Brittle Fracture in Heavy Section Welded T-Joints: Correlation Between Stress Intensity at Fracture and Small-Specimen Toughness Tests

1990 ◽  
Vol 112 (1) ◽  
pp. 53-57 ◽  
Author(s):  
W. R. Tyson ◽  
O. Vosikovsky ◽  
B. Faucher ◽  
D. J. Burns
Keyword(s):  
Stress Intensity ◽  
Residual Stresses ◽  
Fatigue Tests ◽  
Small Sample ◽  
Substantial Contribution ◽  
Test Results ◽  
T Joints ◽  
Heavy Section ◽  
Sample Test ◽  
Brittle Fractures

A fracture mechanics analysis has been made of brittle fractures encountered during a program of fatigue tests of welded plate T-joints. Fracture toughnesses are in reasonable agreement with small-sample test results, if the following factors are taken into account: a specimen size effect (with larger samples having lower toughness); existence of a substantial contribution to the stress intensity factor from residual stresses; and shakedown of residual stresses, with shakedown increasing with increasing applied stress.

Research on Reliability Assessment for the Armored Equipment Based on Multi-Source Information Fusion

2013 ◽  
Vol 760-762 ◽  
pp. 2091-2094
Author(s):  
Jian Du ◽  
Bao Jun Fei ◽  
Ying Liu ◽  
Guo Zheng Yao
Keyword(s):  
Field Test ◽  
Test Data ◽  
Information Fusion ◽  
Reliability Assessment ◽  
Small Sample ◽  
Test Results ◽  
Fuzzy Information ◽  
Source Information ◽  
Sample Test ◽  
Fusion Theory

In order to solve the problem of reliability evaluation for armored equipment, used Bayes fusion theory, combined with minimal amounts of reliability information on the field test, the paper fusioned reliability information of the same model for armored equipment, and completed the reliability assessment for a certain type of armored equipment. The test results show that the technology of multi-source information fusion can effectively solve the fusion problem of the prior fuzzy information and small sample test data, improve the accuracy of the reliability assessment, prove the feasibility and effectiveness for the multi-source information fusion in the armored equipment assessment.

Designing Sampling Plans to Detect Foreign Material in Bulk Lots of Shelled Peanut1

2008 ◽  
Vol 35 (2) ◽  
pp. 159-164 ◽  
Author(s):  
T. B. Whitaker ◽  
A. B. Slate ◽  
F. G. Giesbrecht
Keyword(s):  
Binomial Distribution ◽  
Small Sample ◽  
Sampling Plan ◽  
Test Results ◽  
Foreign Material ◽  
Sampling Plans ◽  
Sample Test ◽  
The Mean ◽  
Mean Variance ◽  
Food Manufacturer

Abstract When food manufacturers specify a maximum limit for the amount of foreign material (FM) in the lot, handlers estimate the true percent FM in a commercial lot by measuring FM in a small sample taken from the lot before shipment to a food manufacturer. Because of the uncertainty (variability) in FM among samples taken from the same lot, it is difficult to obtain a precise estimate of the true FM in the lot. The objectives of this study were to (1) measure the variability and FM distribution among sample test results when estimating the true lot proportion of FM in a lot of shelled peanuts, (2) compare the measured variability and FM distribution among sample test results to that predicted by the binomial distribution, (3) develop a computer model, based upon the binomial distribution, to evaluate the performance (buyer's risk and seller's risk) of sampling plan designs used to estimate FM in a bulk lot of shelled peanuts, and (4) demonstrate with the model the effect of increasing sample size to reduce misclassification of lots. Eighty-eight samples, 9 kg (20 lb) each, were selected at random from each of six commercial lots of shelled medium runner peanuts. The percent FM (PFM), based upon number of kernels was determined for each sample. The mean, variance, and distribution among the 88 sample test results were calculated for each of the six lots. Results indicated that the variance and distribution among the 88 sample test results are very similar to that predicted by the binomial distribution. The performance of various sampling plan designs was demonstrated using the binomial distribution.

DETERMINATION OF RESIDUAL STRESSES AND STRESS INTENSITY FACTORS BY REMOVING LOCAL MATERIAL

2017 ◽  
Vol 48 (4) ◽  
pp. 377-398
Author(s):  
Svyatoslav Igorevich Eleonskii ◽  
Igor Nikolaevich Odintsev ◽  
Vladimir Sergeevich Pisarev ◽  
Stanislav Mikhailovich Usov
Keyword(s):  
Stress Intensity ◽  
Residual Stresses ◽  
Stress Intensity Factors ◽  
Intensity Factors ◽  
Local Material

scholarly journals Hopkinson rod test results and constitutive description of TRIP780 steel resistance spot welding material

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 961-967
Author(s):  
Xiaomin Li ◽  
Jianrong Zhang
Keyword(s):  
Spot Welding ◽  
Steel Strip ◽  
Strain Curve ◽  
Test Machine ◽  
Strain Rates ◽  
Test Results ◽  
Welding Material ◽  
Static Tensile ◽  
Split Hopkinson ◽  
Brittle Fractures

Abstract A quasi-static tensile test was performed on a 1.4 mm-thick TRIP780 steel strip with welding points. An MTS810 material test machine was used in the test, and a Split Hopkinson tension bar device was used in performing impact stretch loading at different strain rates. The dynamic tensile stress–strain curve of the spot welding material with different strain rates was obtained through the finely designed Hopkinson rod test, and the strain rate dependence of a TRIP780 steel spot welding material was discussed. According to the dynamic constitutive equation of the TRIP780 steel spot welding material, the test results were numerically simulated, the constitutive description and test curves were compared, and the simulation results and test results were discussed and analyzed. The fractures of the test recovery specimen were scanned with the scanning electron microscope, and the fracture mechanism of the TRIP780 steel spot welding material was explored by observing the fractures. The surfaces of the fractures surface showed obvious cleavage river patterns, and the evolution process of microcracks was determined and used in characterizing brittle fractures in specimen spot welding sample subjected to dynamic stretch loading.

scholarly journals Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1083
Author(s):  
Christoph Breuner ◽  
Stefan Guth ◽  
Elias Gall ◽  
Radosław Swadźba ◽  
Jens Gibmeier ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Shot Peening ◽  
Elevated Temperatures ◽  
Stress Amplitude ◽  
Negative Impact ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Positive Effects ◽  
Isothermal Fatigue

One possibility to improve the fatigue life and strength of metallic materials is shot peening. However, at elevated temperatures, the induced residual stresses may relax. To investigate the influence of shot peening on high-temperature fatigue behavior, isothermal fatigue tests were conducted on shot-peened and untreated samples of gamma TiAl 48-2-2 at 750 °C in air. The shot-peened material was characterized using EBSD, microhardness, and residual stress analyses. Shot peening leads to a significant increase in surface hardness and high compressive residual stresses near the surface. Both effects may have a positive influence on lifetime. However, it also leads to surface notches and tensile residual stresses in the bulk material with a negative impact on cyclic lifetime. During fully reversed uniaxial tension-compression fatigue tests (R = −1) at a stress amplitude of 260 MPa, the positive effects dominate, and the fatigue lifetime increases. At a lower stress amplitude of 230 MPa, the negative effect of internal tensile residual stresses dominates, and the lifetime decreases. Shot peening leads to a transition from surface to volume crack initiation if the surface is not damaged by the shots.

scholarly journals Fecal viral DNA shedding following clinical panleukopenia virus infection in shelter kittens: a prospective, observational study

2021 ◽  
pp. 1098612X2110230
Author(s):  
Kyrsten J Janke ◽  
Linda S Jacobson ◽  
Jolene A Giacinti ◽  
J Scott Weese
Keyword(s):  
Small Sample Size ◽  
Point Of Care ◽  
Small Sample ◽  
Enteric Pathogens ◽  
Test Results ◽  
Viral Dna ◽  
Virus Shedding ◽  
Feline Panleukopenia Virus ◽  
Viral Shedding ◽  
Point Of Care Test

Objectives The aims of this study were to determine the magnitude and duration of fecal viral DNA shedding after diagnosis of feline panleukopenia (FP) in a group of shelter cats using quantitative real-time PCR (qPCR); to assess the utility of a negative point-of-care test or the resolution of diarrhea and systemic signs as proxy measures for qPCR positivity; and to investigate patterns of additional enteric pathogens in relation to feline panleukopenia viral shedding duration. Methods Feline panleukopenia virus (FPV) infection in clinically affected shelter cats was confirmed by a commercial qPCR test. Observations were made on days 0, 3, 7, 14 and 21 post-diagnosis. Fecal flotation, FPV qPCR and the canine parvovirus IDEXX SNAP Parvo ELISA (SNAP) test were performed on fecal samples. Results Forty cats and kittens with confirmed panleukopenia were initially enrolled. Sixteen kittens were sampled until day 14, and 12 were followed to day 21. Median DNA viral copy numbers fell below the diagnostic cut-off by day 7, with 13/16, 6/16, 1/16 and 0/12 testing PCR-positive on days 3, 7, 14 and 21, respectively. The SNAP test was positive in 12/16 kittens on day 0 and only 3/16 on day 3. SNAP test results, diarrhea and systemic signs were inconsistent in relation to qPCR positivity post-diagnosis. Additional enteric pathogens were common. The presence of additional pathogen types was suggestive of a longer PCR shedding duration, but this was not tested statistically owing to the small sample size. Conclusions and relevance These findings suggest that cats should be isolated for at least 14 days after a diagnosis of FP, but that release from isolation after this point is reasonable, in association with a multifaceted infection control strategy. The study findings did not support using SNAP test results, diarrhea or systemic signs as proxy measures for virus shedding.

A Reliability-Based Approach to Assess Fatigue Behaviour Based on Small Incomplete Data Sets

2008 ◽  
Vol 44-46 ◽  
pp. 871-878 ◽  
Author(s):  
Chu Yang Luo ◽  
Jun Jiang Xiong ◽  
R.A. Shenoi
Keyword(s):  
Incomplete Data ◽  
Standard Procedure ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Small Sample ◽  
Data Sets ◽  
Safe Life ◽  
A New Technique ◽  
And Performance

This paper outlines a new technique to address the paucity of data in determining fatigue life and performance based on reliability concepts. Two new randomized models are presented for estimating the safe life and pS-N curve, by using the standard procedure for statistical analysis and dealing with small sample numbers of incomplete data. The confidence level formulations for the safe and p-S-N curve are also given. The concepts are then applied for the determination of the safe life and p-S-N curve. Two sets of fatigue tests for the safe life and p-S-N curve are conducted to validate the presented method, demonstrating the practical use of the proposed technique.

scholarly journals Analysis of the Correlation between the Static and Fatigue Test Results of the Interlayer Bondings of Asphalt Layers

2016 ◽  
Vol 62 (1) ◽  
pp. 83-98 ◽  
Author(s):  
A. Szydło ◽  
K. Malicki
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Test Results ◽  
Static Tests ◽  
Bonding State ◽  
Road Pavement ◽  
The Future ◽  
Pavement Structure

Abstract The bonding state of the asphalt layers in a road pavement structure significantly affects its fatigue life. These bondings, therefore, require detailed tests and optimization. In this paper, the analyses of the correlation between the results of laboratory static tests and the results of fatigue tests of asphalt mixture interlayer bondings were performed. The existence of the relationships between selected parameters was confirmed. In the future, the results of these analyses may allow for assessment of interlayer bondings’ fatigue life based on the results of quick and relatively easy static tests.

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