Understanding the Forces on Bows in Archery: A Materials Selection Analysis

[jackimini]

I wasn't sure where to post my question, but its for my materials selection course... (please forgive me if I posted in the wrong place :)

I'm doing a research project on the materials used for bows in general (longbows and recurves mostly), and I've been having trouble finding information on how the forces on a bow are loaded. I do have an actual bow to work with, but it would be really helpful if I could find some info about how they are loaded during use. My colleagues and I aren't exactly experienced with archery, so aside from the obvious bending and tension stresses, we aren't sure what else goes on.

Any help would be greatly appreciated :)

 

[Astronuc]

Well there is obviously tension in the string and in the bow structure, there is tension on the foward surfaces, compression on the backside, and bending/shearing of varying magnitude along the length of the bow.

I would have thought that someone would publish an FEA of a bow, but I haven't found one.

Here's a site with some mention of materials.
http://www.bowstick.com/mongolian.html

Somewhere I have some additional information. I just have to find it.

 

[jackimini]

Oh awesome! Thanks :)

 

[jim mcnamara]

article that may interest you:
Shape optimization of a bow
M. Pagitz & K.U. Bletzinger1
Journal Structural and Multidisciplinary Optimization
Jul 2004 28:1 p73-78

AFAIK there is no finite element analysis in the field of archery except for compound bows. Bear (company name) claims they used FEA to enhance their equipment, for example. http://www.beararcheryproducts.com/

I would guess everybody thinks it has been done before, just like Astronuc clearly does. Might make a great publication, there Astronuc. Assuming it isn't an overwhelming task.

 

[Astronuc]

I would imagine that if FEA has been done on a bow, it is proprietary. If one has a good or bad design, one does not wish to share that information with competitors.

I was doing some research some months ago on Mongolian bows, after reading that the Mongols had significant advantage over the tribes they invaded because their arrows had greater range.

There are numerous companies that manufacture Mongolian bows from modern materials.

 

[rdt2]

The geographical variations in bows are interesting. Esssentially, the recurve bow requires a composite material that's good in compression on one side (often made of bone) and good in tension on the other side (often made of leather). In a cool, wet climate, such as the U.K, that's not a viable solution (wet leather isn't goood in tension) and so recurve bows were most common in mediterranean or middle eastern countries. English merchant ships were compelled, by law, to bring back a consignment of Spanish yew on their trading voyages, specifically for the manufacture of 'English' longbows.

JE Gordon, who was mentioned on another thread and who was a one-time acquaintance of mine, goes into this in his book "Structures - or why you don't fall through the floor".

Modern bows are often designed to have a draw force that reduces as the deformation increases, i.e to be 'soft' nonlinear springs.