Clive Neal-Sturgess

Optimization of passenger car design for the mitigation of pedestrian head injury using a genetic algorithm

The problem of pedestrian injury is a significant one throughout the world. In 2001, there were 4724 pedestrian fatalities in Europe and 4882 in the US. Significant advances have been made by automotive safety researchers and vehicle manufacturers to address this issue with respect to the design of vehicles, but the complex nature of pedestrian accident scenarios has resulted in great difficulty when using traditional statistical methods. Specifically, problems have been encountered when attempting to study the effects of individual parameters of vehicle front-end geometry on pedestrian head injury. This paper attempts to demonstrate the feasibility of applying the field of evolutionary computation to the problem of pedestrian safety by using a simple genetic algorithm to optimize the centre-line geometry of a cars front-end for the reduction of pedestrian head and thoracic injury. The fitness of each design is assessed by creating a multi-body mathematical model of the vehicle front and simulating impacts with models of different sized pedestrians, and ranking according to the combined injury scores.

APROSYS in-depth database of serious pedestrian and cyclist impacts with vehicles

The APROSYS in-depth database is a compilation of 70 detailed pedestrian and cyclist or ‘VRU’ (Vulnerable Road User) accident cases from around Europe. This paper presents a descriptive statistical analysis of the sample data, including impact speeds, road conditions, vehicle make and model, VRU age and gender, side struck, head impact location points on the vehicle and specific injuries sustained. Comparisons are made with British and European epidemiology where available. Also, the relationships between variables such as impact speed and injury severity are discussed together with a comparison between different injury severity scoring systems.

A thermomechanical theory of impact trauma

Abstract A review of injuries in impact trauma reveals a plethora of ‘injury criteria’, many of which are enshrined in legislation. It is assumed here that injuries can be modelled as mechanical dissipative processes, and the formalism of continuum damage mechanics based on irreversible thermodynamics is applied to impact trauma. It is shown that peak virtual power (PVP) predicts the severity of injury, measured on the abbreviated injury scale, in around 90 per cent of cases for all types of injury to all body regions (brain, skull, thorax, spine, upper and lower extremities) for car occupants from the CCIS and NASS-CDC databases. Consideration of injury to body regions shows that PVP predicts the form of acceleration-based criteria, the head injury criterion and the viscous criterion. It is shown that in general the lower bound of severity of injury is proportional to δV3 or (ETS)3, where ETS is equivalent test speed, for restrained vehicle occupants, and the upper bound proportional to δV2 or (ETS)2 for unrestrained occupants. It is concluded that PVP is a suitable candidate for an objective universal injury criterion which can be correlated to real-world injury experience.

MADYMO reconstruction of a real-world collision between a vehicle and cyclist

Numerical simulations of vulnerable road user impacts are becoming increasingly popular in the field of vehicle design for pedestrian and cyclist safety, as representations of humans are becoming more sophisticated using both the multi-body and finite-element (FE) approaches. Several previous studies have involved the reconstruction of pedestrian real-world accidents using multi-body models, but cyclists have been the subject of less research attention. In order to study the kinematics involved in cyclist accidents as well as the specific injuries and the points of contact on the vehicles, a real accident for which sufficient data was available was reconstructed using mathematical dynamic model (MADYMO) crash simulation software. Initial conditions were found that matched the relevant accident details from the police and post-mortem reports with regard to contact between the cyclist and vehicle, bicycle and street furniture and resulting injuries.

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.

Bologna and the MEng: ‘Sleepwalking into Unknown and Unpredictable Territory’

The background to the Bologna process is that there was considerable concern in the 1990s at governmental level in the EU nation states over economically unsustainable, grossly inefficient higher education systems. The Bologna process of three cycles of higher education, the first being the ‘mobility degree’ (Bachelors level) after three years of study, the second (Masters level) after a further two years of study, and a third cycle of postgraduate study as yet undefined, has received widespread agreement across now 45 nation states, and has gained worldwide interest. For certain sections of UK higher education, such as engineering, science, architecture and medicine, where the degree cycles do not fit with the Bologna cycles, the Bologna process presents significant diffiulties. This paper explores those difficulties, and possible responses, none of which are themselves without difficulty.

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.

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.

An investigation into neck injuries in simulated frontal impacts

Spinal injury is one of the most debilitating and costly injuries. It is a devastating condition that disrupts the life of the injured and their families. Vehicle crashes are the most common cause of fractures, soft tissue injuries and dislocations of the neck and cervical spine. Among vehicle crashes frontal impacts are the most frequent cause for head and neck injuries. Neck injuries are often caused due to unusual head motion. Improvement of the knowledge of the correlation between crash dynamics, human body behaviour and internal neck phenomena could contribute to the development of new protection systems for the neck. The most acceptable way to study the behaviour of the human body and internal interactions during car crashes is mathematical modeling as it is non-invasive and repeatable. In this work, computer simulations have been performed using a multibody dynamic model of the cervical and thoracic-lumbar spine, where rigid bodies are connected by articulated joints and spring-damper elements. The models were developed using the ‘Working Model 2D’ and were used to simulate frontal impacts in vehicles. The models were validated based on experimental data available in literature. The verified models were used to analyse the behaviour of the driver and vehicle kinematics and calculate the internal neck forces and motion. Principle virtual power of neck was applied at inter-vertebral levels for various impact speeds. Principle virtual power of neck was then correlated with real world crash data of neck injuries. It has been shown that principle virtual power of neck at each intervertebral level correlates well with the crash data and can be used as a predictor of neck injuries.