RE Bending moment and shear force diagram

[gbradley]

Almost there guys.

I've manage to draw the shear force diagram from some given numbers, I'm now trying to plot the bending moment diagram but for some reason I'm getting an error on the moment axis.

any suggestions or assistance would be greatly appreciated.

[RichardJ]

M is a function of x, so you should have x.m on one axis and M(x.m) on the other.

However, you have an error in the definition of M. W is a two element vector, but i ranges from 1 to 4, so the index is out of range.

[gbradley]

Thanks Richard, I'll have a look and get back to you

[Fred_Kohlhepp]

There's an easier, more general way to do this type of problem; vectors for plotting are poor for this.

[gbradley]

Thanks Fred, although the way you've shown is the generally way to do this. with the vectors, the mathcad sheet can be given to someone with hardly any knowledge of mathcad. so the only thing they need to do is add as many point loads and UDL's to the span of the beam and the sheet will work it out.

They don't need to go into the formula's to re write the equation.

See new attachment with the original problem

[Fred_Kohlhepp]

So your challenge is to write the functions from the vectors . . .

[gbradley]

Thanks Guys, shear force and bending moment diagram drawn, two more questions, how can a invert the graph so the bending moment and shear are the other way?

and how do I change the units to kN.m and m to the graph.. you can see the numbers at present are not correct

model attached

[RichardJ]

Divide the variables on the axes by the appropriate unit. Then type limits into the top and bottom placeholders on the y-axis.

[gbradley]

Thanks Rich, is that the only way to invert the graph by typing the upper and lower limits in the place holders

[RichardJ]

is that the only way to invert the graph by typing the upper and lower limits in the place holders

Yes. Unfortunately there is no setting for this.

[Fred_Kohlhepp]

You program crashes for a distributed load w = (10 0) produces no moment!

(Note that for a distributed load shear will not be a horizontal line but will have a slope equal to the negative of the distributed load. For that case the moment should be a second order curve. Plotting vectors would require a straight line point-to-point function.

[gbradley]

yes, I've had this working once but looks like I've changed something... any idea?

[gbradley]

infact this file still gives me the max bending moment. its the formula for plotting the bending moment diagram which is erroring out.

[gbradley]

manage to sort the erroring out of the bending moment. just need to inverse the plot automatically

[gbradley]

I can attach the file Fred it you'd like to have a look

[Fred_Kohlhepp]

Try this.

Still needs work.