The fatigue crack initiation from notch root and the short-crack growth laws of two medium carbon alloying structural steels—35CrMo and 42CrMo are investigated under the different stress ratios R =0.1, 0.3) and th...The fatigue crack initiation from notch root and the short-crack growth laws of two medium carbon alloying structural steels—35CrMo and 42CrMo are investigated under the different stress ratios R =0.1, 0.3) and three-point bending condition. The relationships between the maximum stress range at the notch root Δ σ max and the number of cycles before fatigue crack initiation N i are determined. The threshold stresses of fatigue crack initiation (Δ σ max ) th are got, and the smallcrack growth laws are obtained for these steels. An effective and convenient method is proposed for predicting the fatigue life of the notch specimens.展开更多
Based on experimental restilts of brittle, intact sandstone under uniaxial compression, the micro-parameters were firstly confirmed by adopting particle flow code （PFC2D）. Then, the validation of the simulated model...Based on experimental restilts of brittle, intact sandstone under uniaxial compression, the micro-parameters were firstly confirmed by adopting particle flow code （PFC2D）. Then, the validation of the simulated models were cross checked with the experimental results of brittle sandstone containing three parallel fissures under uniaxial compression. The simulated results agreed very well with the experimental results, including the peak strength, peak axial strain, and ultimate failure mode. Using the same micro- parameters, the numerical models containing a new geometry of three fissures are constructed to investigate the fissure angle on the fracture mechanical behavior of brittle sandstone under uniaxial compression. The strength and deformation parameters of brittle sandstone containing new three fissures are dependent to the fissure angle. With the increase of the fis- sure angle, the elastic modulus, the crack damage threshold, and the peak strength of brittle sandstone containing three fissures firstly increase and secondly decrease. But the peak axial strain is nonlinearly related to the fissure angle. In the entire process of deformation, the crack initiation and propagation behavior of brittle sandstone containing three fissures under uniaxial compression are investigated with respect to the fissure angle. Six different crack coalescence modes are identified for brittle sandstone containing three fissures under uniaxial compression. The influence of the fissure angle on the length of crack propagation and crack coalescence stress is evaluated. These investigated conclusions are very important for ensuring the stability and safety of rock engineering with intermittent structures.展开更多
文摘The fatigue crack initiation from notch root and the short-crack growth laws of two medium carbon alloying structural steels—35CrMo and 42CrMo are investigated under the different stress ratios R =0.1, 0.3) and three-point bending condition. The relationships between the maximum stress range at the notch root Δ σ max and the number of cycles before fatigue crack initiation N i are determined. The threshold stresses of fatigue crack initiation (Δ σ max ) th are got, and the smallcrack growth laws are obtained for these steels. An effective and convenient method is proposed for predicting the fatigue life of the notch specimens.
基金supported by the Fundamental Research Funds for the Central Universities (China University of Mining and Technology) (Grant 2014YC10)the National Basic Research 973 Program of China (Grant 2014CB046905)
文摘Based on experimental restilts of brittle, intact sandstone under uniaxial compression, the micro-parameters were firstly confirmed by adopting particle flow code （PFC2D）. Then, the validation of the simulated models were cross checked with the experimental results of brittle sandstone containing three parallel fissures under uniaxial compression. The simulated results agreed very well with the experimental results, including the peak strength, peak axial strain, and ultimate failure mode. Using the same micro- parameters, the numerical models containing a new geometry of three fissures are constructed to investigate the fissure angle on the fracture mechanical behavior of brittle sandstone under uniaxial compression. The strength and deformation parameters of brittle sandstone containing new three fissures are dependent to the fissure angle. With the increase of the fis- sure angle, the elastic modulus, the crack damage threshold, and the peak strength of brittle sandstone containing three fissures firstly increase and secondly decrease. But the peak axial strain is nonlinearly related to the fissure angle. In the entire process of deformation, the crack initiation and propagation behavior of brittle sandstone containing three fissures under uniaxial compression are investigated with respect to the fissure angle. Six different crack coalescence modes are identified for brittle sandstone containing three fissures under uniaxial compression. The influence of the fissure angle on the length of crack propagation and crack coalescence stress is evaluated. These investigated conclusions are very important for ensuring the stability and safety of rock engineering with intermittent structures.
