scholarly journals Crack growth monitoring in corrosion-fatigue tests using back face strain measurement technique

2018 ◽  
Vol 13 ◽  
pp. 261-266
Author(s):  
Ali Mehmanparast ◽  
Pietro Albani ◽  
Victor Igwemezie
Keyword(s):  
Crack Growth ◽  
Corrosion Fatigue ◽  
Measurement Technique ◽  
Strain Measurement ◽  
Fatigue Tests ◽  
Growth Monitoring ◽  
Back Face

Experimental Evaluation of the Markl Fatigue Methods and ASME Piping Stress Intensification Factors: Part II

2014 ◽  
Author(s):  
Chris Hinnant ◽  
Tony Paulin ◽  
Charles Becht ◽  
Charles Becht ◽  
William Santiago Lock
Keyword(s):  
Crack Growth ◽  
Fatigue Test ◽  
Research Group ◽  
Experimental Evaluation ◽  
Fatigue Curve ◽  
Fatigue Tests ◽  
Growth Monitoring ◽  
Straight Pipe ◽  
Test Procedures ◽  
Failure Data

Part 1 of this paper was presented by Mr. Chris Hinnant at the 2008 PVP Conference in Chicago. Since 2008 additional fatigue test data has become available to the Paulin Research Group (PRG) which includes tests on unreinforced fabricated tees intended to support the fatigue curve approach established in the 2008 paper, and twenty-five additional straight pipe cantilever fatigue tests on carbon, stainless, duplex, CuNi, P91, X42 and X65 materials. These more recent experimental results confirm the fatigue slope recommended for cantilevers in the 2008 paper, but suggest that the original Markl slope may be more suited for some configurations of branch connections. Comparisons of the B31 Code allowable with failure data, tests, reviews of ratcheting behavior in pipe systems, and crack growth monitoring help draw conclusions about design equations in the B31 Codes and fatigue test procedures.

Crack Detection and Monitoring Crack Growth in Fastener Holes Using the DMI Optical SR-2 Strain Measurement Technology

2007 ◽  
Author(s):  
William F. Ranson ◽  
Reginald I. Vachon ◽  
Gregory L. Hovis ◽  
Jerrell A. Nardiello ◽  
Robert D. Fidnarick ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Crack Growth ◽  
Strain Measurement ◽  
Crack Detection ◽  
Measurement Technology ◽  
Growth Monitoring ◽  
Strain Gages ◽  
Strain Measurements ◽  
Shear Strains

Results are presented for crack initiation detection and crack growth monitoring using DMI SR-1 Strain Gages and DMI SR-2 Reader in two Northrop Grumman aluminum test coupons subjected to cyclic loading. Results demonstrate the utility of the technology to detect cracks and crack growth in holes. The DMI SR-1 strain gage is applied so that it frames the hole in the test coupon. This results in strain measurements at tangents to hole and associated shear strains. A differential strain reading between gage lengths on parallel and opposing sides of a hole, resulting from discontinuities in the material surrounding a hole, indicates crack initiation and as the crack grows the differential reading increases.

The Effect of Corrosion Inhibitors on Environmental Fatigue Crack Growth in Al-Zn-Mg-Cu

2014 ◽  
Vol 891-892 ◽  
pp. 230-235
Author(s):  
Sarah E. Galyon Dorman
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Corrosion Inhibitors ◽  
Corrosion Damage ◽  
The United States ◽  
Polymer Coatings ◽  
Fatigue Tests ◽  
Corrosion Prevention

Corrosion fatigue is an area of concern for the United States Air Force (USAF) and other Department of Defense (DoD) organizations. Often DoD corrosion prevention systems include chromate containing coatings, typically in the form of chromate conversion coatings and polymer primers. Chromate has been used successfully for many years within the DoD to prevent corrosion damage. However the environmental and personnel risks associated with chromate coatings have caused the USAF to pursue non-chromate containing corrosion prevention coatings [1]. To fully quantify chromate replacement coatings, an understanding of the effects that chromate has on corrosion fatigue crack growth rates must be fully characterized. Some researchers have shown that high levels of chromate added to 0.6 M NaCl full immersion corrosion fatigue tests on 7xxx series aluminum alloys slow the fatigue crack growth rate substantially [2,3]. The limitation of that research was that the amount of chromate present in the test solution environment was not connected to expected leach rates of chromate from polymeric coatings and a high solubility salt was used. The majority of DoD assets are protected from corrosion by polymer coatings loaded with corrosion inhibitors. For these coatings to slow fatigue crack propagation the corrosion inhibitors must become mobile as a consequence of hydration of the polymer coating matrix. Based on this mechanism of corrosion inhibitor release, the examination of atmospheric corrosion fatigue becomes important to help understand how inhibitors work in real world situations with hydrated salt layers rather than only fully immersed solutions.

Fracture Behavior of Ceramics Used in Multilayer Capacitors

1986 ◽  
Vol 72 ◽  
Author(s):  
Theresa L. Baker ◽  
Stephen W. Freiman
Keyword(s):  
Crack Growth ◽  
Fracture Behavior ◽  
Ceramic Materials ◽  
Fatigue Tests ◽  
Internal Stresses ◽  
Crack Growth Behavior ◽  
Multilayer Capacitors ◽  
Materials Used ◽  
Aging Phenomena

AbstractThis study involved the determination of the effects of composition and microstructure on the fracture toughness and susceptibility to environmentally enhanced crack growth of several ceramic materials used in multilayer capacitors. Indentation-fracture procedures were used to measure KIC as well as to assess the possible effects of internal stresses on the fracture behavior of these materials and to correlate dielectric aging phenomena with strength. The environmentally enhanced crack growth behavior of these materials was determined by conducting dynamic fatigue tests in water.

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