Numerical assessment of the apparent fracture process zone length in wood under mode I condition using cohesive elements

Author(s):  
Marek Romanowicz
2019 ◽  
Vol 29 (4) ◽  
pp. 646-666 ◽  
Author(s):  
M Moazzami ◽  
MR Ayatollahi ◽  
A Akhavan-Safar

This paper presents an experimental research on the length and shape of the fracture process zone of rocks under mode I, mixed mode (I + II) and mode II loading conditions for different geometries of cracked specimens made of two types of rocks, using the digital image correlation approach. Single edge notch bending (SENB) and semi-circular bend specimens are the two geometries considered. In order to investigate the effect of the specimen size on the fracture process zone length, rocks with three different sizes are produced and tested. To investigate the effect of the mode mixity on the fracture process zone length of marble and sandstone, the specimens are tested under different modes of loading. According to the experimental results, it is found that the fracture process zone length changes with mode ratio, specimen size, geometry and the material properties. The fracture process zone length increases when the mode of loading moves from mode I to mode II. Experimental results also show that fracture process zone becomes longer for specimens with larger sizes. The fracture process zone is also affected by the specimen geometry.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Chenmeng Ji ◽  
Chengzhi Qi

Evaluation of the shape and size of the fracture process zone near the mode I dynamic crack tip is still a problem unsolved completely at present. The research on the relationship between the fracture process zone and crack velocity near the mode I dynamic crack tip is quite limited, and some researchers have also developed experimental methods or numerical methods. In this research, based on the theory of elastodynamics and the complex stress function method, an approximate method for solving the mode I dynamic crack problem was proposed. The fracture process zone near the mode I dynamic crack tip was analyzed. The results showed that the areas of the fracture process zone determined based on the approximate method are nearly the same as the results obtained based on the well-known stress fields. The approximate method could provide a good reference for determining the fracture process zone near the mode I dynamic crack tip since no analytic methods had been found for evaluating the fracture process zone near the dynamic crack tip to the authors’ knowledge.


Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3203
Author(s):  
Guodong Li ◽  
Zhengyi Ren ◽  
Jiangjiang Yu

The size of the fracture process zone (FPZ) has significance for studying the fracture mechanism and fracture characteristics of concrete. This paper presents the method of assessing the FPZ of Mixed-Mode I-II for quasi-static four-point shearing concrete beams with pre-notched by Lagrangian strain profiles from digital image correlation (DIC). Additionally, it explores the influences of volume rates of the coarse aggregate of 0%, 28%, 48%, and 68%, and the specific surface areas of 0.12 m2/kg, 0.15 m2/kg, and 0.26 m2/kg on the size of the FPZ. It shows that the size of FPZ in four-point shearing concrete beam can be characterized by the displacement field and strain field using DIC. The size of FPZ conforms to linear positive correlation with the volume rate of coarse aggregate, and linear negative correlation with the specific surface area of coarse aggregate. It presents that the crack initiation of the four-point shearing beam with the pre notch is dominated by mode I load, and the propagation and fracture of Mixed-Mode I-II cracks are caused by the combined effect of Mode I and Mode II loading.


1993 ◽  
Vol 46 (6) ◽  
pp. 1041-1049 ◽  
Author(s):  
Zhi Kai Guo ◽  
Albert S. Kobayashi ◽  
Neil M. Hawkins

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