Application of XFEM to Model Stationary Crack and Crack Propagation for Pressure Containing Subsea Equipment

2016 ◽  
Author(s):  
Sam (Kwok Lun) Lee ◽  
David Martin
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Crack Growth ◽  
Displacement Field ◽  
Internal Surface ◽  
Contour Integral ◽  
Integral Approach ◽  
Thick Wall ◽  
Element Mesh ◽  
Integrity Assessment

The extended finite element method (XFEM) [1, 2] can approximate the discontinuous displacement field near cracks independently of the finite element mesh through the use of interpolation functions, which can describe the displacement field near cracks in the structure. Therefore, XFEM is appearing as an alternative to conventional contour integral method for crack growth analysis. Most benchmarks for XFEM in published literature were mostly for the through-wall crack or loadings were under tension or bending moment. Subsea equipment provided by FMC Technologies is used under the most extreme conditions of pressure and temperature. Due to the fact that most equipment in subsea is pressure containing, assessment of cracks and crack growth under pressure cycles is an essential part of the integrity assessment. The implementation of fracture mechanic based fatigue to analysis can extend equipment life while improving model accuracy. In this paper, crack growth modelling in a thick wall cylinder was performed by XFEM embedded in Abaqus [3]. The case study of semi-elliptical axial surface crack at internal surface was selected. The fracture and fatigue results based on LCF analysis were compared with contour integral approach and published experimental data [4]. One of the advantages of XFEM is it can easily accommodate changes in the crack propagation direction for mixed mode loading.

The Implementation of Inter-Element Model for Crack Growth Simulation

2004 ◽  
Vol 261-263 ◽  
pp. 687-692 ◽  
Author(s):  
Ahmad Kamal Ariffin ◽  
Syifaul Huzni ◽  
Nik Abdullah Nik Mohamed ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Problem ◽  
Adaptive Mesh ◽  
Element Model ◽  
Error Norm ◽  
Element Analysis ◽  
Element Mesh

The implementation of inter-element model to simulate crack propagation by using finite element analysis with adaptive mesh is presented. An adaptive finite element mesh is applied to analyze two-dimension elastoplastic fracture during crack propagation. Displacement control approach and updated Lagrangean strategy are used to solve the non-linearity in geometry, material and boundary for plane stress crack problem. In the finite element analysis, remeshing process is based on stress error norm coupled with h-version mesh refinement to find an optimal mesh. The crack is modeled by splitting crack tip node and automatic remeshing calculated for each step of crack growth. Crack has been modeled to propagate through the inter-element in the mesh. The crack is free to propagates without predetermine path direction. Maximum principal normal stress criterion is used as the direction criteria. Several examples are presented to show the results of the implementation.

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.

Dynamic Crack Propagation and Arrest in PWR Pressure Vessel Steel: Interpretation of Experiment With the X-FEM Method

2007 ◽  
Author(s):  
B. Prabel ◽  
S. Marie ◽  
A. Combescure
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Strain Rate ◽  
Thermal Shock ◽  
Crack Growth ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Pressure Vessel Steel ◽  
Vessel Steel

In the frame of analysis of the pressure thermal shock in a PWR RVP and the associated R&D activities, some developments are performed at CEA on the dynamic brittle propagation and crack arrest. This paper presents a PhD work on the modeling of the dynamic brittle crack growth. For the analyses, an important experimental work is performed on different geometries using a French RPV ferritic steel: Compact Tension specimens with different thickness, isothermal rings under compression with different positions of the initial defect to study a mixed mode configuration, and a ring submitted to thermal shock. The first part of this paper details the test conditions and main results. To propose an accurate interpretation of the crack growth, a viscous-elastic-plastic dynamic model is used. The strain rate influence is taken into account based on Cowper-Symond’s law (characterization was made from Split Hopkinson Pressure Bar tests). To model the crack propagation in the Finite Element calculation, eXtended Finite Element Method (X-FEM) is used. The implementation of these specific elements in the CEA F.E. software CAST3M is described in the second part of this paper. This numerical technique avoids re-meshing, because the crack progress is directly incorporated in the degrees of freedom of the elements crossed by the crack. The last part of this paper compares the F.E. predictions to the experimental measurements using different criteria. In particular, we focused on a RKR (Ritchie-Knott-Rice) like criterion using a critical principal stress in the front of the crack tip during the dynamic crack extension. Critical stress is found to depend on crack speed, or equivalently on strain rate. Good results are reported concerning predictive simulations.

A research on fatigue crack growth monitoring based on multi-sensor and data fusion

2019 ◽  
pp. 147592171986572
Author(s):  
Chang Qi ◽  
Yang Weixi ◽  
Liu Jun ◽  
Gao Heming ◽  
Meng Yao
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Data Fusion ◽  
Crack Propagation ◽  
Finite Element Model ◽  
Crack Length ◽  
Crack Growth ◽  
Lamb Wave ◽  
Element Model

Fatigue crack propagation is one of the main problems in structural health monitoring. For the safety and operability of the metal structure, it is necessary to monitor the fatigue crack growth process of the structure in real time. In order to more accurately monitor the expansion of fatigue cracks, two kinds of sensors are used in this article: strain gauges and piezoelectric transducers. A model-based inverse finite element model algorithm is proposed to perform pattern recognition of fatigue crack length, and the fatigue crack monitoring experiment is carried out to verify the algorithm. The strain spectra of the specimen under cyclic load in the simulation and experimental crack propagation are obtained, respectively. The active lamb wave technique is also used to monitor the crack propagation. The relationship between the crack length and the lamb wave characteristic parameter is established. In order to improve the recognition accuracy of the crack propagation mode, the random forest and inverse finite element model algorithms are used to identify the crack length, and the Dempster–Shafer evidence theory is used as data fusion to integrate the conclusion of the two algorithms to make a more accountable and correct judge of the crack length. An experiment has been conducted to demonstrate the effectiveness of the method.

Finite Element Modeling for Energy Release Rate in Human Cortical Bone

Volume 2 ◽  
2004 ◽  
Author(s):  
Saiphon Charoenphan ◽  
Apiwon Polchai
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Finite Element Modeling ◽  
Energy Release Rate ◽  
Cortical Bone ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Slow Crack Growth ◽  
Finite Element Models

The energy release rates in human cortical bone are investigated using a hybrid method of experimental and finite element modeling techniques. An explicit finite element analysis was implemented with an energy release rate calculation for evaluating this important fracture property of bones. Comparison of the critical value of the energy release rate, Gc, shows good agreement between the finite element models and analytical solutions. The Gc was found to be approximately 820–1150 J/m2 depending upon the samples. Specimen thickness appears to have little effect on the plane strain condition and pure mode I assumption. Therefore the energy release rate can be regarded as a material constant and geometry independent and can be determined with thinner specimens. In addition, the R curve resulting from the finite element models during slow crack growth shows slight ductility of the bone specimen that indicates an ability to resist crack propagation. Oscillations were found at the onset of the crack growth due to the nodal releasing application in the models. In this study light mass-proportional damping was used to suppress the noises. Although this techniques was found to be efficient for this slow crack growth simulation, other methods to continuously release nodes during the crack growth would be recommended for rapid crack propagation.

Automated Fracture Mechanics and Fatigue Analyses Based on Three-Dimensional Finite Elements

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Hitoshi Nakamura ◽  
Wenwei Gu ◽  
Seiichi Tajima ◽  
Osamu Hazama
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Three Dimensional ◽  
3D Fem ◽  
Element Mesh ◽  
Fem Model ◽  
Steel Pipes ◽  
Fatigue Initiation ◽  
Propagation Analysis ◽  
History Of

This paper describes the structure and application of a software system that automates the fatigue initiation and crack propagation analysis based on finite element method (FEM). The system automatically performs necessary procedures to track propagation history of cracks: insertion of a crack and updating of three-dimensional (3D) finite element mesh in accordance with the crack propagation. The system is equipped with a function to automatically perform fatigue analyses using the stress–strain histories at nodes of a 3D FEM model. Some analyses for several examples were carried out for validation. The important example is the surface crack propagation in steel pipes with residual stress.

scholarly journals The Crack Propagation Trend Analysis in Ceramic Rolling Element Bearing considering Initial Crack Angle and Contact Load Effect

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhe Yuan ◽  
Bohan Wang ◽  
Chao Liu ◽  
Zhan Wang ◽  
Xiaochen Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Silicon Nitride ◽  
Crack Propagation ◽  
Crack Growth ◽  
Surface Crack ◽  
Initial Crack ◽  
Silicon Nitride Ceramic ◽  
Ball Surface ◽  
Crack Angle ◽  
Bearing Ball

Silicon nitride ceramic bearings are widely used for their excellent performance. However, due to their special manufacturing method, cracks will occur on ceramic ball surface, and this initial surface crack will propagate under the action of cyclic stress, which will lead to material spalling. This will greatly limit its service life in practical applications, especially under heavy load at high speed. Therefore, it is necessary to study the surface crack propagation of silicon nitride ceramic bearings. In this paper, the effect of initial crack angle and contact load on crack growth is analysed by the finite element method (FEM). A three-dimensional finite element model of a silicon nitride bearing ball containing an initial crack is created by the FEM. The cracks are initially classified based on the angle between the crack and the bearing ball surface, and the location of the most dangerous load for each type of crack is known by theoretical analysis. The stress intensity factors (SIFs) are calculated for the crack front to investigate the effect of load position on crack growth. Subsequently, the SIFs are calculated for each type of crack angle subdivided again to investigate the effect of crack angle on crack propagation.

Validation of the K and J Parameters in a Compact Tension Specimen Containing Intergranular and Straight Crack Paths

2010 ◽  
Author(s):  
A. N. Mehmanparast ◽  
C. M. Davies ◽  
K. M. Nikbin
Keyword(s):  
Finite Element ◽  
Grain Boundary ◽  
Crack Growth ◽  
Crack Tip ◽  
Compact Tension ◽  
Growth Direction ◽  
Compact Tension Specimen ◽  
Contour Integral ◽  
Transgranular Crack ◽  
Crack Profile

Methods have been examined to evaluate the fracture mechanics parameters J and K in finite element (FE) analyses on a compact tension, C(T), geometry using a mesh appropriate for the evaluation of both intergranular and transgranular microstructural damage processes. Realistic grain and grain boundary microstructures were modelled using ABAQUS. Both straight and deviating crack profiles were considered, representing transgranular and intergranular crack growth processes, respectively. Elastic and elastic-plastic finite element analyses were performed on a C(T) specimen model with a standard straight and deviating crack profile to derive and compare the stress intensity factor, K, and J parameter values under plane stress and plane strain conditions. Considerations as to the validity of the J domain integral calculations that ABAQUS computes are discussed. It has been found that the values of K and J obtained from FE simulations are consistent with theoretical solutions and the stress distribution ahead of the crack tip is very close to that of expected from analytical studies for the case of a straight fronted transgranular crack. Reasonable values of K and J parameters could also be achieved from the FE contour integral values of a deviating crack when the contours selected were adequately far from the crack tip. However, significant differences were found between the analytical and FE contour integral values of a deviating crack when the crack growth direction was considered to continue at the angle defined by its grain boundary. The values of J obtained by from the load line displacement measurements were uninfluenced by the crack profile and in good agreement with other analytical solutions.

Sign in / Sign up

Export Citation Format

Share Document