Research on Lateral Scale Effect and Constitutive Model of Rock Damage Energy Evolution

2018 ◽  
Vol 36 (4) ◽  
pp. 2415-2424 ◽  
Author(s):  
Xi Yan ◽  
Li Jun ◽  
Zeng Yijin ◽  
Ding Shidong ◽  
Jiang Tingxue
2020 ◽  
Vol 8 (4) ◽  
pp. 1050-1067 ◽  
Author(s):  
Yuwei Li ◽  
Yudong Zhao ◽  
Jizhou Tang ◽  
Liyuan Zhang ◽  
Yuyang Zhou ◽  
...  

Author(s):  
ZhaoPeng Hao ◽  
JiNing Li ◽  
YiHang Fan

Abstract The traditional material constitutive model can effectively simulate the mechanical properties during the cutting process. However,the scale characteristics contained in materials are not considered in traditional cutting model, and the inherent scale effect of materials are also ignored. Therefore, the traditional cutting constitutive model cannot effectively reflect the size effect in cutting process, and then cannot obtain the accurate stress, strain and temperature. In this present paper, a material constitutive model which can reflect the scale effect is established based on the strain gradient plasticity theory. Through the established model and secondary development of ABAQUS, the two-dimensional dynamic Finite Element Simulation model of cutting Inconel 718 is established. By comparing the cutting experiment results with the simulation results, the established simulation model can more accurately reflect the effects of temperature, strain gradient effect, equivalent stress and its scale effect on cutting deformation during the machining process.


2012 ◽  
Vol 557-559 ◽  
pp. 2217-2220 ◽  
Author(s):  
Hua Lin Liao

Based on the probability distribution theory of rock micro-unit strength and taking the Mohr-Coulomb damage criterion as the distribution variable, the theoretical equations for the evolution of damage variables and the statistical constitutive model of rock damage in triaxis test were established. The arbitrary triaxis experimental data w ere used to calculate the parameters in the model by using curve fitting method and extreme value method. The calculated results of the model agree well with the experimental data. This constructive model can reflect effectively the deformation characteristics of rocks under loads and the constructive relation between elastic strain and stress of rock damage.


2021 ◽  
Vol 144 (1) ◽  
Author(s):  
Shengyu You ◽  
Jinyuan Tang ◽  
Yuqin Wen

Abstract The micro-surface asperity scale of grinding metal parts is within several microns. When two grinding surfaces are in contact, the unevenness of the plastic deformation of the asperities at the micro-scale leads to greater plastic hardening strength of the material. The results of the nano-indentation experiment conducted in this paper confirmed this phenomenon. Based on conventional mechanism-based strain gradient (CMSG) plasticity theory, the micro-scale plastic constitutive equation of materials is given and then is verified by the nano-indentation experiment. Finite element software abaqus and the user-defined element (UEL) subroutine are used to build three-dimensional rough surface elastoplastic contact models. By calculating the grinding rough surface contact in the macro-scale constitutive model based on J2 theory and in the CMSG plasticity constitutive model, the influence law of plastic micro-scale effect on contact performance is obtained.


2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ying Chen ◽  
Lin Zhang ◽  
Hui Xie ◽  
Jianfeng Liu ◽  
Hong Liu ◽  
...  

The study of damage characteristics of rock mass is of great significance to the analysis of rock mass structure. According to the characteristics of the microscopic unit strength of rock with random distribution, the Weibull distribution is widely used as the statistical functions of the strength of the microunit of rock to establish the damage constitutive model. The concepts of damage ratio De and damage index Cc are proposed. Damage ratio is mainly used to describe the law of damage evolution in rock. Damage index can be used to evaluate the damage degree of rock. The influence of confining pressure on distribution parameters and damage ratio is analyzed through uniaxial and triaxial compression tests of sandstone. The results show that damage ratio is an index of structural characteristics of rock damage, which can reflect the evolution characteristics of microcracks in rock under spatial stress. Critical damage ratio refers to the damage ratio corresponding to the peak stress of rock and can be used as a parameter to characterize the strength of rock for corresponding to the peak strain one to one. The critical damage ratio is linearly related to the logarithmic function of confining pressure. Its relationship is as follows: Der=Ccln⁡σ3+b. With the increase of σ3, the increasing trend of Der slows down and gradually tends to a certain value. The larger the damage index is, the more serious the damage of rock is. The smaller the damage index is, the less serious the damage of rock is. Therefore, the damage index can be used to evaluate the damage degree of rock. It will be an important direction of rock damage mechanics research to distinguish the severity of rock damage by using damage index as the limit value.


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