<VV> VV: Re: windshield removal

[mhicks130 at cox.net]

>
> How does "cleaning up" a chip "remove any stress raisers?" How does this
> work, and what is it? I know what a chip is, and I know what emery paper is,
> but the rest has got me guessing.
> 
> Joe Potts

A stress riser comes from having a sudden change in local geometry - ie a sharp edge.  By grinding down and sanding smooth all the sharp edges of a chip, you allow the stresses to smoothly find their way around.  Stress risers cause highly localized areas of stress around the riser that are significantly higher than they would be without it.  If this happens in a ductile material like mild steel, the material deforms a little, the stresses spread out and everything is fine.  In brittle materials like glass, there's no deforming and spreading - just sudden failure - cracking.  

mike