Love the article, Dominique, and definitely on point for new and early practitioners to seriously consider.
I struggle seeing posts online where FEA tool users are struggling to debug very, and in my view unnecessarily, complex models. I don’t see free body diagrams, hand calculations with an initial prediction of the anticipated results, appropriate use of mixed elements (generally just a solid mesh of test or sometimes hex elements), and no use of an incremental complexity approach.
My only addition would be to your list of references. Blevins’ Formulas for Natural Frequency and Mode Shape (the dynamics version of Roark’s) and I always kept a copy of Timoshenko’s Plates and Shells in case I ran across a situation not covered in Roark’s.
Thank you Scott, this is a great addition. You are describing exactly the pattern I keep running into as well, models that get complex fast because the basics got skipped: no free body diagram, no predicted result before running, everything meshed in solid tet by default, and no incremental build up from a simple representative model.
Blevins is a great catch, I should have included it alongside Roark's since natural frequency and mode shape estimates deserve the same hand calc discipline as static deflection and stress. And Timoshenko's Plates and Shells is the right fallback for exactly the cases you describe, when a geometry or loading condition falls outside what Roark's covers directly.
Since I am an aerospace engineer I would also add "Analysis And Design Of Airplane Structures" by E. F. Bruhn. I am using it a lot.
Welcome aboard, Anilkumar! Great to see that hand calculation remains part of your toolkit. It is a skill that pairs well with FEA and helps build the engineering judgment needed to validate simulation results.
Great article. I completely agree that hand calculations are not about replacing simulation, but about building confidence in the results. A quick analytical check before or after an FEA run often helps identify issues with assumptions, loads, constraints, or unexpected behaviour. Looking forward to the upcoming discussions in Beyond the Mesh.
Thank you, and well put Mahendher. That is the core of it, hand calculations are there to build confidence, not compete with the model. Whether it is a quick check before running to set expectations or a sanity check after to explain something unexpected, they earn their place either way. Glad you're looking forward to Beyond the Mesh, more of this kind of discussion is exactly what I have planned there.
Thank you Vuk, glad it hit the mark. Niu's books are an excellent addition, all three (Airframe Structural Design, Composite Airframe Structures, and Airframe Stress Analysis and Sizing) are staples for exactly the kind of hand calc discipline the article is about, especially on the aerospace structures side. Appreciate you adding them to the list.
I once did a training, per the suggestion of my manager, called Practical Stress Analysis for Design Engineers, by Flabel. It was a handful of years after I had started my career and when I’d already had exposure to FEA. I recall wondering, “Why do I need to (re)learn how to do all these calculations by hand?” The lessons (and book) proved to be pivotal in my career.
Not too many years later, I ran into an issue with an FEA of my own design that was struggling to pass. I paused my simulation efforts to attempt some multi-step hand calcs. Not only did my hand calcs get very close to the results I was seeing in FEA, but they also revealed the big load component that was the biggest contributor to the stress problem (and thus provided the ideal fix).
Thank you, Josh, and that is a great story. The instinct to question "why relearn this by hand" is a common one early in a career when FEA feels like the whole toolkit, and it usually takes an experience like yours to show why it isn't.
The part that stands out is how the hand calc did not just confirm your FEA results, it decomposed the problem enough to isolate the dominant load component driving the stress. That is often the real value, an FEA model gives you a number, but a hand calc built from free body diagrams forces you to understand where that number comes from.
Flabel's book is a solid one to have had early, it is very design engineer focused and pairs well with Roark's for exactly this kind of structural sizing and troubleshooting work.
Love the article, Dominique, and definitely on point for new and early practitioners to seriously consider.
I struggle seeing posts online where FEA tool users are struggling to debug very, and in my view unnecessarily, complex models. I don’t see free body diagrams, hand calculations with an initial prediction of the anticipated results, appropriate use of mixed elements (generally just a solid mesh of test or sometimes hex elements), and no use of an incremental complexity approach.
My only addition would be to your list of references. Blevins’ Formulas for Natural Frequency and Mode Shape (the dynamics version of Roark’s) and I always kept a copy of Timoshenko’s Plates and Shells in case I ran across a situation not covered in Roark’s.
Thank you Scott, this is a great addition. You are describing exactly the pattern I keep running into as well, models that get complex fast because the basics got skipped: no free body diagram, no predicted result before running, everything meshed in solid tet by default, and no incremental build up from a simple representative model.
Blevins is a great catch, I should have included it alongside Roark's since natural frequency and mode shape estimates deserve the same hand calc discipline as static deflection and stress. And Timoshenko's Plates and Shells is the right fallback for exactly the cases you describe, when a geometry or loading condition falls outside what Roark's covers directly.
Since I am an aerospace engineer I would also add "Analysis And Design Of Airplane Structures" by E. F. Bruhn. I am using it a lot.
Welcome aboard Scott. Great to have you here.
Great topic to kick off the new newsletter with. If there is only one lesson I'd like new Engineers to learn and remember, this is it!
Thank you Matt for your feedback. I agree with you, I think it is an important topic. Welcome aboard.
Great article to start off towards understanding the FEA to its core.
Earlier I missed this part in my day to day task. But now it has taken major part.
Welcome aboard, Anilkumar! Great to see that hand calculation remains part of your toolkit. It is a skill that pairs well with FEA and helps build the engineering judgment needed to validate simulation results.
Great article. I completely agree that hand calculations are not about replacing simulation, but about building confidence in the results. A quick analytical check before or after an FEA run often helps identify issues with assumptions, loads, constraints, or unexpected behaviour. Looking forward to the upcoming discussions in Beyond the Mesh.
Thank you, and well put Mahendher. That is the core of it, hand calculations are there to build confidence, not compete with the model. Whether it is a quick check before running to set expectations or a sanity check after to explain something unexpected, they earn their place either way. Glad you're looking forward to Beyond the Mesh, more of this kind of discussion is exactly what I have planned there.
Great article. It is exactly what I am looking to improve. I would add all 3 books from Niu. I find using these often.
Thank you Vuk, glad it hit the mark. Niu's books are an excellent addition, all three (Airframe Structural Design, Composite Airframe Structures, and Airframe Stress Analysis and Sizing) are staples for exactly the kind of hand calc discipline the article is about, especially on the aerospace structures side. Appreciate you adding them to the list.
Great article.
I once did a training, per the suggestion of my manager, called Practical Stress Analysis for Design Engineers, by Flabel. It was a handful of years after I had started my career and when I’d already had exposure to FEA. I recall wondering, “Why do I need to (re)learn how to do all these calculations by hand?” The lessons (and book) proved to be pivotal in my career.
Not too many years later, I ran into an issue with an FEA of my own design that was struggling to pass. I paused my simulation efforts to attempt some multi-step hand calcs. Not only did my hand calcs get very close to the results I was seeing in FEA, but they also revealed the big load component that was the biggest contributor to the stress problem (and thus provided the ideal fix).
Thank you, Josh, and that is a great story. The instinct to question "why relearn this by hand" is a common one early in a career when FEA feels like the whole toolkit, and it usually takes an experience like yours to show why it isn't.
The part that stands out is how the hand calc did not just confirm your FEA results, it decomposed the problem enough to isolate the dominant load component driving the stress. That is often the real value, an FEA model gives you a number, but a hand calc built from free body diagrams forces you to understand where that number comes from.
Flabel's book is a solid one to have had early, it is very design engineer focused and pairs well with Roark's for exactly this kind of structural sizing and troubleshooting work.