Fracture Initiation in Pressure Tube Specimens of Hydrided Irradiated Zr-2.5Nb Materials With Split Circumferential Hydrides

2017 ◽  
Author(s):  
Shin-Jang Sung ◽  
Jwo Pan ◽  
Poh-Sang Lam ◽  
Douglas A. Scarth
Keyword(s):  
Crack Initiation ◽  
Crack Front ◽  
Room Temperature ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Fracture Initiation ◽  
Pressure Tube ◽  
Computational Results ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Fracture initiation for axial cracks in pressure tube (PT) specimens of hydrided irradiated Zr-2.5Nb materials with split circumferential hydrides at room temperature is examined by conducting three-dimensional finite element analyses. With a strain-based fracture criterion with consideration of stress triaxiality, the location for the earliest crack initiation is determined near the middle of the axial crack front. For PT specimens with split circumferential hydrides, three types of strain concentration are observed in the ligaments ahead of the crack front. The computational results suggest that the internal pressure for crack initiation of hydrided irradiated PT specimens with many randomly distributed split circumferential hydrides needs only 55% to 70% of that for unhydrided irradiated PT specimens. The computational results can be used to explain the near 40% reduction of the fracture toughness at room temperature obtained from hydrided irradiated PT specimens when compared with that from unhydrided irradiated ones.

Fracture Initiation in Compact Tension Specimens of Hydrided Irradiated Zr-2.5Nb Materials With Split Circumferential Hydrides

2017 ◽  
Author(s):  
Shin-Jang Sung ◽  
Jwo Pan ◽  
Poh-Sang Lam ◽  
Douglas A. Scarth
Keyword(s):  
Room Temperature ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Compact Tension ◽  
Transverse Tensile ◽  
Stress Strain Relation ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Fracture initiation in compact tension (CT) specimens of hydrided irradiated Zr-2.5Nb materials with split circumferential hydrides is examined by conducting three-dimensional finite element analyses with submodeling. The stress-strain relation for the irradiated Zr-2.5Nb materials is based on the experimental results of transverse tensile tests. For CT specimens with split circumferential hydrides, plastic strain concentration is observed in the middle of the ligaments ahead of the crack front. With a strain-based failure criterion with consideration of stress triaxiality, the necessary fraction of the load for crack initiation is about 0.55 to 0.70 to fracture the ligaments when compared to that for a CT specimen without split circumferential hydrides. The computational results can be used to explain the near 40% reduction of the fracture toughness at room temperature obtained from hydrided irradiated curved compact tension specimens (CCTSs) when compared with that from unhydrided irradiated ones.

Influence of Interference and Clamping on Fretting Fatigue in Single Rivet-Row Lap Joints

2000 ◽  
Vol 123 (4) ◽  
pp. 686-698 ◽  
Author(s):  
K. Iyer ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Crack Initiation ◽  
Three Dimensional ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Lap Joints ◽  
Element Analysis ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Fretting Damage

Primary fretting fatigue variables such as contact pressure, slip amplitude and bulk cyclic stresses, at and near the contact interface between the rivet shank and panel hole in a single rivet-row, 7075-T6 aluminum alloy lap joint are presented. Three-dimensional finite element analysis is applied to evaluate these and the effects of interference and clamping stresses on the values of the primary variables and other overall measures of fretting damage. Two rivet geometries, non-countersunk and countersunk, are considered. Comparison with previous evaluations of the fretting conditions in similar but two-dimensional connections indicates that out-of-plane movements and attending effects can have a significant impact on the fatigue life of riveted connections. Variations of the cyclic stress range and other proponents of crack initiation are found to peak at distinct locations along the hole-shank interface, making it possible to predict crack initiation locations and design for extended life.

Stress Intensity Factor of an Elliptical Crack With a Wavy Crack Front

2016 ◽  
Author(s):  
Masayuki Arai
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Front ◽  
Perturbation Technique ◽  
Three Dimensional ◽  
Elastic Field ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, the stress intensity factor KI for the crack front line a − ε(1 + cosmθ), which is slightly perturbed from a complete circular line with a radius of a, is determined. The method used in this study is based upon the perturbation technique developed by Rice for solving the elastic field of a crack whose front slightly deviates from some reference geometry. It is finally shown that the solution for the stress intensity factor matches the results of a three-dimensional finite element analysis.

scholarly journals Calculation and 3D analyses of ERR in the band crack front contained in a rectangular plate made of multilayered material

2018 ◽  
Vol 16 (1) ◽  
pp. 516-519
Author(s):  
Arzu Turan Dincel ◽  
Surkay D. Akbarov
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Rectangular Plate ◽  
Release Rate ◽  
Crack Front ◽  
Three Dimensional ◽  
Geometrical Parameters ◽  
3D Fem ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

AbstractAn investigation into the values of the Energy Release Rate (ERR) at the band crack’s front in the rectangular plate made of multilayered composite material is carried out for the opening mode. The corresponding boundary-value problem is modelled by using threedimensional linear theory and solved numerically by using 3D FEM (Three Dimensional Finite Element Method). The main purpose of the current investigation is to study the influence of mechanical and geometrical parameters on the Energy Release Rate (ERR) at this crack front. The numerical results related to the ERR, and the effect of the mechanical and other problem parameters on the ERR are presented and discussed.

scholarly journals A semi-analytical method to evaluate the J-R curve for the surface-cracked round bar under three-point bending

2021 ◽  
Author(s):  
Guangwei He ◽  
Lixun CAI ◽  
Chen Bao ◽  
Xudong Qian
Keyword(s):  
Finite Element ◽  
Crack Front ◽  
Analytical Method ◽  
Three Dimensional ◽  
Element Analysis ◽  
Round Bar ◽  
Dimensional Finite Element ◽  
Load Displacement ◽  
Three Dimensional Finite Element ◽  
Analytical Expressions

The current paper presents a semi-analytical method for obtaining J-R curves of round bars with elliptical cracks. This method derives the semi-analytical expressions between load and displacement, J-integral and displacement for surface-cracked round bars, based on the energy density equivalence principle, taking into account the effect of material and crack size. The validity of semi-analytical expressions examined by three-dimensional finite element analysis shows that load~displacement curves and J-integral~load curves predicted by the expressions match well with the simulation results. Through fracture toughness testing conducted on the carbon steel 45, the load~displacement data are used to calculate the average J-R curves for the surface-cracked round bar by the semi-analytical expressions. With the distributions of J-integral along the crack front obtained from three-dimensional finite element analyses, this study also determines the J-R curves at different crack-front points.

Fatigue Behavior and Deformation of Aluminum and Steel HVOF Sprayed with WC-Co Coatings

1997 ◽  
Author(s):  
A. Ibrahim ◽  
C.C. Berndt
Keyword(s):  
Fatigue Life ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Element Model ◽  
Fatigue Tests ◽  
Dimensional Finite Element ◽  
Life Distributions ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Abstract The effect of WC-Co coating on the high cycle fatigue (HCF) behavior of SAE 12L14 steel and 2024-T4 aluminum was investigated. The fatigue tests were performed at room temperature and 370°C. The fatigue life distributions of specimens in the polished, grit blasted, peened, and coated conditions are presented as a function of the probability of failure. HVOF sprayed WC-Co coating has influenced the fatigue life of aluminum and steel. Factors contributing to this influence, which include grit blasting, elastic modulus, and residual stress, are discussed. A three-dimensional finite-element model (FEM) of the coated specimen was used to calculate the stress distribution across the coating and the substrate. The results of the analytical model are in good agreement with fatigue lives observed experimentally.

Real 3D Crack-Front and Crack Trajectory Analyses of Single-Side Repaired Thick Aluminium Panels

2008 ◽  
Vol 47-50 ◽  
pp. 777-780 ◽  
Author(s):  
Hossein Hosseini-Toudeshky ◽  
Masoud Saber ◽  
Bijan Mohammadi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Front ◽  
Three Dimensional ◽  
Growth Trajectories ◽  
Crack Trajectory ◽  
Single Side ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, fatigue crack growth trajectories, crack-front shape and life of the single-side repaired thick aluminium panels with glass/epoxy patch are analyzed. This investigation is performed using three dimensional finite element fracture analyses in general mixed-mode conditions (Mode I, II and III). The obtained fatigue crack growth trajectories, crack-front shapes and lives of the repaired panels with the patch lay-ups of [90]4 and [-45]4 are compared with the available experimental results produced by the authors.

Investigation on T11-Stress for Semi-Elliptical Surface Cracks in Finite Thickness Plates under Remote Tension

2012 ◽  
Vol 525-526 ◽  
pp. 237-240
Author(s):  
Wei Xie
Keyword(s):  
Finite Element ◽  
Crack Front ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Fracture Analysis ◽  
Surface Cracks ◽  
Finite Element Analyses ◽  
Current Stress ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In the present work, three-dimensional finite element analyses have been conducted to calculate the-stress for semi-elliptical surface cracks in finite thickness plates under remote tension. The-stress solutions are presented along the crack front for cracks with values of 0.2, 0.4, 0.6 or 0.8 and values of 0.2, 0.4, 0.6 or 1.0. The current-stress solutions are suitable to be used as the constraint parameter for the fracture analysis.

scholarly journals Interaction of void spacing and material size effect on inter-void flow localisation

2020 ◽  
pp. 1-13
Author(s):  
Ingrid Holte ◽  
Ankit Srivastava ◽  
Emilio Martínez-Pañeda ◽  
Christian F. Niordson ◽  
Kim L. Nielsen
Keyword(s):  
Size Effect ◽  
Strain Gradient ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Void Coalescence ◽  
Porous Metals ◽  
Dimensional Finite Element ◽  
Stress States ◽  
Three Dimensional Finite Element ◽  
Ligament Size

Abstract The ductile fracture process in porous metals due to growth and coalescence of micron scale voids is not only affected by the imposed stress state but also by the distribution of the voids and the material size effect. The objective of this work is to understand the interaction of the inter-void spacing (or ligaments) and the resultant gradient induced material size effect on void coalescence for a range of imposed stress states. To this end, three dimensional finite element calculations of unit cell models with a discrete void embedded in a strain gradient enhanced material matrix are performed. The calculations are carried out for a range of initial inter-void ligament sizes and imposed stress states characterised by fixed values of the stress triaxiality and the Lode parameter. Our results show that in the absence of strain gradient effects on the material response, decreasing the inter-void ligament size results in an increase in the propensity for void coalescence. However, in a strain gradient enhanced material matrix, the strain gradients harden the material in the inter-void ligament and decrease the effect of inter-void ligament size on the propensity for void coalescence.

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