An innovative method to detect fiber preform problems and design optimum resin flow strategy in vacuum assisted resin transfer molding (VARTM) process, a common manufacturing process in composite industry has been created. In this new method, prior to part production, a removable test liquid, such as alcohol, is infused into the production mold with fiber preform laid up inside. The flow pattern of the test liquid is recorded for flow analysis purpose. The test liquid is then removed by vacuum and temperature. As the test liquid flow behavior is similar to that of resin, the acquired test liquid flow pattern information can be used to direct and optimize process design/control of resin flow to eliminate flow-induced defects. For instance, the test liquid flow pattern can be used to detect the locations where defects might occur and the corresponding control action can then be determined for production (resin flow).
An advantage of this method is that it does not need any sensors, but instead, uses the low cost test liquid (such as alcohol) to pre-infuse the fiber preform prior to the resin infusion to detect any fiber perform problems and to predict resin flow pattern, through which the optimum resin flow process design can be obtained. The method provides effective and practical technical solutions to facilitate process design and control of VARTM process for defect-free part fabrication. This new method can significantly reduce the manufacturing cost by improving first-time success rate (reducing the defects related wastes/cost). This technique is particularly useful for large and complex part fabrication where flow-induced defects are common in manufacturing.
