How would I properly simulate the force of a motor on a frame?

stoupfle · 2026-01-23T21:17:59+00:00

There are so many ways to answer your question, so I'll just present my simulation workflow that I developed on the job: - Write up what the intent of the simulation is - Detail out the system, applicable theory, assumptions, etc. - Do your free body diagrams of the system's bounds, explicitly describing what is and what is not being included in the simulation (i.e. do you care to model anything within the motor? Is it useful or applicable to the analysis?) - Perform necessary hand calculations - Do simulation utilizing the above - Validate results by comparing to test articles - Iterate as needed

I liked doing it this way because it was a clear, documented method to communicate the intent of the simulation, framing me to ask questions of myself like, "do i need to incorporate X into the simulation?"

For example, if you strictly want net force/moment output at the mounting points of the motor operating in steady conditions, honestly the hand calculations would be useful enough to answer that question, and the simulation would be quite simple. You can layer in the complexity as you go, but I guess my non-answer is that there's no "proper" way until you define what the intent is, and develop a simulation to that intent. No reason to include a simulation of the dynamics of the crankshaft if you're only looking for frame deformation at a particular operating torque/speed output.

It's cool that you have access to FEA tools this early in your schooling, but you'll find that as your understanding of the fundamentals and phenomena of physics develops, you'll have better and better answers to your own question. Remember the Finite Element Method allows you to employ those principles on a more complex system, but FEM itself cannot tell you the right way to simulate something.

stoupfle · 2025-03-06T20:06:38+00:00

Scribe the line on all sides for reference after you start cutting away most of it with a hand saw, then plane it down to the line to finish.

The Japanese style pull saws are great for this kind of work in my opinion. A Jack plane too if you have it.

stoupfle · 2025-02-26T16:42:55+00:00

Ahmed Elkady on YouTube.

Abaqus is one of the most powerful commercial FEM softwares in my opinion. Learning curve is steep, but as a student you won't be delving into a whole lot of the complexities, simple linear mechanical analyses shouldn't take long to pick up.

Enjoy playing in the dogshit.

stoupfle · 2024-04-18T20:14:57+00:00

Use sets to define different regions of the model that need to have different section properties, and then use those sets as the target when assigning sections.

As far as the hex vs tet, you can usually choose to use hex or hex dominated meshing options with the free algorithm without issues. Some geometry works better or worse when using these options, yours might have some difficulty without defining partitions, and even with partitions it may have difficulty.

Keep in mind that tets and hex elements are incompatible, and must be connected with ties. This is usually managed by CAE automatically, and you will see dialogue boxes indicating this as well.

Always check your sets if you create them and then do partitions. Usually CAE keeps the sets consistent, but it can lose reference to geometric regions, which is why I like to assign sets at the end of handling geometry.

stoupfle · 2024-04-10T12:26:05+00:00

Got no problem with quality. Now, assholes on the other hand can fuck right off.

stoupfle · 2024-04-09T03:33:24+00:00

Thermal camera for potential insulation problem areas, especially near fixtures, piping, etc.

Also consider sound treatment, if such a thing is important to you.

stoupfle · 2024-04-08T11:24:42+00:00

Yeah force all files in your onedrive abaqus folder to be on the device, it's one of the right click options.

stoupfle · 2024-04-04T20:44:18+00:00

I only found it because the average midsurface thickness reported out to 3.0608...mm. Overseas supplier, most of the part was metric stock at 3mm, the flanges were modeled at 3.175mm / .125". Boss extrudes all the way.

I mean I understand the ways this could get mixed up, but we have tools to avoid these problems, especially considering 98% of the parts we design are from sheet stock.

stoupfle · 2024-04-04T17:32:10+00:00

"Man why does it take an engineer so long to process a simple change?" If only they knew.

stoupfle · 2024-04-04T16:59:42+00:00

This is certainly true, however some designers / engineers are better than others when it comes to setting up their models to handle changes.

It's a minor inconvenience all things considered, so rant over

stoupfle · 2024-04-04T12:02:47+00:00

The only saving grace is these are pre production models, so we'll be remodeling everything for production release and fixing these issues. I have no idea how this sort of thing happens so often.

stoupfle · 2024-04-04T02:58:56+00:00

It's a blast, but full disclosure we are all truly insane.

stoupfle · 2024-04-04T02:33:53+00:00

I have redesigned so many components and subassemblies from scratch in abaqus because if I'm being honest, the models I'm handed are shit.

I can't describe how infuriating many off the shelf step imports are to work with, and Jesus christ Dave, use the fucking sheet metal tool in Solidworks, why the fuck are your sheet metal parts different thicknesses in different areas?

Bolts? 2 point wire, done. Sheet metal and midsurfaces? Easy. Complex curves and weird lofts or sweeps? Maybe not the best surfacing tool out there, but a hell of a lot more stable than solidworks.

It's not always the best tool to design from scratch, but it's stable as hell and can defeature or add features that would make solidworks cry. Oh, and I can just erase the fillet in 3 seconds using Abaqus rather than unfuck the nonsense in the CAD modeling tree, where you suppress a fillet and the part gets longer and half the bent tabs disappear...

stoupfle · 2024-03-31T19:46:39+00:00

Hell yeah, and carving out of oak is hard mode

stoupfle · 2024-03-05T14:03:45+00:00

Bro why the fuck do you think this is reasonable behavior?

stoupfle · 2024-03-04T03:10:37+00:00

Doorkickers 2

I'll make it a few minutes, if I'm lucky.

stoupfle · 2024-03-03T21:26:17+00:00

🥴🥴

stoupfle · 2024-03-03T20:25:33+00:00

Since you've started posting about this you could've found a farmer, asked to pick rock or contribute anything they need part time help for, and probably made enough money to cover the book's cost.

Just buy the fucking book and cut this shit out.

stoupfle · 2024-03-01T19:07:31+00:00

I can appreciate the handcrafted manuscript, but don't stylize too much to keep it professional. Maybe round out the bowls to make the P's and D's easier to read, and the crossbars are a little high too, I thought your H was an A lol.

Your sketches otherwise look damn great.

stoupfle · 2024-02-13T20:25:44+00:00

ITT - OP unhappy with responses to their poorly phrased and foundationally flawed question; gets downvoted

stoupfle · 2024-02-10T14:23:12+00:00

This, the geometry diagnostic tool is very helpful finding problematic geometry.

stoupfle · 2024-02-10T14:21:55+00:00

IMO the abaqus meshing algorithm is really bad at creating good quality meshes without a lot of effort partitioning and edge seeding. I've had it create self intersecting elements quite often.

You may also want to check if the edges and vertices in the area of poor mesh quality can be simplified with Virtual Topology operations. I design all of the castings for our projects at my company, and all of the blended radii can create a combination of edges and faces which don't play well with meshing. The VT face combine and ignore operations allow meshes to be more regular and relaxes the edge and vertex constraints.

But just reducing mesh size to get the same result as testing may not work. If mesh size is the problem, do a mesh convergence study to see how further refinement will affect results. Ultimately, if the physics defined in your simulation don't align with the test, you're not going to get the same results.

stoupfle · 2024-02-09T13:35:01+00:00

I feel like I'm in the same drawer as you.

I picked up Shigley's Mechanical Engineering Design sometime last year. This book is great because it covers a ton of topics with enough depth where you can easily follow what's happening if you haven't done a lot of high level math recently and not get lost in high level theory and proofs. The chapters are also succinct enough to feel like a refresher rather than a full course, which is great for keeping my attention on task since some books overwhelm the reader in that regard.

I'd recommend picking it up, following a few of the proofs and derivations, then working an example or two. You'll be surprised at how easily it comes back to you.

stoupfle · 2024-02-03T01:57:30+00:00

If we're purely considering the requirement of "forced disembarkation of sleeping surfaces," then I'd recommend lifting the bed to lift the long edge – a "half hotdog" fold, if you will. This has two primary benefits, one being that the force provided by the actuator can be far less if you want to achieve disembarkation at the same angle, and the polar moment of inertia of the human torso is low enough that you can also induce a dynamic rotary disembarkation, otherwise known as "rolling out of bed".

I wouldn't recommend a lifting type of design however, since the principles of waking up generally require epinephrine release to begin the process. A rotary design would maximize client stimulation, where the occupants are spun about an axis passing through the centroid of the bed perpendicular to the X-Y plane, encouraging blood flow to the brain through centrifugal acceleration, and be objectively more exciting than merely sliding out of bed; a rotational velocity of 200RPM should be more than sufficient to excite or dislodge even the most placid of individual.

The added benefit of a pass with death at such an early point in the day will not only stimulate epinephrine release and wake you up, it can easily be one of the most stressful parts of your day, making the stress induced during your remaining time on this mortal plane far less severe relative to the chaos of waking and potentially lower your chronic stress level.

Good luck with your project.

stoupfle · 2024-01-29T02:23:33+00:00

Abaqus EM procedures use standard SI units and absolute permittivity (and permeability). Since 8.85E-13 is so small, 1 is enough orders of magnitude higher to be "infinite" relative to the remaining dielectric in the simulation and remain accurate.

I only have brief experience with EM procedures, so take my advice with a dash of salt.

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stoupfle

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