EFFECT OF APPLIED CONSOLIDATION PRESSURE IN DIRECT DIGITAL MANUFACTURE OF CONTINUOUS FIBER REINFORCED COMPOSITES

摘要

Research and development in the field of advanced continuous fiber reinforced thermoplastic matrix composites is currently being catalyzed by both the aerospace and automotive sectors. Key aspects of technology development are precise and repeatable process control, reduced tooling requirements and an ability to vary design parameters within a product cycle. As such, a significant body of work regarding the integration of automated fiber placement with additive manufacture has become relevant. Current methods of integrating automated fiber placement with additive manufacture often suffer from high void content, relatively low fiber volume fraction and inadequate process control. In these processes, there has been little documented research into the effects of applied consolidation pressure. The current research focuses specifically on the effects of controlled, applied consolidation pressure on the quality of high fiber volume fraction, continuous fiber reinforced, thermoplastic matrix composite demonstration articles with significantly reduced tooling requirements. A dual gantry 3-axis additive manufacture system, incorporating a novel method for the active application of consolidation pressure, is utilized to investigate improvements in composite quality in the direct digital manufacture of continuous fiber reinforced test articles. Mechanical and metallographic evaluations are utilized to assess the effectiveness of applied consolidation pressure as a tuneable process parameter during the printing process. The application of consistent consolidation pressure is shown to be effective in terms of improved mechanical properties, reduced void content and consistently high fiber volume fraction. Use of controlled consolidation pressure as a tune-able parameter in the direct digital manufacture of high fiber volume fraction continuous fiber reinforced thermoplastic matrix composite materials results in an increase in process control as well as resulting material qualities.