Mi Chengji, Huang Zhonglin, Wang Haibo, Zhang Dong, Xiong Tao, Jian Haigen, Tang Jiachang, Yu Jianwu
Department of Mechanical Engineering, Hunan University of Technology, Zhuzhou 412007, China.
Department of Mechanical Engineering, Hunan Automotive Engineering Vocational College, Zhuzhou 412001, China.
Materials (Basel). 2022 Jun 28;15(13):4558. doi: 10.3390/ma15134558.
Pre-loading on engineering materials or structures may produce pre-strain, especially plastic strain, which would change the fatigue failure mechanism during their service time. In this paper, an energy-based method for fatigue life prediction on high-strength-steel welded joints under different pre-strain levels was presented. Tensile pre-strain at three pre-strain levels of 0.2%, 0.35% and 0.5% was performed on the specimens of the material Q345, and the cyclic stress and strain responses with pre-loading were compared with those without pre-loading at the same strain level. The experimental work showed that the plastic strain energy density of pre-strained welded joints was enlarged, while the elastic strain energy density of pre-strained welded joints was reduced. Then, based on the strain energy density method, a fatigue life estimation model of the high-strength-steel welded joints in consideration of pre-straining was proposed. The predicted results agreed well with the test data. Finally, the validity of the developed model was verified by the experimental data from TWIP steel Fe-18 Mn and complex-phase steel CP800.
对工程材料或结构进行预加载可能会产生预应变，尤其是塑性应变，这会在其服役期间改变疲劳失效机制。本文提出了一种基于能量的方法来预测不同预应变水平下高强度钢焊接接头的疲劳寿命。对Q345材料的试样施加了0.2%、0.35%和0.5%这三种预应变水平的拉伸预应变，并将预加载时的循环应力和应变响应与相同应变水平下无预加载时的情况进行了比较。实验工作表明，预应变焊接接头的塑性应变能密度增大，而弹性应变能密度减小。然后，基于应变能密度法，提出了考虑预应变的高强度钢焊接接头疲劳寿命估算模型。预测结果与试验数据吻合良好。最后，通过TWIP钢Fe-18 Mn和复相钢CP800的实验数据验证了所建立模型的有效性。
