Consolidation and Forming of Aerospace Graded Composite Materials : An experimental study of prepreg characteristics

Sammanfattning: The topic of this project is an experimental study of prepreg characteristics, such as tack, consolidation and temperature sensitivity during forming. The aim has first been tounderstand how the material reacts during different manufacturing processes. Secondly, to recommend suitable parameter settings, based on the findings, in order to get a good andreliable manufacturing process.In a literature study it was found that the prepreg tack is difficult to measure. It is debated by the scientific community today how to best describe prepreg tack, and the answer is affectedof what parameters that are sought to be reproduced. Consolidation tests have, in this study, been performed in an Instron machine. The relaxation of two different materials has beenmeasured in room temperature, 40 °C and 60 °C, with a maximum pressure of 2-10 bar. These limits are set to cover the temperature- and pressure scope in a robot forming process.Results show that neither of the materials will experience full consolidation during these tests, and therefore, neither in a robot forming process. It is therefore recommended toconsolidate the material in a separate process, if forming it with a robot. The material 6376/HTS is more temperature sensitive than the other tested material, an aerospacegraded prepreg with T800 fibres.Forming tests was carried out in a vacuum forming box with the goal to find a temperature where no forming defects can be seen by eye. This is found to be true at temperatures above50 °C for the material 6376/HTS when stacked in sequence [45, 0, -45, 90]4s.None of the materials are recommended to be robot formed in room temperature. Results show that one can see correlations between the forming tests and the consolidation tests.The tests are also assessed as a good way to gain basic understanding of the characteristics of a specific material.