the complex deformation mechanisms that occur within the composite sheet during the forming, are main problems in the practical production of parts. Thermoforming is an effective fabrication method due to the reversible solid-liquid phase transformation of thermoplastic materials. Deep drawing of these materials involves heating the composite to its melt/softening temperature and then applying suitable force to form the composite to the required shape. In the present study the influence of essential processing parameters on the forming behavior and quality of the profiles was examined experimentally. The base material was polypropylene and unidirectional glass fibers were used as reinforcement. The appropriate processing temperature, pressure and heating time for producing and deep drawing of thermoplastic composite sheet obtained. In order to study the process analytically, finite element ABAQUS software package has been employed. In this investigation, fiber properties gained from experiments were considered. Finally, apparent deformation of fibers and logarithmic axial strain are compared between ABAQUS and experimental results and these comparisons are represented graphically. Consequently these comparisons lead to optimum film stacking among selected lay-ups to prevent wrinkling in deep drawing process. (C) 2008 Elsevier B.V. All rights reserved.