I am trying to analize a bolting application have where I have a 1/4 -
20 GR 5 HHCS bolting a steel back plat to a piece of copper. In trying to analyze this construction, I am using example 8-3 to help with this. I do have a gasket I will have to consider. In the middle frustrum there is a D= 1.293 in. where the heck does this come from? I would have assumed the 1.51 in D2. I have scoured the chapter but it is lacking.Thanks for the help if anyone can shed some light.
Best Regards, Daniel Lee
The middle frustum is the top part of the lower cone on the top plate. D for the middle frustum can be calulated by using the 30 deg cone. One solution is to start with D for the lower frustum and add the additional taper due to the thickness, as follows.
D2 = D3 + 2*t3*tan(30deg) = 0.9375in + 2*0.3125in*tan(30deg) = 1.298 in
where, D2 = middle frustum minimum outer diameter, D3 = lower frustum minimum outer diameter, t3 = lower frustum thickness.
Another solution is to start with D1 and subtract off the taper, as follows.
D2 = D1 - 2*t2*tan(30deg) = 1.51in - 2*0.1875in*tan(30deg) = 1.293 in
where, D2 = middle frustum minimum outer diameter, D1 = maximum cone diameter (problem listed 1.51 in), t2 = middle frustum thickness.
They must have worked it out the second way. D1 is 1.515 in, rounding to 4 sign. figures. So rounding is the difference.
Thanks for the info.. I went clear past that solution as I had come up with 1.298... I didn't think to check whether or not he was using all the significant digits or not.
Thanks, Daniel
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