Help Please-Applications of Trajpar Variable

Hi All,
I expect help regarding trajpar variable and its usage
1)Examples where it is used I saw its application only in Var Sec Swp
2)In relation where part dimensions are assigned to sketcher dimension
the relation do not works. Can anybody provide little bit insight.
Ex- sd3=d12-d15*trajpar

d12 and d15 are part dimension of curve created before using these in
relation.

 

1)... application only in Var Sec Swp

That's the main one, if not only one.
(For future reference; there's also a
trajpar_of_pnt function.)

What does "not works" mean?

For ...

.... sd3 will be
equal to [d12 - (d15 * 0)] at start of sweep,
equal to [d12 - (d15 * 1)] at end of sweep.

Your best bet is to post a model somewhere so people
can see WHAT IS and explain what you want to happen
instead.

 

AFAIK, trajpar works only with VSS which is designed to allow the section to
vary. I couldn't get trajpar to work, for example, on an ordinary sweep.
Looking at your relation, I don't see anything which, in principle, should
prevent it from working. I'm not 100% sure of how your relation will
evaluate, but I'd try enclosing d15*trajpar in parentheses to make sure it
doesn't evaluate to zero. Also, since trajpar (like t) varies from 0 to 1
when driving the sweep section dimension, make sure d12-d15 is never
negative. Both zero and negative sketcher feature dimensions (zero length
lines, zero diameter circles) are impossible and illegal. In short, get the
evaluated max and min values that your relation generates and vary the
section, manually, to these numbers to make sure it is capable of that
variation.

BTW, there is some useful stuff in Help on trajpar under Part Mode.

David Janes

 

Hi ,
I will put the steps of creation as follows,
1)Datum curve of specific height and another of specific length
2)created trajectory for VSS
3)created section for VSS and then
4)entered relation for that
sd3=d12-d15*trajpar

After this I observed no change in section sometimes proe falls into
Resolve mode.
So please let me know how it can be tackled.
Also I want to know how it is possible to drive section with Graph
feature.

 

I tried to duplicate your problem by following your
steps and could not do so. Do I have to (in which
case you should be using Inventor) explain why?

You use Google for email. Try their search functions.
They are just so cool!!!

http://www.google.com/search?hl=en&...ariable+section+sweep"+|+vss+trajpar+tutorial

http://groups.google.com/groups?as_q="variable+section+sweep"+|+vss+trajpar+tutorial

 

Patil, are you familiar with a sweep? It has two elements: a sketched
section and a path (trajectory) that the section follows (sweeps).
Generally, the path is created first and when the sweep is created and the
trajectory selected, Pro/e sets up a sketch plane normal to the trajectory
to sketch the section on. This is true also for the VSS. The first curve
selected is the origin trajectory. As a side point, if it is composed of
several curve segments, these may have to be combined into a single curve
(composite, exact or approximate) with a copy/paste operation. If you don't
know how to do this, you need to be asking about these detailed techniques.
Additionally, the VSS provides the ability to select other trajectories that
guide, not just the section direction (which is all the first trajectory
does), but the shape of the section, the real VARIABLE section. With one or
two additional trajectories, roughly following the first, the section,
locked to those trajectories, will change shape as it follows the origin
trajectory. How many trajectories can be used depends on section geometry. A
circle, for example, can be varied in only one dimension ~ the radius, so
two trajectories, at most, are needed. A conic arc could follow two or three
trajectories. A box could follow at least two, depending on what was tied to
the trajectory curves. A spline can follow any number of trajectories.

In your example or the steps presented, a couple things aren't clear. You
have a curve of a "height" and a curve of a "length" but are these
trajectories? How many trajectories? If a single trajectory, meaning they
are joined so the VSS can follow them, the section needs to identify this
single trajectory as the origin. Then, while in sketcher, make a sketcher
relation that evaluates the feature dimensions and varies the sketcher
dimension accordingly. Here my previous cautions apply regarding how this
relation evaluates times 'trajpar' (mustn't evaluate to zero or negative for
size dimensions). Following these simple rules, you should have no trouble
using feature parameters in a sketcher relation. On the other hand, if you
had a problem doing it this way, why not just use real numbers or ordinary
parameters which can also be used in relations.

As to driving sections with a graph, this is also a particular function that
can be used in a relation called EVALGRAPH. The graph is created first with
'Insert>Model Datum>Graph', then draw the dimensions and shapes that will
guide the section dimension through its variation, e.g., starting dim,
ending dim, distance, and the graphical equivalent of an algebraic equation.
Or a starting dim, angle and distance or length. Or starting dim, starting
angle and ending angle. There's stuff in the Help files on EVALGRAPH. The
graph is evaluated in the same incremental way, over some limits, as if 't'
or 'trajpar' were doing the incrementing.

David Janes

 

Hi David,
I have drawn these two curves for using them in equation to drive VSS
section, it is not for the purpose of trajectories. With these curves
we frequently do not have to go for Relation editor to edit equation
and enter values; we just need to change the dimensions of these two
curves and we get the work done.
Regards,
Mukundraj.

 

Neat, so what sketch parameter does the evaluation of these curves'
length/height govern? And when it doesn't work as you'd expect, does the
evaluation through the range of trajpar (0 to 1) make sense, is it
physically possible? I'm sure you can change the curves in such a way, with
certain values, to MAKE the section fail. I gave two circumstances where any
size variable will fail if the product of trajpar evaluates to zero or a
negative number. You didn't respond that this was NOT going on so I have to
assume you didn't check or that your relation already checks for both
conditions and prevents impossible values from being used. When the section
fails to change, does the relation show errors? Are there any error messages
at all? What version of Pro/e are you using? In WF3 there is now, under
Options within the VSS definition, a check box for Constant section. If
that's checked, it seems to override the relation. That's just a side point
as your intermittent problem doesn't really sound like this situation, that
is, unless this problem just started when you switched to WF3, then I'd
check the VSS definition.

David Janes