Author(s): Seongjin Kim, Woojeong Jeon, Jongchan Park
Slidedeck Presentation Only (no paper submitted):
In low velocity vehicle impact accident, an occupant can have injuries such as neck tension and muscle strain. However, in many cases, occupants claim an excessive amount of insurance even for an accident that has very little possibility of injury. Recently, to solve this problem, the police and investigative agency have increasingly requested injury assessment to National Forensic Service in South Korea. Therefore injury assessment has been performed by referring to research papers and reconstructing the accident using MADYMO simulation.
Because crash test dummy models in MADYMO tend to have higher tension, introduction of a proper model for low velocity accident reconstruction is urgently needed. Recently, MADYMO active human model(AHM) has been developed and released by TNO. Active human model which was built based on actual human shows more realistic human behavior. The aim of this study is to develop simulation model and process including active human model to assess injury in low velocity impact accident.
The simulation process is divided into PC-Crash impact simulation and MADYMO injury simulation. At first, vehicle impact simulation is performed in PC-Crash. 3 translational motions and 3 rotational motions are achieved and those 6 degree-of-freedom motions are used as input motion for MADYMO simulation. 3D scan data of real seat was achieved and finite element seat model was constructed. Pre-simulation of seat positioning and settling(dynamic relaxation) were also performed. Finally, MADYMO injury simulation model including active human model and finite element seat model was constructed.
An actual rear impact accident case at a low velocity was implemented and accident reconstruction was performed in PC-Crash and MADYMO. From active human model simulation, neck flexion and extension moments were achieved and those moments were compared with injury thresholds. Both moments were below 6 % of injury thresholds. It is observed that neck extension moment was lower than flexion moment because the occupant head was restrained enough by headrest.
There is no threshold to evaluate extremely minor neck injury and discomfort. Therefore quantitative decision is not possible for now. The comparison between neck moment and threshold shows only qualitative evaluation results. Even though it is difficult to determine whether extremely minor injury and discomfort occurred, the simulation result shows that the possibility of causing severe injury is quite low.
In this study, 3D scan and CAE technologies were integrated to utilize MADYMO active human model. This is expected to be the first case in which active human model is used for a specific work process in the world, and provide more reliable evaluation results by reflecting the tension of human body more accurately. However, there are limits to consider personal physical status, medical history of illness, unexpected occupant posture and unique seat features.