CAJ | 학술논문

对建筑用Q235结构钢分别在单轴和多轴载荷下进行低周疲劳试验，并利用测得的试验结果对寿命评估方法进行研究。研究结果表明：在相同Von Mises等效应变幅值下，材料的比例拉扭路径疲劳寿命高于单轴拉压疲劳寿命，而非比例路径疲劳寿命低于单轴拉压疲劳寿命。按等效应变法进行寿命预测，在非比例加载路径下的预测结果远远超出2倍寿命安全范围区；按临界面法的KBM和Socie模型进行寿命预测能够得到较好的结果，但对圆形路径的高应变幅区得到的结果则过高估计了材料的寿命。在考虑循环过程临界面法向应变影响的基础上，提出了一个改进的考虑临界面拉伸影响的模型，其对比例和非比例路径循环下低周疲劳寿命的评估与实测吻合较好。
대건축용Q235결구강분별재단축화다축재하하진행저주피로시험，병이용측득적시험결과대수명평고방법진행연구。연구결과표명：재상동Von Mises등효응변폭치하，재료적비례랍뉴로경피로수명고우단축랍압피로수명，이비비례로경피로수명저우단축랍압피로수명。안등효응변법진행수명예측，재비비례가재로경하적예측결과원원초출2배수명안전범위구；안림계면법적KBM화Socie모형진행수명예측능구득도교호적결과，단대원형로경적고응변폭구득도적결과칙과고고계료재료적수명。재고필순배과정림계면법향응변영향적기출상，제출료일개개진적고필림계면랍신영향적모형，기대비례화비비례로경순배하저주피로수명적평고여실측문합교호。
Low cycle fatigue tests on Q235 steel under uniaxial and multiaxial loadings were conduc-ted, and the fatigue life evaluation formulas were studied based on experiments .The low-cycle ex-perimental results of strain show that the fatigue life of the metal under proportionally multiaxial load -ing is longer than that under uniaxial loading , but the fatigue life of the metal under non-proportion-ally multiaxial loading is shorter under the condition of given Von Mises'equivalent strain amplitude controlled by machine .Using the equivalent strain approach to evaluate the low-cycle fatigue life, it can be found that the life value under non-proportionally multiaxial loading was 2 times larger than that given in the experiments .Adopting KBM or Socie model of the critical plane approach , al-though the life prediction become better evidently , over estimation is still inevitable for the low-cycle fatigue under round loading path with large strain amplitude .Based on the consideration of the ten-sion effect on normal of the critical plane during the cycle , a modified critical plane model is pro-posed, in which the tension factor can be determined directly by using the given parameters for a certain loading path .And the life evaluation given by the present model agrees with the experimental result .