Shear, BM and deflection diagram

[alacasse]

I realize that there is probably some simple way to do this, but we are designing a gear shaft for a school project, and I need to know how to plot the shear force, BM and deflections diagrams using mathcad. The shaft has loading in multiple locations and multiple directions (2 helical gears, 2 bearings). So the functions describing the shear force, BM and deflections are piecewise.

[TomGutman]

Functions can be define piecewise using the programming if construct. Such functions can be evaluated and plotted like any other.

Since this is a very common and standard construct, you'd think the manual and/or the help would have clear explanations of this, and make these easy to find. But noooooo ... no manual to speak of, and if it's in the help it's not indexed under the obvious terms.
__________________
� � � � Tom Gutman

[mzeftel]

Tom,

What do you suggest be added to the search or index of Help? Piecewise is searchable.

I can ask the Documentation group to add new terminology.

Mona

[TomGutman]

Piecewise is searchable. But it does not point to a section on how to define a function piecewise. Rather the only index entry relates to identifying those few built in Mathcad functions that are not continuous.

The help should have a section on defining functions piecewise, and that should be indexed under piecewise, as well as the other obvious index terms.

And the user's guide badly needs a section on programming (how can you have even an introduction to Mathcad without the basic programming concepts?), and that should include piecewise definitions as one of the simplest and common uses of programming structures.
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� � � � Tom Gutman

[ELSID]

Mona, Please forward the suggestions on updating the guide.
Please read my post here
http://collab.mathsoft.com/~Mathcad2000/read?122504,63
I have been struggling with the programming for days.
Thank you

[ptc-1368288]

On 4/1/2009 5:14:17 PM, ElSid wrote:
>Mona, Please forward the
>suggestions on updating the
>guide.
>Please read my post here
>http://collab.mathsoft.com/~Ma
>thcad2000/read?122504,63
>I have been struggling with
>the programming for days.
>Thank you
_______________________________

Programming in Mathcad is a savant art that depends mostly upon understanding the Mathcad structure first. Programming applications are vast if not infinite. The PTC library would be a good starter. In reference to your link, i.e: your first work sheet, I doubt anybody will understand what you are suggesting to update based on a random user example that as far as today is not clear, neither done. Specific pre-built modules ? There are 10's of 1000's in circulation in this collab.

Just a comment

jmG

[ELSID]

jmG,
Programming in general is an art. MAthCAD appears to be a little above due to it's structures. Good solidly explained examples go a long way towards allowing others to "work things out on their own" Due to the responses, it is obvious that a few col collaboratory members are way ahead of every one else. I for one, had not used MathCAD since version 8 and NEVER did any programming in MathCAD.

I am incredibly thankful for people like yourself, Tom, Fred, Richard, etc. who help people like me

Mona my $0.02,
Examples explaining what the programming is doing goes a long way in understanding MathCAD's structure

On 4/1/2009 8:23:23 PM, jmG wrote:
>On 4/1/2009 5:14:17 PM, ElSid wrote:
>>Mona, Please forward the
>>suggestions on updating the
>>guide.
>>Please read my post here
>>http://collab.mathsoft.com/~Ma
>>thcad2000/read?122504,63
>>I have been struggling with
>>the programming for days.
>>Thank you
>_______________________________
>
>Programming in Mathcad is a savant art
>that depends mostly upon understanding
>the Mathcad structure first. Programming
>applications are vast if not infinite.
>The PTC library would be a good starter.
>In reference to your link, i.e: your
>first work sheet, I doubt anybody will
>understand what you are suggesting to
>update based on a random user example
>that as far as today is not clear,
>neither done. Specific pre-built modules
>? There are 10's of 1000's in
>circulation in this collab.
>
>Just a comment
>
>jmG
>
>
>

[LarryLederer-di]

On 4/2/2009 12:30:39 AM, ElSid wrote:
>Mona my $0.02,
>Examples explaining what the
>programming is doing goes a
>long way in understanding
>MathCAD's structure

If you have Mathcad version 14.0, then there is a free ebook called Inside Mathcad Programming. you can find it on the PTC website's Mathcad Resources page under books. Here is the link directly to the ebook for downloading.

http://www.ptc.com/appserver/wcms/standards/fileothumbredirect.jsp?&im_dbkey=62803&icg_dbkey=888

[ptc-1368288]

On 4/2/2009 12:30:39 AM, ElSid wrote:
>jmG,
...
>
>I am incredibly thankful for
>people like yourself, Tom,
>Fred, Richard, etc. who help
>people like me
>...
_____________________________

In most of the cases, programming discontinuous functions is the wrong approach. Here is a good example. That data set is typical of the "Geothermal layers" but it can be anything as you want. And it will adapt itself to any discontinuous data set that evoluates in real time, then in the work sheet. Try adapt your data set and the model and you will see it working and giving you more insight about the cumulative energy consumption.
Very easy to make it speak more like adding units in any kind of systems, i.e: mass flow rate in lbm/hr, tons/hr ... etc.

jmG

[PaulusSapiens-d]

alacasse:

This is not very complicate for hand, in your case have a helical gears, the difference with this example (see attach file) is that you need include the components of load (horizontal and vertical) in your free body diagram.
The horinzontal component generate a moment (horizontal component X primitive radius of gear) in your shaft, and when you make the balance of forces and moments should include this.

Pablo

[TomGutman]

Not all that complicated for Mathcad, either. Biggest hurdle is the MC14 bug with assign/evaluate and the symbolic processor, when units are involved.
__________________
� � � � Tom Gutman

[TerryKoen]

J is the polar moment of inertia
TOK