Is having to do calculations absolutely key as a mechanical engineer? & How complex are they? 4

Most companies hire you for your capabilities, not to train you in the fundamentals. Being able to do simple calculations is, I believe, necessary. How do you know if FEA or any other software is correct or even close if you don't understand the math? Study up.

Ted

So I understand that you have been doing engineering for 8 years now as a junior engineer. However you want to get into FEA stress analysis, which you have no experience in, but your company doesn't have any entry level positions in their FEA department so you are looking to other companies. However other companies appear to be looking for someone who already has experience and can work on thier own. In any case you want to make FEA analysis your carreer path. Correct?

You have a problem in that with 8 years experience you are really no longer an entry level and you are getting out of the range of junior engineer and are almost at a point where you are expected to work on your own. Perhaps you can discuss with your company that you really want to make FEA your carreer and to allow you to join their FEA department on an entry level basis. It would probably only take a few months working with others before you get up to speed and are able to work on your own if you are working with someone who knows the programs. Maybe you can talk to the person in charge of FEA and convice them that you are a good person to take a chance on. If you have worked for the same company for 8 years then you already should have some people who can give you a good recommendation to the FEA department.

Otherwise you may find an opening for entry level FEA in another company and possibly can take some courses to learn the program beforehand so that at least you can tell them you have some experience using the programs.

Long ago, when I was in college, I found that the college library (in Texas, USA) had a subscription to the British mechanical engineering society's magazine. As best I could tell, over there, "mechanical engineer" had a lot more overlap with "mechanic" or "operating engineer" than it does here. My point is that some of the usage and the expectations may vary depending on where you are.
That said, there is endless variety in mechanical engineering jobs, and it's not like we all just sit around doing FEA analysis every day, either.
You can work on what you're lacking in, as suggested above. But also take a good hard look at what you DO know, what you do have experience in- there are probably engineers out there missing that knowledge as well.

I work as a consultant in general industry (chemical/pulp&paper/power) and for our stuff there is basically zero FEA done on a regular basis. Things like pipe stress modeling (simplified beam theory) or flow modeling are done all the time, but FEA only really ever comes up when something HAS to be a certain way and the "normal" methods suggest it fails or something like that.

Tank/Vessel/Equipment manufacturers frequently do FEA for nozzle loads on their side of things. But in my experience as a consultant, I'm not designing new components that need FEA modeling to get things perfect. We're using normal flanges, following piping codes, etc...it's only the really off the wall situations where we need a sub to do FEA. Your mileage may vary.

My first job out of uni was to compare the results of a shell FEA with a beam element and spring approach with hand calcs, which were usually, but not always based on Bruhn. Other fun jobs in that year were speccing out a composite leaf spring, and writing an element ordering program (wavefront optimisation as it is called, done automagically these days). So in my book you are 8 years behind the curve. You must brush up on hand calcs, and free body diagrams, and statics. You need to sit down with your management and get into your stress group.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

At companies doing lots of novel/custom work, design engineers decide which calculations are necessary.

At companies who do design without extensive novel design work, the engineers typically have calculation tools that make the common calculations a basic input/output exercise.

At large companies, there are typically analysis specialists who do nothing but the detailed calculations.

At any company, there are detailed and time consuming calculation methods and simple napkin estimates. Know both, and when to use both. Too many engineers spend a career building a perfect framing hammer and persist in hammering screws too. Some also get pedantic, demanding a slew of input values to perform a highly advanced calculation that is actually garbage out because other users are forced to input garbage to proceed. The pedants often have a singular past experience that taught them to include that 'one more thing' but it's just as important to know when those extras can be safely left out or covered with conservatism.

*In all cases* a successful and responsible engineer will understand the accuracy/validity of the inputs, the basic way the calculation works, and the sensitivity of the outputs to the inputs, assumptions, and algorithm. This should apply to all of the roles I mentioned above, but sadly most companies engineering teams have a minority of their staff who can truly think holistically and consider *all* of the important things in reasonable balance. Analysts get good at making calculations, sales engineers get good at providing numbers and inputs that keep the transaction moving forward, etc.

Some companies / departments might expect their FEA analysts to be able to long-hand the matrix math of the solution algorithm. I'm finding that's less common now as models grow and the algorithms and supporting tools refine. What really matters is fully using the tools that help confirm convergence and/or validity and knowing how to bracket your assumptions and inputs to ensure your analysis is actually useful. I will, without shame, admit I use FEA for structural modeling and I cannot do the matrix math. But I have worked hard to understand every other aspect and I'm always thinking of ways to verify the modeled scenarios against tested reality.

No matter where you go or which role you might fulfill, you need to learn the analytical stuff starting where you are and build in complexity based on success of the simpler cases first. Most everyone by now is aware of how much they forgot from their uni and will forgive you if you have self-awareness of which calculation methods you have had chance to practice and which ones you have not. If the job description methods stress analysis, go back and quickly refresh on the terms and concepts. Unless you're applying for an advanced position with very specific expertise, conversation like that should be a green flag not a yellow or red flag on you as a canditate.

Last word of my lecture is conservatism. Conservatism is speed/simplicity/safety. It is a balance between the cost and risk of the final product against design cost and risk. Understand where your business applies it, how much is required considering the accuracy of the inputs and calculations, and when there is too much or too little conservatism.

what field are you working in ?

there are many fields where the "engineer" doesn't do calcs (merely looks up manuals and such, like customer support or project "weenies" who run schedules)

if you're working in a technical field (like stress analysis) and not doing calcs then I fear for what you produce.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

A quote about a PE from a different field, long ago- "All he's ever done is watch them lay asphalt."

If i had to guess I'd bet that a majority of engineers only perform calculations occasionally if at all (members of this forum are not a representative sample), and when they do calculations they are mostly just entering data into a spreadsheet or commercial software package.

For many engineering jobs an engineering degree is required to interview for the position but not required to perform the activities of the job.


-Christine

I see a lot of comments about engineering calculations are now done by just punching numbers into a spreadsheet. Either I am really old school or severely behind the times: my engineering notebook has all calculations written out and can be followed step for step by others should they wish. Even if I run a stress analysis in Solidworks, I have hand calcs to support the basic range of results. Occasionally, a spreadsheet output is used to try multiple iterations but the basis was already written by hand. The design elements I work on are generally static conditions, and no extreme dynamic forces so that does reduce some need for advanced analysis. I believe in paper!

yes you are (and so am I)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

Yep, you are old school. SOP these days seems to be bludgeon the problem with a huge FEM and blindly believe the results. Asking someone to draw out a free body diagram often seems like asking them to flap their arms and fly.

Banana Duck said:

Is having to do calculations absolutely key as a mechanical engineer?

Click to expand...

Yes it is.

Even if you are in a position where you aren't doing them every day, you need to know how.

See all of the questions here on Eng-Tips from people asking for help doing their calculations.

Who do you want to be in the future, one of the people always asking for help, or one of the people always able to give help to others?

Which do you think has the better long term employment prospect?

Brian Malone said:

I see a lot of comments about engineering calculations are now done by just punching numbers into a spreadsheet. Either I am really old school or severely behind the times: my engineering notebook has all calculations written out and can be followed step for step by others should they wish. Even if I run a stress analysis in Solidworks, I have hand calcs to support the basic range of results. Occasionally, a spreadsheet output is used to try multiple iterations but the basis was already written by hand. The design elements I work on are generally static conditions, and no extreme dynamic forces so that does reduce some need for advanced analysis. I believe in paper!

Click to expand...

My current company uses MathCAD for a lot of calculations. The MathCAD calculation can be compacted to show just inputs and outputs or expanded to show every step of the calculation. Excel is scary because the formulas are hidden and I don't think they take reliability seriously. MathCAD has the speed and versatility of digital tool with all of the benefits of a longhand calculation.

(That said, it's too bad that PTC bought MathCAD and tore the program down to its current state. It's much slower and less reliable now and every long-time customer will tell you about how they changed file format and gave us garbage support for our existing files. Maybe there is a MathCAD alternative that doesn't have the mega-corp rot yet)

Christine74 said:

If i had to guess I'd bet that a majority of engineers only perform calculations occasionally if at all (members of this forum are not a representative sample), and when they do calculations they are mostly just entering data into a spreadsheet or commercial software package.

Click to expand...

Not to go off-track again but there are many roles advertised as Engineers whose 'design' is choosing options and minding error messages to ensure the configuration is within corporate operating limits. Never underestimate the number of babysitters and sheepherders required to support the sales team of a technical product company. That support team is usually degreed engineers and they mostly do heavy lifting for the sales reps. HR and management will sell these roles as engineering when in fact 95% of the work is sales administration. Rule of thumb, if a job role places you directly against sales in the business process, it will take most of your time and effort and stress to extract the information you need with sufficient accuracy. And the job title will probably include 'engineer'.

For all of us praising the benefits of our powerful electronic tools (CAD, spreadsheets, MathCad), remember this: An engineer is always capable of making huge mistakes, regardless of the tools he chooses to use. His own human judgement is his best defense against that possibility. Best example - years ago NASA crashed a robotic explorer on the surface of Mars because some highly educated engineer neglected to convert mm to inches.

MintJulep "Which do you think has the better long term employment prospect?"

I think this is debatable because technical tasks are easy to send overseas, but non-technical skills like managing projects and interfacing with clients are harder to come by in a global marketplace.

On top of that, technical proficiency in a specific field isn't generalizable to other engineering fields, but soft skills like management are relatively easy to transfer from one company to the next.


-Christine

Sounds like the OP's employer is stuck in the 90s. IME analysis is almost entirely done by the generalist design engineer who created the 3d model whether its hand-calc, spreadsheet, FEA, CFD, or otherwise. Niche analysis depts do exist but they're not going to run a modal analysis for every bracket, clip, or other simple part - that's the generalist's job. There are also engineering roles that are mostly non-engineering like customer support, product-definition/planning, PM, etc but getting hired into those roles generally requires time spent in design so yes, analytical skills are important. I recommend the OP have an honest discussion with their supervisor and the FEA dept about opportunities to develop their analytical knowledge/skillset bc its not really optional. Technology has become so cheap and common that there's no good excuse to justify not using/understanding it.

"technical proficiency in a specific field isn't generalizable to other engineering fields, but soft skills like management are easy to transfer from one company to the next."

Oh my. Where's the popcorn?

Ah heck I'll bite. Technical proficiency for engineering, in the sense used here for mech engineers, and the ability to do hand or computer-based calcs (thermal, structural, chemistry, and general physics modelling) is absolutely portable across multiple disciplines and fields. Knowing how to solve math problems in electronics can be used to help solve math problems in acoustics/mechanics/structures and dozens of other completely unrelated regimes. And thermal modelling is useful everywhere.

But "soft" management skills, in the form of the crap taught to MBA's? Yeah, not gonna find much love for that here. It's like going to a class where the teacher is completely unfamiliar with the course material, and claims "I don't need to know anything to teach it, I just need to know how to teach". Uh hunh, until somebody asks a question... Same for MBAs with no technical knowledge, and without backup when they negotiate with customers - the number of times that they sold something technically impossible and ask the engineers to just "make it work" are uncountable.

What? d'ya mean us Engineers need to Know stuff ?? nah, surely there's an app for that ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.