Research on vibration fatigue life of welded frame based on modal structural stress method
Combined with the modal superposition method,a structural stress calculation method based on the modal method is proposed.Then,based on the rigid-flexible coupling theory,a dynamic model of rigid-flexible coupling considering the flexibility of the frame was established,and the real service envi-ronment of the bogie frame was realized by using the virtual excitation method.The dynamic weak posi-tions of the welded frame under service conditions were identified,10 dynamic weak points on the welded frame were determined,and the highest structural stress(root mean square value of 65 Mpa)was ob-served at the weld joint connecting the outer vertical plate and the lower cover plate of the side beam.Fi-nally,based on the main S-N curve method,the service life of the weak position of the welded frame is predicted.The results show that with the increase of the radius of the curve,the damage of the weak posi-tion of the frame shows a gradual decreasing law.The maximum damage position occurs at the weld joint position of the side beam outer vertical plate and the anti-roll torsion bar seat,and the damage is 2.74 under the life requirement of 12 million kilometers,and the safety margin is low.
welded framerigid-flexible coupling dynamicsstructural stressmodal superposition methodfatigue life prediction
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