Full-Field Measurements of Fracture Initiation and Crack Growth in Superelastic Nitinol

2009 ◽  
Vol 6 (2) ◽  
pp. JAI101874 ◽  
Author(s):  
Kenneth E. Perry ◽  
Paul E. Labossiere ◽  
Kenneth L. Jerina ◽  
Michael R. Mitchell ◽  
Terry O. Woods ◽  
...  
Keyword(s):  
Crack Growth ◽  
Field Measurements ◽  
Fracture Initiation ◽  
Full Field

Improved infrared temperature mapping of elastohydrodynamic contacts

2009 ◽  
Vol 223 (8) ◽  
pp. 1165-1177 ◽  
Author(s):  
T Reddyhoff ◽  
H A Spikes ◽  
A V Olver
Keyword(s):  
Effective Means ◽  
Field Measurements ◽  
Operating Conditions ◽  
Mapping Technique ◽  
Shear Stresses ◽  
Measured Temperature ◽  
Ir Camera ◽  
Full Field ◽  
Group I ◽  
Increased Sensitivity

An effective means of studying lubricant rheology within elastohydrodynamic contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. In the current work, the experimental approach initially developed by Sanborn and Winer and then by Spikes et al., has been advanced to include a high specification infrared (IR) camera and microscope. Besides the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions: namely lower loads, speeds, and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. These new possibilities have been used to investigate and compare the rheological properties of a range of lubricants: namely a group I and group II mineral oil, a polyalphaolephin (group IV), the traction fluid Santotrac 50, and 5P4E, a five-ring polyphenyl-ether. As expected, contact temperatures increased with lubricant refinement, for the mineral base oils tested. Using moving heat source theory, the measured temperature distributions were converted into maps showing rate of heat input into each surface, from which shear stresses were calculated. The technique could therefore be validated by integrating these shear stress maps, and comparing them with traction values obtained by direct measurement. Generally there was good agreement between the two approaches, with the only significant differences occurring for 5P4E, where the traction that was deduced from the temperature over-predicted the traction by roughly 15 per cent. Of the lubricants tested, Santotrac 50 showed the highest average traction over the contact; however, 5P4E showed the highest maximum traction. This observation is only possible using the IR mapping technique, and is obscured when measuring the traction directly. Both techniques showed the effect of shear heating causing a reduction in traction.

In-situ Full Field Measurements During Inter-Facial Debonding in Single Fiber Composite Under Transverse Load

2018 ◽  
Vol 58 (9) ◽  
pp. 1451-1467 ◽  
Author(s):  
I. Tabiai ◽  
R. Delorme ◽  
D. Therriault ◽  
M. Levesque
Keyword(s):  
Fiber Composite ◽  
Field Measurements ◽  
Single Fiber ◽  
Transverse Load ◽  
Full Field

SCC Management and Integrity Planning in a Gas Pipeline

2006 ◽  
Author(s):  
David Katz ◽  
Sergio Limon ◽  
Ming Gao ◽  
Rick McNealy ◽  
Ravi Krishnamurthy ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Detection ◽  
Management Strategies ◽  
Field Measurements ◽  
Gas Pipeline ◽  
Oil Pipeline ◽  
Integrity Management ◽  
Crack Growth Rates

Stress Corrosion Cracking (SCC) is a major integrity management concern for many gas and oil pipeline operators. Predictive models for Stress Corrosion Crack growth were developed using laboratory test data from the mid 1970’s, and limited inspection data and excavation measurements from the early 1990’s. Extensive efforts continue to be made to develop strategies for a better management of the SCC problem. In this paper, a study of crack growth rates was conducted on the Williams 16-inch gas pipeline using data from two consecutive in-line crack detection tool runs and direct field measurements. Findings from this study provide a direct measurement of crack growth rates for ILI crack features with depths ranging from 12.5%wt to 40%wt. Future integrity of the pipeline was assessed. The integrity management strategies could be further refined using the calculated crack growth rate, field excavation data and fracture mechanics based API 579 FAD approach.

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