Most people at this point would take the results with a grain of salt because of the lack of structure in the model but after running through this process to the end, I trust a good deal of this shape. With a 75% mass reduction I ended up with a FOS of 2.1 but the geometry is very thin. This 50% reduction laughably gave me a FOS over 3.2 still almost mocking me вЂ“ no- daring me to go lower.Д¬hallenge accepted, letвЂ™s try 75% mass reduction! I could tell SOLIDWORKS where to leave enough material around the sprocket mount as well as the wrist where the claw attached so that the study would leave a region of material around that area. I ran my first Topology Optimization on this robot part and went with the goal to reduce the weight of the part by 50%. How lightweight could we have really made that part which is still being used on some robots in the shop even to this day?ДҐ0% Mass reduction, first pass topology optimization When SOLIDWORKS 2018 came out and Topology Optimization was a part of the new release I remember optimizing this particular part with my students manually in 2015 simulation and I remember the fear in their eyes as we cut that first hole on the drill press. It weighed in at 119.8 lbs out of an allowable 120 and we didnвЂ™t look backД®xcept I did look back. We cut hole pockets into several components, swapped to lighter panels, went with thinner tubing wall thicknesses, and moved on to win tournaments with this robot. The FOS was 4.2 вЂ“ still a huge amount of overkill. We got to an almost 40% weight savings on these two components at the end but after running a FOS check again we learned that we barely made a dent in the performance of the part at all. We ended up playing with the hole pattern in SOLIDWORKS multiple times to make our decision and the results were that we could reduce the mass of the part by a decent amount and get the weight of both arms down to about 3.1 pounds total. Static Stress of the arm after hole saw pocketing.

We needed to know for sure that we were making the right choices so we ran another simulation and it was determined that if we had placed some holes too close to the joints that it was obvious the arms were going to fail. If we remove too much weight are we going to compromise the design? That was the biggest fear factor in this challenge. At one point the robot needed to lose 15 pounds total for an additional system so we dove into SOLIDWORKS to remove material from our machine in the digital sense before we started attacking our robot with tooling. If a robot needs to lose weight most teams usually grab the trusty hole-saw bit and put the robot on a diet. Static Stress of the arm without any pocketing. For our aluminum material (yield strength 40,000 psi or so) this means we start with a Factor of Safety of 4.34 вЂ“ Overkill! Running a quick static stress analysis of the tube before any pocketing tells us that the tube weighs 2.4 pounds or 4.8 pounds for both arms and due to the applied load we can expect a stress of about 9,187 psi. We treat the other end of this beam as though it were mounted through the fixed hinge fixture to emulate being held in place by the bolts and sprocket mounting pictured above. The roller claw and game piece weigh about 15 pounds but due to some other loading conditions we assume each arm (there is one on each side) needs to resist about 20 pounds just to make sure. Roller claw on the two arms before final assembly. To simplify the problem we can take the robot arm made out of 2Г—1 tubing pictured below and run a simple static stress analysis in SOLIDWORKS to begin.

So in the case of extreme pocketing where can weight be safely removed without completely compromising the part in operation? Where can weight be removed that will leave the part virtually unaffected in operation? Like team 148вЂ™s robot chassis for example! Because of this constraint, teams often pocket every single part imaginable to maximize the performance of their machines. Each robot has a maximum weight limit of 120 pounds unloaded so every pound must be utilized carefully per the rules.

Draftsight professional overkill