An Experimental Investigation of Fracture Criteria for Combined Extension and Bending

1969 ◽  
Vol 91 (4) ◽  
pp. 841-849 ◽  
Author(s):  
R. H. Wynn ◽  
C. W. Smith
Keyword(s):  
Experimental Investigation ◽  
Lower Bound ◽  
Crack Closure ◽  
Crack Extension ◽  
Fracture Criterion ◽  
Fracture Criteria ◽  
Cylindrical Bending ◽  
Cracked Plates

Experiments were performed on cracked plates loaded in combined extension and approximately cylindrical bending. A fracture criterion was developed from the Sih-Hartranft bending theory, which, when modified to account for precatastrophic crack extension, agreed well with the experiments in regions where the crack remained open at fracture and appeared to provide a lower bound in the region where crack closure occurred.

An Experimental Investigation of the Efficacy of Lawyers' Letters

2002 ◽  
Vol 21 (1) ◽  
pp. 79-93 ◽  
Author(s):  
Jack L. Krogstad ◽  
Mark H. Taylor ◽  
Maribeth J. Stock
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Lower Bound ◽  
Financial Statements ◽  
Law Students ◽  
Potential Loss

This experimental study investigates the efficacy of lawyers' letters in providing auditors with corroborating evidence about litigation contingencies. Fifty second- and third-year law students indicate their willingness to provide auditors with estimates of the likelihoods of unfavorable outcomes and potential damages for two realistic litigation cases. The findings indicate that (1) the potential loss of attorney-client privilege and (2) likelihoods of unfavorable litigation outcomes that approach auditors' lower bound for accrual both may inhibit lawyers' responses to auditors. Overall, these findings raise doubts about the efficacy of this widely utilized auditing procedure and lead to concerns about whether litigation contingencies and corresponding losses may be underreported in financial statements.

Prediction of Burst Pressure in Multistage Tube Hydroforming of Aerospace Alloys

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
M. Saboori ◽  
J. Gholipour ◽  
H. Champliaud ◽  
P. Wanjara ◽  
A. Gakwaya ◽  
...  
Keyword(s):  
Fracture Criterion ◽  
Tube Hydroforming ◽  
Burst Pressure ◽  
Forming Limit ◽  
Fracture Criteria ◽  
Material Models ◽  
Aerospace Alloys ◽  
Simulation Results ◽  
Experimental Trials ◽  
Internal Pressures

Bursting, an irreversible failure in tube hydroforming (THF), results mainly from the local plastic instabilities that occur when the biaxial stresses imparted during the process exceed the forming limit strains of the material. To predict the burst pressure, Oyan's and Brozzo's decoupled ductile fracture criteria (DFC) were implemented as user material models in a dynamic nonlinear commercial 3D finite-element (FE) software, ls-dyna. THF of a round to V-shape was selected as a generic representative of an aerospace component for the FE simulations and experimental trials. To validate the simulation results, THF experiments up to bursting were carried out using Inconel 718 (IN 718) tubes with a thickness of 0.9 mm to measure the internal pressures during the process. When comparing the experimental and simulation results, the burst pressure predicated based on Oyane's decoupled damage criterion was found to agree better with the measured data for IN 718 than Brozzo's fracture criterion.

Stable Crack Extension through AISI 4340 Steel: Experimental Investigation

2004 ◽  
Vol 261-263 ◽  
pp. 207-212 ◽  
Author(s):  
Abdel-Hamid I. Mourad ◽  
M.G. Alghafri ◽  
O.A. Abu Zeid
Keyword(s):  
Experimental Investigation ◽  
Crack Extension ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Aisi 4340

Behavior of Short Fatigue Crack at Notch Root

2011 ◽  
Vol 465 ◽  
pp. 515-518 ◽  
Author(s):  
Koshiro Mizobe ◽  
Masanobu Kubota ◽  
Yoshiyuki Kondo
Keyword(s):  
Crack Closure ◽  
Crack Extension ◽  
Notch Root ◽  
Crack Opening ◽  
Stable Condition ◽  
Fatigue Tests ◽  
Short Crack ◽  
Stress Intensity Factor Range ◽  
Root Radius ◽  
Wide Range

It has been recognized that the threshold stress intensity factor range Kth of a short crack is lower than that of a long crack. The short crack behavior in plain specimen has been studied by many researchers. However, the behavior of a short crack at the root of a long notch is not yet clear. The crack closure behavior is considered to be affected by the constraint at notch root and it is dependent on the length and the root radius of notch. In this study, fatigue tests on specimens with short pre-crack at long notch were done and the difference in crack closure behavior was studied. As a result, short crack effect appeared in any notch root radius. In a sharp notch, the crack opening point easily reached its stable condition after a small amount of crack extension. On the contrary in a dull notch, the opening point was lower than the stable condition and consequently short crack effect lasted in relatively wide range of crack extension. The small crack effect of notched specimen was discussed based on crack closure behavior.

Analysis and Study of Damage of Forging Cracks

2011 ◽  
Vol 189-193 ◽  
pp. 2735-2741 ◽  
Author(s):  
Xing Wang Duan ◽  
Jian Sheng Liu ◽  
Xiu Zhi Zhang ◽  
Xiao Dong Zhao
Keyword(s):  
Ductile Fracture ◽  
Damage Mechanics ◽  
Fracture Criterion ◽  
Future Research ◽  
Fracture Parameter ◽  
Fracture Criteria ◽  
Existing Problems ◽  
Ductile Fracture Criteria ◽  
Mesoscopic Models ◽  
Scope Of Application

This paper dealt with the outstanding problems which were forging cracks existing in the process of forging.The forming reasons of forging cracks were analyzed. From the perspective of damage mechanics, the conventional mesoscopic models and fracture criteria of ductile metal material damage were introduced. The problems in recent research of forging cracks were pointed out. Some corresponding suggestions for the future research of forging carcks were put forward based on the existing problems. The existed ductile fracture criteria have only predicted the damage of specific process yet ,while the diversities of metal forming processes require ductile fracture criterion to have wide scope of application,so,for reason given above,the emphasis is placed on the necessity of establishing new ductile fracture criteria and fracture parameter library with the method of combination of theory and experiment and numerical simulation.

scholarly journals Using DEFORM Software for Determination of Parameters for Two Fracture Criteria on DIN 34CrNiMo6

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 445
Author(s):  
Ivana Poláková ◽  
Michal Zemko ◽  
Martin Rund ◽  
Ján Džugan
Keyword(s):  
Fracture Criterion ◽  
Damage Model ◽  
Material Model ◽  
Mechanical Tests ◽  
Fracture Criteria ◽  
Stress States ◽  
Determination Of Parameters ◽  
Accuracy Of Prediction ◽  
Good Agreement

The aim of this study was to calibrate a material model with two fracture criteria that is available in the DEFORM software on DIN 34CrNiMo6. The purpose is to propose a type of simple test that will be sufficient for the determination of damage parameters. The influence of the quantity of mechanical tests on the accuracy of the fracture criterion was explored. This approach was validated using several tests and simulations of damage in a tube and a round bar. These tests are used in engineering applications for their ease of manufacturing and their strong ability to fracture. The prediction of the time and location of the failure was based on the parameters of the relevant damage model. Normalized Cockroft-Latham and Oyane criteria were explored. The validation involved comparing the results of numerical simulation against the test data. The accuracy of prediction of fracture for various stress states using the criteria was evaluated. Both fracture criteria showed good agreement in terms of the fracture locus, but the Oyane criterion proved more suitable for cases covering larger triaxiality ranges.

Investigation of Warm Prestress for the Case of Small ΔT During a Reactor Loss-of-Coolant Accident

1979 ◽  
Vol 101 (4) ◽  
pp. 298-304 ◽  
Author(s):  
F. J. Loss ◽  
R. A. Gray ◽  
J. R. Hawthorne
Keyword(s):  
Experimental Investigation ◽  
Statistical Analysis ◽  
Vessel Wall ◽  
Crack Extension ◽  
Crack Tip ◽  
Material Behavior ◽  
Virgin Material ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Failure Temperature

An experimental investigation was conducted to characterize the benefits of warm prestress (WPS) in limiting crack extension in the wall of a nuclear vessel during a LOCA-ECCS. The present research emphasized material behavior under conditions of a small ΔT between the temperature of WPS and the failure temperature as might occur during a LOCA. The results have demonstrated that fracture will not occur during a simultaneous unloading and cooling of the crack-tip region following WPS even though the critical KIc of the virgin material is achieved. Based on a statistical analysis, it is concluded that WPS produces an “effective” elevation in KIc; furthermore, it is suggested that this elevation will limit crack extension in the vessel wall so as to retain the coolant.

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