The Two-Parameter Approach for Fracture Mechanics: Some Industrial Applications

2016 ◽  
pp. 105-134 ◽  
Author(s):  
M. Hadj Meliani ◽  
O. Bouledroua ◽  
M. Ould-M’beirick ◽  
K. El-miloudi ◽  
Dj. Neggaz ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Industrial Applications ◽  
Parameter Approach ◽  
Two Parameter

scholarly journals Validation of a finite element model for fracture mechanics specimens

2012 ◽  
Vol 3 (1) ◽  
pp. 8-18
Author(s):  
M. Cauwelier ◽  
J. Maelfait ◽  
M. Verstraete ◽  
S. Hertelé ◽  
K. Van Minnebruggen ◽  
...  
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Finite Element Model ◽  
Element Model ◽  
J Integral ◽  
Constraint Effects ◽  
Analytical Expressions ◽  
Parameter Approach ◽  
Two Parameter ◽  
Good Agreement

Single parameter formulations have shown to be insufficient to describe constraint effects infracture mechanics specimens. This has lead researchers to a two parameter approach like the J-Q theory.In order to investigate constraint effects, the authors have developed a generic finite element model. Priorto drawing conclusions this model must first be validated, which is the topic of this paper. This validationhas been done by comparing analytical expressions of the J-integral with those obtained from theperformed simulations. The compared geometries were center cracked tension (CCT) and double edgenotched tension (DENT) fracture mechanics specimens. The results showed good agreement with theanalytical expressions and, as such, the model can now be confidently applied to determine values of the Jintegral. This is a first step towards evaluating two parameter J-Q constraint.

scholarly journals 3D SSY Estimate of EPFM Constraint Parameter under Biaxial Loading for Sensor Structure Design

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 735
Author(s):  
Ping Ding ◽  
Xin Wang
Keyword(s):  
Fracture Mechanics ◽  
Biaxial Loading ◽  
Structure Design ◽  
Theoretical Research ◽  
Small Scale ◽  
Validation Process ◽  
Wide Range ◽  
Sensor Structure ◽  
Estimate Method ◽  
Parameter Approach

Conventional sensor structure design and related fracture mechanics analysis are based on the single J-integral parameter approach of elastic-plastic fracture mechanics (EPFM). Under low crack constraint cases, the EPFM one-parameter approach generally gives a stress overestimate, which results in a great cost waste of labor and sensor components. The J-A two-parameter approach overcomes this limitation. To enable the extensive application of the J-A approach on theoretical research and sensor engineering problem, under small scale yielding (SSY) conditions, the authors developed an estimate method to conveniently and quickly obtain the constraint (second) parameter A values directly from T-stress. Practical engineering application of sensor structure analysis and design focuses on three-dimensional (3D) structures with biaxial external loading, while the estimate method was developed based on two-dimensional (2D) plain strain condition with uniaxial loading. In the current work, the estimate method was successfully extended to a 3D structure with biaxial loading cases, which is appropriate for practical sensor design. The estimate method extension and validation process was implemented through a thin 3D single edge cracked plate (SECP) specimen. The process implementation was completed in two specified planes of 3D SECP along model thickness. A wide range of material and geometrical properties were applied for the extension and validation process, with material hardening exponent value 3, 5 and 10, and crack length ratio 0.1, 0.3 and 0.7.

A Novel Method of Obtaining Honing Tool Profile for Machining Gears With Profile Modifications

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Michał Batsch
Keyword(s):  
Mathematical Model ◽  
Design Process ◽  
High Precision ◽  
Prediction Error ◽  
Industrial Applications ◽  
Helical Gears ◽  
Profile Deviation ◽  
Tool Profile ◽  
Novel Method ◽  
Two Parameter

Abstract In this study, a mathematical model of the honing process for helical gears with external teeth was developed. The proposed novel method of obtaining the two-parameter envelope of a family of surfaces proved useful in simulated machining by means of a tool with a profile deviation. Based on performed simulations and industrial applications, it was found that this method can be useful in predicting the accuracy of machined gear and therefore can be used in the design process of honing tool for high precision aerospace gears. For the example provided, the average absolute prediction error of machined tooth profile was 0.28 µm.

Multiaxial Fatigue Failure Criterion Considering Formation and Growth of Small Cracks

2010 ◽  
Author(s):  
Yukio Takahashi
Keyword(s):  
Life Prediction ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
New Approach ◽  
Small Cracks ◽  
Failure Life ◽  
Parameter Approach ◽  
Realistic Prediction ◽  
Two Parameter

Treatment of stress multiaxiality in fatigue assessment is practically important in many components subjected to cyclic loading during their operation. Based on the results of fatigue tests on hollow and solid bar specimens of SUS316NG and SGV410 under various combinations of axial and torsional stresses, accuracy of fatigue life prediction based on the conventional parameters as well as a two parameter approach newly proposed here was studied. The conventional parameters tended to provide conservative prediction of the failure life for shear-dominated cases especially for SUS316NG while the new approach was able to give more realistic prediction of failure lives.

Adjusted J-R Toughness Curve for Pipes Using J-A2 Crack Constraint of CT Specimens and 3D Crack Meshes

2019 ◽  
Author(s):  
Greg Thorwald ◽  
Ken Bagnoli
Keyword(s):  
Fracture Mechanics ◽  
Test Data ◽  
Crack Front ◽  
Test Specimen ◽  
Closed Form Solution ◽  
Form Solution ◽  
Specimen Geometry ◽  
Ductile Tearing ◽  
Two Parameter ◽  
Axial Surface

Abstract The objective of this paper is to use two-parameter fracture mechanics to adjust a material J-R resistance curve (i.e. toughness) from the test specimen geometry to the cracked component geometry. As most plant equipment is designed and operated on the “upper shelf”, a ductile tearing analysis may give a more realistic assessment of flaw tolerance. In most cases, tearing curves are derived from specimen geometries that ensure a high degree of constraint, e.g., SENB and CT Therefore, there can be significant benefit in accounting for constraint differences between the specimen geometry and the component geometry. In one-parameter fracture mechanics a single parameter, K or J-integral, is sufficient to characterize the crack front stresses. When geometry dependent effects are observed, two-parameter fracture mechanics can be used to improve the characterization of the crack front stress, using T-stress, Q, or A2 constraint parameter. The A2 parameter was be used in this study. The usual J-R power-law equation has two coefficients to curve-fit the material data (ASTM E1820). The adjusted J-R curve coefficients are modified to be a function of the A2 constraint parameter. The measured J-R values and computed A2 constraint values are related by plotting the J-R test data versus the A2 values. The A2 constraint values are computed by comparing the HRR stress solution to the crack front stress results of the test specimen geometry using elastic-plastic FEA. Solving for the two J-R curve coefficients uses J values at two Δa crack extension values from the test data. A closed-form solution for the adjusted J-R coefficients uses the properties of natural logarithms. The solution shows the adjusted J-R exponent coefficient will be a constant value for a particular material and test specimen geometry, which simplifies the application of the adjusted J-R curve. A different test specimen geometry can be used to validate the adjusted J-R curve. Choosing another test specimen geometry, having a different A2 constraint value, can be used to obtain the adjusted J-R curve and compare it to the measured J-R curves. The geometry of the component is also expected to have a different A2 constraint compared to the material test specimen. The example examined here is an axial surface flaw in a pipe. The A2 constraint for an axial surface cracked pipe is computed and used to obtain an adjusted J-R curve. The adjusted J-R curve shows an increase in toughness for the pipe as compared to the CT measured value. The adjusted J-R curve can be used to assess flaw stability using the driving force method or a ductile tearing instability analysis.

Grain Growth during Annealing: Experiments and Modelling

2012 ◽  
Vol 715-716 ◽  
pp. 611-616 ◽  
Author(s):  
M. Candic ◽  
Bao Hui Tian ◽  
Christof Sommitsch
Keyword(s):  
Grain Growth ◽  
Second Phase ◽  
Excellent Correlation ◽  
Grain Sizes ◽  
Second Phase Particles ◽  
Different Temperatures ◽  
Grain Growth Kinetics ◽  
Parameter Approach ◽  
Annealing Experiments ◽  
Two Parameter

In the present work, for the description of grain coarsening, a probabilistic and a deterministic 2D cellular automaton simulation setup were developed. The results of the simulation have been validated by solution annealing experiments of austenitic stainless steel 304L (Fe-18Cr-8Ni) at different temperatures and times. Both cellular automata models show an excellent correlation between the experimental determined data and grain growth kinetics based upon considerations of temperature and second phase particles. Additionally, a two parameter approach of the probabilistic model was implemented, resulting in determining the grain sizes limiting normal and abnormal grains and accurate description of grain growth.

Sign in / Sign up

Export Citation Format

Share Document