deflection calculator

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freddyfingaz

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To build pedal bike such like forks, front suspensions, rear suspension and frame work. Is deflection calculator must have tool for those kind jobs to selecting properly materials to use? For pedal bike?

That stuff doesn't make any sense for cavemen like me. I just grab lightest one and jump on it to se if it's holding.
 
Sure; It is called FEA (Finite Element Analysis). This is software that runs off of the 3D solid CAD models. You can run this as a static or dynamic test. The requirements are : an engineering workstation (computer), high end CAD program, FEA program, and it helps to have at least a BS in mechanical engineering.
 
c.p.odom said:
Sure; It is called FEA (Finite Element Analysis). This is software that runs off of the 3D solid CAD models. You can run this as a static or dynamic test. The requirements are : an engineering workstation (computer), high end CAD program, FEA program, and it helps to have at least a BS in mechanical engineering.
Click to expand...

I gotta to take a look at this.
 
Anyway, I was given couple formulas to do calculate to determine strength that material will support. I'm still in process studying these formula.. haven't bullseye it yet. Just to display my work... of course it's wrong.

15mph is 22 feet per second.
Estimate weight whole bike include my weight would be about 250lbs.
(250lbs)22ft/sec^2=5,500 lbs of impact forces. (Hitting curb at 15mph)

This formula was given to determine Inertia.
I=force(length^2)/(( modulus of elasticily)3.14^2)

Modulus of elasticity for stainless steel round tube at 93 degree would be 27.6lbs per inches.

5500lbs/2bars=2750lbs each bars

I=2750(48in)^2/(27.6)3.14^2)
I=6336000/272.12496
I=0.00004

Then to find material Inertia to match by this link.

http://www.engineeringtoolbox.com/pipe- ... _1335.html

It doesn't make sense. I'm trying find out what wrong I have done. It's giving me a headaches. Lol
 
Do anyone know their math stuff that could correct my work? Im not sure if this is correct but lets see.

15mph=22 feet per second
300/2=150lbs
(150)22x22= 72600 impact force
72600/2=36300 lbs strenght require each bar
27.6(10^6)= 27600000 Modulus of elasicatly for 316Stainless Steel
I=36300(48)^2/((27600000)(3.14^2)
I=(1742400x1742400)/(27600000x9.8596)
I=3.035957e+12/272124960
Movement of interia=.999999998682
:?
 
The reason Why I do this s Cuz my local doesn't have much materials to select but ordering Thur online and I don't want make poor choice that my design will collapse.
 
For those of us with limited math/mechanical engineering skills, the answer is to overbuild. If you make it strong enough for a 900 lb. gorilla, it will certainly work for you. Gary
 
B607 said:
For those of us with limited math/mechanical engineering skills, the answer is to overbuild. If you make it strong enough for a 900 lb. gorilla, it will certainly work for you. Gary
Click to expand...

Yea. I'm wondering how builder picking their materials if they don't have access to see it in physical. I was looking at lightest until I realized its only support 5lbs. Overbuild it would be a way to do. Beside I'm that too far ahead cuz impact force formula freak me out and made me want to pick right. Lol. Yea I gotta rid of this nonsense out of my mind.
 
c.p.odom said:
Sure; It is called FEA (Finite Element Analysis). This is software that runs off of the 3D solid CAD models. You can run this as a static or dynamic test. The requirements are : an engineering workstation (computer), high end CAD program, FEA program, and it helps to have at least a BS in mechanical engineering.
Click to expand...

Hey, I have (or have access to) all of those things! In fact, I'll be in Cincinnati in 2 weeks for training on using the FEA program we bought.

But at the end of the day, while the "jumping on the lightest one and see if its holding" is a bit sketchy to me, there really isn't a huge amount of load when you're dealing with just casual riding. Yes, the old overbuild school of thought works, and if something does give out, you have an excuse for an upgrade. But if it came to dealing with bikes that see extreme loads - downhill MTB, cyclocross, track events, etc, then I'd think you want to be a bit more careful with your calculations...
 
expjawa said:
c.p.odom said:
Sure; It is called FEA (Finite Element Analysis). This is software that runs off of the 3D solid CAD models. You can run this as a static or dynamic test. The requirements are : an engineering workstation (computer), high end CAD program, FEA program, and it helps to have at least a BS in mechanical engineering.
Click to expand...

Hey, I have (or have access to) all of those things! In fact, I'll be in Cincinnati in 2 weeks for training on using the FEA program we bought.

But at the end of the day, while the "jumping on the lightest one and see if its holding" is a bit sketchy to me, there really isn't a huge amount of load when you're dealing with just casual riding. Yes, the old overbuild school of thought works, and if something does give out, you have an excuse for an upgrade. But if it came to dealing with bikes that see extreme loads - downhill MTB, cyclocross, track events, etc, then I'd think you want to be a bit more careful with your calculations...
Click to expand...

Agreed, this impact force formula saying whole weight will be 20 times when it hit curb at 15 mph. I think it wouldn't ever happen anyway and I will just use same material as my frame has.
 
I had a fun with this free mobile apps called forceeffect. This result I got from. It doesn't do deflection material calculator tho.

PicsArt_1346967571719.jpg
 
Ok I read this post and since I build frames It makes me wonder....What the heck you would
need to know this information for. If its required to build a frame , I must have missed it. If
your planning on hitting a curb at 15mph tell me first and I will be there with a video camera
to put it on Youtube. I would think if you do choose to do that...the least of your worries will
be the frame. Maybe your front wheel and then your face. :shock: :shock: :shock: :shock:
 
Uncle Stretch said:
Ok I read this post and since I build frames It makes me wonder....What the heck you would
need to know this information for. If its required to build a frame , I must have missed it. If
your planning on hitting a curb at 15mph tell me first and I will be there with a video camera
to put it on Youtube. I would think if you do choose to do that...the least of your worries will
be the frame. Maybe your front wheel and then your face. :shock: :shock: :shock: :shock:
Click to expand...


Exactly right. Lol. Actually what I was try to do is pick lightest materials off the online store but it's scary to do without pyshical see it. So, while picking up the formulas to calculating materials load capacity to support. The impact force got in the way which it took me all the way over there. Lol. Forget it, I will just pick same material as my frames has. I felt stupid but I have an excuse which is I'm noobie. No body answer my question. How do y'all picking your material for ur bikes.
 
Also I happened to found out most of productions at the markets are required to met safety factor formula which it's multiple of the lbs force. That make me all the way over there too. Lol
 
I use 16 gauge tubing and I weld the heck out of it. I know you could take my frame and
run over it with a truck and it will look just like it did when you started. I think your welding skills
will also determine how strong a frame is. You might be over thinking this a little bit. Its a bicycle
not the space shuttle.
 
Yea, I don't weld since college. Lol. I'm ch :D :D :D :D anging my mind. I'm gonna do my father's way by keep it simple on original bike. He has cool ideas. I probably need to remove this topic before confuse everyone else.
 
I built a recumbent with 3/4" electrical conduit. EMT its called. It held up fine.
I weld at work, and order my steel at a local steel fab shop. Its as simple as saying" 1inch thin wall" Or 1inch thick walled tubing. I dont know guage. Square tubing is what I mostly use. Thick wall is 1/4" thick,thin is 1/8th.JMHO.
 

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