Abstract
A numerical model of thermal cracking with a thermo-mechanical coupling effect was established. The theory of tensile failure and heat conduction is used to study the tensile failure process of brittle materials, such as rock and concrete under high temperature environment. The validity of the model is verified by thick-wall cylinders with analytical solutions. The failure modes of brittle materials under thermal stresses caused by temperature gradient and different thermal expansion coefficient were studied by using a thick-wall cylinder model and an embedded particle model, respectively. In the thick-wall cylinder model, different forms of cracks induced by temperature gradient were obtained under different temperature boundary conditions. In the embedded particle model, radial cracks were produced in the medium part with lower tensile strength when temperature increased because of the different thermal expansion coefficient. Model results are in good agreement with the experimental results, thereby providing a new finite element method for analyzing the thermal damage process and mechanism of brittle materials.
Highlights
Temperature changes can cause thermal stress in brittle materials, such as rock and concrete
When the thermal stress exceeds the strength limit of the material, it will break; the mechanical behavior and mechanical properties of the material will change.[1,2]. In rock engineering, such as nuclear waste treatment, coal underground gasification, and petroleum tertiary mining, rock is prone to thermal cracking because of its the high temperature environment threatens the safety of the project.[3,4,5,6]
This study investigated the failure modes of thermal stress caused by temperature gradient and different thermal expansion coefficients and analyzed the crack patterns and the stress transfer process
Summary
Temperature changes can cause thermal stress in brittle materials, such as rock and concrete. A great deal of research has been conducted by scholars worldwide on the thermal stress and damage of rock and concrete brittle materials.[7,8,9] In an indoor experimental research, physical experiments show that the strength, elastic modulus, Poisson’s ratio, and thermal conductivity of concrete materials decrease with increasing temperature.[10,11,12,13] In previous studies,[14,15,16] different experimental methods were used to observe the failure mode and failure process of granite in a high temperature environment.[17] observed the dynamic compressive strength of Longyou sandstones under high temperature and high pressure conditions via microcomputer-aided tomography They summarized an empirical formula of the relationship between damage variables and dynamic compressive strength by experimental data.[18] used field emission scanning electron microscopy to observe the internal thermal cracking of Ganurgarh shale in India. ESTABLISHMENT OF FINITE ELEMENT MODEL OF THERMO-MECHANICAL COUPLING TENSILE FAILURE
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