In many accidents, the exact progression of events is unclear. The time difference between an impact and the following movement can be as short as a fraction of a second, making it difficult for witnesses or the parties involved in an accident to accurately recall details relating to the specific event. Additionally, reactions to both direct and indirect impacts are complex, and often difficult to accurately determine using the simple analytical methods approach. NBI’s experts use validated computational simulation and analysis software to approach these types of cases. Simulation software packages apply mathematical models and numerical analysis methods to define the physical system that is being studied. This approach enabled the consideration of a more comprehensive analysis as the use of a computer and the developed methods allows for more complex and time-consuming calculations to be performed in a more efficient way.
Our experts have experience with several simulation software packages, each of them being suited to specific applications. Accident reconstruction analysis often includes physics-based simulations, in combination with physical evidence and damage analysis, to model the progression of events and determine accident parameters. PC-Crash and Virtual Crash are commonly used by our accident reconstruction and biomechanics experts to computationally recreate incidents involving motor vehicles, bicycles, and/or pedestrians. These software are capable of modeling both specific vehicles and scaled human bodies, supporting both vehicle-based and biomechanical analyses. MADYMO is a software package which can be used for biomechanical analyses in a variety of cases, which include motor vehicle accidents and falls. It differs from other similar software by the fact that it able to provide models for both crash test dummies and humans. The human models are designed to include the effects of both passive and active muscle control, providing the most realistic biological responses developed yet. MADYMO can be integrated with accident reconstruction software, such as PC-Crash, allowing our experts to visualize and analyze occupant motion throughout events such as a motor vehicle accident. These software are all based on standard and peer-reviewed analysis methods and have been validated over the years against real life collision tests, supporting the dependability and accuracy of the results acquired through the modeling that our experts perform. Other software, such as MATLAB, provide an environment for the development of numerical analysis models, as well as aid with complex calculations. A variety of predefined functions, including differential equation solvers, allows for the analysis of equations of motion as well as other parameters. The results of these computational simulations may be used independently or in conjunction with other physics-based analysis methods to inform our experts of accident conditions and the potential for injury production.
As an example, simulation techniques were recently used by NBI’s experts, in a case involving a car experiencing two consecutive collisions. The vehicle was first impacted on its side, causing it to rotate and strike a vehicle parked on the side of the road. This accident produced a complex set of vehicle reactions and occupant motions over a very short period of time, which were challenging to analyze manually with the available information. Accident reconstruction analysis provided several accident parameters, including the direction and duration of forces experienced by the impacted car, as well as its change in velocity as a result of the impacts. Using this information, our biomechanics experts calculated linear accelerations and forces experienced by the occupant of the impacted car. However, determination of the angular velocity experienced at the head was completed through a simulation analysis. Virtual Crash was used to recreate the conditions of the accident, and the angular velocities of the head segment of the occupant model over time produced by the software were used for the determination of the potential for TBI occurrence. The complex motion modeling and analysis completed through the use of the simulation software in this case provided a more accurate and comprehensive estimate of occupant kinematics than it would have been possible to ascertain through a simpler manual calculation.