# CAD tip # 10721:   %  platform  category ## How to draw a catenary or other parametric curve in Inventor? The catenary curve (also called a chainette, alysoid, funicular, see wiki) - the curve of hanging chain or cable or other fibre in a homogenous gravitational field - is used in many design tasks. To create a sketch shapes as a catenary in Inventor you can zse the function "Equation curve" and specify the curve parametrically.

On the above linked wiki page you can find the generalized equation of a planar catenary curve:

y = a * cosh (x / a)

where a is the parameter of uniform scaling of the curve.

Start the function Equation curve (Sketch > Create > Line > Equation curve): and enter the equation directly to the equation fieleds - choose the equation option "Explicit" and "Cartesian". Just make sure the correct units are combined - i.e. convert the length value of "x" to angle (mm->rad). Using the value of a = 1.8 and the range x -2 to 2:

y = 1.8 * cosh (x / 1 mm * 1 rad / 1.8) For possible subsequent editing of the curve, you the function "Edit equation curve" from the context menu in the model browser tree.

 Inventor  *  CAD 31.1.2016    8017× applies to: Inventor ·

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