基于局部应力应变法的桥式起重机用钢丝绳疲劳寿命估算
Fatigue Life Prediction of Bridge Crane Wire Rope Based on Local Stress-strain Method

为保证桥式起重机的提升作业安全性，以32t×42 m双梁桥式起重机用钢丝绳为研究对象，采用局部应力应变法估算其承载从自由状态到额定载荷的两个载荷步时的疲劳寿命。通过有限元数值算法得到钢丝绳的应力分布，由此确定可能发生疲劳破坏的危险部位在钢丝绳与绳芯接触处，应力大小为1 060.3 MPa，寿命为7 233.6次。根据Manson-Coffin公式，通过平均应力修正，得到基于局部应力应变法的疲劳寿命计算模型，计算得到疲劳寿命为7 937.4次，与有限元数值算法得到的寿命相差8.87%，阐明了局部应力应变法估算钢丝绳疲劳寿命的可行性。
To ensure the safety and reliability of 32t×42m double girder overhead crane, the local stress-strain method is adopted to estimate the fatigue life of the wire rope when bearing from the free state to the rated load. Finite element numerical algorithms are utilized to obtain the stress distribution of the wire rope, and the dangerous parts of the wire rope fatigue failure are located at the contact zone of the wire rope and the cord. The simulation value of the wire rope stress and the life are 1 060.3 MPa and 7 233.6 lifting times respectively. In order to prove above results, the calculation model of the wire rope life is established according to Manson-Coffin equation when the mean stress is considered. The fatigue life is 7 937.4 lifting times. The deviation between the numerical life value and the calculation model is 8.87%. Therefore, the calculation model is indicated suitable for predicting the wire rope fatigue life in the practical application