scholarly journals Determination of the Crack Propagation Direction in Mixed-Mode Missions due to Cyclic Loading

2021 ◽  
Vol 11 (4) ◽  
pp. 1673
Author(s):  
Jury Rodella ◽  
Guido Dhondt ◽  
Paul Köster ◽  
Manuela Sander ◽  
Steven Piorun
Keyword(s):  
Experimental Data ◽  
Phase Shift ◽  
Crack Propagation ◽  
Mixed Mode ◽  
Industrial Applications ◽  
Propagation Direction ◽  
Crack Propagation Direction ◽  
Angle Criterion ◽  
Large Phase

The evaluation of cyclic crack propagation due to missions with varying mixed-mode conditions is an important topic in industrial applications. This paper focuses on the determination of the resulting propagation direction. Two criteria are analyzed, the dominant step criterion and the averaged angle criterion, and compared with experimental data from tension-torsion tests with and without phase shift. The comparison shows that the dominant step criterion yields better results for small to moderate values of the phase shift. For a large phase shift of 90°, the experimental results are not very consistent, and therefore, no decisive conclusions can be drawn.

Automatic 3-D Crack Propagation Calculations in Industrial Components: A Pure Hexahedral versus a Combined Hexahedral-Tetrahedral Approach

2007 ◽  
Vol 348-349 ◽  
pp. 45-48
Author(s):  
Guido Dhondt
Keyword(s):  
Crack Propagation ◽  
Computing Time ◽  
Propagation Direction ◽  
Hexahedral Elements ◽  
Crack Propagation Direction ◽  
Low Weight ◽  
Out Of Plane ◽  
Hexahedral Meshes ◽  
Crack Faces

In recent years, increased loading and low weight requirements have led to the need for automatic crack tracing software. At MTU a purely hexahedral code has been developed in the nineties for Mode-I applications. It has been used extensively for all kinds of components and has proven to be very flexible and reliable. Nevertheless, in transition regions between complex components curved cracks have been observed, necessitating the development of mixed-mode software. Due to the curvature of the crack faces, purely hexahedral meshes are not feasible, and therefore a mixture of hexahedral elements at the crack tip, combined with tetrahedral in the remaining structure has been selected. The intention of the present paper is to compare both methods and to point out the strength and weaknesses of each regarding accuracy, complexity, flexibility and computing time. Furthermore, difficulties arising from the out-of-plane growth of the crack such as the determination of the crack propagation direction are discussed.

scholarly journals Experimental and FE Modeling of Mixed-Mode Crack Initiation Angle in High Density Polyethylene

2018 ◽  
Author(s):  
Abdelwahab Zerrouki ◽  
Abdelkader Boulenouar ◽  
Mohamed Mazari ◽  
Mohamed Benguediab
Keyword(s):  
Numerical Analysis ◽  
Energy Density ◽  
Crack Propagation ◽  
High Density Polyethylene ◽  
Strain Energy Density ◽  
Mixed Mode ◽  
Strain Energy ◽  
Propagation Direction ◽  
Crack Propagation Direction ◽  
Loading Direction

In this paper, an experimental and a numerical analysis were carried out using High density polyethylene (HDPE). Sheets with an initial central crack (CCT specimens) inclined with a given angle are investigated and compared to the loading direction. The kinking angle is experimentally predicted and numerically evaluated under mixed mode (I+II), as a function of the strain energy density (SED) around the crack-tip, using the Ansys Parametric Design Language (APDL).According to the experimental observations and numerical analysis, the plan of crack propagation is perpendicular to the loading direction. Moreover, as suggested by Sih in the framework of linear elastic fracture mechanics (LEFM), the minimum values Sminof the factor S are reached at the points corresponding to the crack propagation direction. These results suggest that the concept of the strain energy- density factor can be used as an indicator of the crack propagation direction.

Prediction of Mixed Mode Crack Propagation Direction in Carbon Fiber Reinforced Plastic Plate

2006 ◽  
Vol 324-325 ◽  
pp. 271-274
Author(s):  
Shao Qin Zhang ◽  
Jun Lin Li ◽  
Wei Yang Yang
Keyword(s):  
Carbon Fiber ◽  
Crack Propagation ◽  
Mixed Mode ◽  
Fracture Criterion ◽  
Propagation Direction ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Reinforced Plastic ◽  
Crack Propagation Direction ◽  
Mixed Mode Crack ◽  
Reinforced Plastic

A newly developed Z-fracture criterion is introduced in this paper by introducing the new concepts of in-plane dilatational strain energy density factor, in-plane average strain and reciprocal function. The Z-fracture criterion is applied to predict the mixed mode crack propagating direction in carbon fiber reinforced plastic (CRP) plate. The test results show that the Z-fracture criterion can be successfully used to predict the mixed mode crack propagation direction in CRP plate.

Cyclic Mixed-Mode Crack Propagation due to Time-Dependent Multiaxial Loading in Jet Engines

2011 ◽  
Vol 488-489 ◽  
pp. 93-96
Author(s):  
Guido Dhondt
Keyword(s):  
Crack Propagation ◽  
Mixed Mode ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Propagation Direction ◽  
Time Dependent ◽  
Multiaxial Loading ◽  
Jet Engines ◽  
Crack Propagation Direction ◽  
K Factor

Components in jet engines are subject to time-dependent multiaxial loading. This creates a time-varying mixed-mode stress state at the crack tip. Mixed-mode loading leads to out-of-plane crack propagation and has been treated in previous articles [1,2]. This paper concentrates on coping with the time-dependent character. Key issues are the crack propagation rate and the crack propagation direction in three-dimensional space. In order to determine the prevalent crack propagation direction the dominant loading case is determined based on its crack propagation rate. Then, a mixed-mode equivalent K-factor is calculated for all other loading cases based on the closeness of their associated crack propagation direction with the dominant one. Subsequently, a cycle extraction is performed on the crack propagation rate for all loading cases. The extracted cycles are processed based on their mimimum and maximum equivalent K-factor and the maximum temperature. The mission crack propagation rate consists of the sum of the rate of all extracted cycles.

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