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2 Journal of Theoretical and Applied Mechanics

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Damage evolution of vehicle motor rotor under single working condition based on GTN model

He Liange, Yuan Zhou, Shi Wenjun, Qu Xiang

Journal of Theoretical and Applied Mechanics

2022

Vol. 60 nr 4

561--577

To study evolution of the void in the material of a motor rotor under different working conditions from a mesoscopic perspective, damage analysis of the rotor has been carried out based on thermal-mechanical coupling theory. According to the test methods of GB/T 228.1-2010 Part 1 and GB/T 228.2-2015 Part 2, tensile tests were conducted on rotor ma- terials at different temperatures to obtain basic mechanical property parameters, and pa- rameters of the fine-scale damage model at different temperatures were fitted by combining orthogonal tests and a finite element inverse calibration method. Then, the accurate tem- perature distribution law of the motor rotor was obtained through CFD calculation. Based on the material parameters and temperature data, the void evolution of the rotor material under thermal-mechanical load was studied by using the finite element method. The results show that: under the rated conditions, the stress concentration of the rotor is mainly ap- peared in the joint with the shaft, the maximum stress was 304.1MPa, which did not reach the yield limit of the material. No plastic deformation occurred, so the volume fraction of voids inside the rotor material did not change still for the initial pore volume fraction of 2.5 · 10−3. In the peak condition, the stress concentration appeared in the rotor plate across the joint of the magnetic bridge and pole shoe with a maximum stress of 354.4MPa and a small plastic strain of 1.133 ·10−3. The pore volume fraction increased to 2.503 ·10−3, where the initial pore growth of 2.150 · 10−6 and the secondary pore nucleation of 2.079 · 10−12.

Stress and load distribution analysis in bolt connection with modified thread profile under high temperature conditions

He Liange, Zhang Bin, Guo Caidong, Shi Wenjun

Journal of Theoretical and Applied Mechanics

2021

Vol. 59 nr 3

469--480

In this paper, the load distribution of a bolt connection structure with a variable thread profile at high temperature is investigated. The parameters of time-hardening creep model of aluminum alloy at high temperature were obtained by fitting the uniaxial creep tensile test data of aluminum alloy at 250◦C. Based on ABAQUS, a two-dimensional axisymmetric model of the bolt connection structure was established, and according to the thread load distribution considering linear elasticity, plasticity and creep characteristics, modification of standard metric thread profile was carried out. The load distribution law of the thread of the modified bolt connection structure were investigted. The results show that the load- -bearing ratio of the first thread can be significantly reduced and the load-bearing distribu- tion uniformity of all threads can be improved when the modified thread is applied to the bolt connection structure.