The Stability Analysis Of U-Shaped Bellow Under Torsion Load

The stability of U-shaped bellows under torsion load is numerically analyzed in the thesis. The buckling mode and critical torsion of bellows are predicted by nonlinear finite element method (FEM). The effects of each geometrical parameter on the buckling characteristics are discussed based on the predicted buckling critical torsion of bellows with different dimensions. As the number of convolutions increases, nonlinear buckling critical torsion decreases gradually. Thickness has great effect to the buckling critical torsion. As it increased, nonlinear buckling critical torsion augments fleetly. With the increase of the convolution height nonlinear buckling torsion decreases. The change of arc radius has little effect on the nonlinear buckling critical torsion. As the diameter of convolution rage increases, nonlinear buckling critical torsion increases too. Then, the results calculated by linear method and nonlinear method respectively are compared. The post-buckling performance of bellows is simulated using arc-length method. And, an approximate formula for calculating the buckling critical torsion is presented in according with the analytical results.The stability of bellows under both inner pressure and torsion load is further studied based on the previous analyse. The effect of the number of convolutions on buckling critical torsion under inner pressure is discussed. The effect of inner pressure on buckling critical torsion varies with the different of convolution number. A corresponding FE parametrical model is created for complex structure of multilayer bellows. The buckling characteristics of bellows with different number of layers and under torsion load are studied. The distributions of each stress of multilayer bellows and monolayer bellows that have the same thickness as multilayer ones are compared when they are subjected to their buckling critical torsion, respectively. The contact between every layer of multilayer bellows is discussed primarily.