I saw this on LinkedIn showcasing “topology optimization”.

“Part too weak? Make it out of vibranium”

I’m a mechanical engineer but work as a project engineer for the federal government so my technical skills compared to engineers in the private industry are low. I’ve never had the opportunity to be apart of an industry design team that is innovative and refines a product as this (i was in college but not in a professional setting).

Are sections of this product broken up into several teams and those teams design a very specific part? Do engineers spend countless hours on google researching parts? What sort of engineering questions are asked? Is there software that helps?

Sorry for all the questions. I yearn for something more technical and wish I could be a part of a very technical team.

Photoelasticity (often called photostress) was the go-to way to “see” stress in transparent parts from about the 1940s to the 1980s. Engineers coated or made models from special plastics, then viewed them under polarized light—stress showed up as colorful fringe patterns, making high-stress areas easy to spot.

Before that, stress was measured with mechanical strain gauges or calculated by hand. Today, it’s mostly replaced by digital strain gauges and finite element analysis (FEA), which give faster, more precise results without physical models.

AeroJAX GitHub Repository - Drop a ⭐ if you find this kind of real-time CFD interesting

Real-time CFD comparison: sedan vs hatchback wake structures

The hatchback develops a much larger rear recirculation zone, which is one of the reasons hatchbacks tend to accumulate more dirt on the rear surface.

2D LBM simulation running live in JAX.

(apologies in advance if this is the wrong sub for such questions)

why is it that most modern passenger airliners place wings below the fuselage (indicated with upward pointing arrow)

but wings are often placed above the fuselage (indicated by downward pointing arrow) for heavy transport aircrafts

and what explains it not being so clear cut for fighter jets

what factors come to determine such designs? aerodynamics? structural/mechanical? manufacturing?

Weaklings Short version:

25yo mech engineering grad in Brazil. Love the math/theoretical/CAE side, hate repetitive CAD/BOM corporate tasks. Scared freelancing will only yield simple low-end projects without heavy experience. Not a fan of academic research. Looking for career path advice.

_______________________________________

Recently, I decided that I’m willing to give up higher compensation if it means doing work I actually enjoy.

I graduated from a top-tier public university in Brazil with one of the best academic performances in my class, and I'm currently interning in R&D at a solid company.

I have a strong passion and aptitude for the theoretical and mathematical sides of engineering. However, I have zero interest in sitting for public civil service exams, becoming a professor, or grinding away in academia just to "publish papers."
On the other hand, I really dislike the corporate world. I feel like I'm just another cog in the machine and that my work barely matters. On top of that, it gets extremely tedious just clicking around in CAD, checking if a "part fits," preparing BOMs, documenting, and sending files off to manufacturing.

At most, I look through supplier catalogs to select a component, do some GD&T stack-up analysis, or use some creativity to design sheet metal, welded assemblies, or machined parts following DFM/DFA best practices. That’s the most "technical" part of the job. Still, in my view, it demands very little deep study, conceptual understanding, or advanced knowledge.

Other than that, at most I might do a simple beam or fluid flow calculation.

What I actually enjoy is the creative and mathematical side of design—tasks that require study, thorough preparation, and deep conceptual thinking. Things that not just anyone can do, where you actually have to dive into equations or complex concepts to get the design right.

I thought about going full freelance/independent consultant, but I feel like I would just be swapping a boss for a client. Sure, I’d have more flexibility and a stronger sense of ownership over my work, but the projects would likely remain simple. I doubt I'd get to do high-complexity analysis unless the client is from a high-risk, high-value industry like Oil & Gas, Naval, Aerospace, or Defense. And let’s be honest: those companies only hire contractors with years of experience, not a fresh graduate like me.

I feel stuck. Staying corporate means going to the same place, seeing the same people, and doing the same repetitive tasks with little recognition or sense of purpose.

Going freelance gives me flexibility, but leaves me with simple projects and the financial instability of running my own business.

I don't know. I’d love to hear your thoughts or learn from anyone who has been in a similar position

The goal was to develop a low-cost 6-DOF robotic arm platform that lets me build foundational robotics and ROS 2 skills on real hardware instead of only simulation. I wanted a system where I could explore the entire robotics stack, including embedded firmware and motor control all the way up to motion planning and digital-twin simulation.

It has also been a great opportunity to experiment with custom and unconventional joint and reducer designs that I haven’t seen implemented on any robotics platforms.

Mechanical Architecture:
Each joint section was designed and built independently, and later connected using clamped carbon fiber tubes. This modularity allows each joint to be iterated on separately, while the tube lengths can be swapped to change the arm’s reach or payload capacity accordingly.

Joint & Reducer Designs:
The base joint uses a traditional planetary gearbox. While the shoulder and elbow joints use a split-ring planetary gearbox, by utilizing two slightly offset ring gears driven by a common set of compound planets, this design provides an incredibly high torque density in a compact form factor. Which is what allowed me to achieve a 70:1 and 40:1 gear reduction respectively, while keeping a large contact area to minimize stress between the plastic gears, all without the bulk or backlash of a multi-stage system.

Because this gearbox configuration does not provide an accessible output shaft for a conventional encoder, I implemented a custom sensing approach: alternating polarity magnets were mounted around the output ring gear, and a magnetic encoder is positioned perpendicular to the axis with an offset, allowing it to perceive the alternating magnetic fields as a spinning radially magnetized magnet.

The spherical wrist uses an inverted belt differential with a custom bearing track to maintain consistent pressure on the belt to prevent skipping. All three wrist motors are mounted behind the elbow joint so they act as a counterweight, reducing inertia at the wrist and improving dynamic performance.

Embedded Control & Firmware:
The robot is controlled by a STM32 microcontroller, where I developed custom firmware in C to manage SPI communication with 6 daisy-chained encoders, CAN bus communication with a Raspberry Pi, PID loops and step generation for motor control, and a state management safety system.

Higher-level planning will run on a Raspberry Pi using ROS 2, where the arm will interface with MoveIt for motion planning and simulation; this is still under development.

A write-up of the mechanical design, CAD, and firmware architecture is available on my portfolio, with a deeper breakdown of the ROS-based software stack coming eventually: https://jcgullberg.github.io/projects

For an application that’s crucial to be weight saving and easy to service, why are there a million screws? I think these on the picture (from a Boeing 737-800 that I’m on right now) are quick release fasteners.

Sums it up

They exist. This is not a test. Mcmaster cards are live at fabtech

Designed this simple latch mechanism that can unlatch without need for additional actuators, but I can’t find anything similar, it seems so simple it must be used somewhere?

All that just to make the file 15mb lol.

When i open it after a day it feels like ancient text

I have been working on a sci-fi planetary exploration vehicle for a while and right now while detailing the chassis I keep wondering what a mechanic/engineer would say about it. How realistic is it? Would it fall apart if it was built? This is just a question in general, for the future, so I can make my next vehicle better.

Edit:
REALLY HUGE THANKS to all the comments and looking up all the new terms, I have been going through them all day and started to make a list of things I want to add:
- another rubber boot where the CJ Joint enters the wheel (drive shaft to wheel)
- U-shape thingy so that the drive shaft bends where the two parts of chassis meet.
- more Drive Shaft support
- undercarriage cages
- pumps for all the Hydraulics
✘- shock absorbers need springs no need for this, cause now I got "advanced magneto hydraulics"
- breaks on drive shaft or parts that go from chassis to wheels
- add grease nipples on hydraulics - not sure where yet.
- axle breaks
- make lower arm that goes from frame to the wheel a hydraulic, so it could control the tilt angle of the wheel.
- anti-fall harness track inbound of the railing
✓ done - change how turning mechanism (hydraulics) attach to the wheel part. From ball baring to high-misalignment spacers.

There were many other great suggestions, pointers and things people noticed, but I am just making an essential list of things I can add, that does not need to severely alter the model.

Thank you everyone!

In case you want to see some renders, here is my ArtStation: https://www.artstation.com/artwork/ndwE3O
I also have a short render animation from a few weeks ago: https://www.youtube.com/watch?v=53fEGQGGd4M
And if anyone wants to follow the long and boring process of creation, I post almost daily updates on X: https://x.com/AKantemirov

Keep your engineers cool and hydrated