I see the question about how wide to make a limb pretty regularly and have considered the question myself when working with a new species of wood. So, I sat down and came up with this quasi-emperical equation to give myself a starting point. I present it here for comment and discussion.
G=specific gravity
D=draw length (in)
L=working limb length (in)
P=draw weight (lbs)
Width = (P*D^2) / (L*G^1.13*1400)
* is multiply
/ is divide
^ is to the power
Now, for those that want more info, this equation is based upon:
Cantilever beam stress equation
67% of the MOR as calculated from the Specific Gravity
A basic limb thickness of 0.60" (this is on the thin side, but that makes the answer more conservative)
A string to tip angle of 90deg
A string to arrow angle of 45deg
Basic "do-able" bow geometry, IE. you can't have a 10" limb with a 28" draw
I did write a more involved equation that includes the angles and thickness but only wanted to present the simplified version for review.
I tend to make laminated bows so I start with boards. With a caliper, tape measure, scale and RH; I can calculate the specific gravity pretty well. I can post that process for anyone interested.
Ken
Note: I add 1/8" to the calculated width for safety.