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2-D plot resolution

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2-D plot resolution

I made a shear and moment diagram plot in mathcad and it should look like this:

shear.JPG

However, in mathcad, mine is looking like this:

shear.JPG

The problem, in particular is that on the moment diagram at about x= 1" there's a "knee" in the moment diagram that shouldn't be there.

Does anyone know the cause of the "knee?" Anyway to increase the resoltion of the plot?

17 REPLIES 17

Re: 2-D plot resolution

What happens when x = gap? The definition of v is the issue.

Please upload a worksheet.

Re: 2-D plot resolution

Thanks for your response

Re: 2-D plot resolution

You don't show how x is defined, but looking at the graph I'll guess it's a range variable 0*in,1*in..15*in. So you get a point every 1 inch. Make the increment much smaller, say 0*in,0.01*in..15*in.

If that's not the problem, please post a worksheet.

Re: 2-D plot resolution

How exactly would you decrease the increment?

Re: 2-D plot resolution

See attached.

Re: 2-D plot resolution

It's clearly a resolution problem. Presumably a low resolution has been set because the Moment integration takes too long otherwise. But the integration is simple to do analytically, so:

vM.PNG

If you set n to 20 in the above you get the same corner cut-offs in M as in your original.

Alan

Re: 2-D plot resolution

Thanks!

Re: 2-D plot resolution

Don't rely on the quickplot feature of Mathcad. It gets lots of people into trouble. Use a range variable to define the x-axis range and increment.

Re: 2-D plot resolution

Maybe that is a flaw with the quickplot feature. I think the user should be able to change the quickplot scale, to allow as in this instance, the increment to be reduced.