This week I was working on refining the ROV Re-Design. I started by sketching the cutouts for the Frame Panels. I structured them such that the outer and inner edges would be able to deflect without shearing whilst still being supported by the other edge. I also ensured that each cutout was triangular to take advantage of the shape’s dimensional stability.
Each edge is curved to provide smooth transfers of strain and remove points of stress accumulation. This helps to prevent fracture under impact.
I also Added mounting holes for the Light. I sized the clearance holes up from M3 to M4 for an extra loose fit. This ensures that the Light’s seal won’t be interrupted by the frame deflecting as it is designed to do.
The Large clearance hole for the Wetlink Penetrater saves weight along with providing clearance for tools if I need to fix the Light while it is installed.
Finding the dimensions for the new dome was exceedingly difficult because the technical drawings for the retaining ring was incomplete and in a totally separate place from the drawing for the dome. Compounding the difficulty was the fact that almost everything in the drawings was in Chinese.
The majority of this week was spent performing stress simulations on the ROV. I was unable to include images of the simulations because they take an incredibly long time to load, and I forgot to take screenshots when I was analyzing them.
I started by teaching myself the simulation workspace. Then I simplified my model using the “Simplify” tool-set in the simulation workspace. For the Frame simulations I Combined the entire enclosure assembly then filled in it’s holes and made it solid. I did this to ensure I was getting information on the frame specifically.
My simulations showed that in the weakest orientation the frame had a safety factor of 250x. Because of this, I generously added cutouts and changed the thickness from 0.5″ to 0.25″. It retained a very significant safety factor after this.
For the pressure vessel simulations, I removed every component except for the enclosure assembly. I then applied a pressure of 743 PSI (expected Load) to every external face and a pressure of 14 PSI to every internal face (underestimated internal air pressure).
The entire enclosure except for the front dome had a safety factor above 8x. The goal for safety factor on the enclosure was 5x. the end caps, especially the one with the dome had a safety factor far above that 8x value. However the front dome only had a safety factor of ~1.2x. This was completely unacceptable. So I found a new front dome that had been extensively tested to 1000m depth.
