Numerical Simulation of Fatigue Crack Growth of New-Material Track Rollers

2012 ◽  
Vol 157-158 ◽  
pp. 1471-1476
Author(s):  
Chang Liu ◽  
Xu Hong Guo ◽  
Xin Xin Gao
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
Growth Direction ◽  
Maximum Principal Stress ◽  
Fem Modeling ◽  
Stress Theory ◽  
Linear Elastic ◽  
New Material ◽  
Crack Growth Direction ◽  
Elastic Fracture

Because of the excellent mechanical properties of Austempered Ductile Iron (ADI), track rollers can be made out of this material. The casting may lead to cracks forming inside rollers and there will also be some scratches in the surface when rollers work, which will greatly affect the lifespan of rollers. It is helpful to use crack propagation method based on the Finite Element Method (FEM) to simulate the crack growth. Firstly, define the position and the value of the force imposed on rollers. If the load is compressive, contact pairs should be set between the crack surfaces. After the model is established, Stress Intensity Factors (SIF) KI and KII can be calculated with the node displacement theory by using the commands of FEM software. With the maximum principal stress theory, crack growth direction can be determined. Since the values of KI and KII calculated by the software are positive, we should judge weather the values are positive or negative to get a right propagating angle. The analysis applies linear elastic fracture mechanics and FEM modeling the crack propagation in the elastic state.

THE EFFECT OF RESIDUAL STRESSES IN FILLET WELDS ON THE FATIGUE BEHAVIOR: A LEFM APPROACH

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Wim Nagy ◽  
Hans De Backer ◽  
Philippe Van Bogaert
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Fatigue Behavior ◽  
Growth Direction ◽  
Steel Bridge ◽  
Civil Structures ◽  
Linear Elastic ◽  
Real Behavior ◽  
Crack Growth Direction ◽  
Elastic Fracture

Residual stresses are present in many civil structures due to manufacturing actions causing plastic deformations. Nevertheless, these stresses are not often taken into account when considering the design of these structures, especially when assessing fatigue problems. This remains true for orthotropic steel bridge decks. Due to their many complex welding details, these decks are sensitive to fatigue. To increase the understanding of the fatigue behavior of welded details, an improved analyzing tool using linear elastic fracture mechanics is proposed in this paper. Apart from the fatigue life of the weld detail, the crack propagation and crack growth direction are also evaluated with an XFEM model. Application of this method to the case of the orthotropic steel Temse Bridge in Belgium results in crack propagation very similar to reality. It also demonstrates that the fatigue calculations need to include residual stresses to comply with the real behavior of crack propagation.

scholarly journals 2D and 3D numerical simulation of fatigue crack growth path and life predictions of a linear elastic

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Abdullateef H. Bashiri
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Circumferential Stress ◽  
Numerical Data ◽  
Three Dimensions ◽  
Stress Theory ◽  
Linear Elastic

Abstract This paper describes implementation of the finite element method (FEM) to investigate crack growth problems in linear elastic fracture mechanics and the correlation of results with experimental and numerical data. The approach involved using two different software to compute stress intensity factors (SIFs), the crack propagation trajectory, and fatigue life estimation in two and three dimensions. According to the software, crack modeling might be run in various ways. The first is a developed source code program written in the Visual Fortran language, while the second is the widely used ANSYS Mechanical APDL 19.2 software. The fatigue crack propagation trajectory and the corresponding SIFs were predicted using these two software programs. The crack direction was investigated using the maximum circumferential stress theory, and the finite element (FE) analysis for fatigue crack growth was done for both software based on Paris's law. The predicted results in both software demonstrated the influence of holes on the crack growth trajectory and all associated stresses and strains. The study's findings agree with other experimental and numerical crack propagation studies presented in the literature that reveal similar crack propagation trajectory observations.

scholarly journals Fatigue Crack Growth Analysis with Extended Finite Element for 3D Linear Elastic Material

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 397
Author(s):  
Yahya Ali Fageehi
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Crack Growth ◽  
Mixed Mode ◽  
Propagation Path ◽  
Loading Conditions ◽  
Extended Finite Element ◽  
Linear Elastic

This paper presents computational modeling of a crack growth path under mixed-mode loadings in linear elastic materials and investigates the influence of a hole on both fatigue crack propagation and fatigue life when subjected to constant amplitude loading conditions. Though the crack propagation is inevitable, the simulation specified the crack propagation path such that the critical structure domain was not exceeded. ANSYS Mechanical APDL 19.2 was introduced with the aid of a new feature in ANSYS: Smart Crack growth technology. It predicts the propagation direction and subsequent fatigue life for structural components using the extended finite element method (XFEM). The Paris law model was used to evaluate the mixed-mode fatigue life for both a modified four-point bending beam and a cracked plate with three holes under the linear elastic fracture mechanics (LEFM) assumption. Precise estimates of the stress intensity factors (SIFs), the trajectory of crack growth, and the fatigue life by an incremental crack propagation analysis were recorded. The findings of this analysis are confirmed in published works in terms of crack propagation trajectories under mixed-mode loading conditions.

Study on Ductile Fracture Including Shear-Lip Fracture under Mixed Mode Loading Condition

2008 ◽  
Vol 33-37 ◽  
pp. 23-28
Author(s):  
Masanori Kikuchi ◽  
Shougo Sannoumaru
Keyword(s):  
Numerical Simulation ◽  
Crack Growth ◽  
Fracture Zone ◽  
Mixed Mode ◽  
Loading Condition ◽  
Growth Direction ◽  
Dimple Fracture ◽  
Shear Lip ◽  
Crack Growth Direction ◽  
Fracture Tests

Dimple fracture tests are conducted under mode I and mixed mode lading conditions. Dimple fracture zone and shear-lip fracture zone are observed by scanning electron microscope precisely. It is found that crack growth direction is affected largely by the change of loading condition. It is also found that the differences of fracture pattern between mid-plane and at free surface are very large. Void diameter and crack growth direction are measured. Numerical simulation is conducted to simulate fracture tests in three-dimensional field. Gurson’s constitutive equation is used and large deformation analyses are conducted. It is assumed that void nucleation is controlled by both plastic strain and stress. Numerical results are compared with those of experiments. It is found that results of numerical simulation agree well with those of experiment qualitatively.

Influence of the Interface and Residual Stresses on the Apparent Fracture Toughness of Layered Ceramic Composites Based on Alumina-Zirconia

2014 ◽  
Vol 606 ◽  
pp. 209-212
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composites ◽  
Layered Composites ◽  
Material Interfaces ◽  
Linear Elastic ◽  
Apparent Fracture Toughness ◽  
Elastic Fracture ◽  
Layered Ceramic ◽  
Good Agreement

This paper deals with the fracture behaviour of layered ceramic composite with residual stresses. The main goal is to investigate the effect of residual stresses and material interfaces on crack propagation by more complex 3D finite element models. The crack behaviour was described by analytical procedures based on linear elastic fracture mechanics (LEFM) and generalized LEFM. The influence of laminate composition with residual stresses on critical values for crack propagation through the laminate interfaces was also determined. Good agreement has been found to exist between numerical results and experimental data. The results obtained can be used for a design of new layered composites with improved resistance against crack propagation.

Handling Uncertainty in the Remnant Fatigue Life Assessment of Offshore Process Pipework

2016 ◽  
Author(s):  
Arvind Keprate ◽  
R. M. Chandima Ratnayake
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Life Assessment ◽  
Assessment Process ◽  
Linear Elastic ◽  
Fatigue Life Assessment ◽  
Process Piping ◽  
Growth Laws ◽  
Elastic Fracture ◽  
Offshore Industry

A typical procedure for a remnant fatigue life (RFL) assessment is stated in the BS-7910 standard. The aforementioned standard provides two different methodologies for estimating RFL; these are: the S-N curve approach and the crack growth laws (i.e. using Linear Elastic Fracture Mechanics (LEFM) principles) approach. Due to its higher accuracy, the latter approach is more commonly used for RFL assessment in the offshore industry. Nevertheless, accurate prediction of RFL using the deterministic LEFM approach (stated in BS-7910) is a challenging task, as RFL prediction is afflicted with a high number of uncertainties. Furthermore, BS-7910 does not provide any recommendation in regard to handling the uncertainty in the deterministic RFL assessment process. The most common way of dealing with the aforementioned uncertainty is to employ Probabilistic Crack Growth (PCG) models for estimating the RFL. This manuscript explains the procedure for addressing the uncertainty in the RFL assessment of process piping with the help of a numerical example. The numerically obtained RFL estimate is used to demonstrate a calculation of inspection interval.

Application of Multi-Parameter Fracture Mechanics to Study of Crack Propagation Angle in Selected Mixed-Mode Geometry

2013 ◽  
Vol 592-593 ◽  
pp. 209-212 ◽  
Author(s):  
Lucie Šestáková Malíková ◽  
Václav Veselý
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Mixed Mode ◽  
Initial Crack ◽  
Propagation Angle ◽  
Linear Elastic ◽  
Higher Order Terms ◽  
Elastic Fracture ◽  
Cracked Specimens ◽  
Crack Propagation Angle

The multi-parameter fracture mechanics becomes more and more significant, because it is shown that it can help to describe fracture processes occurring in cracked specimens more precisely than conventional linear elastic fracture mechanics. In this paper, the concept based on the Williams expansion derived for approximation of stress/displacement crack-tip fields is presented and applied on a mixed-mode configuration. Two fracture criteria for estimation of the initial crack propagation angle are introduced. A parametric study is performed in order to investigate the dependence of the crack propagation angle on the stress intensity factors ratio. Influence and importance of taking into account the so-called higher-order terms of the Williams expansion are discussed and some recommendations are stated.

Estimation of the Crack Propagation Direction of a Crack Touching the Interface between Two Elastic Materials

2007 ◽  
Vol 567-568 ◽  
pp. 225-228 ◽  
Author(s):  
Luboš Náhlík ◽  
Lucie Šestáková ◽  
Pavel Hutař
Keyword(s):  
Crack Propagation ◽  
Protective Coatings ◽  
The Body ◽  
Elastic Behavior ◽  
Layered Composites ◽  
The Finite Element Method ◽  
Elastic Materials ◽  
Linear Elastic ◽  
Composites Materials ◽  
Elastic Fracture

The objective of the paper is to investigate the direction of a further crack propagation from the interface between two elastic materials. The angle of crack propagation changes when the crack passes the interface. The suggested procedure makes it possible to estimate an angle of propagation under which the crack will propagate into the second material. The assumptions of linear elastic fracture mechanics and elastic behavior of the body with interfaces are considered. The finite element method was used for numerical calculations. The results obtained might contribute to a better understanding of the failure of materials with interfaces (e.g. layered composites, materials with protective coatings) and to a more reliable estimation of the service life of such structures.

scholarly journals Subcritical crack propagation as a mechanism of crevasse formation and iceberg calving

2004 ◽  
Vol 50 (168) ◽  
pp. 109-115 ◽  
Author(s):  
Jérôme Weiss
Keyword(s):  
Crack Propagation ◽  
Subcritical Crack Growth ◽  
Body Wave ◽  
Critical Crack ◽  
Ice Shelves ◽  
Wave Speeds ◽  
Linear Elastic ◽  
Iceberg Calving ◽  
Elastic Fracture ◽  
Natural Way

AbstractRecent investigations of crevassing on alpine glaciers and ice shelves have been based on linear elastic fracture mechanics (LEFM). However, LEFM is unable to explain some aspects of crevasse formation such as the initiation of crevasse propagation from crystal-scale (mm) microcracks, the slow propagation of large fractures in ice shelves, and the acceleration of crevasse opening before breaking of the ice terminus. Here another mechanism to account for these observations is proposed: subcritical crevassing. Subcritical crack growth, documented in many materials though not yet explored in ice, is characterized by a crack velocity that scales as a power of the tensile stress intensity factor, but is much less than that associated with critical crack propagation. This mechanism allows crevasse propagation from mm-scale microcracks at velocities much lower than body wave speeds, and explains crevasse-opening accelerations in a natural way. Subcritical crevassing is theoretically explored for several simplified situations but is limited by a lack of available data on crevasse evolution.

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