Modeling a car wheel -SIEMENS NX

BY DIMITAR CHESHELOSKI

In this example I am modeling a wheel of Audi R8: the alloy wheel, tire, bolts and the brakes.

The idea is to make the model as realistic as possible

* The images used in this example can be found on internet *

AUDI R8 WHEEL _ SIEMENS NX 2

AUDI R8 WHEEL _ SIEMENS NX 3

First, a reference plane is needed, in this case raster image of the wheel is set up on YZ plane.Overall translucency is set to 80% so the image won’t interfere with visibility of the sketches and the geometry.

AUDI R8 WHEEL _ SIEMENS NX 4

Creating the initial sketch, outlining the rim and spoke features.

AUDI R8 WHEEL _ SIEMENS NX 5

Extruding the external rim feature using the Extrude command.

For defining the frontal outer shape of the spokes another sketch was created on the XZ plane.

AUDI R8 WHEEL _ SIEMENS NX 6

Revolving this sketch creates limit face for spokes extrusion.

AUDI R8 WHEEL _ SIEMENS NX 7

Extruding the bulk of one spoke.Circular pattern will be used to create the other 4 spokes.

AUDI R8 WHEEL _ SIEMENS NX 8

Extrude and subtract from the bulk of the spoke.

AUDI R8 WHEEL _ SIEMENS NX 9

After extruding the inner rectangle od the spoke (reference first sketch) and applying Boolean Subtract operation we have the original U shape of the spoke.

By using Pattern Geometry we copy the original into circular pattern: span angle 360⁰, count 5.

AUDI R8 WHEEL _ SIEMENS NX 10

Detailing the spokes by applying Draft command.Thus making them wider on one side and narrower on the opposite.

AUDI R8 WHEEL _ SIEMENS NX 11

Blending the inner sharp edges.

AUDI R8 WHEEL _ SIEMENS NX 12

Now I am creating another sketch on the XY plane which I will revolve and use as defining back face for the spokes thickness.

AUDI R8 WHEEL _ SIEMENS NX 13

Revolved sketch.

AUDI R8 WHEEL _ SIEMENS NX 14

Trimming the spokes geometry with the revolved face.

AUDI R8 WHEEL _ SIEMENS NX 15

Next, creating another sketch for the center of the wheel.In this sketch I am using Studio Spline with applied continuity tangent constraints to simulate the curvature of the

original.This sketch will be revolved.

AUDI R8 WHEEL _ SIEMENS NX 16

Trimming the newly revolved sketch with previously created revolved face (green).

AUDI R8 WHEEL _ SIEMENS NX 17

Merging the center of the wheel and the spokes into one solid body.

AUDI R8 WHEEL _ SIEMENS NX 18

The center face is flat.To create dome-like shape and the concave groove around the center of the wheel,

couple of steps need to be done:Split the body using extrude section as a tool option (in this case the green circle sketch)

AUDI R8 WHEEL _ SIEMENS NX 19

The result of the Split Body command.

AUDI R8 WHEEL _ SIEMENS NX 20

Next: make another sketch on XY plane using geometric constraints to constrain the end points of the spline, one to the edge of the split body and the other to the center axis of the wheel.

AUDI R8 WHEEL _ SIEMENS NX 21

Revolving the previously created sketch we get that dome-like shape.

AUDI R8 WHEEL _ SIEMENS NX 22

Now I am creating reference lines with the help of sketch – Intersection Curve option.This command creates cut lines between the selected faces and in this case,

XY plane since the sketch lies on that plane.

AUDI R8 WHEEL _ SIEMENS NX 23

Finally, I can use Bridge Curve command to fit a curve that can connect the reference lines with G2 – curvature connectivity.

AUDI R8 WHEEL _ SIEMENS NX 24

With the revolving of the bridge curve, I get that concave groove face I was aiming for.

With this, the dome-like shape and the concave groove for the center of the wheel is finished.However, geometry needs to be cleaned so there is no geometry overlapping.

AUDI R8 WHEEL _ SIEMENS NX 25

I am deleting this section of the original body. By this I am creating a gap so I can incorporate the newly formed revolved face

and avoid geometry overlapping.

AUDI R8 WHEEL _ SIEMENS NX 26

The revolved bridge curve it’s a face feature, not a body, in order to make it a body and incorporate it into the main body I am extruding the face itself with the End option: until selected, and select the back face of the main body.

At the same time I can unite the newly created extrude body with the main, choosing Unite as a Boolean operation or do the Unite operation separately, however, the result is the same.

AUDI R8 WHEEL _ SIEMENS NX 27

Now, I am creating a sketch to model the remaining geometry of the wheel.By using the Project Curve option I can project any edge of the existing parts or assemblies onto the working sketch

plane and by this saving time and making sure everything is aligned.

AUDI R8 WHEEL _ SIEMENS NX 28

Extrude the sketch and mirror the extruded geometry.

AUDI R8 WHEEL _ SIEMENS NX 29

Circular pattern of the mirrored geometry.

AUDI R8 WHEEL _ SIEMENS NX 30

Extrude the holes (simple sketch with circle) through the whole body and circular pattern applied.

AUDI R8 WHEEL _ SIEMENS NX 31

At the end I am applying circular Edge Blend with various radii.

AUDI R8 WHEEL _ SIEMENS NX 32

Simple render and texture applied to a finished alloy wheel.

The rest of the parts, such as:the tire, the bolts, the disc brake and the disc caliperare modeled using the same or similar techniques.

*the following slides will only show finished models*

AUDI R8 WHEEL _ SIEMENS NX 33

AUDI R8 WHEEL _ SIEMENS NX 34

The Tire

AUDI R8 WHEEL _ SIEMENS NX 35

The Bolts

AUDI R8 WHEEL _ SIEMENS NX 36

The Disc Break

AUDI R8 WHEEL _ SIEMENS NX 37

The Disc Caliper

AUDI R8 WHEEL _ SIEMENS NX 38

The whole wheel and all its components.