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Occupant Safety

Overview of pedestrian analysis setup and post-processing using the Oasys LS-DYNA Environment with a focus on new features

The Oasys LS-DYNA Environment provides a comprehensive solution across the whole LS-DYNA workflow. One aspect of that workflow in automotive engineering is pedestrian protection. Pedestrian protection is important to the design and development of the front end of vehicles. The various protocols, impactors and methods relating to pedestrian protection mean that the CAE process can be complex and time consuming. The Oasys tools aid in this process. These tools are available for both head and leg impact analyses and have been used successfully on past and current vehicle design projects within Arup and in OEM’s to accelerate the workflow. This paper gives an overview of the tools, with a focus on the latest features introduced to the recent releases of the Oasys LS-DYNA Environment – The HIC Area Calculator and the Pedestrian Run Builder.

Definition of Peak Virtual Power Brain Trauma Variables for the use in the JSOL THUMS injury post-processor web-based estimator

Road traffic accidents and falls are catastrophic events leading to serious injury and in some cases fatality. The dichotomy is that traumatic injuries are assessed using the Abbreviated Injury Scale (AIS), which is a measurement of the probability of death, whilst the engineering tools available to support the understanding of injury causation rely on engineering measurements of stress and strain. Further to this, the problem of ageing is not adequately dealt with using existing engineering tools. The research proposes the development of a generic mathematical injury severity model, based on Peak Virtual Power (PVP) [1], to establish relationships between AIS, ageing and collision speed. This method, newly implemented JSOL THUMS injury post-processor web-based estimator, has the ability to calculate all AIS levels from the white and grey matter and is defined as a polynomial function. This paper explains the underpinning of the Peak Virtual Power theory, as well as provide the coefficients to calculate brain injury severity under blunt trauma impact.

A critique of the THUMS lower limb model for pedestrian impact applications

The Total Human Model for Safety (THUMS) is widely used for biomechanics research and validated at the component and full-body levels. Nonetheless, some authors have reported differences in predictions between the model and real-life injuries, particularly in the lower limbs. This study aims to perform an extensive critique of the THUMS lower limb and identify areas for improvement. The THUMS model was assessed across quasi-static and dynamic validation tests to understand geometry, material properties and response to impact. The study has highlighted that the THUMS’ geometry is comparable to published cadaveric data for bones and ligaments, but soft tissues (muscle, adipose and skin) and fascia have significant simplifications.

Human Body Model Positioning using Oasys PRIMER

Human body models (HBMs) are detailed bio-fidelic finite element models of the human body and are primarily used to simulate human body kinematics and injury responses and risks in a variety of simulated impact scenarios. The current generation of HBMs, such as the industry leading THUMS and GHBMC family of models, encompass different genders, ages, and physiques, including detailed skeletal structures, internal organs (including the brain) and other soft tissues like skin, flesh and ligaments. Some HBM model variants also include muscle-activation features to simulate changes in occupant posture, taking into account changes in musculature activity, prior to a vehicle collision. Thus, combined emergency manoeuvres and crash events, or other long duration crash events, can be simulated.

Real Time Biofidelic positioning of Human Models with ANSA

The use of Human Body Models, for safety simulations, in the automotive industry, has not been widespread for various reasons. One was that the specific models had not reached expected sophistication levels as they are mainly used in the research phase and not in production. Nevertheless, from their first introduction in late nineties until now, a lot of development and research effort has been invested. The parallel growth in computational power during the same period resulted in much more complex and realistic models that can cover the needs of the occupant safety engineering community.

Coupling feedback control loop-based model in Simulink to finite element model in LS-Dyna: Application to reposition forward leaning occupant to upright posture

Forward leaning postures have been observed for current car passengers [1] and are expected to occur even more frequently in future autonomous vehicles [2]. For existing restrain systems a strategy to provide optimized protection is to deploy mechatronic belt pre-pretensioner (MBPPT) before the crash targeting to maintain or better prevent possible forward leaning postures, mostly induced through pre-crash vehicle maneuvers [3 - 5]. Where for future restraint systems in highly automated vehicles [6 - 9] an additional load case for MBPPT might become important. Here the airbag restraint system is mounted into the seat, enclosing the upright occupant during deployment. If the occupant is out-of-position, the enclosure of the restrain system might not function optimally. Hence, a pre-triggered MBPPT can be used to bring the occupant back to the upright position before the crash.