Experiments and numerical analysis of compression after impact (CAI) behavior of CF/PIXA stiffened panels for HSCT structure

Abstract

Compression after impact (CAI) behavior of stiffened panels using T-shaped stringers made of heat resistant thermoplastic composites, CF/PIXA, was obtained by tests at room temperature and 180°C. Excellent impact resistance in terms of delamination area was verified for the present composite panels due to the special fusion bonding film. Room temperature CAI strengths of the stiffened panels were found to be better than CF/PEEK panels in a rough comparison, without regard to differences in stacking sequence and geometry. Relationships between temperature and CAI strengths for CF/PIXA stiffened panels were compared with the results for flat plates (SACMA) and a compatibility between flat plate and stiffened panel data was observed. It is clarified that damage tolerance properties of CF/PIXA stiffened structure are so remarkable at room temperature that compression strengths are quite insensitive to relative impact energy. Its damage tolerance capability is also excellent at high temperature for High Speed Civil Transport structures. Linear and nonlinear buckling analyses based on simple models without delamination and interlaminar stresses were conducted using a finite element code. The results agreed well basically with experimental results. In the case of prediction of the final strength, several points of improvement are identified. The present prediction provides the initial step to discuss the possibility of post-buckling strength design at high temperature stiffened panels.

Keywords:

• HEAT RESISTANT THERMOPLASTIC COMPOSITES
• FUSION BONDING
• DELAMINATION RESISTANCE
• ULTRASONIC C-SCAN
• BUCKLING
• FINAL FAILURE
• NONLINEAR FINITE ELEMENT ANALYSIS