Mechanical Design, January Interim
Finite Element Analysis
Over Calvin College's January Interim, both mechanical engineers took a course on Finite Element Analysis (FEA). During that class, we were able to create a new model of our frame and test how the vibrations resulting from the cutting tool would affect our design.
The first step was creating a new model that could be used in the FEA program we were using: Algor FEMPRO
From there, we had to load it properly, including the mass of the drill, and accounting for the reality of our table not being perfectly rigid.
Finally, the frame was loaded to model a 1 gram unbalance and a distance of 1 centimeter from the rotating axis, which would be far worse than anything we might reasonably face.
Once we had a model, we had Algor Fempro calcuate all the natural frequencies between 0 and 1500 Hz. Our dremel will be operating at about 1170 Hz.
Running the analysis yielded positive results for us. The worst deflection was 0.00031 inches. Since our tolerances are on the order of 1/1000 of an inch, we're satisfied with our design.