Bike project

[liamwoolley]

Hello everybody. I am a automotive technology student and for my project i have designed a script for accelerating the design of bike frames. I have several questions… I need to establish if the process is possible, i do not need to go into much detail as its not the critical part of my project.

First is regarding FEA, if I assume the lay up covers all directions can i assume it is isotropic? I haven’t got access to composite FEA software…

Second is what pre pregs are suited to bladder moulding for bike joints?

Finally i have spoken to lectures and they believe it is ok to bond aluminium to carbon fibre… The bike will experience temps of -20 to + 45 in operation, will thermal expansion be an issue? Also i have heard about galvanic corrosion… from what i have read im not sure if my lectures are correct?

Any help will be much appreciated as it is not a huge section of my project and it is preventing me from moving on as i will only carry on if i know what im doing is possible…

[fleisch]

No, you won’t be able to model it as isotropic, but I have heard of people modeling it as orthotropic with appropriate lay up.

If you are a student, then you can download a student version of ABAQUS CAE for free. This program has composite capabilities.

I’ve never heard of any prepregs not suitable for bladder molding (I would be curious to know if that were the case though…).

Thermal expansion and galvanic corrosion are issues. I have heard people simply adding in a layer of fiberglass between the carbon fiber and Aluminum as it has a CTE between the two materials. Also, fiberglass does not conduct electricity, so it solves the galvanic corrosion problem, too.

[Rotorage]

Thermal expansion and galvanic corrosion are issues. I have heard people simply adding in a layer of fiberglass between the carbon fiber and Aluminum as it has a CTE between the two materials. Also, fiberglass does not conduct electricity, so it solves the galvanic corrosion problem, too.

+1 for the glass layer

[datas_br]

Hi,

can’t answer your question about FEA.

As far as Prepreg ist concerned you should be able to use anything that fulfills the strength and stiffness requirements you have for that area of the frame.

Thermal expansion won’t be a problem for bike parts. Galvanic corrosion is different. You will need to insulate the two materials from each other. Add a thin layer of glass if you are co-molding. If you bond post cure then you shouldn’t have a to deal with it since the adhesive needs a gap to bond properly.

Post pics of your progress and good luck.

[canyon]

Hello everybody. I am a automotive technology student and for my project i have designed a script for accelerating the design of bike frames. I have several questions… I need to establish if the process is possible, i do not need to go into much detail as its not the critical part of my project.

First is regarding FEA, if I assume the lay up covers all directions can i assume it is isotropic? I haven’t got access to composite FEA software…
.

You definitely can’t assume isotropic. However most FEA software can handle composite modeling. I know Catia, Ansys and Nastran can do it. What software do you have available to you?

[system]

Hi all from tishGirl

[liamwoolley]

Wow cheers for the response guys! The parts will be bonded so the corrosion issue is sorted… Ahh i have access to CATIA… im aware of the composite modeller but can you the analyse it? Nastran looks very good, but i assume its expensive Thanks again people

[fleisch]

Wow cheers for the response guys! The parts will be bonded so the corrosion issue is sorted… Ahh i have access to CATIA… im aware of the composite modeller but can you the analyse it? Nastran looks very good, but i assume its expensive Thanks again people

ABAQUS… student version is free…