Investigation of the RTM/ Bladder Molding Process

摘要

Today, engineering research activity are directed toward the development of environementally friendly systems. For that reason, a lot of efforts are spent on the development of new materials and new processes to reduce energy consumption, enhance safety and comfort. One class of materials that has huge potential to reach these targets is composite materials. They offer extensive design freedom, comsume less energy owing to their light weight structures and allow the production of integrated and complex structures. A key ingredient in the successful production of these structures is a cost effective and reliable manufacturing method. Among candidate structures, one can mention hollow parts with complex shapes such as pipes elbows and artificial leg shell. Conventional processes for producing hollow parts such as filament winding and pultrusion, have two major drawbacks: (1) limitation to simple geometry, i.e., pipes, pressure vessels, and (2) a poor surface finish at the outer surface. Resin transfer molding offers high potential for part integration and automation. In addition equipment cost is relatively low compared to other processes such as Sheet Molding Compound (SMC). Complex parts with integrated core are also produced by this process. The core material being consisting of rigid foam (ex: PUR-Foam, thermoplastics). However, difficulties arise when inserting the core and reinforcement materials into the mold. An alternative option to rigid core consists of using inflatable bladder. The bladder is pressurized to keep a constant thickness of the reinforcement. Combining inflatable bladders with resin transfer molding process will allow the production of hollow complex parts.