Fiberglass composite study in SolidWorks, Help !

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firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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thanks for the info sgthomas,

well i have a question concerning the composite, i was watching some seminar about composite and solidworks yesterday, and the guy said if you use Linear Elastic Isotropic, the fiber orientation would not matter then, as we know the isotropic has same properties in all direction so doesn't that mean that it may concern the CSM for example ?

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mep
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Joined: 11 Oct 2003, 15:48
Location: Germany

Re: Fiberglass composite study in SolidWorks, Help !

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It is more the other way around; if the fibre orientation does not matter you can use isotropic properties. That is the assumption we are talking about. You have chopped strand mats which have a random orientation, but only in the x-y plane as sgth0mas pointed out. However, you pic the material properties which match a random orientated chopped strand mat. Those will be lower than what can be maximally achieved by UD but it will allow to build a much simpler simulation model because the material is assumed to be quasi isotropic. Obviously the final part will end up heavier but that’s the compromise taken for the simpler modelling and for safety.

firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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mep wrote:It is more the other way around; if the fibre orientation does not matter you can use isotropic properties. That is the assumption we are talking about. You have chopped strand mats which have a random orientation, but only in the x-y plane as sgth0mas pointed out. However, you pic the material properties which match a random orientated chopped strand mat. Those will be lower than what can be maximally achieved by UD but it will allow to build a much simpler simulation model because the material is assumed to be quasi isotropic. Obviously the final part will end up heavier but that’s the compromise taken for the simpler modelling and for safety.
ah ok well sounds fine as a solution, and i would like to know one more thing, if i want to make a study for layers with orientation angle then what type i must choose in the properties ? nonlinear elastic ?

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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Nonlinear elastic is technically correct, but it only benefits you if you load the material properties correctly to reflect the behavior over different strains. Clicking a button wont do too much wothout loading advanced properties. In FEA, especially non linear, you cant just use tensile strength, yield strength, modulus and density From one point. All of this data will be tabulated to detail the response at different strains, temperatures...etc.

If you are approximating this to be isotropic, i would also approximate non linear. The non linear is actually a less drastic approximation than isometric...especially if you have a lot of design margin.

This wont be taken to a race track correct?

firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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sgth0mas wrote:Nonlinear elastic is technically correct, but it only benefits you if you load the material properties correctly to reflect the behavior over different strains. Clicking a button wont do too much wothout loading advanced properties. In FEA, especially non linear, you cant just use tensile strength, yield strength, modulus and density From one point. All of this data will be tabulated to detail the response at different strains, temperatures...etc.

If you are approximating this to be isotropic, i would also approximate non linear. The non linear is actually a less drastic approximation than isometric...especially if you have a lot of design margin.

This wont be taken to a race track correct?
ah i see, well this is a simulator cockpit where u sit it's just a simulator cockpit, now the second one i must do it a cockpit for an RC car which is 1/4 from the real one, let's say the real one is 1800mm in length, so mine should be 450mm in length

well about the properties the problem is that i didn't find a source that give me those properties ! i found one but doesn't really help :S

btw in the properties manager of solidworks, when i put the type as non linear, i get only 4 options to enter ! which are : Poisson's ratio in XY, Thermal Expansion coefficient in X, Mass Density and Tensile strength in X

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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Does your package allow for non-linear? Are you sure there arent other tabs?

Also, if you dont have the material properties, theres no sense in trying to solve a non linear.

What are the properties for the resin youre using (in psi please:))

firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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sgth0mas wrote:Does your package allow for non-linear? Are you sure there arent other tabs?

Also, if you dont have the material properties, theres no sense in trying to solve a non linear.

What are the properties for the resin youre using (in psi please:))
here is a picture of how it looks like when i put non-linear elastic type
Image

about the resin well i did not enter any properties :( i simply searched for the properties of E-Glass

and the resin i will be using is CRYSTIC® 125PA Scott Bader

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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as i use mostly ansys, im not sure why its not allowing more in solidworks. It may just be the package you have. Also, the tables and curves tab is where you would put the non-linear data related to the stress strain curves and such.

Your tensile stregth is waaaaaayyyy too high...you cant use just fiber strength because its likely an order of magnitude greater than reality.

Again, treat this as a linear isotropic but go with very conservative material properties if you cant find a close representation online or through testing. I dont think you have any other options. I mean almost resin only strength with a higher modulus. Thats your only choice as its the most conservative and you have actual values for that material. This is a good example of why FEA still requires someone well aware of what theyre doing with mechanics and materials.

And to throw in a disclaimer, this method would never be used in practice to design deliverable parts to a customer. I think youre simply going this route to satisfy academic requirements Correct?

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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Also, i dont mean any offense by my comments and hope theyre not taken that way. This type of simulation is just very difficult...and doing it wrong on a safety critical component is unacceptable in actual practice. A model is different.

firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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hahaha first no offese taken don't worry :lol:
sgth0mas wrote:as i use mostly ansys, im not sure why its not allowing more in solidworks. It may just be the package you have. Also, the tables and curves tab is where you would put the non-linear data related to the stress strain curves and such.
well yesterday i was on the phone with one of my friends in his work he uses ansys for simulation, so he told me something about that curve, but what is it exactly, i mean is it just a relation between the stress and strain ? and where can i get it ? i tried some search on google but wasnt successful for e-glass fiber
sgth0mas wrote: Your tensile stregth is waaaaaayyyy too high...you cant use just fiber strength because its likely an order of magnitude greater than reality.
well this is what i found in my search from datasheets to other sources :S
what do you mean exactly by "you cant use just fiber strength because its likely an order of magnitude greater than reality" ?!
sgth0mas wrote: Again, treat this as a linear isotropic but go with very conservative material properties if you cant find a close representation online or through testing. I dont think you have any other options. I mean almost resin only strength with a higher modulus. Thats your only choice as its the most conservative and you have actual values for that material. This is a good example of why FEA still requires someone well aware of what theyre doing with mechanics and materials.

And to throw in a disclaimer, this method would never be used in practice to design deliverable parts to a customer. I think youre simply going this route to satisfy academic requirements Correct?
the problem is that we took some courses, about cercle de mohr and stress and strain, composite course, non-linear mechanics of structures, ... but we have some problems with that because we don't really know where to use these :cry:

well i am making a final representation for diploma yes but not only for that i must make a decent study for my application to a university in UK

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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Itll take me a bit to prepare a response for all that, but id be more than happy to help. What time country/timezone are you in...and when is your analysis due?

firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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sgth0mas wrote:Itll take me a bit to prepare a response for all that, but id be more than happy to help. What time country/timezone are you in...and when is your analysis due?
thank you so much, i am in the Time zone UTC+2:00,
i'm sorry i didn't understand your last question :?

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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my last question was asking when you need to complete the solidworks analysis.

I will be tied up this weekend but can probably respond sunday evening or monday. Im in texas which i think is utc -6, im not sure if that changes with daylight savings time.

firasf1dream
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Joined: 18 Apr 2014, 21:26

Re: Fiberglass composite study in SolidWorks, Help !

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sgth0mas wrote:my last question was asking when you need to complete the solidworks analysis.

I will be tied up this weekend but can probably respond sunday evening or monday. Im in texas which i think is utc -6, im not sure if that changes with daylight savings time.
yesterday i was in a meeting with my tutor, i will have to make the composite analysis done totally next week max on tuesday

well thanks a lot for the help really appreciate it, my problem is the non linear analysis must learn more about it and the problem is that you can't find any tutorials about composite, no video or pdf nothing ! the only videos i found are basic for start only

sgth0mas
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Joined: 18 Mar 2015, 03:42

Re: Fiberglass composite study in SolidWorks, Help !

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Yeah its incredibly tough to get information on it and in all honesty the fea programs for composites are in their infancy. Many companies have their own proprietary data that they will not share.

it looks like you are gong to have to use a linear isotropic solver...which will probably satisfy the academic requirement. But in practice it would not be sufficient. As long as this steering wheel isnt on a moving vehicle you probably have no major safety concerns. That would still be up to you to analyze.

I looked at a few data sheets and it appears your CSM composite will probably be closer to 100 MPa yield strength. thats wayyyy lower than what you have, but still within the margin of your analysis. I dont remember the modulus. The values you are using now are at least 20x greater than what you can really expect from the composite.

As you gain more experience...you will realize there arent many how-to articles on what youre doing...so application of theories becomes paramount.