Numerical Simulation on Mixed Mode I-II Crack Propagation Process in Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 233-236 ◽  
Author(s):  
Qing Xu ◽  
Wei Dong ◽  
Zhi Min Wu
Keyword(s):  
Crack Propagation ◽  
Mixed Mode ◽  
Uniaxial Tensile ◽  
Mode I ◽  
Displacement Curve ◽  
Uniaxial Tensile Strength ◽  
Unstable Failure ◽  
Crack Propagation Process ◽  
The Difference ◽  
The One

A crack propagation criteria is proposed for mixed mode I-II fracture in concrete based on the initial cracking KⅠ-KⅡ curve obtained from experiment. Once the difference between the stress intensity factor at the crack tip caused by the external load and the one caused by the cohesive force attains the above KI-KII curve, the crack begins to propagate. Based on this criteria, the finite element method was used to simulate the mixed mode I-II crack initiation, stable propagation and unstable failure in concrete. For the four-point shear concrete specimens, the crack propagation trajectory and P-CMSD (Crack Mouth Sliding Displacement) curve were obtained. Upon the comparison with the experimental results, the calculated results show good agreement. It is concluded that, if the elastic modulus E, the uniaxial tensile strength ft and the initial cracking KI-KII curve of concrete are measured from experiment, the complete process of mixed mode I-II crack propagation can be simulated using the proposed criterion.

Experimental and Numerical Study on Mode I-II Crack Propagation for Small Size Specimens of Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 908-912
Author(s):  
Wei Dong ◽  
Hua Nan He ◽  
Zhi Min Wu
Keyword(s):  
Crack Propagation ◽  
Numerical Study ◽  
Initial Crack ◽  
Mode I ◽  
Propagation Process ◽  
Crack Propagation Process ◽  
Series Of Experiments ◽  
The Difference ◽  
The One ◽  
Good Agreement

The crack criterion is important to determine the crack propagation for mode I-II fracture in concrete. The paper aims to obtain the initial crack criterion of four-point shearing beams experimentally, which can be applied in the numerical simulation for crack propagation process. A series of experiments of four-point shearing notched beams of concrete with five different heights of 80mm, 100mm, 120mm, 140mm and 160mm respectively were carried out to measure the initial loading Pini. The different combinations of KiniI and KiniII corresponding to Pini were obtained according to different positions of pre-cracks in the specimens, and the initial crack criterion was fitted using the combinations of KiniI and KiniII. With the assumption that the crack will extend when the difference between the stress intensity factor at the crack tip caused by the load P and the one caused by the cohesive force attained the above KiniI- KiniII curve, the criterion was applied to simulate the crack propagation process in the paper. It was found that the numerical analysis showed a good agreement with the experimental results and that the size effect is not remarkable for the KiniI-KiniII curves of different heights specimens in the test.

Pre-Strain Effects on Mixed-Mode Fatigue Crack Propagation Behaviour of the P355NL1 Pressure Vessels Steel

2018 ◽  
Author(s):  
João Ferreira ◽  
José A. F. O. Correia ◽  
Grzegorz Lesiuk ◽  
Sergio Blasón González ◽  
Maria Cristina R. Gonzalez ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Mixed Mode ◽  
Pressure Vessels ◽  
Mode I ◽  
Pure Mode

Pressure vessels and piping are commonly subjected to plastic deformation during manufacturing or installation. This pre-deformation history, usually called pre-strain, may have a significant influence on the resistance against fatigue crack growth of the material. Several studies have been performed to investigate the pre-strain effects on the pure mode I fatigue crack propagation, but less on mixed-mode (I+II) fatigue crack propagation conditions. The present study aims at investigating the effect of tensile plastic pre-strain on fatigue crack growth behavior (da/dN vs. ΔK) of the P355NL1 pressure vessel steel. For that purpose, fatigue crack propagation tests were conducted on specimens with two distinct degrees of pre-strain: 0% and 6%, under mixed mode (I+II) conditions using CTS specimens. Moreover, for comparison purposes, CT specimens were tested under pure mode I conditions for pre-strains of 0% and 3%. Contrary to the majority of previous studies, that applied plastic deformation directly on the machined specimen, in this work the pre-straining operation was carried out prior to the machining of the specimens with the objective to minimize residual stress effects and distortions. Results revealed that, for the P355NL1 steel, the tensile pre-strain increased fatigue crack initiation angle and reduced fatigue crack growth rates in the Paris region for mixed mode conditions. The pre-straining procedure had a clear impact on the Paris law constants, increasing the coefficient and decreasing the exponent. In the low ΔK region, results indicate that pre-strain causes a decrease in ΔKth.

Numerical Investigation on Mixed Mode (I-II) Fracture Propagation of CCBD Specimens Under Confining Pressure

2021 ◽  
pp. 2050111
Author(s):  
Jiuzhou Huang ◽  
Jianxiong Li ◽  
Xin Pan ◽  
Tianzhou Xie ◽  
Wen Hua ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Numerical Method ◽  
Mixed Mode ◽  
Early Stage ◽  
Relative Length ◽  
Confining Pressure ◽  
Secondary Development ◽  
Weight Functions ◽  
Mode I ◽  
Initiation And Propagation

A new numerical method, verified by the analytical solution of the weight functions and experimental paths, is developed to evaluate the crack initiation and propagation generally in mixed mode (I-II). This numerical method combining the interaction integral method and the maximum tangential stress (MTS) criterion is based on the finite element method of secondary development. The influence of combined confining pressure and diametric forces on crack propagation trajectories for CCBD specimens are studied. It is indicated that the crack propagation direction independent of the confining pressure keeps the same with the line of original crack as the loading angle is equal to [Formula: see text]. But when the loading angle is greater than [Formula: see text], the curvature of the curve trajectory in the early stage of crack propagation increases with a larger confining pressure. Further, it is found that larger values of the loading angle and relative length will make the effect of confining pressure more significant at the early stage of crack growth.

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