- #1
WannaBeME
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I am in a course this semester, Mechanical Engineering Design, and the bulk of the course is a semester long project that you must design/analyze/build. It's a relatively small device that won't exceed about (6x5x4)inches in volume. One requirement is that it must withstand (4.5±2) G's while it is placed on a machine that will test this by shaking it. My group is at the point where we had what we thought was a solid final design, and when we consulted our client (a professor, just not the professor to the course) his concerns were mainly that it would not hold up to the vibrations and topple over. Here's a pic.
The point of concern is the left tube, the one with the piston inside. The plate it is on is an aluminum base plate with a bored hole to seat the tube. The tube will have an adhesive on the bottom of the surface to attach to the aluminum, as well as some type of epoxy of caulking around the top of the aluminum to ensure it's sealed and also does not come out during the vibrations test.
Vibrations is a senior level course at my college, so no one in my group has an idea how to analyze this device with only give the acceleration it might experience. We recognize the point of concern at where the caulking would be, and that the biggest stress will occur from the lid as it is at the top and relatively heavy being aluminum and will cause the maximum bending stress. During the testing I would leave the piston at the lowest position trying to keep the center of gravity as low as possible. Is that something practical to calculate? And is a roll center something that is possible to calculate on this tube as well?
My main question is how we should approach analyzing this device, especially when it comes to vibrations. We are all thinking that this small device does not have anything truly to calculate aside from vibrations, and we have searched up and down for an idea on how to do that. This is a course where we learn about fatigue/shaft design/load&stress analysis for design/etc. so having a nice couple pages of calculations is expected.
Any help is really appreciated, even if it's just pointing us in the right direction.
The point of concern is the left tube, the one with the piston inside. The plate it is on is an aluminum base plate with a bored hole to seat the tube. The tube will have an adhesive on the bottom of the surface to attach to the aluminum, as well as some type of epoxy of caulking around the top of the aluminum to ensure it's sealed and also does not come out during the vibrations test.
Vibrations is a senior level course at my college, so no one in my group has an idea how to analyze this device with only give the acceleration it might experience. We recognize the point of concern at where the caulking would be, and that the biggest stress will occur from the lid as it is at the top and relatively heavy being aluminum and will cause the maximum bending stress. During the testing I would leave the piston at the lowest position trying to keep the center of gravity as low as possible. Is that something practical to calculate? And is a roll center something that is possible to calculate on this tube as well?
My main question is how we should approach analyzing this device, especially when it comes to vibrations. We are all thinking that this small device does not have anything truly to calculate aside from vibrations, and we have searched up and down for an idea on how to do that. This is a course where we learn about fatigue/shaft design/load&stress analysis for design/etc. so having a nice couple pages of calculations is expected.
Any help is really appreciated, even if it's just pointing us in the right direction.