Composite Structures, Volume 97, March 2013, Pages 76-83.
John Montesano, Zouheir Fawaz, Habiba Bougherara.
Dept. of Aerospace Eng., Ryerson University, 350 Victoria St., Toronto, Canada M5B 2K3 and
Dept. of Mechanical and Industrial Eng., Ryerson University, 350 Victoria St., Toronto, Canada M5B 2K3.
Thermography was used to investigate the fatigue behavior of a braided carbon fiber polymeric composite plate. A thermographic approach, originally developed in an earlier study for metallic alloys, was employed to rapidly determine the composite high cycle fatigue strength. The method yielded a fatigue threshold value that was in excellent agreement with that obtained through a conventional experimental test program. The damage mechanisms responsible for the increased heat dissipation and ultimately failure were identified, which provides support for the existence of a fatigue threshold for this material. An extension of the thermographic technique to rapidly determine the entire fatigue stress-life curve for the composite plate provided a direct correlation to the stress-life curve determined through a conventional test program. Energy dissipation was also used as an indicator to determine the high cycle fatigue strength, providing support for the thermographic approach. A relationship between the dissipated heat, the intrinsic energy dissipation and the number of cycles to failure has been clearly established.
“A novel infrared thermographic technique was used to rapidly determine the fatigue strength and the entire fatigue stress-life curve for carbon fiber-reinforced polymeric composite materials. The technique, which was originally developed for metallic alloys, measures heat dissipation caused by the material intrinsic energy dissipation, which is a result of local damage progression caused by cyclic loading. The results of this study provide strong support for the application of this technique, and may lead to a reduction in certification costs for composite materials in the industry due to a reduction in the required experimental characterization which is a significant benefit.”
Experimental setup employing the infrared camera, with an image of a captured thermograph