Yuanzhi Hu

Kinematics simulation and head injury analysis for rollovers using MADYMO

This study demonstrates the applicability of occupant kinematics simulation and head injury analysis with MADYMO simulation for rollovers. Two real-world rollover crashes, together with an SAEJ2114 rollover test, were reconstructed, followed by a further investigation of the relationship between the roof intrusion and head injury in the Society of Automotive Engineers (SAE)J2114 simulation. For the head injury study, the head injury criteria (HIC), head impact power (HIP) and peak virtual power (PVP) values from the hybrid III dummy model were compared with head injury tolerance limits. A finite element (FE) head model was introduced to examine the intra-cranial responses of the head during the rollovers. The von Mises stress related to the occupant injuries was exported to evaluate the head injurys possibilities. The occurrence of the head skull fracture can be predicated by HIC and PVP/HIP values. The PVP/HIP measures indicated the rank of head injuries reasonably well, and the Abbreviated Injury Scale (AIS) injury level based on PVP score correlated well with the head injuries from the documentary evidence. The probabilities of the brain neurological injury can be indicated by von Mises stresses from the FE head simulations. In this study, the SAEJ2114 simulation result indicated that the roof intrusion velocity was the main cause of the head injury in that case. It is concluded that more real-world rollover crashes need replicating and simulating, with the analysis conducted at the level of head injury, not roof crush, to obtain causal relationships between the operative parameters.

Simulation of vehicle kinematics in rollover tests with quaternions

Abstract The paper provides a method to simulate the vehicle kinematics in rollover tests. There are several rollover tests in use: SAE J2114 dolly rollover, ditch rollover, corkscrew, curb trip, and soil trip. Sensors located on board the vehicle record the various accelerations and make it possible to reconstruct the whole event with high accuracy, which is difficult in real-world accidents. Euler parameters, as a useful method to describe the orientation of a rigid body, have been widely used in three-dimensional multi-body and rollover crash simulations. A method based on the Euler parameters derived from the test data is used to simulate the vehicle rollover kinematics in a SAE J2114 dolly rollover test. The detailed procedure from the raw data to the Euler parameters is described and the influence of gravity included in the test data is removed by projecting to a local vehicle reference system. The method is validated by simulating the dolly rollover test in MADYMO, using a simple rigid body model to represent the vehicle. Good agreement is obtained from the comparison between the simulated vehicle orientation and the test video, and the comparison between simulated displacements and calculated displacements using the recorded test accelerations at the same points. This demonstrated that the method proposed is a useful and effective method for simulating vehicle kinematics in rollover tests.

A study of an Asian anthropometric pedestrian in vehicle–pedestrian accidents using real-world accident data

Abstract Real-world road accident data involving pedestrians were obtained from police records in Beijing. In total, 158 vehicle–pedestrian accidents were included in this study, from which the accident characteristics were identified. The data were analysed and the overall epidemiology established. In addition representative cases were studied in depth using MADYMO reconstructions. For accuracy, a MADYMO pedestrian model based on Chinese anthropometric values was developed. A comparable European-size MADYMO model has also been used to demonstrate the differences between the two anthropometric types. Using the Chinese pedestrian model, a complete accident event is reconstructed, in terms of pre-impact behaviour, causation, injury characteristics and post-impact kinematics.

Modelling the Effects of Seat Belts on Occupant Kinematics and Injury Risk in the Rollover of a Sports Utility Vehicle (SUV)

The aims of this study are to investigate the responses of a Hybrid III dummy and a human body model in rollover crashes of an SUV, and to assess the effect of seat belts on occupant kinematics in rollover events. A SAEJ2114 rollover test of a 1994 Ford Explorer for two front row dummies with an inflatable tubular structure (ITS) is reconstructed and validated in MADYMO. By removing the ITS, the simulations of the Hybrid III dummy occupants with and without seat belts are obtained. By replacing the dummy models with human body models, with and without seat belts, two other combinations are also modelled. The kinematics and injury risks of the two occupant models are compared and evaluated. Significant differences exist in the motions, and injury levels of the dummies and human body models with and without seat belts. Seat belts can significantly mitigate against occupant ejection. The flexibility of the spine and the neck of the human body models significantly affects the kinematics and the severity of the injuries of the occupants modelled compared to that of the dummies.

Modelling the effects of an inflatable tubular structure (ITS) on occupant kinematics and injury risk in the rollover of a sports utility vehicle (SUV)

Abstract The aims of this study are to investigate the responses of a Hybrid III dummy and a human body model in rollover crashes of an SUV, and to assess the effect of an inflatable tubular structure (ITS) on the unrestrained occupant kinematics in rollover events. A SAEJ2114 rollover test of a 1994 Ford Explorer with an inflatable tubular structure (ITS) is simulated for two front row occupants, and validated in MADYMO. By removing the ITS, the simulation of the Hybrid III dummy occupants without ITS is obtained. By replacing the dummy models with human body models, with and without ITS, two other simulations are also modelled. The kinematics and injury risks of the two occupant models are compared and evaluated. Significant differences exist in the motions, and injury levels of the dummies and human body models with and without ITS. ITS can offer significant protection to the head by cushioning the impact of the head on the roof or side windows, and can mitigate against occupant ejection. The flexibility of the spine and the neck of the human body models significantly affects the kinematics and the severity of the injuries of the occupants modelled, and so would also affect the relevance of the design of countermeasures developed from dummy tests to real-world rollover crashes of human beings.

Lower leg injury simulation for EuroNCAP compliance

Occupant lower leg injury prediction is a difficult procedure due to the complex interactions between the occupant and vehicle structure. This study presents a method to simulate the lower leg kinematics and injuries with MADYMO in the European New Car Assessment Programme (EuroNCAP) 40% offset deformable barrier (ODB) crash test. This study also addresses how to model the vehicle motion, intrusion of the instrument panel (IP), steering wheel, dash panel and accelerator pedal for crash tests. The modelling of the IP surface and the footrest for both driver and passenger is presented. The model was correlated to a full vehicle ODB crash test, and the overall results for the tibia index were found to be acceptable.

Study on the Relationship between Intrusion Velocity and Occupant Injury of Side Impact

The injury outcomes in side impact are correlated to the door trim design, vehicle motion, as well as the side restraint system. A well controlled side intrusion can vastly reduce the injury index of the thorax, abdomen during the side impact. For the safety issue, it is essential to know the sensitivity of side structures intrusion velocity upon occupant injury in side impact. Objective: This paper is focusing on the influences of different side intrusion velocities upon occupant injuries, based on a validated MADYMO side impact simulation model. Method and Material: With the Prescribed Structure Motion method, the side impact model was built up and correlated with the physical impact test to ensure the accuracy of the model. Through the method of Prescribed Structure Motion Scaling, the different doors intrusion velocities corresponding to the chest region were realized. Upon the MADYMO simulations, the side structure intrusion velocity effects on occupant injuries were evaluated. Results: The study indicates that the doors intrusion velocity corresponding to the chest region has significant effects on the rib deformation and T12-Mx index. By increasing the intrusion velocity from 5.87m/s to 7.5m/s, the maximum of low rib deformation could be increased by 58.6% and T12-Mx index could be increased by 78.4%.

Virtual Evaluation of Headrest Geometry on C-NCAP Whiplash Injury Outcomes

This paper is aimed to evaluate the protective performance of different headrest geometry parameters (including the height and horizontal distance), based on a validated china new car assessment program (C-NCAP) whiplash sled test simulation model.A virtual mathematical dynamic model (MADYMO) simulation model with the BioRID II dummy was built up and correlated with a sled test to ensure the accuracy and comparability of the virtual model. Based on this baseline model, the headrest geometry parameters including the height and horizontal distance were evaluated.The study indicates that headrest geometry parameters have significant effects on both dummy kinematics and the related injury index, the neck injury criteria (NIC) value could be reduced by 31%, while the upper neck My index could be improved by 15% in this case study.Virtual simulation is efficient to evaluate the headrest design changes effect on dummy kinematics and injury results. By evaluating the NIC index and other neck injury results from the virtual sled simulations, the optimal seat headrest design was proposed. For further validation of the research results, sled test of the optimal case is highly recommended