Topology Optimization of Racecar Suspension Uprights · 2019-06-24 · Topology Optimization of Racecar Suspension Uprights. Billy Wight. Luxon Engineering. Altair Engineering, An

9/25/2008 © 2008 Luxon Engineering Slide 1

Topology Optimization of Racecar Suspension Uprights

Billy WightLuxon Engineering

Altair Engineering, An Introduction to Optimization in IndustrySeptember 25th, 2008

Tustin, California


Company Description

Luxon Engineering is a Full Service Mechanical Design Consulting Company

• CAD Modeling and Manufacturing Drawings• Concept Development• Mechanical Design and Analysis• Finite Element Analysis/Optimization• Product Development

• Located in San Diego• Small Company, 2 Employees• In Business Since January, 2007

Presenter

Presentation Notes

Full service mechanical design consulting company Located in San Diego Been in business since January 2007 We serve a wide variety of clients Ranging from single individuals to large companies Projects in industries ranging from medical device to racecars


Client Description

F1000 (Formula B) Class• Open Wheel• Stock 1000cc Motorcycle Engine• 1000 lbs Minimum Weight• 155 mph Max Speed• ~ 1200 lbs Downforce @ 155 mph• 2.4 g’s Lateral Acceleration

• Base Price $39,900 (Roller, No Engine)

D Sports Racer (DSR) Class• Closed Wheel• Modified 1000cc Motorcycle Engine• 900 lbs Minimum Weight• 165 mph Max Speed• ~ 2000 lbs Downforce @ 165 mph• 2.8 g’s Lateral Acceleration

• Base Price $59,900 (Roller, No Engine)

Presenter

Presentation Notes

This presentation focuses on one client in particular Stohr Cars Portland, Oregon Manufacturer of 2 different cars Both for SCCA competition D Sports Racer Formula 1000 Both cars utilize a 1000cc motorcycle engine and are very light weight Leads to an impressive power to weight ratio and performance capabilities


Previous Project - Differential

Modified Salisbury Differential• Collaborative Effort Between Luxon Engineering and Williams Racing Developments (WRD)• Chain Drive from 1000cc Motorcycle Engine • Direct Replacement for Stohr Cars

•Fits Other Manufacturers• Speeds, Phoenix, Radical, etc.

• Substantial Weight Savings and Performance Benefits vs. Stock

Presenter

Presentation Notes

Our involvement with Stohr started with an earlier project Collaborative project between Luxon and WRD to design a new differential Offered substantial weight savings and performance benefits over the stock differential Throughout this project I saw other potential areas of improvement in the Stohr cars


Design Challenge: Suspension Uprights

Simple, Inexpensive• Multi-Piece (Bolt-on Brackets)• Designed to “Get the Job Done” at an Inexpensive Price Point

• Necessary to Maintain a Reasonable Price for the Base Car

(front) (rear)

Stock Stohr Uprights (Current Design)

Presenter

Presentation Notes

One area in particular was the suspension uprights Essentially a large bracket Connecting point for wheel hub, brake caliper, suspension arms Stohr design very simplistic Designed to get the job done at a reasonable price point From a performance standpoint there is a lot of room for improvement Tyres are arguably the most important part of the vehicle All forces are transferred through the tyre from the racing surface to the vehicles suspension Focus on “keeping the tyres happy” To accomplish this, Minimize unsprung mass Increases the suspensions ability to respond to bumps and dynamic conditions Increase steering response Increase stiffness Important to remove the extra “springs” in the system Minimize the variables for suspension tuning



Luxon Revised Uprights (New Design)

Performance Goals:• Light Weight - Minimize Unsprung Mass• High Stiffness - Minimize Compliance

• Suspension Compliance =• One Piece Design – Remove Failure Modes

Design Constraints:• 6061-T6 Material

• Readily Available• Low Cost• Good Strength to Weight Ratio

• 3-Axis CNC Manufacturing• Readily Available• Reasonably Priced

• Keep Stresses Low, ≤ 160 MPa for Main Loadcases

What is the most efficient method of achieving our goals subject to the design constraints?

( , )f Springs Dampers

Presenter

Presentation Notes

In addition to the performance goals, we were also subjected to some design constraints Wanted to use 6061-T6 and 3 Axis CNC manufacturing Readily available and reasonably inexpensive Wanted to keep stress levels fairly low Brings up the question of How to meet design goals while satisfying constraints? How to do this quickly and efficiently?



16 Different Loadcases• 5 Main Loadcases

• Typical Racing Environment• 11 Additional Loadcases

• Bump Loading, Off Track Loading, etc.• Derived from:

• Vehicle Datalog Measurements• Suspension Kinematics• Tyre Data• Aerodynamic Data

Meet Design Goals Satisfying Constraints• Minimize Design Iterations

• Decrease CAD Modeling Time• Decrease Analysis Setup Time

• Engineering Time = $$$• Decrease Product Development Time

• Introduce Product to Market ASAP

Luxon Revised Uprights (New Design)

TOPOLOGY OPTIMIZATION

• Supports Multiple Loadcases • One Analysis Run Reveals Optimum Load-Paths

• Stress Constraint • Manufacturing Constraints

Presenter

Presentation Notes

Need to minimize design iterations Result in a decrease in modeling and analysis time In addition to this, the uprights see a fairly complicated loading due to the various dynamic conditions the car experiences Wanted to use 16 different load-cases Derived from vehicle datalog, suspension kinematics, tyre, and aerodynamic data These requirements all pointed toward topology optimization using the Altair HyperWorks and Optistruct products Minimized design iterations Supported multiple loadcases Manufacturing and stress constraints


Topology Optimization

Front Uprights – Optimization Parameters/Constraints

3- Axis CNC Manufacturing

• Split (Both Sides) Draw Direction Constraint• Ensures No Undercutting in the Result

Multiple Loadcases

• Stress Constraint, 100 MPa• Weights Each Loadcase Equally• Maintains Target Stress Levels

Minimize Unsprung Weight

Optimization Goal: Minimize Mass

Presenter

Presentation Notes

Various optimization parameters and constraints were used for the topology runs Draw direction constraint Ensures no undercutting will be in the result Allows for a castable or machinable design Optistruct supports multiple loadcases for topology optimization These were subjected to a stress constraint to help weight the importance of each loadcase equally Finally, the optimization goal was set to minimize mass



Front Left Upright – Analysis Sequence

TET4 Design Space (Yellow)“Material that CAN be there”

Topology Result“Material that

NEEDS to be there”

CAD Interpretation

Final Design TET10 Analysis Model

Presenter

Presentation Notes

Analysis Sequence: Front Uprights Design space is modeled as material that can be there Topology analysis runs on that model resulting in the optimum loadpaths This result can be exported to CAD using Altair’s OS-Smooth feature Using this result a CAD model is made to represent the geometry New model is then re-analyzed and a few iterations are preformed to end up with the final design on the left 3 iterations in this case Between original interpretation and final design



Rear Uprights – Optimization Parameters/Constraints

3- Axis CNC Manufacturing

Split (Both Sides) Draw Direction Constraint• Ensures No Undercutting in the Result

Decrease Cost

Symmetry Constraint• Ensures Symmetry in the Result• Rear Uprights are the Same Part Left/Right

Multiple Loadcases

Stress Constraint, 100 MPa• Weights Each Loadcase Equally• Maintains Target Stress Levels

Minimize Unsprung Weight

Optimization Goal: Minimize Mass

Presenter

Presentation Notes

Parameters and constraints for the rear uprights are similar to the fronts Exception of the symmetry constraint Rear loading is nearly symmetric Stock geometry points towards symmetry Planar symmetry was enforced in the solution Allows right and left side to be the same part Decreases cost Optistruct allows for various symmetry constraints including 1, 2, and 3 plane, as well as cyclical symmetry



Rear Upright – Analysis Sequence

TET4 Design Space (Yellow)“Material that CAN be there”

Topology Result“Material that

NEEDS to be there”

CAD Interpretation

Final DesignTET10 Analysis

Model

Presenter

Presentation Notes

Again, the analysis procedure is similar to the front uprights Notice the symmetry in the topology result due to that constraint


Results

Performance Results: Optimized Uprights vs. Stock UprightsMass – Decrease of 40%

• ~ 1.5 lbs per wheel

Stiffness – Increase of 225%• Measured via Deformation of a Node at the Tyre Contact Patch

Stress – Goals Achieved• Stress < 160 MPa (Main Loadcases)• Stress < 220 MPa (All Loadcases)

Presenter

Presentation Notes

This project yielded some impressive performance benefits over the stock components Unsprung mass decreased by 40% Equates to about 1.5 lbs per wheel Stiffness went up by 225% Stress constraints were achieved as well Peak stresses for the main loadcases are below the fatigue life of the material Peak stresses for all loadcases are below the yield strength of the material


Results

Benefits of Optimization Techniques

Engineering Time = $$$

• Optimization Eliminates the Multiple Iterations of Traditional FEA• Typical Problems Would Have Taken 15+ Iterations

• The Optimized Design is Often Non-Intuitive• Unlikely that Traditional FEA Would Yield the Same Result

Optimization Techniques Substantially Reduces Engineering Overhead and

Decrease Time To Market

Presenter

Presentation Notes

We saw substantial time savings by utilizing topology optimization in the design process Traditional FEA - Each iteration requires modification to the CAD model and updating the FE model with the new geometry Typical problems would have taken 15-20 iterations using standard finite element methods Topology optimization revealed the optimum loadpaths in one analysis run The optimum results are also rather non-intuitive It is unlikely traditional methods would arrive at the same result Overall, we saw a substantial decrease in engineering time as well as a decrease in time to market by using optimization through the design process

9/25/2008 © 2008 Luxon Engineering Slide 14Slide 14

Billy Wight PresidentLuxon Engineering858.586.1100 [email protected]

Questions, Comments?

Presenter

Presentation Notes

Questions or comments?

Documents

Topology Optimization of Racecar Suspension Uprights · 2019-06-24 · Topology Optimization of Racecar Suspension Uprights. Billy Wight. Luxon Engineering. Altair Engineering, An