03-03-2009, 12:32 AM
And to follow up...
If the shield is made from wood that has been excavated so that the grain is interrupted on the downslope to the rim, the likely break points are in that downslope. If the wood is planed so that each surface follows a growth ring and steam bent, it will flex like a bow, and bows tend to fail at the anchored point in stress (near the grip).
In the case of an aspis I'd guess that assuming the shield is under pressure outward from the hand and forearm and shoulder, and possibly the knee, you would tend to see failure near the centre.
Of course, this ignores all the other possibilities like hide shields, wicker, willow strips, and what not.
All this said I do buy in to the broad flatter shield being better in a push as it would have more room to deform due to it not having been previously stressed or excavated to change its shape.
There is one more possibility for failure I forgot to list. Wood will fail along a hide glue join as the wood is weaker than the glue, so differential pressure on two planks can snap the wood along the glue joint. So this raises the question of the orientation of planks (assuming planked construction) to avoid this problem.
Have fun!
Cole
If the shield is made from wood that has been excavated so that the grain is interrupted on the downslope to the rim, the likely break points are in that downslope. If the wood is planed so that each surface follows a growth ring and steam bent, it will flex like a bow, and bows tend to fail at the anchored point in stress (near the grip).
In the case of an aspis I'd guess that assuming the shield is under pressure outward from the hand and forearm and shoulder, and possibly the knee, you would tend to see failure near the centre.
Of course, this ignores all the other possibilities like hide shields, wicker, willow strips, and what not.
All this said I do buy in to the broad flatter shield being better in a push as it would have more room to deform due to it not having been previously stressed or excavated to change its shape.
There is one more possibility for failure I forgot to list. Wood will fail along a hide glue join as the wood is weaker than the glue, so differential pressure on two planks can snap the wood along the glue joint. So this raises the question of the orientation of planks (assuming planked construction) to avoid this problem.
Have fun!
Cole
Cole
