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This study provides a detailed failure analysis of galvanized steel wires(3 mm in diameter) for a 35 k V transmission and distribution line, which was carried out by combining the conventional material analysis methods with the finite element method(FEM). It is found that the failed material had good plasticity(5% in elongation),and under the soft torsion loading condition(0.75 in stress state soft coefficient), the ductile fracture should occur on the material. Additionally, the theoretical number of torsions calculated by the FEM was 26.2 times, while the actual number of torsions achieved by the test was only 2.2 times and the local fracture surface exhibited brittle fracture characteristics. The results showed that the local torsion brittle fracture of the material with good plasticity was caused by triaxial stress in the torsion condition, which led to the formation of cavity in the pulling stress area in the material's center, and the finite element calculation results indicated that the stress state soft coefficient at the cavity was distributed between 0.31 and 0.38, and the stress concentration at the cavity was more than twice the normal value. Besides, the Widmanstatten structure formed as the improper hot working process is the corresponding structural reason. 相似文献
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To determine the physical significance of the impact toughness parameters and accurately characterize the low temperature impact toughness of transmission tower material Q420 B,the finite element model of Charpy impact test is established on the basis of experiment.The simulation and test results are verified,and the specimen fracture is analyzed by scanning electron microscope.The formation and growth mechanism of the crack are dynamically analyzed.On this basis,energy separation method is used to investigate the effect of low temperature on impact toughness.The results show that the simulation and test results are in good agreement,and the ductile-brittle transition temperature of Q420 B is about-50 ℃.The breaking process of the specimen is divided into the crack formation and propagation.When temperature drops from 20 to-60 ℃,the crack propagation energy decreases from 51.0 to 11.9 J,the crack formation energy reduces from 39.9 to 15.8 J,and the fracture time of the material drops from 1.8 to 0.6 ms. 相似文献
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