Strain gage based determination of stress intensity factors in cracked orthotropic materials

No Thumbnail Available
Journal Title
Journal ISSN
Volume Title
In the last few decades considerable attentions have been paid by researchers in extending the concepts of LEFM pertaining to homogenous, isotropic materials to orthotropic composite materials. Stress intensity factor (SIF) being an important parameter in LEFM, accurate determination of SIF of cracked orthotropic materials have been an important area of research. Existence of cracks and notches in laminated composites warrants that SIFs are known to assess whether such cracks grow further during service leading to interlaminar or intralaminar defects in orthotropic laminates. Strain gage technique being one of the simplest experimental method for determination of SIFs could not be successfully used in the case of cracked orthotropic materials. This is due to the fact that unlike isotropic materials, proper theoretical formulations supporting such experimental determination were not reported for orthotropic materials. Even though there were one/two attempts but there were no theoretical guidelines suggesting the number of strain gages and more importantly their locations ensuring accurate determination of SIFs. The present thesis works towards filling these gaps with an objective to facilitate strain gage based accurate determination of SIFs of cracked orthotropic materials. Starting with Westergaard’s stress function, and using a three parameter strain series, a single strain gage technique has been developed for accurate determination of IK in cracked orthotropic materials.
Supervisors : D. Chakraborty and K.S.R.K Murthy