I will try to describe how I model a rope in Rhino instead of Autodesk Inventor. I am sure you can adopt these steps to Autodesk Inventor.
The commands that you will need will beas follows;
Flow (along curve)
First of all to draw a rope you will need to know exact lenght. As you can see in reference picture we will draw a straight line which lenght's is equal to your final rope lenght.
In second step we will draw circles around our reference line. The number of circles, Radius of circles and lenght of the final rope model will affect how the rope seems like.
Now extrude the circles along the refence line.
At this step you will TWIST the extrusions. For your reference you can check this web site to see TWIST command in action.
Now it is time to adopt our twisted rope to our final rope shape. We will use FLOW command and flow the extrusions along final rope line.
Again for your reference you can see how FLOW command works at the following Rhino's web site.
As seen in the picture you can use 8 circles instead of 4 and a core.
The final extrusion will be like this.
The twisted extrusion of 8 circles and a core.
The twisted extrusion of 8 circles and a core are applied to final reference line of rope.
Here is the anothe example. The twisted extrusion is applied to a helix.
Consequently, you can try to change;
a. Number of reference circles
b. Radius of circles.
Also lenght of the rope and degree of twisting will affect your final result. So you should change inputs until you will satisfy with what you get.