internal forces when steam bending wood

Jun 2019
10
1
uk
Hi all, first of all is this the most appropriate forum of the many options to pose some questions relating to the forces created when wood steam bent .

I understand the practical aspects but I cant get the relevant maths to tally,


a few facts first ..

when bending the wood the outside surface is totally restricted from expanding by the green strap with end blocks . so as the wood bend the inside surface is compressed. the force to compress the wood is a constant . a value i have practically tested. the strap has a tension gauge at G. so i know the tension force being exerted within the restraining strap.
It seems logical that the force in the strap should be equal to the compression constant x area,
However the the force within the strap is far less than this figure , only about 3- 40 % . can anyone explain where the force is coming from to compress quite a volume of timber . ( without he strap the timber would break across the outer surface as it is relatively weak in tension.)
 

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