By Kenny Santos
At Burgoynes, we are dedicated to providing precise, science-backed collision reconstruction services. A reconstruction can be carried out through analytical or computational methods. Reconstruction of collisions involving vulnerable road users (including pedestrians, cyclists, and motorcyclists who account for over 50% of global road fatalities), for example, sometimes needs to incorporate models encompassing the road users, including human body biomechanical models and vehicle models. With PC-Crash, we can accurately model complex scenarios [1], and its advanced multibody simulation capabilities allow us to replicate the movements of vehicles and individuals with remarkable accuracy, providing a clear view of how collisions unfold in real time.
Presented below is a case study [2] where, first and foremost, a detailed collision reconstruction was performed using PC-Crash, demonstrating its robust simulation capabilities for accurately modelling the dynamics of a motorcycle colliding with the front side door of a passenger car (Figure 1 and Figure 2). To further validate the accuracy and precision of PC-Crash, two additional reconstruction methods were applied afterwards, and these methods confirmed PC-Crash's ability to reconstruct real-world collision scenarios. The incident occurred at a junction where the car was turning left and was required to give way to the motorcycle. It was found that the motorcycle was travelling at more than twice the speed limit.
Fig 1 Police Sketch Fig 2 Vehicles' damage and rest positions
The collision dynamics were first established through a PC-Crash simulation where detailed models of the car, motorcycle and its rider were used (Video 1). PC-Crash’s multibody modelling feature provided insight into the projection of the rider’s body due to the impact. Subsequently, a finite element simulation was conducted in Ansys LS-DYNA to analyse the impact between the motorcycle tyre and the car's door, using the impact configuration and speeds (47 mph for the motorcycle and 6 mph for the car) obtained in PC-Crash (Video 2). Only the tyre-door model was included in this simulation since the motorcycle rider was projected over the car and did not influence the motorcycle-to-car impact.
To validate both the finite element model and the PC-Crash results, an experimental pendulum impact test was performed (Video 3). Considering the high impact speed of the motorcycle in the collision with the car (47 mph), the impact test was simplified and performed with a pendulum impact speed of 12 mph. An additional finite element simulation of the same configuration as the pendulum impact test was performed (Video 4). A good correlation in terms of kinematics and damage sustained was obtained between the impact test and the finite element simulation.
All these details of this case study are presented in [2] and serve as a testament to PC-Crash’s power in performing accurate collision reconstructions. As expected, PC-Crash proves to be a powerful tool for aiding collision reconstruction, allowing us to consider detailed incident conditions and produce results that correlate strongly with real-world scenarios. Collision reconstruction utilising advanced tools like PC-Crash software assists us in delivering in-depth and highly accurate results for our clients, providing insights crucial for understanding collision dynamics, investigating causes, and assigning liability.
Video 1 - Motorcycle and rider multibody simulation
Video 2 - Finite elements impact simulation
Video 3 - Experimental impact test
Video 4 - Finite elements impact test
References
[1] Santos, K., & Dias, J. P. (2020). Motorcycle accident reconstruction: Influence of structural deformation or failure. Engineering Failure Analysis, 115, 104597.
[2] Santos, K., Silva, N. M., Dias, J. P., & Amado, C. (2023). A methodology for crash investigation of motorcycle-cars collisions combining accident reconstruction, finite elements, and experimental tests. Engineering failure analysis, 152, 107505.