Living in Knoxville, Iowa I find myself spending my Saturday nights during the Summer watching winged sprint cars at Knoxville Raceway, known as the Sprint Car Capital of the World. Sprint cars are open-wheel race cars with a 900hp 410-cubic inch engine, weighing 1400 pounds. These cars race on quarter mile to a five-eighths mile dirt tracks across the United States, Canada, Australia, New Zealand, and South Africa.

In motorsports the difference between winning and losing is how your car handles. One aspect of how your car handles is the weight distribution of the car. Race teams can move weight to improve how a car turns in various track conditions. By minimizing the weight of specific components, we can move more weight to ideal locations to improve performance. 

In this blog we will look at how we can optimize the design of the LH steering arm for a sprint car to minimize the weight without reducing the performance of the part.


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Figure 1 Sprint Car

Original Part

The first step in optimizing the LH steering arm is to analyze existing designs. A search of the internet identified several unique designs. We selected one of the designs as a baseline and modeled it in Altair Inspire.  

2-3Figure 2 Original design

Supports and Loads

We added supports and estimated loads to the model and performed an initial analysis. This provides a baseline for the performance of this part which we will compare to the new optimized part.

For this part we applied a grounded bolt to the holes where the steering arm connects to the spindle. We created several load cases to represent left and right turns at various angles. This should give us a good representation of the loads placed upon this part during a race. We applied a bearing force of 1500N to the locations where the tie rods connect. 

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Figure 3 Displacement of original design

Simplified

The next step in the optimization of the LH steering arm is to simplify the part to maximize the design space and identify non-design space. Design space is the geometry the forms the boundary of the optimized shape. Altair Inspire provides many tools to simplify the part to maximize the geometry that can be used to create the design space.

The image that follows shows the design space in a coffee color and the non-design spaces in grey. 

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Figure 4 Part with design space identified

Optimization

Using the supports and loads applied to the original part we performed a topology optimization on the part with design space. This optimization will find the most effective design for the design space in response to the applied loading conditions. Figure 5 shows the results of the optimization. This shape represents the minimum amount of material required for the part to perform as required.  

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Figure 5 Optimized design space

We performed an analysis of the optimized shape to confirm the shape exceeds the minimum performance requirements of the design. 
 

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Figure 6 Displacement of optimized shape

PolyNURBS

Once the optimized design meets the performance requirements of the design the shape, we can smooth the optimized shape using Altair Inspire’s PolyNURBS tools. These tools are used to create a part that can be manufactured and is more aesthetically pleasing.

The final part is shown below. We can perform an analysis of the final part to confirm this part meets the design requirements. 

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Figure 7 New optimized part

Results

Through optimization we can reduce the weight of this part from 1.68 pounds to 0.745 pounds. The maximum displacement improves from 2.215e-03 in to 2.049e-03 in. The factor of safety or the existing design is 7.1, the optimized design has a factor of safety of 5.9. The optimized part is lighter and performs better than the original part.

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Figure 8 Original part results
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Figure 9 Optimized part results


Altair Inspire

Altair Inspire is a tool that allows engineers to optimize their designs quickly and easily. This can help engineering teams deliver higher quality designs in a shorter timeframe. This will impact your company by providing your customers with better products helping them to win the race in business.

About the Author

Greg Johnson is a Manufacturing Simulation Specialist at Altair and has been with them since 2021.  Prior to that, he spent 20+ years in industry in Aviation and Heavy Machinery.  

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