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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2016, Vol. 37 ›› Issue (2): 617-625.doi: 10.7527/S1000-6893.2015.0042

• Solid Mechanics and Vehicle Conceptual Design • Previous Articles     Next Articles

Torsional low-cycle fatigue behavior of C250 steel using funnel specimens at elevated temperature

ZHAO Xinghua1, CAI Lixun1, BAO Chen1, JIANG Zhihua2   

  1. 1. Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China;
    2. AVIC Beijing Institute of Aeronautical Materials, Beijing 100095, China
  • Received:2014-12-26 Revised:2015-02-05 Online:2016-02-15 Published:2015-02-11
  • Supported by:

    National Natural Science Foundation of China(11472228);Sichuan Youth Science and Technology Innovation Team(2013TD0004)

Abstract:

Torsional fatigue rupture is one of C250 steel's main failure forms. In order to obtain torsional fatigue characteristics of C250 steel and eliminate the disadvantages of straight rod specimen, a series of torsional fatigue tests on C250 steel at three different elevated temperatures, 150, 200, 350℃ using funnel specimens has been carried out, and the curves of nominal torque-nominal torsional angle for C250 steel at each temperature are given. Based on the test results and finite-element-analysis aided testing(FAT) method, the effective cyclic constitutive relationships of C250 steel at those temperatures have been obtained. By using these effective cyclic constitutive relationships, 3D finite element analyses of funnel specimen under torsion are used to reveal the transforming relationship between the torque and shear stress at the root of funnel specimen, as well as the relationship between the nominal torsional angle and shear strain at the root of funnel specimen. On the basis of those test and analyzing methods, the curves of shear stress-times cycles、shear strain amplitude-cyclic fraction and stable hysteresis loop of shear stress-shear strain have been obtained. The material shows cyclic softening by the analysis of the low-cycle fatigue behavior, and the typical Manson-Coffin model is employed to predict the torsional fatigue life of C250 steel at three different elevated temperatures.

Key words: torsional low-cycle fatigue, FAT method, C250 steel, funnel specimen, torsional behavior, Manson-Coffin mode

CLC Number: