Yesterday evening I put the entire thing together for the first time. Here are some pictures.

Well, this is it. The hopper assembly is mounted in the frame by two 5/8 inch bolts. At one end, the mounting bolt is connected to the vibration exciter. This is basically a beefy loudspeaker. At the center of the cone is a mounting point which will supply vibrations to the assembly. The function generator is mounted near the bottom of the frame, and the amplifier is mounted on top.






This is a better shot of the electrical equipment. Eventually, two metal brackets will hold the function generator in place, and two nylon straps will hold down the amplifier.










This picture gives a better view of how the vibration exciter lines up with the hopper assembly.











This is a closeup of the vibration exciter and how it connects to the mounting bolt. The idea was to use washers and rubber o-rings as a sort of spring to push the assembly against the exciter, but a few quick tests proved that this might not be a good idea. It seems to damp out almost all of the vibrations, so we'll have to make some adjustments.






The reason why we are supplying vibrations to the assembly is because of the difficult flow characteristics of the lunar soil simulants. In lab tests on the ground, our Principal Investigator showed that the soils (especially the NU-LHT simulant) would not flow at all. The particles in the soil are so irregular that they interlock with one another and stop flow. Therefore, we are supplying vibrations to force the stuff to flow, and are investigating exactly how this works in lunar gravity.

Once we get everything working properly, we will disassemble everything to do load testing on our frame. NASA would like us to show proof that the welds on our frame are good ones by hanging weights from the frame. As part of the equipment design, the frame and assembly must withstand 9Gs in one direction. This puts some severe loads on the structure, and they want to make sure everything will be ok in the event of an emergency landing. Our plan for this test is to hang the frame vertically from the anchor points and hang weights off the corresponding mounting points for each individual piece of equipment. I'll certainly get some pictures up of that test as well. Personally, I'm not worried at all about the strength of the frame, because it looks like you could park a car on top of it with no problems.

That should pretty much get everyone caught up to where we are right now. I'm going to be in the lab again this afternoon with Nick to work through some more bugs. I'll make another post hopefully in the next couple days to update everyone on our progress.