Fabrication of High Quality, Large Wet Lay-Up/Vacuum Bag Laminates by Sliding a Magnetic Tool.

Mehrad Amirkhosravi,Maya Pishvar,M Altan,Marli Sussmann

doi:10.3390/polym10090992

Abstract

This study presents a novel method to fabricate high-quality, large composite parts which can be used in a wet lay-up/vacuum bag (WLVB) process. The new method utilizes a commercial lifting magnet, which is commonly used for transporting ferrous plates, to apply a magnetic consolidation pressure on the WLVB composite lay-up. The pressure is applied on a large area of the laminate by slowly sliding the magnet over the vacuum bag surface, which leads to an improved laminate quality. When further improvement is desirable, multiple passes of the magnet can be performed, where each pass successively compacts the lay-up. To explore the feasibility of implementing this technique, random mat and plain weave glass/epoxy laminates were fabricated, and their properties compared to conventional WLVB laminates. The effects of the number of moving passes of the lifting magnet on the laminate microstructure and properties are also investigated. As a result of multiple passes, the fiber volume fraction in random mat and plain weave laminates increases to 34% and 53%, representing 80% and 16% improvements, respectively. In addition, the void volume fraction reduces almost by 60% to a very low level of 0.7% and 1.1%, respectively. Consequently, the flexural properties considerably enhance by 20–81%, which demonstrates the potential of the proposed method to produce WLVB parts with substantially higher quality. It is also shown that there exists an optimal number of passes, depending on the fabric type where additional passes induce new voids as a result of excessive resin removal.

Highlights

IntroductionComposite materials are extensively used in structural applications ranging from aerospace [1,2], marine [3,4], and automotive [5,6] applications due to their low weight and high mechanical properties.Among the various composite manufacturing techniques, wet lay-up (aka hand lay-up) vacuum bagging is a relatively low-cost, flexible method that does not require special tooling [7,8]
Composite materials are extensively used in structural applications ranging from aerospace [1,2], marine [3,4], and automotive [5,6] applications due to their low weight and high mechanical properties.Among the various composite manufacturing techniques, wet lay-up vacuum bagging is a relatively low-cost, flexible method that does not require special tooling [7,8]
We propose for the first time the use of a commercial, hand-held lifting magnet to fabricate high-quality, medium to large wet lay-up/vacuum bag (WLVB) laminates that may be adopted in industrial-scale applications

Summary

Introduction

Composite materials are extensively used in structural applications ranging from aerospace [1,2], marine [3,4], and automotive [5,6] applications due to their low weight and high mechanical properties.Among the various composite manufacturing techniques, wet lay-up (aka hand lay-up) vacuum bagging is a relatively low-cost, flexible method that does not require special tooling [7,8]. A squeegee and a roller are used to fully impregnate the fabric and remove entrapped air This process is repeated for multiple plies until the desired laminate thickness is achieved, and the vacuum is applied to remove excess resin and volatiles generated during cure. This technique is widely used in fabrication of large, complex composite parts like wind turbine blades [9], marine hulls [10], bridge decks [11], and housing components with relative ease and low cost. A wet lay-up/vacuum bag (WLVB) is commonly used for structural repair and maintenance of large composite parts [12,13,14,15], whereby on-site restoration of a damaged part is possible without complex tooling

Methods

Results

Conclusion