Formation of cryobiaxial-induced damage in tape-laminate composites

摘要

The aim of this study is to investigate progressive formation of cryobiaxial-induced damage in tape-laminate composites intended for use in space-launch-vehicle cryotanks. A new test method is developed to evaluate three stacking sequences subjected to biaxial loading at room and liquid-nitrogen temperatures. Ex situ X-ray computed tomography is used intermittently between loading intervals to image formation and progression of plylevel damage. The mechanisms governing damage evolution are found to be the same for all stacking sequences, regardless of test temperature; however, at a given mechanical load, the low-temperature specimens exhibit significantly more cracking due to increased thermal-residual stresses. In all cases, ply damage is dominated by formation of stitch cracks, which only propagate through-thickness when the relative angle between adjacent plies is less than 45 degrees. Based on findings in this study, a set of guidelines are proposed for the design of tape-laminates that are resistant to cryobiaxial-induced loading.