DaSalo
Mechanical
- Apr 27, 2010
- 213
Hello,
Using NX 6. I am trying to create a sketch of a conic section that will be used in a through curves feature. The profile is a "D" shape laid on its side with the flat edge constrained with a dimension. The curved part of the "D" is a conic section with the start and end points on the end points of the "D" base line. The control point of the conic is the end point of a reference line that is constrained vertical and to the midpoint of the base line. This reference line is not constrained in length so the control point of the conic can float up and down but can not deviate from center side to side. Now imagine a circle of a fixed diameter that must sit inside that 'D' shape. The base line of the D is constrained tangent to this circle and the upper most point of the conic is also constrained tangent to this circle. This all works fine and the sketch is fully constrained. The tangent constraint between the conic and the circle locks in the floating degree of freedom of the reference line. Now comes the tricky part. I need to be able to change the rho parameter of the conic and have the sketch update. When I change the rho the sketch immediately becomes conflicted. Then if I delete the tangent constraint between the conic and the circle, drag the conic so that it is very close to being tangent with the circle again, and reapply the tangent constraint everything is fine again. So, there is a solution but the system is unable to automatically move the defining point of the conic to keep the tangent constraint valid. Once I get it in the ball park it is able to successfully solve the constraint. This works until the rho drops down to a very low number, somewhere below .150. Once the rho gets way down there the system is no longer able to solve the tangent constraint no matter how close to tangent I place the conic manually. Unfortunately, for my purpose I need the rho very low so the conic is close to a circular arc. The exact value that I am shoooting for is determined by the area of the cross section created, which I am checking using advance geometric properties > area from curves. I have a target value for this area and I am fiddling around with the rho until I hit my value.
So my questions are:
1)What happens when the rho drops very low that prevents the tangent constraint from solving. Is this just a matter of the system having to solve out to too many decimal places for the constraint to succeed?
2)Is there a better way for me to constrain the conic to achieve my design intent?
3)Is it possible to set up the optimization feature to automatically produce a cross section that will meet my area target?
Any and all help and thoughts appreciated!
Thanks.
Dasalo
Using NX 6. I am trying to create a sketch of a conic section that will be used in a through curves feature. The profile is a "D" shape laid on its side with the flat edge constrained with a dimension. The curved part of the "D" is a conic section with the start and end points on the end points of the "D" base line. The control point of the conic is the end point of a reference line that is constrained vertical and to the midpoint of the base line. This reference line is not constrained in length so the control point of the conic can float up and down but can not deviate from center side to side. Now imagine a circle of a fixed diameter that must sit inside that 'D' shape. The base line of the D is constrained tangent to this circle and the upper most point of the conic is also constrained tangent to this circle. This all works fine and the sketch is fully constrained. The tangent constraint between the conic and the circle locks in the floating degree of freedom of the reference line. Now comes the tricky part. I need to be able to change the rho parameter of the conic and have the sketch update. When I change the rho the sketch immediately becomes conflicted. Then if I delete the tangent constraint between the conic and the circle, drag the conic so that it is very close to being tangent with the circle again, and reapply the tangent constraint everything is fine again. So, there is a solution but the system is unable to automatically move the defining point of the conic to keep the tangent constraint valid. Once I get it in the ball park it is able to successfully solve the constraint. This works until the rho drops down to a very low number, somewhere below .150. Once the rho gets way down there the system is no longer able to solve the tangent constraint no matter how close to tangent I place the conic manually. Unfortunately, for my purpose I need the rho very low so the conic is close to a circular arc. The exact value that I am shoooting for is determined by the area of the cross section created, which I am checking using advance geometric properties > area from curves. I have a target value for this area and I am fiddling around with the rho until I hit my value.
So my questions are:
1)What happens when the rho drops very low that prevents the tangent constraint from solving. Is this just a matter of the system having to solve out to too many decimal places for the constraint to succeed?
2)Is there a better way for me to constrain the conic to achieve my design intent?
3)Is it possible to set up the optimization feature to automatically produce a cross section that will meet my area target?
Any and all help and thoughts appreciated!
Thanks.
Dasalo