Jianhui Liu

Bio: Jianhui Liu is an academic researcher from Lanzhou University of Technology. The author has contributed to research in topics: Damage mechanics & Stress concentration. The author has an hindex of 2, co-authored 4 publications receiving 12 citations.

Method for Predicting Crack Initiation Life of Notched Specimen Based on Damage Mechanics

Abstract: Based on the theory of damage mechanics, a method for fatigue crack initiation life prediction of notched components is proposed in this paper. The damage evolution equation of notched specimen under tensioncompression loading is obtained in term of closed-form solution. The crack initiation life of notched specimen is estimated by the proposed method even when material and stress concentration factor are different. It has been verified that the result calculated by the proposed method agrees with the experimental result. The proposed method is concise, effective and feasible to practical application.

Notched Component Fatigue Life Prediction in Torsional Loading

Abstract: Considering the situation that fatigue life prediction of notched component is an indispensable part in the process of design in engineering, it is necessary to find some ways to solve such problems effectively. The stress and strain state of notched specimen is more complex, compared with smooth specimen. As a result, some researchers take advantage of the finite element method to analyze the mechanical properties of these kind of specimens, they can get the stress and strain state at the dangerous point directly instead of using theoretical methods. At the same time, the equation of shear stress is fitted by analyzing stress distribution of the section of notch root. The integral of shear stress in the section is equal to the external load, and the true stress value of notch root is derived. Then, the fatigue damage evolution equation of notched specimens under torsional load is proposed based on the closed-form solution in this paper. Meanwhile, the nonlinear fatigue life prediction model of notched specimens under the torsional load is given by using the damage mechanics theory. The proposed model is validated by experimental data (30CrMnSiNi2A steel and 45# steel). The results show that the predicted life is not only close to the experimental results, but also tends to be safe. The fatigue life of notched specimen is predicted by using notch geometric parameters and material constants. The model has more concise calculation process, avoids complicated fatigue tests, and facilitates engineering application.

Correction Method for Calculating Critical Plane Position of Geometric Discontinuity Steel Structure Under Multiaxial Loading

Abstract: Critical plane method is one of the most promising approaches to predict the fatigue life when the structure is subjected to the multiaxial loading. The stress-strain status and the critical plane position for smooth specimens are calculated using theoretical approaches when the loading mode is a continuous function. However, because of the existence of stress concentration and the characteristic of multiaxial non-proportion, it is difficult to calculate the stress-strain status and the critical plane position of geometric discontinuity structure by theory method. In this paper, a new numerical simulation method is proposed to determine the critical plane of geometric discontinuity structure under multiaxial loading. Firstly, the strain status of dangerous point is analyzed by finite element method. Secondly, the maximum shear strain amplitude of arbitrary plane is calculated using coordinate transformation principle. Finally, the plane which has the maximum shear strain amplitude is defined as the critical plane. The critical plane positions are analyzed when loading mode and notch parameters are different. Meanwhile, the relationship between notch depth and associated parameters on critical plane as well as that between loading amplitude and associated parameters on critical plane are given quantitatively.

Strain energy-based rubber fatigue life prediction under the influence of temperature.

Abstract: Aiming at the problem of the fatigue life prediction of rubber under the influence of temperature, the effects of thermal ageing and fatigue damage on the fatigue life of rubber under the influence...

A novel model for low-cycle multiaxial fatigue life prediction based on the critical plane-damage parameter.

Abstract: Multiaxial fatigue of the components is a very complex behavior. This analyzes the multiaxial fatigue failure mechanism, reviews and compares the advantages and disadvantages of the classic model. ...

An improved fatigue life prediction model for shock absorber cylinder with surface roughness correction

Abstract: The purpose of this paper is to obtain a more accurate fatigue life of structures by introducing the surface roughness into fatigue life prediction model.,Based on the fatigue life prediction model with surface roughness correction, the shock absorber cylinder is taken as an example to verify the feasibility of the improved method. Based on the load of the shock absorber cylinder during driving, fatigue experiments are performed under longitudinal and lateral forces, respectively. Then, the fatigue life predicted by the modified model is compared with that predicted by the traditional model.,By comparing with the test results, considering the influence of mean stress, the Manson method is more accurate in life prediction. Then, the modified Manson-Coffin and Manson method with surface roughness is more accurate in life prediction under longitudinal force and lateral forces, respectively. This verifies the feasibility of the improved method with the surface roughness.,The research on the influence of surface roughness on fatigue life can lay the technical foundation for the life prediction of products and have great significance to the quality evaluation of products.