Posted by oscar on Monday, September 30, 2002 at 0:56AM :
In Reply to: Any Structural Engineers out there , need advice posted by Paul (in NY) on Sunday, September 29, 2002 at 10:15PM :
You'll need to describe your design a bit better.Are you just concerned with a transporter or will the engines be running?
Will the frame just be a flat pair of 6 x 2 steel channel with the ends weld to a 36 inch 6 x 2 end channel cross member? Will there be more than 2 cross members? Will there be a full cage over the engine transmission assembly? How will the engine/trans/dyno be mounted? Also how much are you willing to allow the structure to flex/move at full load? The less the structure can move the bigger and heavier everything must be. If the flex of a 1/8 in at full load is ok then the design does not need to be a strong as one to move only 0.002 in.
Most of the strength of the channel is in the direction normal (perpendicular) to the six thickness. Adding 1/16 in in thickness will not greatly increase the strength. If you need more strength use a 8 x 2, 10 x 2 or a 12 x 2. Most of the strength will come from the design of the structure and triangluation. The mount points will be where the loads are concentrated so the metal must be thicker and larger to resist the point loads.
Your local city probably has a PE (professional engineer) on staff. Most PE's seem to be nice folks. Many would be willing to help get a design started without charging a fee (a 10 to 15 minute chat/advise). If you need a full review for liability then their fees are very inexpensive compared to a failure where someone gets hurt.
Good luck
oscar
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