Help! Beam Caluclation
Help! Beam Caluclation
(OP)
Please Help!
My boss gave me a Excel spreadsheet caluclator that calculates the increase in diameter of a cylindrical column needed to evenly distribute a load across that column. It doesnt work and I'm a moron when it comes to this stuff. Does anyone know what that calculation is? I'm desperate and would be greatful for any help. Thanks! ckozlik@newarchery.com
My boss gave me a Excel spreadsheet caluclator that calculates the increase in diameter of a cylindrical column needed to evenly distribute a load across that column. It doesnt work and I'm a moron when it comes to this stuff. Does anyone know what that calculation is? I'm desperate and would be greatful for any help. Thanks! ckozlik@newarchery.com






RE: Help! Beam Caluclation
>My boss gave me a Excel spreadsheet caluclator that calculates the increase in diameter of a cylindrical column needed to evenly distribute a load across that column.
Questions: Is it a beam or a column? A beam-column? What kind of loading - flexure (beam) or compression (column)?
>It doesnt work
What exactly doesn't work? Is the spreadsheet giving you an error or is the answer wrong? Post the spreadsheet cell formulae and we'll take a look.
>Does anyone know what that calculation is? I'm desperate and would be greatful for any help.
I'm not sure. From the e-mail address you've given, my guess is that you work for an archery equipment manufacturer, as such what is the calculation used for?
RE: Help! Beam Caluclation
Even this -if usually more than acceptable- is but a simplification -in that we assume perfect uniformity of the stress at any level- since the column is not prismatic.
RE: Help! Beam Caluclation
Specifically, I'm trying to calculate this:
I have a cylindrical beam that is tapered larger at the base and smaller at the end. It's supported at the base only. I'm trying to find the correct taper that will evenly distribute a bending load applied on the end of the beam when the base end is at a given dia. (lets say .165 dia.)
The spreadsheet that I have to do this MAC format from 1990 and it no longer opens correctly.
This calculation is to help me design an archery broadhead. The loads, both direct impact and side bending are high. I'm trying determine what diameter is needed in the main ferrule to evenly distriute the bending loads that it will be under during impact. (I'm NOT a structual engineer by trade, I'm a manufacturing engineer. Thats why I dont know a lot about these calculations OR terminology)
Thanks. Chris
RE: Help! Beam Caluclation
Imagineer
RE: Help! Beam Caluclation
I may send to you both in doc format or mcd if you have access to. Put if so you want your e-mail address here.
RE: Help! Beam Caluclation
It sounds like you have a cantilever beam with a fixed base and linearly increasing diameter to the base. A good source for this type of problem is Roark and Young, 'Formulas for Stress and Strain'. If you are having problems with Excel, I would definitely steer clear of Mathcad.
RE: Help! Beam Caluclation
I have a Macintosh... What spreadsheet was it originally created on? Wingz? I have a copy of Wingz that might open it. I have other spreadsheets on my Mac, too, and I've been able to open anything, just about, even M$ stuff.
>This calculation is to help me design an archery broadhead. The loads, both direct impact and side bending are high. I'm trying determine what diameter is needed in the main ferrule to evenly distriute the bending loads that it will be under during impact.
Wow! Can you post a picture so we can see what's going on? I'm not a bowhunter and I can only guess at the geometry, etc. But... I'll give it a try off the top of my head, you have a cantilevered plate, the plate is triangularlly-shaped. Roark & Young's Formulas for Strees and Strain should have the formula for this kind of plate. Of course, I don't have a copy of their book handy, wish I did. I'll see what I can come up with, though.
RE: Help! Beam Caluclation
RE: Help! Beam Caluclation
RE: Help! Beam Caluclation
When the arrow is first released, it is under significant compression (force from bowstring on butt, air resistance on tip). This causes a tendency to buckle (there's kl/r again!), but it doesn't, I suspect because the compression wave rebounds to tension very quickly. Then its off to the races with the compression wave alternating in the arrow like a sine wave.
Try getting someone to do an FEA model of this, throwing in the dynamics. Or you could design it like many other products....trial and error!