Fabricating high-quality composite laminates by magnetic compaction

This paper demonstrates the feasibility of using high-power, permanent magnets in developing high consolidation pressure during a variety of fabrication methods for composite laminates. First, the salient features of this new manufacturing method, expected enhancement of the mechanical properties, and possible improvements in part quality are discussed. Then, the method of applying magnetic pressure over composite laminates with relative ease is presented. To validate this new method, a number of E-glass/epoxy and carbon/epoxy composite laminates were manufactured by utilizing Neodymium Iron Boron (NdFeB) magnets. Specific results will be given for: (i) wet lay-up/vacuum bag, (ii) VARTM, and (iii) oven curing (i.e. out-of-autoclave) processes, where the laminates fabricated with and without the magnetic compaction. The mechanical properties were shown to improve substantially, primarily due to increase in fiber volume fraction and decrease in process-induced voids. In most cases, both the flexural strength and modulus of the composites increased even as much as 60%, while the void content was reduced from 4-5% to less than 1%.