Week 11 - Project - A pillar Design with Master Section

A PILLAR DESIGN WITH MASTER SECTION

AIM

To create an A-pillar using the given CLASS-A surface and Master section.

INTRODUCTION

Back in the day, cars were mostly made of steel and over the decades lightweight alternatives have increasingly found their way into automobile designs. Current economic and ecological concerns make the production of fuel-efficient cars a high priority in the automotive industry. Some other benefits of plastics in vehicles include very little corrosion, extended vehicle life, increased design freedom, greater innovation potential, more versatility in integrating components, greater safety, and greater comfort.

In automotive industries, plastic trims (interior and exterior) play an important role in providing the aesthetics of the automobiles. The figure shows different types of plastic trims used in a passenger car.

The properties of plastic materials which helps in creating complex designs are as follows

• They are light in weight and are chemically stable.
• Easily moulded into different shapes and sizes.
• Good insulation and low thermal conductivity.
• Good impact resistance and they do not rust.
• Good transparency and wear resistance.
• Poor dimensional stability and can be easily deformed.

The pillars on a car with permanent roof body style (such as four-door sedans) are the vertical or nearly vertical supports of its window area or greenhouse—designated respectively as the A, B, C and (in larger cars such as 4-door station wagons and sport utility vehicles) D-pillar, moving from front to rear, in profile view. Car pillars are components that support the structure of an enclosed automobile body. Car pillars are designed to stand in near vertical or inclined positions to support the roof.

The A-pillars on each side of the windshield come up to be joined together by the header rail across the top of the windshield.

ROLE OF THE A-PILLAR:

A-Pillar is located on either side of your car’s front window (or windshield).

They also hold the hinges of your front doors. A-pillars are normally made of steel alloys.

Besides being a supporting member, A-pillars are very crucial as far as safety is concerned. A-pillars usually carry a significant amount of load during a frontal collision or a rollover crash. So the larger the width or cross-section, the greater would be the strength but A-pillars always block the driver’s vision (create blind spots) to some extent that can be realized while driving. So, having that said, using thicker A-pillars can make the situation even worst. It might further lower the driver’s vision and raise a question about the vehicle’s and passenger’s safety.

Hence, the design of A-pillars must be optimized giving equal importance to both strength and the driver’s vision.

Firstly, we have to create the required Tooling-Axis for the given Class A Surface while meeting the requirements of the necessary Draft Angle & then perform the Draft-Analysis Operation on the Class A Surface itself.

After that, we have to create the required Class B & Class C Surfaces using which we have to make the Final Plastic Component and perform Draft Analysis on it.

MAIN REPORT:

Types of Surfaces and their importance for an Automotive Plastic Designer:

• Class A Surface: Class A is an aesthetic surface with the highest quality finish. Most Class A Surfaces for an Automotive Component are made using 'Autodesk-Alias' based on the final Concept-Sketch. All Class A surfaces should have 'Curvature-Continuity', meaning the continuity between the surfaces should share the same boundary. It is taken as a reference by the Automotive Plastic Designer to create 'Class B' and 'Class C' Surfaces.

• Class B Surface: The Class B Surface resides below the Class A Surface at a certain thickness. It is created using Engineering Principles that consist of all the necessary features such as Ribs, Bosses, Snaps, etc. This surface isn't visible to the observer from the outside.

• Class C Surface: The Class C Surface is the surface created between the Class A and Class B surfaces to join them with each other.

Now, we will begin by checking the State of Connectivity for the Class A Surface and ensure that there are no gaps between the surfaces as all the surfaces should be joined well together with each other and shouldn't consist of any discontinuities between them.

Our Class A Surface:

To inspect the State of Connectivity for the Class A Surface:

Using the 'Boundary' Command' from the Operations Toolbar:

In this case, we have to click on the 'Boundary' command and then select the Class-A Surface. After that, we'll click on the 'Preview' button to highlight all the boundaries that are on the Class-A surface and check if there are any internal boundaries other than the outer edge boundaries.

In our case, there is only one boundary present on the Class-A Surface which is the Outer-Edge Boundary and hence we can conclude that all the surfaces are well connected.

CLASS A SURFACE WITH MASTER SECTIONS:

PROCEDURE TO CREATE THE MAIN TOOLING AXIS:

Since we have a Master Section provided to us using which we have to create the desired A-Pillar Plastic Component, We'll use that Master Section by extracting the lines as shown below and create a Bisecting Line with respect to those extracted lines to create our Main Tooling Axis.

DRAFT ANALYSIS ON THE CLASS A SURFACE:

Next, We will perform a Draft Analysis on the Class A Surface itself:

Before starting with a Draft Analysis Operation, we will go to the 'Customize View Parameters' option under the 'View Toolbar'. Then we will enter the 'Customize View Mode' where we will go under the 'Mesh' option and select 'Material' and press 'OK'.

To start the Draft Analysis in the 'Generative Surface Design Workbench', we will go to 'Insert' and then look for the option called 'Analysis'. Once found, we will go under that and click on 'Feature Draft Analysis. This will open the 'Draft Analysis' Dialogue box. There, we will ensure that under 'Mode' we have selected 'Quick Analysis', under 'Display' we will select 'Show or Hide the Color Scale' and then select '3 Degrees' as the permissible draft angle. Then, under 'Direction' we will choose the icon with the symbol of the compass on it which stands for 'Use the Compass to define the new current draft direction'.

PROCEDURE TO CREATE THE CLASS B SURFACE:

We'll offset the Class A Surface by 2.5mm as shown below:

It is not offsetting properly due to the complexity of the curvature of the Class A Surface and hence we have to recreate that missing patch using tools such as Sweep Command as shown below.

We'll create two boundaries as shown below so that we can use the sweep command on it:

Then, we'll join the newly created surface with the main offset obtained from the Class A Surface.

Hence, our Class B Surface is created.

PROCEDURE TO CREATE THE CLASS C SURFACE:

To create the Class C surface firstly we have to unhide the Class A Surface and extract it's boundaries.We're going to smoothen these extracted boundaries using 'Curve Smooth'. Then we're going to use the 'Sweep' command with 'Reference Surface' & 'With Draft Direction' to create the Class C Surface as shown below:

Now, we're going to join the Class A and Class C surfaces with each other.

Then, we going to trim it with the Class B surface. To ensure that it will be feasible to trim the Class B surface with the joint surface of Class A & C, we're going to extrapolate the Class B surface by a small amount to obtain the closed body as shown below:

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DRAFT ANALYSIS FOR THE CLOSED BODY USING THE MAIN TOOLING AXIS:

PROCEDURE TO CREATE THE ENGINEERING FEATURE- DOGHOUSE USING THE MASTER SECTION:-

• All the attachment features are added to the main body using Boolean operations.

• DOG HOUSE

Dog houses are designed to avoid SINK MARK created on the CLASS-A surface by screw bosses and to solve the length issues when giving screw bosses which need to be assembled to other components.

It is also useful when perpendicular screw bosses are required on the part to the tooling direction.

Here the dog house is created using the Master section

• Create a positioned sketch on plane created on the master section.
• Extract the required master section and isolate it. Then given the constrains and extrude the sketch.

Using the Master Section we can create a sketch that can be extruded to create the doghouse's walls as shown below:

Side core Axis

Since the dog house's inner walls will not be cleared in the main tooling direction, we need to create the tooling axis for the side core. A min of 0.5 degrees draft is provided on all the walls.

Draft analysis of Dog House using the Side Core Axis

• Given Draft Value is 0.5 degrees

In the Draft-Analysis,

Green Colour stands for regions where the Draft Angle is more than 0.5 degrees,

Blue Colour stands for regions where the Draft Angle is between 0-0.5 degrees, &

Red Colour stands for regions where the Draft Angle is lower than 0 degrees

It is evident from the above images that the Draft Analysis is successful and the A-Pillar with the Doghouse is feasible to manufacture.

Finally, using the Boolean Operation, we're going to add the Doghouse to the Closed Body of the A-Pillar as shown below:

3D VIEWS OF THE FINAL PART