Load Simulations on Chassis on Solidworks!

[Gabriele G]

Hi All, I am a new member of this community. I am the head of chassis design of the University of Leicester (UK) Formula Student team. We have just launched Formula Student at the university this year and we are aiming to compete at silverstone next year.

I am very sorry if these sort of questions have already come up, but after extensive searching I haven't found exact answers to my questions.

I am seeking help regarding load simulations for my designed chassis on solidworks.

First of all I am not quite sure what types of simulations I should carry out. My idea was to carry out the following:

1) Frontal impact, so applying a load at the front of the bulkhead.

2) Side impact: same, but from the side.

3) Torsional Rigidity: applying a rotational force about the whole car.

4) Show where the load paths are going to be.

5) Show which areas are going to be Heat Affected Zones (HAZ)

Now, what would your comments be on this? What other sort of simulations should I carry out?

And secondly, I would really appreciate it if a possibly experienced member of an already existing team helped me with the exact methodology of such simulations.

As what regards 1): I am considering ONLY the space frame tubular chassis, nothing else. So my question is: what load should I apply to the front-most plane of the car (front bulkhead)? I mean, I have read the requirements of the impact attenuator, which has to absorb 7350J of energy, but, in such a scenario, how much force would the actual front bulkhead (so justBEHIND the impact attenuator ) experience? I really am having trouble with this..

in the following link it says "To address this, teams should determine, either by testing or analysis, that their configuration for front bulkhead and anti-intrusion plate can support the required 117,720 N (26,755 lbf) of load from the anti-intrusion plate assuming a uniform pressure applied load across the area where the anti-intrusion plate mounts", but how do you find this out? where does 117kN come from?

"http://fsae.com/eve/forums/a/tpc/f/125607348/m/69420694941?r=18720420051#18720420051"

And what forces would you apply in cases 2) and 3) as well?

Thank you very much in advance for your help, any would be greatly appreciated!

Gabriele

[Gabriele G]

Hi All, I am a new member of this community. I am the head of chassis design of the University of Leicester (UK) Formula Student team. We have just launched Formula Student at the university this year and we are aiming to compete at silverstone next year.

I am very sorry if these sort of questions have already come up, but after extensive searching I haven't found exact answers to my questions.

I am seeking help regarding load simulations for my designed chassis on solidworks.

First of all I am not quite sure what types of simulations I should carry out. My idea was to carry out the following:

1) Frontal impact, so applying a load at the front of the bulkhead.

2) Side impact: same, but from the side.

3) Torsional Rigidity: applying a rotational force about the whole car.

4) Show where the load paths are going to be.

5) Show which areas are going to be Heat Affected Zones (HAZ)

Now, what would your comments be on this? What other sort of simulations should I carry out?

And secondly, I would really appreciate it if a possibly experienced member of an already existing team helped me with the exact methodology of such simulations.

As what regards 1): I am considering ONLY the space frame tubular chassis, nothing else. So my question is: what load should I apply to the front-most plane of the car (front bulkhead)? I mean, I have read the requirements of the impact attenuator, which has to absorb 7350J of energy, but, in such a scenario, how much force would the actual front bulkhead (so justBEHIND the impact attenuator ) experience? I really am having trouble with this..

in the following link it says "To address this, teams should determine, either by testing or analysis, that their configuration for front bulkhead and anti-intrusion plate can support the required 117,720 N (26,755 lbf) of load from the anti-intrusion plate assuming a uniform pressure applied load across the area where the anti-intrusion plate mounts", but how do you find this out? where does 117kN come from?

"http://fsae.com/eve/forums/a/tpc/f/125607348/m/69420694941?r=18720420051#18720420051"

And what forces would you apply in cases 2) and 3) as well?

Thank you very much in advance for your help, any would be greatly appreciated!

Gabriele

[Dash]

1) The 117kN comes from the 40g deceleration limit.
2) I currently don't know any team that has done that kind of analysis. Maybe you could look at the alternative frame rules and see if they give you a loading in that condition.
3) Rigidity doesn't really require any particular number, so long as you can measure the deflection. If you wanted actual degrees on twist you will see, then you will need to do some calculations to figure out on track conditions you will see.
4) Doing some static analysis you will see where the load paths are.
5) HAZ occurs when you weld, so if you are doing a welded frame then they will be everywhere.

[Gabriele G]

Thanks Dash, that was all very useful information and greatly appreciated.

However, as what regards point 1). Silly me, I just realised that figure was calculated with 40g's ( I was working with 20 g's). And yes, it does make sense to work with the peak value, because the chassis must sustain that sort of stress anyway.
I realise that 117kN is the force exerted on the front of the impact attenuator, but wouldn't some of this force in some way "be absorbed" by the attenuator itself? Is the 117kN force actually exerted on the front bulkhead itself?

Cheers

Gabriele

[John_Burford]

Please review the Alternative Frame Rules regarding simulation for the purpose of satisfying structure requirements.

[Dash]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gabriele G:

I realise that 117kN is the force exerted on the front of the impact attenuator, but wouldn't some of this force in some way "be absorbed" by the attenuator itself? Is the 117kN force actually exerted on the front bulkhead itself?

Cheers

Gabriele </div></BLOCKQUOTE>

The force doesn't go away, it has to be reacted somewhere. On the other hand, the energy from the collision should be partially ( or mostly ) absorbed by the impact attenuator.

[Gabriele G]

Thanks John, I didn't realise there were these alternative frame rules that gave precise loads to apply. That helps a lot! And also thanks Dash.

I had a meeting with my supervisor yesterday (chassis design is my third year project) and we established, after having observed many simulations I did, that Solidworks isn't a powerful simulation software at all.
But this may also be due to the fact that I'm no expert with the package.
I was wondering; has any team done their analyses completely on Solidworks? I'm asking because apparently proper analyses would be much more sophisticated than what Solidworks can handle. According to my supervisor a decent tool to do this is Abaqus; I have read that some teams use this for their analyses.
A couple of months back I tried using it, but I simply cannot find a way of importing models from solidworks to abaqus!

[kcapitano]

My team has used solidworks exclusively for some time now and it has worked well for us. We did an analysis of our frame in solid works and followed that up with a torsional rigidity test. I didn't actually conduct the testing, but I believe our measured torsional rigidity was reasonably close to the torsional rigidy found from FEA (within about 10% maybe).

Solidworks may not have the best FEA package out there, but I think for our uses it's pretty good. The problem you will run into with any FEA software is that it is completely dependent on how you set up your model (ie. it's only as good as you make it). This might be a shameless plug, but I recommend checking out this book (http://books.sae.org/book-r-349). It's written by one of my professors who teaches a class on FEA entirely with solidworks.

[typeh]

We are working with Solidworks and it gives good indication. Cases you stated won't get big difference in results in different programs.
Alternative frame rules would give you loads you are searching for and more but first check dynamic loads before checking shocking loads.
Torsional rigidity won't vary with force try it.

AUMotorsports
FSG 2012
Design team head