NiTiNb shape memory alloy pipe fittings strength of the system model and optimization design

NiTiNb pipe joints is a new shape memory alloy pipe joints in piping connections has a good application prospect. The strength of fittings and system optimization design of its structure in its nuclear reactor steam generator vessel piping connections on the application of great significance . This paper studies the NiTiNb alloys at high temperatures sag resistance , and shape memory alloy NiTiNb the response characteristics of various constraints , then the use of solid mechanics knowledge to build up strength NiTiNb fitting a mathematical model system to study the strength of the pipe joint system the variation with temperature , and Hydraulic tube fittings  were optimized . NiTiNb alloy sag resistance will affect the high-temperature strength NiTiNb fittings , so first NiTiNb alloy at different temperatures under different initial anti- stress relaxation properties have been studied , the results showed that: the temperature at 300 ~ 400 ℃, the initial stress at 260 when ~ 360MPa , NiTiNb good stress relaxation resistance alloys , used to prepare the pipe joint in temperature does not exceed 300 ℃, stress does not exceed 360Mpa conditions safely. Shape memory alloy pipe fittings hold on power was taken over from a shape memory alloy phase transition temperature , the restoring force generated constraints