Vehicle Dynamics Testing: Virtual Simulations Expert Article

In this article, automotive engineer, Marcus Mazza, P.E. discusses the merits of utilizing vehicle simulation software to test vehicle dynamics in place of traditional instrumented testing. Vehicle simulation software has the potential to offer validated scientific results for disputes involving vehicle stability at a fraction of the time and expense of traditional instrumented testing.

Testing Vehicle Dynamics with Simulation Software

The vehicle engineers at Robson Forensic utilize CarSim Mechanical Simulation© software to perform scientifically accurate vehicle dynamics simulations and virtual testing at a fraction of the time and expense associated with traditional instrumented handling tests. CarSim is a leading vehicle dynamics software and is utilized extensively by the majority of large automotive manufacturers and suppliers. The accuracy and reliability of simulated test results performed within the CarSim environment serves as a generally accepted scientific test method and is backed by more than 20 years of real-world validation by automotive engineers.

Simulations and virtual testing can be applied in a number of litigation scenarios that have traditionally relied heavily on instrumented testing, manufacturer’s test data, or relevant technical papers. The application of this technology has potentially wide reaching applicability in cases involving:

• Vehicle Rollovers
• Single Vehicle Run Off the Road Incidents
• Dynamics Comparisons in Vehicles With and With Out Electronic Stability Control or ABS
• Dynamics Analyses in Vehicles with Modified Suspensions
• Dynamics Comparisons for Various Payloads or Loading Configurations
• Dynamics Analyses for Vehicles Towing Trailers

Testing with Traditional Instrumented Methods

There are a number of potential shortcomings associated with traditional instrumented testing within the context of legal disputes. Aside from the costs associated with acquiring an equivalent vehicle and outfitting it to match the specifications of the incident vehicle, the dynamic nature of many disputed crashes would make it impossible for engineers to recreate the vehicle maneuvers in a real world environment without risking life and limb.

Through the use of simulation software, automotive engineers can accurately simulate the handling characteristics of any vehicle, regardless of cost or availability, and modify the software specifications to adjust for vehicle component upgrades or owner modifications. Within the virtual environment, engineers are also given the freedom to run multiple simulations and test various hypotheses without incurring exorbitant costs or amassed wreckage. In many scenarios, virtual testing can be completed for less than half the cost of real world vehicle testing.

CarSim Example Simulation

The video and images below were extracted from the CarSim test environment. This simulation was created to model a driver performing an emergency avoidance maneuver followed by an over-correction in the opposite direction. This is a very common maneuver in vehicle crash incidents that often leads to rollover events in larger SUVs. Through the virtual test environment, engineers can determine the rollover propensity of a vehicle.

The image above is an example of a CarSim input screen where automotive engineers can make changes to vehicle parameters such as Center of Gravity Height, Overall Vehicle Mass, and Wheelbase, allowing for quick adjustments to vehicle configurations/designs.

Once a vehicle and model is established by the engineer, virtually any driver input can be simulated within the test environment (steering wheel angle, braking, throttle, environmental inputs). The screen above represents steering wheel input as programmed by the engineer. The double steer maneuver involved in this simulation involves the driver steering hard left, followed by a hard prolonged right turn before bringing the wheel straight. The engineer can also program any variety of environmental/roadway inputs (such as coefficient of friction, roughness, bumps) to emulate the environment in which the actual incident occurred.

Based on the given inputs, the simulation software can output scientifically reliable vehicle data pertaining to its dynamic characteristics within the established test environment. In addition to quantitative data, the CarSim software can also create visual demonstratives that are engaging and sufficiently intuitive to be used in the courtroom. In the video below, you can see visual representation of the above mentioned maneuver along with graphical arrow representation of tire forces.

CarSim results have been extensively validated against real world instrumented test results for more than 20 years. In this model we had the opportunity to validate our simulation results against existing test data for the same vehicle and maneuver.

The image below is an overlay of simulated and actual test data showing strong correlation for the double steer maneuver. The blue line represents simulation data and red line real world. In litigated disputes, validation of CarSim test results can be achieved through discovery by comparing virtual model results against existing OEM test model data.

Vehicle Crash Investigations

From complex crash reconstruction to developing demonstrative evidence for court testimony, the transportation experts at Robson Forensic are well equipped to assist in your investigation. Our experts have in-depth knowledge of how vehicles are designed and built, they are fluent in the regulations affecting trucking operations, and have designed, built, and maintained our nation’s transportation infrastructure.

For more information visit our Vehicles & Roadway Systems practice page.

Featured Expert

Marcus A. Mazza, P.E.

Automotive Engineer & Crash Expert

Marcus Mazza is an automotive engineer with diverse experience in production vehicles, military vehicles, and motorsports. He applies his expertise to intellectual property disputes as well as vehicle… read more.