Influence of Friction Force Between Anti-buckling Device and Specimen on Tensile and Compression Fatigue Life of Sheet

Tensile and compressive fatigue tests were carried out on SAPH440 steel sheet specimen with TC4 titanium alloy sheet anti-buckling device under different torques (1.5-2.5 N·m) and different strain levels (0.25%-1.0%). The effect of friction force on the fatigue life of the sheet specimen was studied, and the applicability of the anti-buckling device was verified. The results show that under the low strain level (0.25%) dominated by elastic strain, the fatigue life of the specimen decreased slightly with the increase of friction force. Under the medium and high strain levels (0.5%-1.0%) dominated by plastic strain, the fatigue life of the specimen increased with the increase of friction force. When the strain levels were 0.25% and 0.5%, the average distance between fatigue striations in the middle section of the crack propagation zone of the specimen was 0.45 μm and 0.86 μm, respectively. As the strain level continued to increase, the fatigue striations became less obvious, and more obvious secondary cracks appeared.