A computational constitutive model for rock in hydrocode. (November 2020)

• Record Type: Journal Article
• Authors: Huang, Xieping; Kong, Xiangzhen; Chen, Zuyu; Fang, Qin
• Is Part Of: International journal of impact engineering. Volume 145(2020)
• Publication Date: 2020-11
• Subjects: Rock material model -- Dynamic damage and failure -- Granitic rock -- Parameter calibration; Impact -- Periodicals; Shock (Mechanics) -- Periodicals; Impact -- Périodiques; Choc (Mécanique) -- Périodiques; Impact; Shock (Mechanics); Periodicals; 620.1125
• DOI: 10.1016/j.ijimpeng.2020.103687
• Languages: English
• ISSNs: 0734-743X

Abstract

Highlights: A new rock material model is proposed in the framework of plastic damage theory. A concise semi-empirical formula is suggested for the definition of DIF varying with strain rate of rock materials, which shows good agreements with available experimental data. A new damage model is proposed to capture the experiment-supported phenomenon that the compressive stiffness could be recovered upon load reversal due to the closure of the microcracks. The new rock model is validated by single element tests and several numerical examples, in which the numerical predictions are comparable to experimental data. Abstract: This study presents a computational constitutive model for rock materials subjected to high pressures and high strain rates. The model is calibrated from a concrete material model proposed by Kong et al. [27]. The parameters required for the model can be classified into three categories, i.e., strength-related parameters, damage-related parameters, and equation of state-related parameters. Methods to determine the parameters of the three categories are presented in detail, and a large amount of suitable experimental data for hard rock is collected to calibrate these parameters. In particular, the ratio of the tensile meridian to the compressive meridian, which plays an essential role in defining the strength surface, has been modified to be suitable for hard rock materials, referring to granite. A concise semi-empirical formula is suggested to describe how the dynamic increase factor (DIF) varies with the strain rate of the rock material, which shows good agreement with the available experimental data. The model is then implemented into LS-DYNA through a user-defined material model. Multi-element numerical simulations for the rock materials are conducted. Comparisons between the predictions from the present model and the JH2 model and the experimental data are presented. Numerical simulations of several selected examples for hard rock, including splitting tests, impacting tests, and ballistic tests, are performed. The numerical predictions are comparable to the experiment results.