Challenge 5 : Concept Modeling of Car Bumper

CONCEPT MODELLING OF CAR BUMPER USING ALIAS SOFTWARE

AIM

The main of this project is to create a concept model of a bumper of Abarth 500 car, using the curves and surface generation features with the help of Alias Software.

INTRODUCTION

Autodesk Alias (formerly known as Alias StudioTools) is a family of Computer-aided industrial design (CAID) software predominantly used in Automotive Design and Industrial Design for generating Class A surfaces using Bézier surface and NURBS modelling method.

The outside portion of the car which people can see from their naked eye is called the class A surface of the car. This surface needs to be designed with the help of concept modelling technique with the help of which the design of the car can be made and visualised. 

In order to make the surfaces smoother and realistic Autodesk Alias software is used. This software enables us to make surface as smooth as possible with the help of different continuities which can be given to the curves and surfaces.

CAR BUMPER

A bumper is a structure attached to or integrated with the front and rear ends of a motor vehicle, to absorb impact in a minor collision, ideally minimizing repair costs.

 Numerous developments, improvements in materials and technologies, as well as greater focus on functionality for protecting vehicle components and improving safety have changed bumpers over the years. Bumpers ideally minimize height mismatches between vehicles and protect pedestrians from injury. Regulatory measures have been enacted to reduce vehicle repair costs and, more recently, impact on pedestrians.

The car for which the front bumper needs to be designed is shown below:

DESIGN METHODOGLY

The steps that are followed to design the concept model of the front bumper is shown below through flowchart.

PROCEDURE:

In order to make the concept model of the car in required width and size a cube will be made with the outer dimensions of the car so that the design can be made more accurately as per requirement.

The cube with the outer dimensions of the car is made and can be seen in the above image.

The first step in this project is to decide which views needs to imported to design the concept model of the  front bumper of the car. As we need to design the front bumper the images of the front and side views of the car will help to design the car bumper. 

1. Importing the front and the side view images of the car.

The image of the views will help us to build the concept model of the bumper.

Steps for importing Image

File -> Import -> Canvas Image -> Go

Scaling the Image:

After placing the different views in different layers the blueprints of the car will be scaled down to appropriate size so that it can be positioned accurately with respect to the other views. This will help in generation of curves at appropriate places and with desired shape of the blueprint.

Steps to scale the image:

-> Press ctrl + shift along with clicking and holding the left mouse button.

-> Select Pick object - Select the image

->  Press ctrl + shift along with clicking the middle mouse button

-> Select Scale

-> Hold left mouse button and move up and down to scale the image larger and smaller.

Steps to move the image:

Palette -> Transform -> Move.

The image is given some amount of transparency so that the curves can be traced easily on it at required positions.

Steps to set transparency.

-> Press shift + ctrl  along with clicking and holding right mouse button.

-> Select plane editor.

-> Set the value of the transparency level for the different views of the image in it.

The complete image of the car with all the views is shown above.

The position of the images in the ALIAS workbench is shown above.

2. Creation of different layers as per requirement.

Layers allow us to organize related objects into groups that you can pick, display, and edit individually or together.

Steps to create Layers

Menu Bar -> Layers -> New

The names of different layers mentioned in this project is shown below:

3. Generatind the curves to trace the required shape of the front bumper.

After placing the images at required positions the curves are traced on it to give desired shape of the front car bumper:

Cv Curve - It lets to create new NURBS on the scene by placing CVs.

In order to join curves at few places blends feature is used to give desired shape.

Steps for showing blends bar-

Palette -> Blend -> Blend Curve Toolbox -> New

Curve Trim

At few places the curves are trimmed to remove curves at certain places where it is not required.

Steps to perform curve trim:

Palette -> curve edit -> crvsct

-> Select the curve -> click on "GO" present in bottom right corner -> select the curve where you want the portion of the original curve to be removed.

The curves for the half portion of the car is made as the other half is exactly the symmetry of it. The curves are made on different layer and then all the curves are assigned in this layer. 

The symmetry feature is selected in this layer for the formation of the other half portion of the bumper.

The above image shows the curves that are made to trace the front bumper of the car.

Different views of the curves.

1. Isometric view

2. Front view

3. Top view

4. Side view

4. Generating the surfaces on the curve to design the concept model of the car.

After the file in which the model of the car is being imported, the surfaces needs to be made with the help of these curves. For this purpose surface features are used which are present inside the palette bar.

 The steps to use the surface generation features are:

Windows -> Palette -> Surface

By following the above procedure the surface generation features can be used.

Few of the  surface generation features that were used in this project is listed below:

1. Square

2. rail

3. skin

4. ffblend

1. Square:

Steps to go to square feature:

Windows -> Palette -> Surface -> Square

Square feature creates surfaces by blending four boundary curves (or curve segments), while maintaining continuity with adjacent surfaces.

Square Control

Continuity Table

Continuity

Free Boundary – This edge is free to move if required by another edge’s continuity or by the Influence sliders (see below). This is the default.

G0 Position – Keep this edge exactly like the boundary curve that created it. In other words, do not let the edge move as with the Free option. This is equivalent to positional continuity.

G1 Tangent – Try to keep tangency with a surface that shares this edge.

G2 Curvature – Try to keep curvature continuity with a surface that shares this edge.

Implied Tangent – Try to keep tangency with an implied surface that shares this edge. The implied surface is the surface that would be created by mirroring the new surface. (The way the Square tool tries to keep tangency with an implied surface is by blending the slopes of the boundary curves.)

This is a powerful feature. It lets you model one half of a symmetrical surface (such as a car body), and maintain continuity at the seam. When you duplicate the surface to create the other half, the seam will already be continuous. For this to work across a symmetry plane, you must make sure the ends of the curves are tangent across the symmetry plane (that is, the tangents are perpendicular to the symmetry plane).

Implied Curvature – Try to keep curvature continuity with an implied surface that shares this edge. The implied surface is the surface that would be created by mirroring the new surface.

2. Rail

Steps to go to rail feature:

Windows -> Palette -> Surface -> Rail

Rail feature creates a surface by sweeping one or more profile curves along one or two path curves (rails).

The Rail Surface tool takes its name from its use of one or two “rail” curves. The generation curves maintain contact with the rails at the same points through the sweep, like a train traveling on a track.

The Rail Surface tool is similar to the Extrude tool, but has many more options and much more power.

The appearance of the Rail Surface icon depends on the Generation Curves and Rail Curves settings in the Rail Surface Options window.

3. Skin

Steps to go to skin feature:

Windows -> Palette -> Surface -> Skin

Skin feature is used to create a surface by connecting a set of profile curves.

4. ffblend - Freeform blend

Steps to go to ffblend feature:

Windows -> Palette -> Surface -> ffblend

Free form blend enables us to create a transitional surface by selecting two input contact lines. These input contact lines can be surface curves or free curves.

To edit the surface, surface edit tools are used to obtain desired shape.

The various surface edit tools used to give desired shape to the surface is shown below:

1. Project

2. Trim

1. Project

Steps to go to Project feature.

Windows -> Palette -> Surface Edit -> Project

This feature is used to create curve on surface of the existing curve which will be projected on the selected surface.

This is like shining a flashlight at the curve, and turning the shadows on the target surfaces into curves-on-surface. The line between the flashlight, the curve, and the shadow is the projection vector.