Mechanical analysis, proven.
Also called: Engineering analysis · Thermal & stress simulation · FEA / hand-calcs · Design verification
Using simulation and hand-calcs to confirm a design hits its targets on paper, before you spend money cutting metal or firing ceramic.
Analysis answers “will it actually work?” with numbers, not hope. For the proofing box that meant modelling a steady 26°C ±0.5°C hold on under 30W, sizing the element, and checking the ceramic survives a knock. Cheaper to be wrong in a model than in tooling.
What mechanical analysis is
Mechanical analysis is the step where you stop guessing and start calculating. You take the design as drawn and ask, in numbers, whether it will do what the specification demands. A thermal model predicts how hot the inside gets and how much power that costs. A stress analysis (by hand for simple cases, by FEA for awkward geometry) predicts whether a part survives the loads it will see. The point is to find the failures in software, where a fix costs an afternoon, rather than in the workshop, where it costs a tooling run.
It is not the same as testing. Testing comes later and confirms the real thing behaves like the model. Analysis comes first and tells you whether building the real thing is even worth the spend. In my experience the teams that skip it are the ones who fire their first ceramic shell, plug it in, and discover the kitchen never gets above 22°C. Two months and a tooling deposit gone, to learn something a spreadsheet would have told them in a morning.
For a heated, structural object like the proofing box, three questions matter. Does it hold temperature on the power budget? How long to warm up? And does the ceramic survive ordinary handling? You answer all three before committing to tooling.
- Fire the ceramic, fit an element, switch it on, see what happens.
- Discover the power budget is blown after the tooling deposit is paid.
- Find out the corner cracks when a customer knocks it off the bench.
- Prove the 26°C ±0.5°C hold on under 30W in a thermal model.
- Size the element with margin before anyone orders one.
- Check the drop case in FEA and design the feet to fix it on paper.
How it fits the bigger picture
Mechanical analysis sits in Stage 07 Engineer. It feeds straight into electrical engineering (07.10.06), where the sized element and control electronics get designed in detail. Alongside it sits FMEA, the failure-modes review that asks what happens when a part does not behave as the analysis assumed. Analysis tells you the design works as intended; FMEA asks what happens when it does not.
What it can do
It turns “we think it will hold temperature” into a number you can defend, before you spend money. It catches the expensive failures (blown power budget, cracked ceramic, never reaching setpoint) while a fix still costs an afternoon. It sizes components properly, so the element, insulation and feet are chosen on evidence rather than on a hunch, and it gives the BS EN 61010 safety work a verified thermal baseline to build on.
What it can’t do
A model is only as good as its assumptions. Analysis predicts behaviour; it does not prove it. The 26°C hold and the 35-minute warm-up are confident estimates that the first physical prototype either confirms or sends you back to the spreadsheet. Treat the numbers as a hypothesis to test, not a guarantee, and never let a clean FEA result substitute for a real drop test on a real shell.
See the full 10-stage process →
Try it yourself
Take your design and write down the three numbers it lives or dies by. For the proofing box those were the temperature hold, the power budget, and the drop survival. Build the simplest model that predicts each one (a heat-loss sum on a napkin counts) and check it against your target. If a number misses, fix it in the model and rerun. Only commit to tooling once every number passes with margin.
Want a structured first pass at which numbers matter? Start the Free Sprint → and the GPT will help you find the make-or-break ones.
Your analysis checklist
Project notes: the model that earned the tooling deposit
▸ From the notebook · optional reading
How a weekend of thermal modelling with Dan and Anna Hartley in Stockport stopped them ordering the wrong element and an under-insulated shell.
3 min read · click to open
Dan wanted to order ceramic tooling and a 40W element the week we finished the design review. I asked for two days first: “Let me build the thermal model. If the numbers say it works, you order with confidence. If they don’t, we just saved the deposit.”
What the model showed
The brief was a steady 26°C, give or take half a degree, in a Stockport kitchen that drops to 14°C overnight, on under 30W. The first heat-loss sum across the double-wall ceramic was ugly: with the insulation Dan had sketched, holding 26°C needed nearer 34W. Over budget, and the 40W element would have run flat out with no margin.
We pushed the insulation thickness up by 8mm and reran it. Steady-state loss dropped to about 18W. That let us spec a 25W element running at roughly 70% duty, which gives headroom for a colder night and a long element life. Warm-up came out at about 35 minutes from cold, which is nothing against an overnight prove.
The drop case nobody had thought about
Then I ran the part most people skip on a kitchen object: the knock. A quick FEA of a corner clipping the bench edge put the peak tensile stress in the Stoke-on-Trent ceramic uncomfortably close to its limit, a safety factor barely above 1. One clumsy morning and a customer has a cracked shell and a refund.
We chamfered the corners and added a 6mm rubberised foot to soak up the worst of a bench knock. Reran the model: peak stress dropped, safety factor came up past 1.5. Good enough to commit, and a real drop test on the first prototype later confirmed it.
What two days bought
- Cost. Two days of modelling before any tooling was ordered.
- Saved. A wrong element order, an under-insulated shell that would have missed the temperature target, and a fragile corner that would have generated returns. Each one a tooling change after the fact, easily £2,000 a time.
Dan placed the tooling order the following week, with the right element and 8mm more insulation, and slept fine doing it. That is the whole job of analysis: turning a nervous order into a confident one.
— Engineer stage, project notes, 2026
— Next in Engineer → Electrical engineering