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What does the FEA process look like at your company?
5

What does the FEA process look like at your company?

What does the FEA process look like at your company?

(OP)
Can anyone chime in with what procedures they go through for an FEA study? I'm supposed to be picking up more responsibility as the "Lead Analyst", and I feel like my view of how an FEA project should go is different than my bosses.

For example lets say we're analyzing a shelf that mounts to the frame rails of a truck with clamps, one assembly, 15 parts. It has quite a few contacts and bolted connections, so when all setup it might take 16 hours to solve.

Do the analysts work independently for the most part, and report back when they have results? Or does the whole team (project lead, FEA lead, management) review every setup before and after it is run? Like sit down and discuss if its the correct way to load, review all the contact sets in detail, review all the bolts, etc? Last week one of my coworkers got the static study ran for a shelf and the setup was reviewed by the owner who has experience in FEA. We reviewed the results on Friday, and determined that it was time to do the fatigue loading studies. They should have the same setup except for loads, so the study could just be copied out and modified. They were setup to run over the weekend. Well something went wrong and the results weren't available until Tuesday. It was then we discovered two sets of contact sets were incorrect and the whole study needs to be re-run, including the static load case. Now my coworker and I are getting flak for not reviewing the setup with the whole team, despite the fact that he reviewed that setup with the owner, and the three people needed to review setup (myself included) were out of the office Friday afternoon. If I'd had him wait until Monday, we would have gotten flak about not taking advantage of the weekend.

They keep wanting the FEA dept to get better at scheduling, and hitting deadlines, but how does that work when studies take 16 hours to solve. It always sounds like they expect us to stay overnight, or whatever to make sure it solves and/or the results are OK. They always like to say that the FEA dept has no urgency and often has a "well it didn't work today, lets try this change, cross our fingers and see if it solves overnight". But to me, that's a big part of the FEA process. It takes time. Staying late doesn't help, outside of instances where its going to finish solving soon, or finishing the setup to run overnight. If we stayed, we'd have to find busy work because technically we're not supposed to charge machine time.

I just feel like FEA is naturally a longer process, and they want to compact it as much as humanly possible. "That study only takes 4 hours to run, well then we should have results for the customer tomorrow". Sometimes thats true, we can get results pretty quick, maybe the next day. But often something happens and pushes the results back and its "just another instance of FEA not having urgency or sticking to a schedule."

So, FEA analysts of Eng-Tips, if you were handed an assembly similar to the one above, what would your general schedule and process look like? Additionally, how do you get your load cases and setups? Usually for us the project lead (young engineer) just knows they need FEA run, they hand it over to us, and then its up to FEA dept to develop all the load cases, design limits, fatigue parameters, etc.

RE: What does the FEA process look like at your company?

I don't work in FEA, gave that up 35 years ago, but I do work with MBD sims. Much of my time is occupied with correlating with real world tests, and the unfortunate fact is that a given correlation that normally takes only 5 days sometimes stretches out to one or even, in one case, 3 months. In the latter case it was a safety related signoff, so they just had to wait.

It seems to me your schedules don't allow for multiple runs and screwups. Both are inevitable. If they want faster results get a Linux cluster. You don't mention how you validate your models.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: What does the FEA process look like at your company?

I would check to see if you're meshing, etc., correctly/efficiently, since a 16-hr turn around does seem awfully slow.

So, if the turnaround time cannot be changed, then each simulation is precious time, so a thorough review needs to be done to ensure not wasting time. But, it would seem to me that some sort of procedural thing is awry, since the notion of needing 3,4, or 5 people looking at a model in detail likewise seems absurd, on the face of it. I assume that the review is going to wind up taking several hours?

If the turnaround time were 2 hrs, would you still want to do a thorough model review? I think not.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: What does the FEA process look like at your company?

My background is make it test it break it fix it. As such quick turnaround is essential.

Oh sorry, to answer the OP, specifically for FEA, ie durability, crash, noise, vibration, and probably three other things i've forgotten about.

The process is - CAD comes up with some pretty shapes meeting Design's requirements. Core FEA then turn that into 3 resolutions of mesh. Various departments run those for their tests. Problems are found, CAD draw up more pretty shapes. Rinse and repeat twice. These get signed off. Parts are built, cars are made and tested, more problems are found, and failures to perform in line with the model predictions are found. Hopefully one more cycle of design sorts it all out. All of this is done inside the overall V framework for developing systems, cascade requirements down the left hand side, build up tests (verification) on the RHS. Loop as low down as you can.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: What does the FEA process look like at your company?

Why do you need to run an FEA of a shelf??

RE: What does the FEA process look like at your company?

3
I've been working as an engineer for 33 years now, the majority of the time with FEA. I've worked at 7 different companies, big and small. Here's my thoughts on this subject:

Before you start on a project, think hard if you can do the analysis using hand calcs. Often times younger engineers tend to jump into using FEA tools because it is flashier and more fun than using traditional classical methods. I've also seen engineers wanting to use FEA because they don't want to bother with understanding fundamental load paths through their structure, etc. They assume the FEA solver will handle all of this for them. I've analyzed equipment shelves on aircraft racks and 80% of our analysis is using hand calcs with free body diagrams, section analysis, etc.

If you decide you need to use FEA for a project, here's the process I would recommend:
  1. Work with your designer on understanding the geometry of the structure. How the various parts are connected together (with rivets, bolts, etc.), how the assembly is connected to your primary structure. What the section properties are of the structure being analyzed.
  2. Confirm with your lead engineer or engineering manager that using FEA is appropriate for this analysis.
  3. Begin making the FEM using the correct element types (shells, bar/beams, solids, connectors, springs) while also noting all assumptions you've made for the modeling. Don't forget to include any relevant stiffness with the structure you are mounting your assembly to.
  4. Once completed, run some basic model checks (linear statics run verifying applied load = reaction load, parts are connected correctly, deflections seem reasonable). You should also try to validate your model by comparing hand calc results with FEA results where possible.
  5. Have a review with your designer, peers, and/or "expert" FEA person in your group. Review basic modeling strategy, how the joints are modeled (which degrees of freedom are constrained and free), applied loads, initial test results. Make sure everyone is in agreement to how you're simulating the actual structure with your FEM.
  6. Decide which load cases are critical for your analysis. You probably don't need to run all potential load cases, just the critical cases.
  7. Once you've had your review and feel confident that your model is running properly, make your runs.
  8. Have another meeting with your peers to review your results to make sure they make sense. It's good to have a fresh pair of eyes looking over your work and results.
These are the basic steps I take when working on a FEA project, and I often suggest the same steps to the novice FEA users in my group. Hope this helps.

RE: What does the FEA process look like at your company?

One practical tip, which was already mentioned is to start with fully linear model. Make
sure the model is working, reaction loads etc.

Then move to non-linear analysis but try to save elements. Make sure the model is working,
for example in ANSYS you can visualize all the contacts at same time. 16h turnaround time
might be fine for the final analysis but not for troubleshooting and fixing errors. HPC might help.

RE: What does the FEA process look like at your company?

I work for a software sales company so I don't do much "real" analysis but I do spend a lot of time troubleshooting customer models and helping them with workflow so I'll offer some suggestions (in no particular order):

1) Make sure you understand what actually needs to be modeled. I see people throw everything under the sun into their model when the could get away with a much smaller scope and some proper boundary conditions.
2) Make sure you're using the right tool for the job. There are tons of "good enough" designer-oriented products that could drastically reduce your turnaround time.
3) Set up debug models. This varies with the type of analysis (fea/mbd/cfd) but starting off with a crappy mesh and rough boundary conditions will help you spot a bad boundary condition before you waste 2 days on an analysis. One thing I like to do is overload forces or something similar to force an exaggerated response, makes spotting errors easier.

Senior Application Engineer
enginsoftusa.com

RE: What does the FEA process look like at your company?

I once worked in a company which was better in creation of quality processes than in FEA (say, Company A) and once in another company which was better in FEA than quality of the process (name it Company B). This is how the process looked like:

COMPANY A
1. Clarify with Client any technical doubts
2. Create four-page summary explaining in general how FEA will look like (peer to check it)
3. Create FE model (peer to check it)
4. Apply loads, constraints and other important settings (peer to check it)
5. Debug model using simplified features (e.g. all contacts bonded)
6. Run model overnight
7. Interpret results (peer to check it)

COMPANY B
1. Create final model and run overnight
2. Debug problems found next day
3. Interpret results (peer to check it)

I would vote for the first process. The essential was this short summary describing what FE-Engineer intends to do. That was great and clear reference, worth 3h to be created so all people participating in decision could give it a green light or stop it. As FEA gets more popular, it is crucial to use quality system along all the process. But, if your top management is not aware of it, then I think a big success in FEA career should not be expected in this particular company. It's simple as that, either everyone understands role of the FEA or we have got a typical miscommunication.

RE: What does the FEA process look like at your company?

Good comments have already been offered. Just one additional thought: I would advise involving an FE expert outside of your immediate group, especially one who uses a different set of tools for their analysis needs. Diversity of perspective helps tremendously.

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RE: What does the FEA process look like at your company?

This was a helpful post. I'm currently stuck on the same boat. I had CFD experience but have been recently asked to do FEA. At this point of time i'm trying to learn hand calcs with design codes along with enrolling in basic NAFEMS courses. FEA is miles apart from CFD - and it does not help that I studied mechanics of materials 7-8 years ago.

RE: What does the FEA process look like at your company?

(OP)
Thanks everyone for the input, there's some good food for thought. I guess my concern is more about the actual work load and how you handle solving times and if you fill that time in with other work or how you balance multiple projects at once. Or even how many projects would you work on at the same time?
We're a very small company. Most of the FEA we do is quoted as a specific FEA project. My boss (who did FEA but hasn't really done it in 5-6 years and is pretty knowledgeable about setup and all that, but his post processing experience/skill is basically set the scale to yield and remove all red elements by changing the geometry) creates an estimate, the customer approves it, he hands the project off to me and says I have 15/30/60/whatever hours to do the analysis. Its not unusual at this point for the customer to think we've already been working on the project for a week or two before this since the estimate review was a few weeks before and they signed the estimate then. Then its up to me to have the kickoff meeting, determine any hard due dates, talk with the customer to get a feel for what they really want, put the project plan together, and be the project manager/lead/contact point and update the customer on hours used, hold weekly meetings and also (generally) do the analysis or work with someone under me to do the analysis.

For short and to the point projects/studies, its fine. A simple steel structure with a handful of loads, sure I can put a plan together and all that and it doesn't require much babysitting. But then we get projects with tons of moving parts (plan wise) or where we've never really done that specific type of analysis before and things get messy. In my bosses view, I would never just be waiting for something to solve. Doing a new type of study and waiting to see how it solves, or how fast it solves, or what effect this setting has on the convergence? We don't charge for solve time, so cram another project in there to keep generating billable hours. Then I end up with 3-5 projects and feeling like I can't really focus, especially if I'm having to hold weekly update meetings, having to update project plans, dole out work unreleated to FEA on non-FEA projects I've been assigned lead on, record all customer questions, requests, and info in the punch lists, for all of my projects. Not to mention proofreading and redlining FEA reports, or other tasks like that.

It feels like they think you should be working (updating plans, doling out work or reviewing models) every minute of every day, and that burns me out. Maybe its just me, and I'm not a great worker. Maybe its just this company. I feel like my ideal setup would be that I work with an actual project lead who can manage customer expectations and set deadlines with them and who tells me what kind of analysis or information they want, and I'm not working directly with customers, except for maybe when I'm needed to explain results or brought in for brainstorming, etc. I'd work with the lead and get deadlines like "we need this information or study done by Friday", and that's essentially my main project I'm working on. Maybe I have another task or two to fill large gaps of time, but it wouldn't be 100% hours driven. Obviously if i'm in the middle of a solve that would take 18 hours, or 3 days then yeah, I would try and fill that time with other productive work. But waiting 45 minutes to see what effect this boundary condition has on a draft mesh study, or an hour to see how this study converges with X setting changed wouldn't be abnormal or seen as "wasting customer's money". But they're also quick to use hours worked as a metric for how much effort is put in. If a study we're having trouble with getting to pass is taking 10 hours to solve, and I spent 15 hours on it through a week because I spent 3 hours each day looking at the errors/results from the previous day's study, researching solutions and testing solutions on a draft quality mesh then setting up and running the next run, they'll bring up that I worked way less than 40 hours on this and this project is hot, so overtime should have occurred. But that involves staying late and waiting for the computer to finish solving. But we aren't supposed to charge for solve time, so it really means that I need to find another project to work on while I'm staying late to get the other study to solve because the way the company is setup they rely on every single of the 40 billable hours every week. In some ways it feels like I'm a mechanic who has to fill the time he's waiting for the fluids to drain out with another task just to stay busy.

I think my point I'm trying to feel out is are there places out there that do FEA work that operate like I think a job like this should be, or am I just wrong in my thinking and expectations on how things like this should go? I hope this makes sense. I'm trying to make sense of it all in my mind at the same time.

RE: What does the FEA process look like at your company?

Quote (FEAChamp)

I spent 3 hours each day looking at the errors/results from the previous day's study, researching solutions and testing solutions on a draft quality mesh then setting up and running the next run

Quote (FEAChamp)

so it really means that I need to find another project to work on while I'm staying late to get the other study to solve

This is not a day in and day out process for me like it sounds like it is for you but I dislike when I have analysis like this. Switching modes while doing technical work and trying to change mental gears is never easy for some individuals. For me, productivity on the project is reduced when I have to find filler tasks to do between FEA run times.

RE: What does the FEA process look like at your company?

(OP)
Thanks for the input, knowing that others really do have issues like that is reassuring. One of the other things that annoys me is I try to bring up some of these issues and immediately get dismissed, like its totally unreasonable to have trouble switching gears like that. Or if I say I'm not really great at an aspect of my work or project management (read: don't enjoy it and struggle with it) they tell me "well you're a smart guy, you can figure it out eventually."

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