Quote:
Originally posted by Socrates:
Strip thickness affects deflection as the square of the thickness difference ratio. This factor accounts then for 3% of the observed difference.
Could you explain the factor you mention?

For the influence of the strip thickness I'd assume that this is for the most part due to the difference in area moment of inertia, which is proportional to the thickness to the power of three. In this case this would account for a difference of 4.7%

Quote:
Originally posted by Socrates:
Hardness affects indent diameter as the fourth root of the hardness ratio. Assuming that an increase in indent diameter gives a direct increase in strip deflection hardness ratio would predict a 1% increase.
In my opinion the indent diameter approach is not correct. The plastic region underneath each indent is much larger than the indent itself and will be larger at lower hardness.
As you have already argued, the influence of strip hardness is complex and difficult to explain with a simple model. However our own small scale test did show a distinct influence. We have continued to monitor it after I posted my first message and again and again we see that (N) strips with lower hardness values have larger deflections. This is opposite to the influence published by Bailey and Champaigne, but they used A strips. Perhaps this gives different results.

As both the work by Sharma and by Bailey and Champaigne are based on experiments conducted more than 17 years ago, a new (and hopefully definitive) study based on the latest insights would indeed be welcome.