Compression and shear response of carbon fiber composite sandwich panels with pyramidal truss cores after thermal exposure

The composite pyramidal truss core sandwich panels with reinforced joints are manufactured by the water jet cutting and interlocking assembly method. The effect of thermal exposure on the out-of-plane compression and shear performances of composite sandwich panels is investigated experimentally. In particular, the out-of-plane compression and shear moduli and strengths of the structures after thermal exposure are predicted theoretically. Experimental results show that the out-of-plane compression and shear performances of composite pyramidal truss core sandwich panels first increase and then decrease with thermal exposure temperature at the thermal exposure of 6 h. The failure modes depend on the particular temperature and time of the applied thermal exposure. As well, the compression and shear performances first increase and then decease with thermal exposure time at 150°C. However, their compression and shear performances have a decreasing tendency with time for a given 230°C exposure temperature. In addition, the destruction responses of composite sandwich panels are also investigated and their possible failure modes (including the crushing, delamination and local buckling of struts) are complemented with the analytic results.