A continuum damage-based three-dimensional fracture simulation method for brittle-like materials

The temperature of a deep shale reservoir may reach more than 100°C, and the effect of thermal shock on shale hydraulic fracturing has rarely not been considered in previous studies. Based on mesoscopic damage mechanics and the finite element method, a thermo-hydro-mechanical-damage (THMD) coupling model considering temperature, seepage, stress, and damage fields was constructed to investigate the effects of reservoir temperature, convective heat transfer coefficient ( h), in-situ stress difference and bedding plane angle ( αθ) on shale hydraulic fracturing. The results show that multiple hydraulic fractures (HFs) can occur under thermal shock and that HFs control the distribution of seepage, temperature, and stress fields. Reservoir temperature, in-situ stress difference and αθ are primary factors affecting hydraulic fracturing, whereas h is a secondary factor. When the reservoir temperature rises from 50°C to 150°C, the initiation and breakdown pressures decrease by 65.5% and 16.7%, respectively. HFs cross the bedding plane more easily, and fracture complexity is obviously enhanced. A higher h is favourable for slightly reducing the initiation and breakdown pressures, but it has little influence on the fracture complexity. Once the in-situ stress difference is low, there is a high fracture complexity, but HFs are more easily captured by bedding planes to limit the propagation of fracture height. When the in-situ stress difference is high, HFs are more likely to form bi-wing fractures. Whether αθ is too large or small, it is not conducive to improving the fracture complexity. In this study, when αθ is 30°, HFs and bedding planes intersect to form a fracture network. Essentially, thermal shock plays a key role in reducing the initiation pressure and forming multiple HFs during the fracturing process, and fracture propagation mainly depends on the injection pressure. The results can serve as reasonable suggestions for the optimization of shale hydraulic fracturing.

Section: Introductionmentioning

confidence: 99%

Numerical simulation on hydraulic fracture propagation in laminated shale based on thermo-hydro-mechanical-damage coupling model

Zhang

Guo

et al. 2023

“…Nowadays, concrete has long been used in various engineering structures such as buildings, utility tunnels, nuclear power plants, and so on (Ahmed et al., 2021; Bai et al., 2022a; Bao et al., 2023; Castillo et al., 2021; Park et al., 2022; Shen et al.,2021; Sun, 2022; Sun et al., 2020; Sun and Xu, 2022; Voyiadjis et al., 2022; Wu et al., 2022; Xu et al., 2018). During the service periods of the engineering structures, fire risk is unavoidable (Aslani and Samali, 2015; Nuruzzaman et al., 2023; Sun et al., 2022a; 2023).…”

Section: Introductionmentioning

confidence: 99%

A multi-scale model from microscopic cracks to macroscopic damage of concrete at elevated temperatures

Sun,

Guo

2023

Self Cite

A multi-scale model is established to describe the relationship between the macroscopic damage evolution and microscopic cracks behaviors of concrete at elevated temperatures. The evolution equation of the ideal microscopic crack system of concrete at elevated temperatures is deduced for construct the model, which can predict the microscopic crack density and macroscopic damage of concrete at elevated temperatures. The multi-scale model fuses some advantages of the traditional microscopic and macroscopic damage models. Finally, multi-scale damage of a concrete block under high temperature is predicted and compared with the corresponding experimental results, which is utilized to support the ability of the developed model. The results show that the developed multi-scale model can be used to evaluate fire damage of concrete structures in macro-scale as well as explain its physical mechanisms in micro-scale.

“…The damage variable is assumed as a scalar for isotropic damage models, and is typically defined as where A is the total cross-sectional area of the mesoscale representative volume element (RVE), trueA˜ is the effective cross-sectional area. The development of CDM provides a new approach to study the damage process and failure for different structures with different materials (Fan et al., 2020; Park et al., 2021; Sun, 2018; Sun and Xu, 2021; Sun et al., 2019). Based on CDM, Chaboche and Lesne (1988), Lemaitre (1987), Lemaitre and Desmorat (2005) successively proposed several models for fatigue damage, which were frequently introduced into studies for finite element simulation of CFCI (Cui et al., 2020; Hu et al., 2016; Jie et al., 2018; Sun, 2018; Zheng and Wang, 2020).…”

Section: Introductionmentioning

confidence: 99%

A continuum damage model for prediction of crack initiation life of pitting corrosion and fatigue

Yang

Fan

2022

Corrosion fatigue damage can lead to degradation of engineering structures and components. As a major stage of the total corrosion fatigue life, the crack initiation of pitting corrosion and fatigue is studied. A continuum damage mechanics model for predicting the crack initiation life of pitting corrosion fatigue is presented based on a pure fatigue damage model and a fracture-mechanics-based pit-to-crack transition criterion. The synergistic effect of pitting corrosion and fatigue are quantified as a time-varying amplification of the fatigue stress field. The proposed model is validated by corrosion fatigue test data of two different metallic materials. The predicted curves of corrosion fatigue crack initiation life are in good agreement with the test data. The model demonstrates a good prediction of corrosion fatigue crack initiation life, i.e., corrosion fatigue life is always lower than fatigue life, and the lower the stress, the more significant the life reduction.