Simulation And Structure Optimization Of NiTiNb Memory Alloy Pipe Coupling Connection System

NiTiNb shape memory alloy pipe-coupling has been widely researched and applied in the aerospace, aviation and other fields. The optimal size and shape design of shape memory alloy pipe-coupling and the calculation of pulling-out force are difficult to solve.The joint models of NiTiNb shape memory alloy pipe coupling to TA18 titanium alloy pipe or 2169 stainless steel pipe were built using the numerical simulation of software MARC, respectively. Influence of different pipe-coupling wall thickness, height and length of the inner rib on the equivalent stress, equivalent strain, radial stress and radial strain with different temperatures were studied, respectively. The results obtained are summarized as follows:Processing within the different wall thickness and height of the inner of piple coupling blasting experiment, it was found that the pipe bursting strength increased with the increase of wall thickness and height of the inner rib. Moreover, the experiment results showed that the best dimension of the NiTiNb Φ6m pipe wall thickness and inner rib height are 1.7 mm and 0.45 mm, respectively.Through the finite element model of the different wall thickness, inner rib height and length of Φ6mm pipe-coupling and TA18 titanium alloy, it was found that the equivalent stress, equivalent strain, radial stress and radial strain of pipe-coupling increased with the increase of wall thickness and height of the inner rib in constant constraint recovery process; The pulling-off force increased with the increasing wall thickness after the restoration is complete; The inner rib length has little effect on the equivalent stress,equivalent strain, radial stress and radial strain of pipe connection system. The pulling-off force slightly decreased with increasing length of inner rib. Eventually, the optimum parameters of connecting Ni TiNb shape memory alloy pipe-coupling and the TA18Φ6mm titanium alloy were determined as follows: wall thickness of 1.65~1.70 mm, inner rib height of 0.2~0.3 mm, length of 22 mm.Through the finite element model of the different wall thickness, inner rib height and length of Φ6mm pipe-coupling and 2169 stainless steel, it was found that the equivalentstress, equivalent strain, radial stress and radial strain of pipe-coupling increased with the increase of wall thickness and height of the inner rib in constant constraint recovery process; The pulling-off force increased with the increasing wall thickness after the restoration is complete; The inner rib length has little effect on the equivalent stress,equivalent strain, radial stress and radial strain of pipe connection system. The pulled-off force decreased with increasing length of inner rib. Eventually, the optimum parameters of connecting NiTiNb shape memory alloy pipe-coupling and the 2169 stainless steel were determined as follows: wall thickness of 1.70 mm, inner rib height of 0.3 mm,length of 22 mm.All the analysis showed that the optimum parameters of connecting NiTiNb shape memory alloy pipe-coupling and the TA18 Φ6mm titanium alloy or 2169 stainless steel were determined as follows: thickness of 1.70 mm, inner rib height of 0.3 mm, length of22 mm.