scholarly journals Investigation of Mixed-Mode I/II Fracture under Impact Loading Using Split-Hopkinson Pressure Bar

2020 ◽  
Vol 10 (20) ◽  
pp. 7149
Author(s):  
Fei Wang ◽  
Zheming Zhu ◽  
Meng Wang ◽  
Hao Qiu ◽  
Lei Zhou ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Numerical Method ◽  
Impact Loading ◽  
Mixed Mode ◽  
Split Hopkinson Pressure Bar ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Hopkinson Pressure Bar ◽  
Mixed Mode Crack ◽  
Pressure Bar

Mixed-mode fracture of construction building materials under impact loading is quite common in civil engineering. The investigation of mixed-mode crack propagation behavior is an essential work for fundamental research and engineering application. A variable angle single cleavage semi-circle (VASCSC) specimen was proposed with which the dynamic fracture test was conducted by using a Split-Hopkinson pressure bar (SHPB). Notably, the mixed-mode crack propagation velocity could be detected by the synchronized crack velocity measuring system. With experimental results, the dynamic initiation stress intensity factors KI and KII were calculated by the experimental-numerical method. Additionally, the crack path of mixed-mode I/II fracture can be predicated precisely by using numerical method. Thus, a comprehensive approach of investigation on mixed-mode I/II fracture under impact loading was illustrated in this paper. The study demonstrates that the mixed-mode I/II crack would transform from complicated mode I/II to pure mode I during crack propagation, and several velocity decelerations induced crack deflection. The dynamic initiation fracture toughness of mixed-mode crack was determined by the experimental-numerical method. The VASCSC specimen has a great potential in investigating mixed-mode fracture problems with the SHPB device.

scholarly journals Dynamic Crack Propagation and Fracture Behavior of Pre-cracked Specimens under Impact Loading by Split Hopkinson Pressure Bar

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Shijun Zhao ◽  
Qing Zhang
Keyword(s):  
Crack Propagation ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Hopkinson Pressure Bar ◽  
Brazilian Disk ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Cracked Specimens

Deformation and fracture of brittle materials, especially crack propagation, have drawn wide attention in recent years. But dynamic crack propagation under impact loading was not well understood. In this paper, we experimentally tested Brazilian disk (BD) fine sandstone specimens containing pre-cracks under cyclic impact loading by the Φ 74 mm diameter split Hopkinson pressure bar (SHPB) test device. The pre-cracked specimens were named central straight through crack flattened Brazilian disk (CSCFBD). By using the low air-pressure loading conditions (0.1 MPa, equal to the impact velocity of 3.76 m/s), a series of dynamic impact tests were detected successfully, and the effects of pre-cracks on dynamic properties were analyzed. Experimental results show that the multiple cracks mostly initiate at/or near the pre-crack tips and then propagate in different paths and directions varying by inclination angles, leading to the ultimate failure. Compared to static or quasi-static loading, dynamic crack propagation and fracture behavior are obviously different. Furthermore, we characterized the crack propagation paths, directions, and fracture patterns and discussed the influences of the pre-cracks during the breakage process. We concluded that the results obtained are significant in investigating the failure mechanism and mechanical properties of brittle materials under impact loading.

scholarly journals FRACTAL CHARACTERISTICS OF CRACK PROPAGATION IN COAL UNDER IMPACT LOADING

Fractals ◽  
2018 ◽  
Vol 26 (02) ◽  
pp. 1840014 ◽  
Author(s):  
YIXIN ZHAO ◽  
SHUANG GONG ◽  
CHENGGUO ZHANG ◽  
ZHENNAN ZHANG ◽  
YAODONG JIANG
Keyword(s):  
Fractal Dimension ◽  
Crack Propagation ◽  
Impact Loading ◽  
Crack Velocity ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Bedding Angle ◽  
Fractal Characteristics ◽  
Pressure Bar

This paper studied the fractal characteristics of crack propagation in coal containing beddings under impact loading condition. Split Hopkinson pressure bar (SHPB) system was applied to determine the prepared notched semi-circular bending specimens. The high-speed camera was used to record the propagation characteristics of cracks. The image processing method and fractal dimension calculation software are combined to further analyze the effects of bedding and loading rate on the fractal characteristics of crack propagation in coal. The experimental results presented that the presence of bedding has a remarkable impact on the crack propagation. The crack velocity of coal samples with [Formula: see text] bedding angle is of the maximum, however, the crack velocity of samples with [Formula: see text] bedding angle is of the minimum. Bedding angles also have obvious influence on the fractal dimension of cracking path, the bedding angle of [Formula: see text] being the largest, and those of [Formula: see text] and [Formula: see text] having the intermediate values, while those of [Formula: see text] and [Formula: see text] being the smallest. Several points of instantaneous fractal crack velocity are close to the Rayleigh wave velocity ([Formula: see text]). The crack velocities of coal specimens with bedding angles of [Formula: see text], [Formula: see text] and [Formula: see text] are prone to the high value.

scholarly journals Development of a True-Biaxial Split Hopkinson Pressure Bar Device and Its Application

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7298
Author(s):  
Shumeng Pang ◽  
Weijun Tao ◽  
Yingjing Liang ◽  
Shi Huan ◽  
Yijie Liu ◽  
...  
Keyword(s):  
Stress Wave ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Stress Waves ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Although highly desirable, the experimental technology of the dynamic mechanical properties of materials under multiaxial impact loading is rarely explored. In this study, a true-biaxial split Hopkinson pressure bar device is developed to achieve the biaxial synchronous impact loading of a specimen. A symmetrical wedge-shaped, dual-wave bar is designed to decompose a single stress wave into two independent and symmetric stress waves that eventually form an orthogonal system and load the specimen synchronously. Furthermore, a combination of ground gaskets and lubricant is employed to eliminate the shear stress wave and separate the coupling of the shear and axial stress waves propagating in bars. Some confirmatory and applied tests are carried out, and the results show not only the feasibility of this modified device but also the dynamic mechanical characteristics of specimens under biaxial impact loading. This novel technique is readily implementable and also has good application potential in material mechanics testing.

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.

Numerical studies on mixed-mode crack propagation behavior for functionally graded material based on peridynamic theory

2018 ◽  
Vol 07 (04) ◽  
pp. 1850027 ◽  
Author(s):  
Fei Wang ◽  
Yu’e Ma ◽  
Yanning Guo ◽  
Wei Huang
Keyword(s):  
Crack Propagation ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Damage Model ◽  
Fortran Program ◽  
Functionally Graded ◽  
Mixed Mode Fracture ◽  
Stress Load ◽  
Gradient Direction ◽  
Mixed Mode Crack

Peridynamics (PD) is a new nonlocal theory that unifies the mechanics of discrete particles, continuum, and continuum with discontinuities, and it has inherent advantages in calculating the mixed-mode crack propagating. Functionally graded materials (FGMs) are the advanced composite materials, fracture behavior of which is complicated to be simulated by the traditional continuum mechanics. Hence, a PD model for FGMs is given to investigate the mixed-mode fracture behavior under quasi-static loading. Basic PD equations, damage model, and PD [Formula: see text]-integral for FGMs are discussed. A FORTRAN program of PD algorithm is coded to calculate the [Formula: see text]-integral and crack propagation of FGMs. The [Formula: see text]-integral and the crack paths of the PD model are verified by comparing with the published numerical and experimental results. Effects of the material gradient, the material gradient direction, and the stress load magnitude on the fracture behavior are investigated. It is shown that the PD [Formula: see text]-integral and the crack path are strongly affected by the material gradient and the gradient direction under the same stress load. When the gradient of FGMs is linear, the material gradient direction decides whether the mixed-mode crack kinks or not and the magnitude of stress determines the kinking angle.

Numerical Method for Mixed-Mode I–II Crack Propagation in Concrete

2013 ◽  
Vol 139 (11) ◽  
pp. 1530-1538 ◽  
Author(s):  
ZhiMin Wu ◽  
Hua Rong ◽  
JianJun Zheng ◽  
Wei Dong
Keyword(s):  
Crack Propagation ◽  
Numerical Method ◽  
Mixed Mode ◽  
Mode I
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