b'Geek Hub | Engineer InnovationMike had to create another simulation with a lid to see how this changed the results. We expected the temperature to rise, but we had to wait to see if this would be a drastic increase."When Mike realized there was a lid missing from the model and the air was escaping through the top, he went back into the geometry, selected the open plane and with a few quick clicks created a lid to close the model at the top. In an intermediate simulation, he obtained very high and unrealistic temperatures. As he was making a quick simulation, hed defined some of the solid components as an insulator material. He also experimented by putting a heatsink on the PCB, and for this comparison the material properties for some of the parts was neglected. Now that the top of the leg is closed, the influence of the material properties becomes more important. The combination of the closed top withFigure 4: Overviewinsulator material, caused the high temperatures. Once this was realized, a simulation was run for both cases with the leg defined as standard stainlessshould not cause any burns or steel. The maximum temperature isdiscomfort.almost equal in both cases, it shows only a very small difference. The openThe information that can be gathered version is 0.1C cooler. What does thisis invaluable, without having to build mean? Most of the heat is convectingmultiple prototypes or having to and radiating from the PCB to the outerredesign later on in the design process.enclosure. For more information:In summary, putting on a lid andwww.limbcare.orgenclosing the casing makes minimal impact. The maximum temperaturesDebbie Searle Blog:reached in either case is 38C. Thehttps://bit.ly/2JJCztVmaximum advised temperature in a consumer product is around 41C. So atReferencesa little over body temperature, Debbies[1]https://grabcad.com/library/ leg, even while working at its hardest,below-knee-prosthesis-1 nFigure 5: Temperature distribution on the PCB Figure 7: Comparison of the two variants73'