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USE OF GRAPH

HarikrishnanR
3-Visitor

USE OF GRAPH

HI, PLEASE LET ME KNOW USE OF "GRAPH",AND WHERE IT IS COMMOMLY USED. THANKS, HARI
6 REPLIES 6

Graphs are regularly used to drive geometry in a Variable Section Sweep. More specifically, a graph typically controls a dimension which continuously changes as the sweeping section follows the primary driving trajectory of the Variable Section Sweep. In this context a graph is used in conjunction with the specific parameter trajpar which varies continuously from 0 to 1 as the section follows the primary trajectory. That is, it has value 0 at the start point of the Sweep, value 0.5 half way along the trajectory, and value 1.0 at the end. Usually this arbitrary 0-to-1 range is multiplied by some factor appropriate to the particular geometry. The graph itself is invoked using the specific EVALGRAPH call followed by the name of the graph in quotes, comma-delimited, then linked to the factor-multiplied trajpar parameter. A graph can be very powerful and useful because you can sketch a varying graphical relationship using lines, arcs, and splines that would be impossible to capture in a simple equation. This is an overview. For more detail look at Variable Section Sweep articles in the Help files and on the PTC website. You should find examples there. Good luck! These can be a lot of fun. David

thank you David,

Hi David, My intension is to control the Francis impeller vane thickness at 3 point (back shroud, middle, front shroud). My doubt is whether we are linking vane thickness to Graph through relation or any other?? Please let me know. Thanks Hari

Hari, O.K., a little more detail, and some syntax. However, as an aside, I am rather doubtful that you really want to use a Graph to control impeller blade thickness. Your geometry variation is likely to be very smoothly varying and devoid of unusual perturbations which are more in the line of Graph control. I would think that a 2 or 3-section Parallel Blend, a General Blend, a Swept Blend, or a Variable Section Sweep with 2 trajectories, maybe using trajpar without a Graph would be better for your purposes. There have been impeller blades and airplane wings in the Pro/E training courses over the years; maybe you can find one of these in PTC's web files. A good use of a Graph is to control a complex cam surface. Imagine an advancing blade with a flat bottom and undulating top cam surface. We want it to gradually get thicker, smoothly dip down to a low on a curved path, come back up, and level out. The Graph we would use might consist of an inclined line, a spline, and a horizontal line, all mutually tangent. In the simplest case the syntax might then look somethng like this (after pre-creating a Graph feature named THICKNESS): sd3=EVALGRAPH("THICKNESS",trajpar*10) Note the "sd3"; the section dimension is changing as it follows the trajectories of the Variable Section Sweep. Note the arbitrary "10"; this is the full length horizontal dimension of your graph. The EVALGRAPH function "reads" the graph over the span-value occuring after the comma; since trajpar goes from 0 to 1 always, we need to multiply by this number to have the entire extent of the graph covered. More commonly, the equation might look more like this: sd3=2.75+EVALGRAPH("THICKNESS",trajpar*10)/50 The leading edge part thickness is "2.75" and your Graph (sketched using a Sketcher Coordinate System) starts from 0; the values are added together. The "50" occurs because the desired thickness changes are so small relative to the length of the cam that, sketched to scale, the Graph would look like a flat, straight line. So we amplify all desired "real" values by 50 in the graph, and factor the multiplication back out in the equation. Have fun! David

Hari, Speaking of Swept Blends, they may be made with Optional Area Control. You could define the 3 sections you need, then define specific area values at other intermediate points along the trajectory. Check this link, or type in "howto" in the Support section of the PTC Website, and filter to ProE/WF3/FEATURE: http://www.ptc.com/cs/cs_26/howto/agf2782/agf2782.htm Might be of some use to you. David

hi sir, Thank you very much for the tips!.I went through graph method,it is really good. we are creating francis vane by using cylindrical co-ordinates points.usually there are minimum 13 points in radial direction ,and axially we are controlling the thickness of the vane at three sections(A,B,C(BOARD SIDE OF FRANCIS VANE)).we r creating vane using boundary blend.but in particular case they(client) want graph method . once again thanks for ur help. thanks and regards, hari
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