If you read my previous post about stress maps, you’ll find I’ve put a link to a blend file in there.
Well, if you download that, then use the “Animated Bake” addon (http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Object/Animated_Render_Baker) to bake out the first hundred frames of the texture on the “wormy” object, then load the blend file linked below and plug the first one of those baked textures into the image texture node on the material on the “wormy” object, then take a look at the render output, you should see that the diffuse shader with the wrinkly normal map is only being mixed in where the bends occur and this is being driven by a shape key.
Basically (heh), there’s a driver attached to the “offset” value of the image sequence texture node in the material such that when the value of the shape key changes it does the maths: frameOffsetToUse = valueOfShapeKey * numberOfFramesIHave which means that given that the shape key goes from 0 to 1, you should get a frame range of 0 to numFramesIHave. This means that when the shape key is fully “on” you get the fully bent texture from the baked sequence, and when it’s fully “off” you get the fully relaxed texture from the baked sequence (plus you get all the gradiation inbetween).
Video Demo: http://youtu.be/69_aZf2fjgM
Link to second Blend File: https://docs.google.com/file/d/0BworKSfkE1_AaV9GbUtOUHU5M3c