Improving laminate quality in wet lay-up/vacuum bag processes by magnet assisted composite manufacturing (MACM)

A novel method, Magnet Assisted Composite Manufacturing (MACM), which utilizes a magnetic compressive pressure, is proposed to improve laminate quality in wet lay-up/vacuum bag (WLVB) processes. This paper first describes the salient features of MACM/WLVB process, and then demonstrates the effectiveness of this process by investigating the void content and mechanical properties of random mat E-glass/epoxy composite laminates. During cure, high-power, N52 Neodymium permanent magnets are placed on the vacuum bag to apply sufficiently high consolidation pressure. Thus, laminate quality successfully improved such that fiber volume fraction increased more than 55% from 17% to 27% and void content decreased by 53% to under 3% compared to the laminates made without magnetic pressure. The flexural strength and modulus were also substantially improved by 60% and 46% to 253.5 MPa and 9.9 GPa, respectively. The effect of time and duration of applying magnetic pressure on the quality of the part were also investigated. The lowest void content of under 2% and 21% increase in fiber volume fraction were observed by only applying magnetic pressure 15 min at the start of the vacuum in WLVB process.