the effect of gauge length on peel stress in a single lap joint

[Chezza]

In a single lap shear test specimen, does altering the gauge length (or the overall length of the specimen) have any effect on the peel stress? ie) would a longer specimen produce a greater peel stress, and cause the specimen to fail sooner?

Sorry, I forgot to mention. Assuming the bond area remains the same, just altering the gauge length of the specimen. I know that altering the bond area effects the level of peel stress, but does altering the gauge length effect it?

 

[runcm]

I do not believe the length of the specimen would change the peel stress which occurs at the ends. The peel stress is caused by the eccentricity of the joint, not the length.

 

[Compositepro]

The peel stress would have to be affected. If you imagine increasing the gage length by a factor of ten but keeping the bond area constant then the joint must have one tenth of the width. But theoretically the total load applied is the same. Applying the same load to one tenth of the width of bond line will increase the peel stress by a factor of ten. The eccentricity doesn't change but the peel does. Another way to look at the problem is that if the joint is made very wide but short the failure will be a shear failure. If the joint is very long and narrow it will fail in peel.