High-Temperature Mechanical Properties of Strain Isolation Pad for Thermal Protection System

Abstract

Flatwise tension, flatwise compression, and flatwise shear experiments were conducted to study the high-temperature mechanical properties of the strain isolation pad (SIP). No damage happened to the test specimens during the flatwise compression experiments. However, the failure mode of the test specimens was related to the thicknesses of the SIP and the load types in the flatwise tension and flatwise shear experiments. Besides, the elasticity modulus and failure strain of the SIP presented obvious anisotropic characteristics, and they reduced by and , respectively in the high-temperature environment as compared with the results in the room-temperature environment. The dispersion of the failure strain was smaller than the dispersion of the failure stress. So, the strain criterion was more suitable than the stress criterion for the strength of the SIP. The numerical analysis model was built to study the strength of the SIP under the simultaneous effects of tension and shear loads. The high-temperature results in the decrease of strength and the thicker SIP enhanced the strength. The strength calculated by the quadratic nominal strain criterion was slightly greater than that calculated by the maximum nominal strain criterion. As the load changed from pure shear to pure tension, the strength of the SIP decrease first and then increased.