Determination of manufacturing distortion in laminated composite components

摘要

Manufacturing distortion of composites has been a problem for many years. Previous efforts have shown these distortions to be related to differences in the in-plane and through-thickness properties. Often tooling is modified to attempt to compensate for these fabrication induced distortions; however, the sources of the problem have not been clearly shown. Earlier efforts have suggested that both the cooldown from process temperature and shrinkage during cure play a role, yet no single work has measured the relative contributions of these effects. Further, researchers have suggested numerous other factors as being responsible for all, or some portion, of the measured distortion. In this work, distortion in autoclave-cured composite specimens has been experimentally measured, at temperatures ranging from 24 deg C to 178 deg C, to determine the reversible and irreversible contributions to manufacturing warpage. The measured reversible sesponse closely matches computed distortion, based solely on the in-plane and through-thickness coefficients of thermal expansion. Further, it seems that the irreversible contributions can be separated into material dependent effects, such as cure shrinkage, and process related effects, such as part/tool interactions. Calculations indicate that both temperature change and cure shrinkage contribute significantly to manufacturing distortion; but, their contribution does not account for the total distortion. Trends in the experimentally observed distortion indicate the presence of other process related contributions.