Fracture Initiation and Propagation in Fatigue Contact Loading of AA6082 Aluminium Alloy

2006 ◽  
Vol 324-325 ◽  
pp. 1091-1094
Author(s):  
Angela Benedetti ◽  
Pier Gabriele Molari ◽  
Piero Morelli
Keyword(s):  
Aluminium Alloy ◽  
Contact Area ◽  
Contact Fatigue ◽  
Fracture Initiation ◽  
Free Edge ◽  
Element Analysis ◽  
Contact Loading ◽  
Linear Finite Element ◽  
Initiation And Propagation ◽  
Microscopy Analysis

This paper presents the results of an experimental investigation on surface contact fatigue of AA6082 aluminium alloy. After testing, microscopy analysis of the specimen contact area shows plastic deformation at the centre and circumferential cracks at the very edge of the print. Major cracks develop at a certain depth under the border of the contact area and propagate beneath the surface, in the direction of both the centre of contact and the lateral free edge of the specimens. No cracks have been observed at the centre of contact, neither on the surface, nor inside the material. Tensile properties of the alloy have been measured and a non linear finite element analysis has been performed in order to calculate the field of deformation and stress in the contact zone. Finally, stress intensities are correlated with the crack initiation points and an interpretation of the propagation paths, in regard to stress distribution, is given.

Chipping Brittle Materials: A Finite Element Analysis

2010 ◽  
Vol 443 ◽  
pp. 433-438 ◽  
Author(s):  
Seyed Saleh Mostafavi ◽  
Liang Chi Zhang ◽  
Jason Lunn
Keyword(s):  
Finite Element ◽  
Brittle Materials ◽  
Front Surface ◽  
Free Edge ◽  
Element Analysis ◽  
External Work ◽  
Edge Chipping ◽  
Compressive Stresses ◽  
Initiation And Propagation ◽  
Crack Tips

Edge chipping by an indenter has been used to investigate the fragmentation of brittle materials. This paper proposed a constitutive model for studying both the initiation and propagation of cracks during the chipping of concrete. The analysis was carried out by the finite element method using a commercially available code, LS-DYNA. The results showed that a zone with very high compressive stresses appears beneath the indenter and causes the material to break or crush. Most of the external work, about 78%, was dissipated in the crushing zone while only a small percentage (less than 17%) contributed to form chips/fragments. As the indentation proceeded, radian-median cracks initiated and propagated downward and parallel to the front surface of the material to form a half penny crack. The crack tips from both sides of the indenter on the surface would then deviate toward the free edge, leading to a chipping scallop at a critical load.

A Finite Element Analysis of Crack Initiation and Propagation in a Notched Disk Submitted to Rolling Contact Fatigue

1998 ◽  
Vol 120 (3) ◽  
pp. 436-441 ◽  
Author(s):  
V. Bordi ◽  
Ch. Dorier ◽  
B. Villechaise
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Initiation ◽  
Crack Growth ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Crack Initiation And Propagation ◽  
Element Analysis ◽  
Initiation And Propagation

A finite element model has been developed to predict crack initiation and propagation in a notched disk submitted to rolling contact fatigue. The aim of this study is to validate the model with experimental results obtained by tests carried out on a two-disk machine. First, a three-dimensional finite element analysis is performed. A unidimensional equivalent damage stress is calculated by applying a plastic criterion in an attempt to estimate the damage location and the time necessary to initiate cracks from the notches. Then a two-dimensional calculation based on linear fracture mechanics is conducted to determine mixed mode stress intensity factors at the tip of a crack initiated from the notch. Several crack growth criteria are used to evaluate crack growth direction and rate. Numerical results are in good agreement with experimental ones.

scholarly journals Discrete Element Analysis of High-Pressure Zones of Sea Ice on Vertical Structures

2021 ◽  
Vol 9 (3) ◽  
pp. 348
Author(s):  
Xue Long ◽  
Lu Liu ◽  
Shewen Liu ◽  
Shunying Ji
Keyword(s):  
High Pressure ◽  
Sea Ice ◽  
Failure Mode ◽  
Contact Area ◽  
Loading Rate ◽  
Discrete Element ◽  
Offshore Platforms ◽  
Marine Structures ◽  
Element Analysis ◽  
Ice Pressure

In cold regions, ice pressure poses a serious threat to the safe operation of ship hulls and fixed offshore platforms. In this study, a discrete element method (DEM) with bonded particles was adapted to simulate the generation and distribution of local ice pressures during the interaction between level ice and vertical structures. The strength and failure mode of simulated sea ice under uniaxial compression were consistent with the experimental results, which verifies the accuracy of the discrete element parameters. The crushing process of sea ice acting on the vertical structure simulated by the DEM was compared with the field test. The distribution of ice pressure on the contact surface was calculated, and it was found that the local ice pressure was much greater than the global ice pressure. The high-pressure zones in sea ice are mainly caused by its simultaneous destruction, and these zones are primarily distributed near the midline of the contact area of sea ice and the structure. The contact area and loading rate are the two main factors affecting the high-pressure zones. The maximum local and global ice pressures decrease with an increase in the contact area. The influence of the loading rate on the local ice pressure is caused by the change in the sea ice failure mode. When the loading rate is low, ductile failure of sea ice occurs, and the ice pressure increases with the increase in the loading rate. When the loading rate is high, brittle failure of sea ice occurs, and the ice pressure decreases with an increase in the loading rate. This DEM study of sea ice can reasonably predict the distribution of high-pressure zones on marine structures and provide a reference for the anti-ice performance design of marine structures.

Finite Element Analysis of a Polymer- Polymer Sliding Contact for Schallamach Wave and Wear

2007 ◽  
Vol 348-349 ◽  
pp. 633-636 ◽  
Author(s):  
Muhammad Azeem Ashraf ◽  
Bijan Sobhi-Najafabadi ◽  
Özdemir Göl ◽  
D. Sugumar
Keyword(s):  
Finite Element ◽  
Polymer Surface ◽  
Sliding Contact ◽  
Quasi Steady State ◽  
Nodal Solutions ◽  
Element Analysis ◽  
Steady State Analysis ◽  
Initiation And Propagation ◽  
Wear Law ◽  
Nodal Level

Sliding polymer-polymer surface contacts, due to their inherent elastic properties, exhibit detachment waves also termed as Schallamach waves. Such waves effect the initiation and propagation of wear along the sliding contacts. This paper presents quasi steady-state analysis of such a sliding contact using finite element. The contact is modeled and nodal solutions for pressure are obtained for small sliding steps. Analysis of orthogonal pressure components at the contact nodes reveals the formation of Schallamach wave phenomenon. Further, appropriate wear law is used for calculation of wear at nodal level.

Specimen positioning effect on microshear test: Non-linear finite element analysis

2012 ◽  
Vol 28 ◽  
pp. e15-e16
Author(s):  
L.H.A. Raposo ◽  
L.C.M. Dantas ◽  
T.A. Xavier ◽  
A.G. Pereira ◽  
A. Versluis ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Non Linear

Initiation and propagation of case crushing cracks in rolling contact fatigue

Wear ◽  
1988 ◽  
Vol 122 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Xiaogang Leng ◽  
Qing Chen ◽  
Eryu Shao
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Initiation And Propagation
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