The pre-tightening axial force of combined composite parts connected mechanically by high-temperature alloy bolts will be reduced in high temperature environments because of different thermal expansion coefficients between composite materials and high-temperature alloys. To overcome the difficulty of connection for hypersonic vehicles and ensure the reliability of thermal structures in high temperature environments, the connection between composite material parts and high-temperature alloy bolts is investigated in this paper. The theoretical formula of a certain type of thermal adaptive bolt with split-piece design is derived, and the consistent result is obtained by numerical model simulation. It is proved, by the typical partial end-frame test, that the residual pre-tightening axial force at high temperature can be improved effectively from about 14% to 80% at 820 ℃, under the condition that the mechanical connection strength of this new design method is the same as that of the former ordinary connection.
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