The Effect of Test Frequency and Geometric Asperities on Crack Closure Mechanisms

2009 ◽  
pp. 112-112-9
Author(s):  
JK Sheth ◽  
WW Gerberich
Keyword(s):  
Crack Closure ◽  
Test Frequency

Calculating Energy Release Rate as a Function of Crack Length Using a Multiple-Step Crack Closure Technique in Tire Finite Element Models

2018 ◽  
Vol 46 (3) ◽  
pp. 130-152
Author(s):  
Dennis S. Kelliher
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Crack Length ◽  
Energy Release ◽  
Crack Closure ◽  
Release Rate ◽  
Fatigue Behavior ◽  
Three Dimensions ◽  
Quantitative Prediction ◽  
Closure Technique

ABSTRACT When performing predictive durability analyses on tires using finite element methods, it is generally recognized that energy release rate (ERR) is the best measure by which to characterize the fatigue behavior of rubber. By addressing actual cracks in a simulation geometry, ERR provides a more appropriate durability criterion than the strain energy density (SED) of geometries without cracks. If determined as a function of crack length and loading history, and augmented with material crack growth properties, ERR allows for a quantitative prediction of fatigue life. Complications arise, however, from extra steps required to implement the calculation of ERR within the analysis process. This article presents an overview and some details of a method to perform such analyses. The method involves a preprocessing step that automates the creation of a ribbon crack within an axisymmetric-geometry finite element model at a predetermined location. After inflating and expanding to three dimensions to fully load the tire against a surface, full ribbon sections of the crack are then incrementally closed through multiple solution steps, finally achieving complete closure. A postprocessing step is developed to determine ERR as a function of crack length from this enforced crack closure technique. This includes an innovative approach to calculating ERR as the crack length approaches zero.

A comparative study of fatigue crack closure

1977 ◽  
Author(s):  
J. RUEPING ◽  
B. HILLBERRY ◽  
S. METTLER ◽  
W. STEVENSON
Keyword(s):  
Fatigue Crack ◽  
Comparative Study ◽  
Crack Closure ◽  
Fatigue Crack Closure

scholarly journals Test Frequency Optimization Using Single Factor ANOVA for Capacitive Oil Palm Fruit Ripeness Sensor

2020 ◽  
Vol 932 ◽  
pp. 012073
Author(s):  
Abdul Hallis Abdul Aziz ◽  
Siti Azura Abuzar ◽  
Mas Elyna Azol ◽  
Nurol Husna Che Rose ◽  
Rohaslida Liyana Mohmad
Keyword(s):  
Oil Palm ◽  
Test Frequency ◽  
Single Factor ◽  
Palm Fruit ◽  
Frequency Optimization

scholarly journals Modeling Effectiveness of Testing Strategies to Prevent Coronavirus Disease 2019 (COVID-19) in Nursing Homes—United States, 2020

2021 ◽  
Author(s):  
Isaac See ◽  
Prabasaj Paul ◽  
Rachel B Slayton ◽  
Molly K Steele ◽  
Matthew J Stuckey ◽  
...  
Keyword(s):  
Nursing Homes ◽  
Infection Control ◽  
Relative Sensitivity ◽  
Turnaround Time ◽  
Potential Effect ◽  
Infection Control Practice ◽  
Healthcare Personnel ◽  
Test Frequency ◽  
Testing Strategies ◽  
Serial Testing

Abstract Background Identifying asymptomatic individuals early through serial testing is recommended to control coronavirus disease 2019 (COVID-19) in nursing homes, both in response to an outbreak (“outbreak testing” of residents and healthcare personnel) and in facilities without outbreaks (“nonoutbreak testing” of healthcare personnel). The effectiveness of outbreak testing and isolation with or without nonoutbreak testing was evaluated. Methods Using published SARS-CoV-2 transmission parameters, the fraction of SARS-CoV-2 transmissions prevented through serial testing (weekly, every 3 days, or daily) and isolation of asymptomatic persons compared with symptom-based testing and isolation was evaluated through mathematical modeling using a Reed-Frost model to estimate the percentage of cases prevented (ie, “effectiveness”) through either outbreak testing alone or outbreak plus nonoutbreak testing. The potential effect of simultaneous decreases (by 10%) in the effectiveness of isolating infected individuals when instituting testing strategies was also evaluated. Results Modeling suggests that outbreak testing could prevent 54% (weekly testing with 48-hour test turnaround) to 92% (daily testing with immediate results and 50% relative sensitivity) of SARS-CoV-2 infections. Adding nonoutbreak testing could prevent up to an additional 8% of SARS-CoV-2 infections (depending on test frequency and turnaround time). However, added benefits of nonoutbreak testing were mostly negated if accompanied by decreases in infection control practice. Conclusions When combined with high-quality infection control practices, outbreak testing could be an effective approach to preventing COVID-19 in nursing homes, particularly if optimized through increased test frequency and use of tests with rapid turnaround.

Performances of Low SNR DVB-RCS Modem Suing Test Frequency Algorithm

2006 ◽  
Author(s):  
C. Bazile ◽  
J.-F. Delaune ◽  
X. Deplancq ◽  
J. Eudes ◽  
G. Lesthievent ◽  
...  
Keyword(s):  
Test Frequency ◽  
Low Snr
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