Ask an Engineer - CAD

Starting this week, we would like to introduce a new segment called Ask an Engineer!  Each month, we will select an overall theme regarding engineering and the Formula SAE competition.  Then, we will explore different components of that theme each week to give readers an in-depth look into the world of UT SAE.  Featuring insight from the engineers of UT SAE's very own design teams, Longhorn Racing IC And EV, we hope to offer a richer understanding of what it means to walk the line between being a student and being an aspiring engineer.  

For the first month, we'll be delving into a hugely important topic for the design teams: the software used in the design process of a Formula SAE car.  This week, our focus is on discussing CAD software, including Solidworks, the specific program used by our design teams.

CAD, or Computer Aided Design, is a software package that people from all walks of life – from engineers to architects to artists – use to design products.  Its popularity among such a wide variety of professions is a result of CAD's ability to create precise models and technical drawings on a level that would have been unthinkable in the age before computers.  CAD software is a huge step up from pen-to-paper drafting and has been lauded for its huge advances in productivity and output by eliminating the need to erase by hand in order to make changes and by introducing a huge range of new tools that can only exist on a computer.  Due to this, the engineering workforce has benefitted because CAD software offers a shortened design cycle and therefore more efficient product development.

Drawings in CAD can be 2D (or, vector-based models) or 3D (solid and surface models), and they enable users to design alternate models of an object without having to render the product in real life to see how it works.  Form and function can both be modeled within the programs and can then be corrected before the product is created, which eliminates the costly process of having to produce a product before seeing how it actually will function.  

In addition, CAD software enables for better communication.  It creates a standardized design process, allows for better documentation because users are able to save various iterations of their work, enables better legibility than hand drawn designs, produces easier adaptability to drawings themselves, and encourages better collaboration between several different people who are all working on the same project.

A specific example of CAD software is Solidworks, which is used by Longhorn Racing in the design of their Formula SAE cars.  Solidworks provides a 3D solid modeling package, which allows users to sketch ideas and experiment with different designs in order to develop full solid models in a simulated environment.  The program offers a full inclusive package that has simulation tools as well.

The Solidworks edition used by Longhorn Racing includes a wealth of helpful tools that enable us to create the best car we can in the most efficient way.  Some of these technologies include motion analysis for kinematic and dynamic simulation, including event-based studies; Computational Fluid Dynamics for fluid and thermal studies; Finite Element Analysis for structural, thermal, impact, and optimization studies; and a costing analysis tool that estimates manufacturing costs that adjust as you modify the design.  Several of these technologies will be discussed in more depth later this month in additional Ask an Engineer segments.

But how do these technologies affect the design process of Longhorn Racing?  Chief Design Engineer Andy Fortin offered his ideas of how he's seen Solidworks benefit the team over the years.  

What is the design process like when using Solidworks?

  • “It starts off with a conceptual understanding of what you're trying to accomplish.  Once you understand that, you create a very simple mechanism that does what it needs to do from a bare-bones perspective.  There's no refinement in the design at all; the part just does what it needs to do.  Once you've created a part that completes its function from a conceptual aspect, the iteration and real design work comes into play when you find out how you can take that object and optimize it from weight, cost, and time perspectives into something that completes the task in the best possible manner given the situation and the scope of the project.

How does Solidworks enable you to test out many different designs?

  • It allows us to check geometric tolerances – whether things will run into each other or not, as well as whether we have the correct interference fits for the bearings, conduct of finite elements, and some CFD which allows us to animate the experience loads that go through a part.  It helps us actually visualize how things work – it's a visualization tool that allows us to see the model in a 3D space.

How does the team collaborate to work together on a single car?

  • The first part of collaboration is having an understanding of how each subsystem interacts with each other – how each components works with the others in the car.  Once you understand that and the relative locations of parts in the car, the real collaboration begins when more specific details, sizings, and geometries will be implemented.  Using Cloud storage devices like Box helps share Solidworks files amongst the teammates in real time.  Having a full car model assembly running helps as well so as the components of the car are designed, you can see before the car comes to life the full geometry of the vehicle meet up with each subsystem.  Of course, actual physical talking collaboration goes on to make sure that the leads of each subteam keep all these things in mind as they design the car.

How do you go from a CAD model to building the actual car?

  • We create engineering drawings of many parts, and they show all the needed dimensions and tolerances in order to create a part for a specific application in the car.  One of the means of creating these parts are mills and lathes for 2D oriented parts.  More complex 3D parts use the CNC machine. Another example is jigging the frame.  We jig a lot of the critical components of the frame such as critical suspension points, running a tolerance of 0.1 inches in the points.  By connecting those points in the frame with tubes that we get laser cut, we get a strong geometric reference in order to connect all other pieces in the car.  The spacing of suspension points encompasses about 1/3 of the car.

CAD software significantly aid in making the lives of UT SAE's design teams easier and help students visualize the designs that they are creating.  By enabling better efficiency and more effective collaboration, CAD software affords both Longhorn Racing IC and EV the technology to make the best possible product for each design and build cycle.  Without it, the already-challenging task of creating a racecar as a student would be infinitely more difficult.