CAD software for equation driven curves

[sebrig]

Hello folks!
I'm looking for a CAD software that allows me to enter curves in parametric form and create a coherent sketch element from it or at least handle the input via a csv o.s. As an example, a curve could be derived from the following formula ("a" corresponds to the variable; 0<a<2*pi):

x = 65*cos(a)-2*13^2/65*sin(2*a)*sin(a)-26*sqrt(cos(a)^2-(13/65*sin(2*a))^2)*cos(a)
y = 65*sin(a)-2*13^2/65*sin(2*a)*cos(a)-26*sqrt(cos(a)^2-(13/65*sin(2*a))^2)*sin(a)

I have already tried it with SolidWorks and Solid Edge.
While in SW you can enter the parameter representation of the curve via the feature "Equation driven curve", it is not possible to create a closed sketch element, because start and end point must not be identical. Subsequently, you have to draw a line manually, which then causes problems, for example, when creating an offset element. With the feature "Curve through XYZ points" half the curve can be created and then mirrored, but before that the data must be edited in such a way that I can't consider it to be part of a feasible workflow anymore.

With SE, the only way to read in a value table and create a closed curve is via "Curve by table", but without any major problems. The only thing that makes me a bit suspicious is that the curve can only be created with the soothing option on (i.e. some or all (?) points are not necessarily touched directly but pass through within a certain tolerance) and afterwards it is not clear to me which points deviate from the actual target. If this is a machine element that is really to be produced and is precisely defined via the parameterization, then this would not be acceptable.

Therefore I wanted to ask the CAD community if there are better alternatives. Has anyone here already had a similar problem and could solve it or find the "perfect" software for it?

I am happy about any suggestion!

Cheers

[MJuric]

Hello folks!
I'm looking for a CAD software that allows me to enter curves in parametric form and create a coherent sketch element from it or at least handle the input via a csv o.s. As an example, a curve could be derived from the following formula ("a" corresponds to the variable; 0<a<2*pi):

x = 65*cos(a)-2*13^2/65*sin(2*a)*sin(a)-26*sqrt(cos(a)^2-(13/65*sin(2*a))^2)*cos(a)
y = 65*sin(a)-2*13^2/65*sin(2*a)*cos(a)-26*sqrt(cos(a)^2-(13/65*sin(2*a))^2)*sin(a)

I have already tried it with SolidWorks and Solid Edge.
While in SW you can enter the parameter representation of the curve via the feature "Equation driven curve", it is not possible to create a closed sketch element, because start and end point must not be identical. Subsequently, you have to draw a line manually, which then causes problems, for example, when creating an offset element. With the feature "Curve through XYZ points" half the curve can be created and then mirrored, but before that the data must be edited in such a way that I can't consider it to be part of a feasible workflow anymore.

With SE, the only way to read in a value table and create a closed curve is via "Curve by table", but without any major problems. The only thing that makes me a bit suspicious is that the curve can only be created with the soothing option on (i.e. some or all (?) points are not necessarily touched directly but pass through within a certain tolerance) and afterwards it is not clear to me which points deviate from the actual target. If this is a machine element that is really to be produced and is precisely defined via the parameterization, then this would not be acceptable.

Therefore I wanted to ask the CAD community if there are better alternatives. Has anyone here already had a similar problem and could solve it or find the "perfect" software for it?

I am happy about any suggestion!

Cheers

Haven't played with SW driven curves or attempted to do what you are asking for here so not much help there.

That being said here are a few other suggestions SW related to look into.

1) SW macro/API. Seems like you could do this fairly easily using that system
2) Excel and then import points, connect the dots. Again maybe you can use the API to automate this process for you. I'm certain you could calculate all the points you needed in Excel and I know all those points can be imported into SW. Certainly you can manually connect the dots but I also think import has an option for running curve/line thru the points although admittedly I've not had great success with that route.

Just a few thoughts

[SPerman]

I'm 99% sure NX has that ability.

[Rob]

In SW you could try a Fit Spline?

2018 attached

[HerrTick]

While in SW you can enter the parameter representation of the curve via the feature "Equation driven curve", it is not possible to create a closed sketch element, because start and end point must not be identical

What the heck do you want? Functions have ranges. Ranges have a beginning and an end.

[Ry-guy]

I'm 99% sure NX has that ability.

Correct.
NX has Law Curves for a long time now.

My old team (15+ years ago) used catenary curve definitions to drive monster assemblies for gas turbine ducting projects. Engineer defined the curve values in a design spreadsheet and the values where pushed down the template assy to create all the stiffeners, sheet metal, x-bracing, etc.. It was beautiful. Taking a 80-120hr design job down to 20 hrs of updating drawings and ensuring bolt patterns and section cuts were good.

[Ry-guy]

Hello folks!
I'm looking for a CAD software that allows me to enter curves in parametric form and create a coherent sketch element from it or at least handle the input via a csv o.s. As an example, a curve could be derived from the following formula ("a" corresponds to the variable; 0<a<2*pi):

x = 65*cos(a)-2*13^2/65*sin(2*a)*sin(a)-26*sqrt(cos(a)^2-(13/65*sin(2*a))^2)*cos(a)
y = 65*sin(a)-2*13^2/65*sin(2*a)*cos(a)-26*sqrt(cos(a)^2-(13/65*sin(2*a))^2)*sin(a)

I have already tried it with SolidWorks and Solid Edge.
While in SW you can enter the parameter representation of the curve via the feature "Equation driven curve", it is not possible to create a closed sketch element, because start and end point must not be identical. Subsequently, you have to draw a line manually, which then causes problems, for example, when creating an offset element. With the feature "Curve through XYZ points" half the curve can be created and then mirrored, but before that the data must be edited in such a way that I can't consider it to be part of a feasible workflow anymore.

With SE, the only way to read in a value table and create a closed curve is via "Curve by table", but without any major problems. The only thing that makes me a bit suspicious is that the curve can only be created with the soothing option on (i.e. some or all (?) points are not necessarily touched directly but pass through within a certain tolerance) and afterwards it is not clear to me which points deviate from the actual target. If this is a machine element that is really to be produced and is precisely defined via the parameterization, then this would not be acceptable.

Therefore I wanted to ask the CAD community if there are better alternatives. Has anyone here already had a similar problem and could solve it or find the "perfect" software for it?

I am happy about any suggestion!

Cheers

If you don't have a smoothing operation occuring then you are creating a very complex curve with a x ^n-1 degree spline- when n= number of defining points.

Smoothing, as I recall, breaks down the curve to 3rd degree curve segments but is still a single entity.
This goes back to how splines are created.

Some systems have "predefined" curve types. But it all depends on the system and their ability to manage the curve. (i.e. sketch-based, spline-based, equation/law based, etc.)

[Imics13]

Hi @sebrig,

Try this file! It is coming from Solid Edge.


BR,