Quote:
Originally Posted by TheOtherGuy
It's probably because 148 isn't cheap or lazy 
One simple alternative: use thinner material without pocketing. I've seen a lot of pocketed designs in FRC that could have been made simpler and cheaper with practically no effect on strength (although, oftentimes can be made stronger) by using thinner material. |
I don't really see using thinner material as the same as "pocketing" A part that is thinner does not have the same structural integrity as a piece of thicker material that has been "pocketed" down to the same weight.
Our team carefully looks at the lines of force in different pieces and designs trusswork that supports the loads put on the part. We (like JVN) call it trussing. You take out material that doesn't add to the strength you are looking for. We also use this same information when we place fasteners. The trusses work WITH the fasteners and need to be designed together.
One can just look for places to make holes but it is really necessary to look at the stress on a given part to know that you have to be able to deal with the various forces being applied (both torsion and compression)
I am confused by the vocabulary anyway, I was always under the impression that "pocketing" was material removal from non-stress areas without making a hole. Just a thinning of the part in non-stress areas. This is often down in castings to save material. They weren't holes. I am probably wrong but that is what I grew up thinking. But then again what is a hole? I can't really dig a hole in the ground if it goes all the way though... I guess I am making pockets in the ground.
We are blessed with the opportunity to do sheet metal designs because of the equipment we have at the school (most notably a waterjet and a brake)
Students are taught how to design trusses that make a part lighter but still strong enough for the application.
Material use is important and there are good lessons to be learned about this.
I guess that the major reason we can do this is because of the predominance of aviation related mentors that we have working with the students. In aircraft, weight is an incredibly important factor.