Establishing a methodology to predict the crack initiation load in through-wall cracked components using tensile specimen test data

2010 ◽  
Vol 87 (12) ◽  
pp. 737-745 ◽  
Author(s):  
Sanjeev Saxena ◽  
N. Ramakrishnan ◽  
J.S. Chouhan
Keyword(s):  
Crack Initiation ◽  
Test Data ◽  
Tensile Specimen ◽  
Specimen Test

scholarly journals A Simple Method for Theoretical Prediction of Fracture Toughness of Multilayered Composites

2003 ◽  
Vol 12 (4) ◽  
pp. 096369350301200 ◽  
Author(s):  
R. Ramesh Kumar ◽  
P.N. Dileep ◽  
S. Renjith ◽  
G. Venkateswara Rao
Keyword(s):  
Fracture Toughness ◽  
Crack Initiation ◽  
Theoretical Prediction ◽  
Test Data ◽  
Fibre Orientation ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Initial Crack ◽  
Simple Method ◽  
Multilayered Composites

Intralaminar fracture toughness of a fibre-reinforced angle ply and cross ply laminates are generally obtained by testing compact tension specimen and theoretically predicted using the well-known MCCI approach. The crack initiation direction, which is treated as a branch direction for the theoretical prediction, is an apriori. A conservative estimation on the toughness value obtained by considering branch crack angle corresponding to each fibre orientation in a laminate shows a gross error with respect to test data. In the present study a new criterion for the prediction of crack initiation angle is arrived at based on Tsai-Hill minimum strain energy density criterion. This shows a very good agreement with test data available in literature on fracture toughness of various multilayered composites with large size cracks with a/w ≥ 0.3. It is interesting to note that in a multilayered composite a simple method of prediction in which crack initiation direction is assumed to be the fibre orientation that is close to the initial crack direction gives a good estimation of the intralaminar fracture toughness.

The Analysis of Acoustic Emission Code and the Research of Acoustic Emission Signal of P355NL1 Under Low Temperature of −40°C

2014 ◽  
Author(s):  
Xiao Biao ◽  
Xiaoying Tang ◽  
Nie Liang ◽  
Yao Jianping ◽  
Li Jianrong
Keyword(s):  
Acoustic Emission ◽  
Low Temperature ◽  
Acoustic Emission Signal ◽  
Tensile Specimen ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Storage Vessel ◽  
Emission Signal ◽  
Whole Process ◽  
Specimen Test

The latest content of acoustic emission code GB/T18182-2012 are shown in this paper. The differences of GB/T18182-2012 and GB18182-2000 are summarized. Acoustic emission method was used to inspect the whole process of tensile specimen test under the temperature of 0°C, −20°C and −50°C. Based on the characteristics of the signal of different temperature condition, some difference of these signals was analyzed and discussed. By using the above result, acoustic emission was applied to inspect a drikold storage vessel.

scholarly journals Probabilistic Modeling of Slip System-Based Shear Stresses and Fatigue Behavior of Coarse-Grained Ni-Base Superalloy Considering Local Grain Anisotropy and Grain Orientation

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 813 ◽  
Author(s):  
Engel ◽  
Mäde ◽  
Lion ◽  
Moch ◽  
Gottschalk ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Test Data ◽  
Grain Orientation ◽  
Fatigue Behavior ◽  
Coarse Grained ◽  
Shear Stresses ◽  
Grain Sizes ◽  
Crack Initiation Life ◽  
Base Superalloy

New probabilistic lifetime approaches for coarse grained Ni-base superalloys supplement current deterministic gas turbine component design philosophies; in order to reduce safety factors and push design limits. The models are based on statistical distributions of parameters, which determine the fatigue behavior under high temperature conditions. In the following paper, Low Cycle Fatigue (LCF) test data of several material batches of polycrystalline Ni-base superalloy René80 with different grain sizes and orientation distribution (random and textured) is presented and evaluated. The textured batch, i.e., with preferential grain orientation, showed higher LCF life. Three approaches to probabilistic crack initiation life modeling are presented. One is based on Weibull distributed crack initiation life while the other two approaches are based on probabilistic Schmid factors. In order to create a realistic Schmid factor distribution, polycrystalline finite element models of the specimens were generated using Voronoi tessellations and the local mechanical behavior investigated in dependence of different grain sizes and statistically distributed grain orientations. All models were first calibrated with test data of the material with random grain orientation and then used to predict the LCF life of the material with preferential grain orientation. By considering the local multiaxiality and resulting inhomogeneous shear stress distributions, as well as grain interaction through polycrystalline Finite Element Analysis (FEA) simulation, the best consistencies between predicted and observed crack initiation lives could be achieved.

Prevention of Pipeline Dent Failure Under Fatigue Loading Conditions

2014 ◽  
Author(s):  
Julien Fontanabona ◽  
Ky Dang Van ◽  
Vincent Gaffard ◽  
Zied Moumni ◽  
Paul Wiet
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Fatigue Test ◽  
Test Data ◽  
Fatigue Crack Initiation ◽  
Full Scale ◽  
Loading Conditions ◽  
Stress Cycle ◽  
Dang Van Criterion

Pipeline dents fatigue life prediction is a subject of high interest for pipelines operating companies. Empreinte is an in-house developed pre and post processor to ABAQUS Finite Element Calculations dedicated to pipeline integrity assessment. Empreinte was first developed and experimentally validated for dents assessments under static loading conditions. As oil but also gas transmission pipelines are submitted to cyclic loading conditions (internal pressure variations, shutdowns, temperature variations …), it was decided to introduce a fatigue life criterion in Empreinte based on the Dang Van theory assuming that local mesoscopic stresses drive fatigue crack initiation. Full scale tests performed for PRCI projects PR-201-927, PR-201-9324 and MD-4-2 were used to validate the proposed fatigue assessment methodology: - the first full scale fatigue test was performed in 1994 on an X52 pipe. For this test, limited material and test data were available. - the second full scale fatigue test was performed in 2007 on an X52 pipe. For this test, material characterization (in particular tensile tests with full stress strain curves) and test data (strain gages measurements, indenter geometry …) were available. Fatigue life assessments were performed following three main steps: 1. using available data: non linear kinematic hardening constitutive laws were identified for the two pipes materials; 2. finite elements elastic-plastic modeling of the denting processes were carried out; 3. fatigue calculations were performed following a new approach using Dang Van criterion for which the parameters were determined from literature data. The elastic shakedown assumption allowed the determination of the local stress cycle from the macroscopic stress cycle. The fatigue criterion integrating the combined influences of shear and hydrostatic stresses was checked on all points of the pipe. Good agreement between experimental and calculated fatigue lives and fatigue crack initiation points was reached. This opens a promising way to assess pipeline defects fatigue life. Efforts are now focused on the standardization of a testing method to identify the Dang Van criterion of a pipeline material at least in air environment.

scholarly journals Evaluation of the Impact of Residual Stresses in Crack Initiation with the Application of the Crack Compliance Method Part II, Experimental Analysis

2010 ◽  
Vol 24-25 ◽  
pp. 261-266
Author(s):  
G. Urriolagoitia-Sosa ◽  
B. Romero-Ángeles ◽  
Luis Héctor Hernández-Gómez ◽  
G. Urriolagoitia-Calderón ◽  
Juan Alfonso Beltrán-Fernández ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Experimental Analysis ◽  
Previous History ◽  
Numerical Procedure ◽  
Tensile Specimen ◽  
Residual Stress Field ◽  
The Impact

The present work is based on a previous numerical simulation used for the introduction of a residual stress field in a modified compact tensile specimen. The main objective in that paper was to evaluate the effect that previous history has in crack initiation and to establish the new loading conditions needed to propagate a fracture. The experimental analysis presented in this paper was performed to compare and validate the numerical procedure. Several modified compact tensile specimens from a biocompatible material (AISI 316L) were manufactured to estimate the beneficial effect of a residual stress field. The specimens were separated in four batches; an initial group of uncracked specimens was used to establish an evaluation of the induction of a residual stress field produced by an overload; the remaining specimens were separated into three groups where a crack was introduced in each specimen (1 mm, 5 mm and 10 mm respectively) and the residual stress field caused by the application of an overload was determined. The assessment of all the residual stress fields introduced into the specimens was done by the application of the crack compliance method (CCM). The results obtained have provided useful information on the correlation between the numerical and experimental procedures. Furthermore, data concerning the understanding of diverse factors related to crack initiation are discussed in this paper. Finally, the beneficial aspects of the residual stresses are discussed.

Statistical and Probabilistic Analysis of Thermal-Fatigue Test Data Generated Using V-Shape Specimen Testing Method

2013 ◽  
Author(s):  
Zhigang Wei ◽  
Burt Lin ◽  
Kay Ellinghaus ◽  
Markus Pieszkalla ◽  
D. Gary Harlow ◽  
...  
Keyword(s):  
Test Data ◽  
Thermal Fatigue ◽  
New Product ◽  
Distribution Functions ◽  
Life Test ◽  
Thermal Fatigue Test ◽  
Probability Distribution Functions ◽  
Testing Method ◽  
Specimen Test ◽  
Rank And Select

V-shape specimen testing is a relatively new, simple and useful technique to characterize the thermal-fatigue resistance of materials subjected to combined thermal/mechanical loadings, and to rank and select materials. However, the V-shape specimen test data, similar to many other life test data, always contain an inherent scatter not only because of material non-uniformity but also of the difficulties in operating control, such as loading, boundary conditions, and environment. Therefore, statistical and probabilistic approaches have to be used to interpret the test data in order to implement the observations into new product designs. In this paper, the V-shape specimen test data are selected, analyzed and the scatter properties of the test data are fitted using several continuous probability distribution functions. The results are compared, and the root failure mechanisms of the V-specimens are also discussed. Finally, the main observations are summarized, and a recommendation is provided.

The determination of curves from single-specimen test data

1985 ◽  
Vol 21 (4) ◽  
pp. 261-284 ◽  
Author(s):  
Zhongxin Guan ◽  
Liang Liu ◽  
Nansheng Yang
Keyword(s):  
Test Data ◽  
Single Specimen ◽  
Specimen Test
Sign in / Sign up

Export Citation Format

Share Document