Concept Modeling of Car Bumper using Autodesk Alias

Title of project: Concept modelling of car bumper

Objective: To create surfaces of the entire car bumper using 3 quarter images of the car.

Tools used:

Freeform blend tool, CV curves, line, circle, skin, align tool, trim, project, intersect, extend, detach tool, transform tools, fillet, dimension box,rail command etc.

Introduction:

Introduction to surface continuities and its types

Continuity is the smoothness of the junction i.e., two mating curves. Continuity is the condition that the more smoothly the adjoining surfaces flow

Generally there are 4 types of surface continuities i.e., we can have surfaces coming in contact in 4 different ways.

They are:

1. G0-position (touching)
2. G1- tangent (angle)
3. G2-curvature (radius)
4. G3-acceleration (rate of change of curvature).
5. G0-position (touching) continuity:

This is less smooth type of joint with common end point. This position is the only condition to satisfy the joint.G0 is the point continuity when one curve touches the other and shares the same boundary

2. G1- tangent (angle):

One can’t have G1 continuity unless you have G0 continuity.it is also called as second order of continuity i.e., to faces meet along a common edge at a tangent plane they share a common angle. The best example for G1 continuity is a fillet.

3. G2-curvature (radius):

G2 adds another order that must match across our pair of curves. For G2 it must a tangent to the curve and have the same curvature a point where they touch I.e., the input geometry must now be curved s well so the input containing a straight line can’t make a G2 curvature.

4. G3-acceleration (rate of change of curvature):

G3 continuity includes the concept of acceleration of the curvature; the amount of change in the curvature over the length of the curve.G3 is looking for balance on the rate of curvature.

Description:

1. Open auto desk alias and choose class a surfacing.
2. Import the canvas image by going to file > import canvas image > always create new layer.
3. Create a dimension box and go to attributes>transform>give the dimensions o the dimension to respective o the dimensions of the car.
4. Make the dimension box inactive by assigning it to a layer.
5. Align the image pivot point to the grid for ease of creating curves, to do that select the image and select set pivot point and align image to the grid.
6. Start the construction of the bumper from side view that is from the wheel.
7. Create the outlines of the wheel area and using ‘skin ’ command create the surfaces of the car wheel area.
8. Using ‘square’ command create the surfaces of the four edges created to complete the geometry.
9. Use ‘rail’ command to create surfaces having a generation and a rail.
11. Make the surfaces according the continuity using ‘align’ command and move the CV’s as per the fit and form.
12. Using 3-quarter views visualize the front part of the bumper and create the patches using CV curves.
13. Divide the patches to give the patch to obtain the required shape.
14. Using ‘intersect’ command intersect the surfaces and using ‘trim’ command trims the unwanted surfaces.
15. Use ‘fillet’ to create smooth edges to the mating surfaces and for better appearance.
16. Create extra details for head lamps for better representation of the model.
17. Using above steps trace and trim the surfaces to complete the model.
18. Using ‘project’ command, project the curves on the surfaces to create the required shapes of the bumper.
19. Assign the surfaces to a separate layer and curves to another layer as the curves must nit create problem while creating geometry.
20. Create symmetry to the layer to which the surfaces are assigned.
21. Create geometry to apply diagnostic shades to the surfaces.
22. Make sure that every patch is aligned as per the continuity and make sure that the surfaces are flowing smoothly.
23. Using 3-quarter views the concept model of the car bumper is completed.

images

car bumber rear

Conclusion: while modelling using orthographic views some parts of the model can’t be visualised ,so using 3-quarter views for visualisation of the model would be really helpful for modelling the car bumper.