Engineering Analysis Tools

FEA/CFD Analysis:  Nascar® Chassis - FEA

The objective of the project was to create and maintain a master simulation model of the chassis and suspension that make up a Sprint Cup Race Car. The simulation model will be used as a basis for new designs, as well as local and global stiffness and strength issues.

The vehicle master draft was used for the CAD basis and a full FEA mesh was developed for the entire car. A bare chassis was first modeled and tested both statically and for natural mode shapes. The bare chassis FEA and testing data showed very good correlation, within 1% on static testing and 4% on modal. The high level of correlation gave confidence in the model and FEA methods. The simulation model then had the body, engine and additional masses added to simulate a finished vehicle.

Nascar Chassis Model

The model has been used for component sensitivity studies, as a crash simulation baseline model, natural frequency mode shapes and frequency prediction, suspension compliance, component failure analysis, and to determine under used or overly stressed material. The model is fully massed and contains fully articulated suspensions. This allows a more accurate G-loading of the full vehicle with restraints at the actual tire contact patches. By loading the model in this manner, the masses are distributed properly and by using large deflection analysis, the full range of suspension geometry can be simulated.

 

FEA/CFD Analysis:  Rocker - FEA

RAETECH engineers use ANSYS products for our Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) investigations. The FEA example shown here is a structural analysis of a suspension “rocker” (which transmits motion from the pushrod to the spring/damper unit) from a prototype sportscar.

FEA analysis can be used to evaluate how efficiently material within a part is utilized. Under stressed areas can be lightened and highly stressed regions reinforced.  Colors on the part represent both stress level and stress gradient. Very low stress means the part is not efficient – it’s heavier than it needs to be. High stress may suggest short service life or low stiffness. This part as originally designed has low stress regions, high stress points and high stress gradients. We were able to both strengthen and lighten this part by removing material from the blue areas and adding a little near the red.

RAETECH demonstrates a unique application for ANSYS analysis tools:  » Downloadable Pdf File

 

FEA/CFD Analysis:  Wing Spar - FEA

The stress plot on the right represents part of the wing spar structure of an ex-military T34 aerobatic aircraft. Following three crashes due to wing separation from aircraft abused in mock air combat, the entire fleet was grounded. RAETECH was consulted to help establish the reasons for the failures. We are very pleased that our FEA analysis was part of a series of measures that resulted in the T34 fleet being able to return to the skies.

Read article in Ansys Solutions Magazine, Spring 2006, pg. 7:  » Downloadable Pdf File

Read an overview of the project:  » 'Keeping Vintage Planes in the Air'

 

FEA/CFD Analysis:  Throttle Body - CFD

Throttle Body CFD Throttle Body CFD

Two CFD images are presented on the left. Both represent throttle plates in intake runners; the difference is the shape of the butterfly and the shaft which supports it. These iso velocity plots show contours of constant gas velocity.

In this case, the light blue surface shows 75 m/s. Flow velocity is below 75 outside the runner’s mouth and above it once inside except where it is affected by the butterfly. The iso velocity contour gives an unusually clear insight into where and how much wake is generated by the unstreamlined round throttle shaft and the screws attaching the butterfly. This turbulent, low velocity wake effectively blocks a portion of the runner for the free-stream flow.

Based on this information, RAETECH redesigned the throttle components and the results can be seen in the next plot. The new trapezoidal section butterfly and a carefully designed shaft attachment provide much less disruption to the airflow in the runner.

We would draw attention to the iso velocity surface being flat across the bellmouth and very close to the inside surface of the runner. These indicate the air is uniformly accelerated into the runner and the runner’s profile is well suited to the flow. These desirable characteristics are both the result of careful CFD work by our engineers.