Issue 53

Q. Zheng et alii, Frattura ed Integrità Strutturale, 53 (2020) 141-151; DOI: 10.3221/IGF-ESIS.53.12 149 F ATIGUE EXPERIMENT luminum plates with different roughness are selected and cut into specimens using electric spark cutting equipment, and riveted with different self-piercing riveting machines to make 5 different samples groups with different roughness and residual stress. And each group consists of three samples. Roughness tester and X-ray diffraction stress tester are used to test the sample parameters. The MTS landmark100 electro-hydraulic servo material testing machine is selected. The specimen is clamped in the machine as is shown in Fig. 9. The maximum stress is 450MPa, the stress ratio is R=0.1 and the frequency is f=20Hz. The sinusoidal stress is used for the tensile-tensile fatigue test. The failed SPR joints for the fatigue tests are shown in Fig. 10. Figure 9: Clamping specimen. Figure 10: Different failed SPR joints for the fatigue tests. The experimental results are shown in Tab. 7. Under the conditions of preset roughness and residual stress, the simulation and experiments are performed on the self-piercing riveting members of aluminum alloy thin plates. The fatigue results of the two are in the same order of magnitude, and the average error is 9.27%. Experiment examples Roughness R Z Residual Stress /MPa Simulation Results /time Experimental Result/time Error/% （ 1 ） 4.16 60 10722 11689 8.3 56 11053 11867 6.9 50 10656 11689 8.8 （ 2 ） 3.28 37 34810 39654 12.2 30 34960 39088 11.3 28 35560 40887 13.0 （ 3 ） 3.12 -100 104326 114528 8.9 -110 114873 126347 9.1 -118 110287 124345 11.3 （ 4 ） 2.45 -150 172708 187368 7.8 -160 175623 189074 7.1 -145 179236 188659 5.0 （ 5 ） 1.34 -200 291486 329463 11.5 -220 292476 329793 11.3 -234 307563 328974 6.5 Average error / / / / 9.27 Table 7: Fatigue test results. A