Experiments on High Temperature Mechanical Properties and Stress Distribution Laws on Strain Isolation Pad

The tile is the main heat insulation part of a thermal protection system, and is attached to the outer surface of an orbiter through a strain isolation pad (SIP). In order to study its high temperature mechanical properties and stress distribution, experiments on flatwise tension, flatwise compression and flatwise shear are conducted in the environments of the room temperature of 23±2℃ and the 300℃ high temperature. The load-displacement curve, elasticity modulus and failure strain of the SIP are measured and calculated. Compared with the experimental results under the room temperature, the tension, compression and shear elasticity modulus of the SIP in the 300℃ high temperature environment fall by 9.68%, 9.24% and 8.73% respectively, and the tension and shear failure strain of the SIP in the 300℃ high temperature environment fall by 11.59% and 12.81% respectively. So, the high temperature causes the decrease of the stiffness and strength of the SIP. Its stress distribution is studied with the experimental results. Under the influence of tension, compression and shear force, the stress distribution of the SIP shows trends of low middle and high edge. Besides, shear stress and normal stress are produced under shear force, and the normal stress is tensile at one side and compressed at the other side. The above analysis shows that the edge of the SIP is high in stress and easy to damage