scholarly journals Using Tolerance Bounds for Estimation of Characteristic Fatigue Curves for Composites with Confidence

Safety ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
Knut O. Ronold ◽  
Andreas T. Echtermeyer
Keyword(s):  
Composite Laminates ◽  
Probability Distributions ◽  
Fatigue Curve ◽  
Statistical Procedure ◽  
Test Results ◽  
Stress Range ◽  
Lower Tail ◽  
Curve Estimation ◽  
Dependent Variables ◽  
Stress Cycles

Fatigue S–N curves provide the number of stress cycles that result in fatigue failure at stress range S and need to be measured for new engineering materials where data are not as readily available as they are for well-characterized and widely used metals. A simple statistical method for the estimation of characteristic fatigue curves defined in terms of lower-tail quantiles in probability distributions of dependent variables is presented. The method allows for the estimation of such quantiles with a specified confidence level, taking account of the statistical uncertainty caused by a limited number of experimental test results available for the estimation. The traditional general approach for estimating characteristic S–N curves by tolerance bounds is complicated and is not much used by engineers. The presented approach allows for calculating the curves with a simple spreadsheet. The only requirement is that the experimental log S data for the S–N curve are fairly uniformly distributed over a finite logS interval, where S denotes the stress range. Experimental fatigue test programs are often designed such that test data fulfil this assumption. Although developed with fatigue of composite laminates in mind, the presented statistical procedure and the presented associated charts are valid for fatigue curve estimation for any material.

scholarly journals The Influence Of Climate Leadership, Organizational Behavior And Discipline Work Against The Performance Of Members Of The Police Of The Republic Of Indonesia Sabhara Units Of The Resort City Of Padang

2020 ◽  
Author(s):  
Anton Kusuma Jaya
Keyword(s):  
Organizational Behavior ◽  
Organizational Climate ◽  
Leadership Behavior ◽  
High Reliability ◽  
Descriptive Analysis ◽  
Test Results ◽  
Know How ◽  
Dependent Variables ◽  
Independent Variable ◽  
The Republic

The purpose of this research was: 1) to explain whether there was a Climate of leadership, Organizational Behavior Disciplines Work on performance of Member unit of the police of the Republic of Indonesia Sabhara Resort City of Padang and 2) measure the magnitude of the influence of Climate leadership, Organizational Behavior Disciplines Work on performance of Member unit of the police of the Republic of Indonesia Sabhara Resort City of Padang.This research was conducted in February-March 2016 in Sabhara units of the police force of the Republic Indonesia's resort city of Padang.The sample used in this study as many as 32 respondents using a sampling of saturated. As for the independent variable of climate leadership, Organizational Behavior Disciplines work, whereas the variable dependennya is the performance of members of the police. This research is explanatory research.The method of data collection is the kuestioner. Data analysis techniques using Descriptive Analysis and Inferensial Analysis.To know how the variables are independent of the dependent variable are partial, used test t. Whereas to know the influence of the variables are independent of the dependent variables simultaneously, use the test F. Assumptions used in the test of validity is if R-female > R-table item is declared valid. R-count shown in the table above, from individual items suggests that R-female > R-table so that the items are declared valid.Based on a test of the validity of the instrument of climate leadership, Organizational Behavior and discipline Work against Performance known to all items stated valid and reliability test results show that the instruments have a high reliability and meets the criteria of a good instrument requirements, i.e., valid and reliability.Free Leadership Behavior variables (X 1) effect significantly to performance (Y), Organizational Climate (X 2) a significant effect on performance, variable (Y) Discipline work (X 3) a significant effect on performance (Y). Hypothesis (H1) until the Union (H3) third.

Development of New Design Fatigue Curves in Japan: Discussion of Best-Fit Curves Based on Large-Scale Fatigue Tests of Carbon and Low-Alloy Steel Plates

2018 ◽  
Author(s):  
Masahiro Takanashi ◽  
Hiroshi Ueda ◽  
Toshiyuki Saito ◽  
Takuya Ogawa ◽  
Kentaro Hayashi
Keyword(s):  
Large Scale ◽  
Phase 1 ◽  
Fatigue Curve ◽  
Fatigue Tests ◽  
Steel Plates ◽  
Phase 2 ◽  
Test Results ◽  
Low Alloy Steel ◽  
Best Fit ◽  
Deep Crack

In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees were organized under the Atomic Energy Research Committee in the Japan Welding Engineering Society and have proposed new design fatigue curves for carbon, low-alloy, and austenitic stainless steels. To confirm the validity of the proposed design fatigue curves, a Japanese utility collaborative project was launched. In this project, fatigue tests were conducted on large-scale and small-sized specimens, and the test data were provided to the DFC Phase 2 subcommittee. This paper discusses the best-fit curves proposed by the DFC Phase 1 subcommittee, focusing on the results of large-scale fatigue tests for carbon steel and low-alloy steel plates. The fatigue test results for large-scale specimens were compared with the best-fit curve proposed by the DFC Phase 1 subcommittee. This comparison revealed that the fatigue lives given by the proposed curves correspond to those of approximately 1.5–4.0-mm-deep crack initiation in large-scale specimens. In this program, fatigue tests with a mean strain were also carried out on large-scale specimens. These tests found that the fatigue lives were almost equivalent to those of approximately 4.4–7.0-mm-deep crack initiation in large-scale specimens. In determining a design fatigue curve, strain-controlled tests are usually performed on small-sized specimens, and the fatigue life is then defined by the 25% load drop. It is reported that the cracks reach nearly 3–4-mm depth under those 25% drop cycles. The test results confirm that the fatigue lives of large-scale specimens agree with those given by the best-fit curve for carbon and low-alloy steels, and no remarkable size effects exist for the crack depths compared in this study.

MANOVA: A Procedure Whose Time Has Passed?

2019 ◽  
Vol 64 (1) ◽  
pp. 56-60 ◽  
Author(s):  
Francis L. Huang
Keyword(s):  
Multivariate Analysis ◽  
Analysis Of Variance ◽  
Research Question ◽  
Statistical Procedure ◽  
Large Majority ◽  
Multivariate Analysis Of Variance ◽  
Dependent Variables ◽  
Research Questions ◽  
Post Hoc ◽  
Published Research

Multivariate analysis of variance (MANOVA) is a statistical procedure commonly used in fields such as education and psychology. However, MANOVA’s popularity may actually be for the wrong reasons. The large majority of published research using MANOVA focus on univariate research questions rather than on the multivariate questions that MANOVA is said to specifically address. Given the more complicated and limited nature of interpreting MANOVA effects (which researchers may not actually be interested in given the actual post hoc strategies employed) and that various flexible and well-known statistical alternatives are available, I suggest that researchers consult these better known, robust, and flexible procedures instead, given the proper match with the research question of interest. Just because a researcher has multiple dependent variables of interest does not mean that a MANOVA should be used at all.

Repair of Composite Laminates-I: Test Results

1998 ◽  
Vol 32 (11) ◽  
pp. 1036-1074 ◽  
Author(s):  
Sung-Hoon Ahn ◽  
George S. Springer
Keyword(s):  
Composite Laminates ◽  
Test Results

Experimental Study on Interlaminar Shear Properties of T300/BMI Composite Laminates

2013 ◽  
Vol 718-720 ◽  
pp. 157-161
Author(s):  
Zong Hong Xie ◽  
Hai Han Liu ◽  
Jian Zhao ◽  
Jun Feng Sun ◽  
Fei Peng ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Shear Test ◽  
Failure Modes ◽  
Shear Failure ◽  
Test Method ◽  
Test Results ◽  
Shear Properties ◽  
Test Fixture ◽  
Iosipescu Shear Test ◽  
Interlaminar Shear

A modified test fixture to measure the shear properties of composite laminates was designed and manufactured based upon Iosipescu shear test method. Tests on interlaminar shear propertis of T300/BMI composite laminates were conducted according to ASTM D 5379 test standard. Interlaminar shear stress/strain curves and shear failure modes were obtained. The test results showed that the modified shear test fixture and test method were effective in measuring the shear properties of composite laminates.

MATHEMATICAL MODELLING OF FORECASTING THE RESULTS OF KNOWLEDGE TESTING / ŽINIŲ TIKRINIMO REZULTATŲ PROGNOZĖS MATEMATINIS MODELIAVIMAS

2008 ◽  
Vol 14 (3) ◽  
pp. 388-401 ◽  
Author(s):  
Aleksandras Krylovas ◽  
Natalja Kosareva
Keyword(s):  
Item Response ◽  
Logistic Model ◽  
Probability Distributions ◽  
Characteristic Functions ◽  
Test Results ◽  
Test Items ◽  
Mathematics Test ◽  
Level Method ◽  
Selection For ◽  
Selection Of

In this paper a mathematical model for obtaining probability distribution of the knowledge testing results is proposed. Differences and similarities of this model and Item Response Theory (IRT) logistic model are discussed. Probability distributions of 10 items test results for low, middle and high ability populations selecting characteristic functions of the various difficulty items combinations are obtained. Entropy function values for these items combinations are counted. These results enable to formulate recomendations for test items selection for various testing groups according to their attainment level. Method of selection of a suitable item characteristic function based on the Kolmogorov compatibility test, is proposed. This method is illustrated by applying it to a discreet mathematics test item. Santrauka Straipsnyje pasiūlytas matematinis modelis žinių tikrinimo rezultatų tikimybiniam skirstiniui gauti. Aptarti šio modelio ir užduočių sprendimo teorijos (IRT) logistinio modelio skirtumai ir panašumai. Išnagrinėti 10 klausimų testo rezultatų tikimybiniai skirstiniai silpnai, vidutinei ir stipriai testuojamųjų populiacijoms parenkant įvairias testo klausimų sunkumo funkcijų kombinacijas. Apskaičiuotos entropijos funkcijos reikšmės. Gauti rezultatai leidžia formuluoti rekomendacijas testo klausimams parinkti skirtingoms testuojamųjų grupėms pagal jų žinių lygį. Pasiūlytas tinkamiausios klausimo charakteristinės funkcijos parinkimo būdas, grindžiamas Kolmogorovo kriterijumi. Ši procedūra iliustruojama taikant ją konkrečiam diskrečiosios matematikos testo klausimui.

Static and fatigue analysis of notched composite laminates

2016 ◽  
Vol 50 (30) ◽  
pp. 4307-4317 ◽  
Author(s):  
Christos Kassapoglou
Keyword(s):  
Composite Laminates ◽  
Fatigue Loading ◽  
Test Results ◽  
Characteristic Distance ◽  
Hole Edge ◽  
Additional Testing ◽  
Number Of Cycles ◽  
Static Failure ◽  
Cycles To Failure ◽  
Good Agreement

An approach to predict static and fatigue failure of composite laminates with holes is presented. Static failure is predicted when the stress averaged over a characteristic distance is equal to the un-notched failure strength. This averaging distance is determined analytically without the use of additional testing or need for extra material parameters. During fatigue loading, the size of the damage region next to the hole is calculated and the strains at the hole edge are determined. These are used along with the stresses just outside the damage region to determine whether failure starts at the hole edge or the edge of the damage region extends. A previously developed fatigue model based on the cycle-by-cycle probability of failure is used to calculate the number of cycles needed for the residual strain at hole edge or the residual strength at the edge of the damage region to fall below the corresponding applied values. The procedure is repeated until laminate failure. The method is also used to predict cycles to failure for impacted specimens. The predictions are in very good agreement with test results.

On Effective Stress Range Factor in Fatigue

1980 ◽  
Vol 102 (1) ◽  
pp. 147-152 ◽  
Author(s):  
K. M. Lal ◽  
S. B. L. Garg ◽  
I. Le May
Keyword(s):  
Fatigue Crack ◽  
Crack Closure ◽  
Effective Stress ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Simplified Model ◽  
Strain Hardening Exponent ◽  
Stress Range ◽  
Stress Cycles ◽  
Good Agreement

A detailed analysis of crack closure during fatigue crack propagation has been made using a simplified model. In addition, experimental work has been conducted using eddy current methods to determine crack closure. It was found that the effective stress range factor, U, depends on the applied stress range, stress ratio, yield strength and strain hardening exponent of the material, and that its value stabilizes in about 10 stress cycles for constant stress amplitude loading. Experimental and predicted results were seen to be in good agreement.

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