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For challenging cases such as airbag deployment in out of position scenarios, airbag simulation technology is being continuously enhanced. The airbag internal pressure can be calculated in different ways. The traditional scheme uses the assumption that the airbag internal pressure is uniform at any given time. This so-called Uniform Pressure (UP) method is efficient and accurate for In-Position frontal impact scenarios, when the occupant-airbag interaction takes place after the airbag is almost fully deployed, and over a relatively long time-span. However, in Out-of-Position scenarios, there is strong interaction between occupant and airbag during the airbag deployment phase and during deployment, the airbag pressure is strongly non-uniform. Complex gas flow (GF) models such as Coupled Lagrangean-Eulerian (CLE) methods and Mesh Free (MF) methods enable a physical description of the gas flow.

To study the mechanics of the neck during rear end impact, in this paper an existing global human body model and an existing detailed submodel of the neck were combined into a new model. The combined model is validated with responses of volunteers and post mortem human subjects (PMHSs) subjected to rear end impacts of resp 5g and 12g. The volunteers (n=7, 7 tests) were seated on a standard car seat with head restraint, while the PMHSs (n=3, 6 tests) were placed on a rigid seat without head restraint. The model shows good agreement with the PMHS responses when muscle tensile stiffness is increased towards published PMHS tissue properties. For the volunteer simulations, initial seating posture and head restraint position were found to strongly influence the model response. More leaning forward (increasing of horizontal distance head head restraint) results in larger T1 and head motions.

Both RAMSIS and MADYMO are widely applied for computer aided vehicle design. Both programs are used to simulate occupant-vehicle interactions where RAMSIS focuses on ergonomics in normal driving conditions and MADYMO focuses on passive safety in impact conditions. This paper describes simulations of human seat interactions using RAMSIS and MADYMO. An interface has been developed to convert RAMSIS human models and postures to MADYMO. Static seat interaction was first simulated using RAMSIS. This provided an estimated posture and a qualitative assessment of comfort. Then the posture as estimated by RAMSIS was analyzed in MADYMO. The seat was modeled in MADYMO as an arbitrary surface, and the combined surface compliance of seat and human tissues was defined in terms of stress versus penetration. The MADYMO analysis of the posture estimated by RAMSIS provided for instance joint loads, seat contact pressures and seat friction.

Mathematical modelling of the human body is widely used for automotive crash-safety research and design. Simulations have contributed to a reduction of injury numbers by optimisation of vehicle structures and restraint systems. Currently such simulations are largely performed using occupant models based on crash-dummies. These models inherit the apparent differences between dummies and the real human body. Furthermore, crash-dummies are only available for a limited set of body sizes. In order to assess passive safety for different body sizes, a method has been developed to generate models representing subjects of varying anthropometry. This method has been applied to “scale” crash-dummy models towards different body sizes and proportions. As a next step, models of the real human body for impact loading have been developed. A combination of modelling techniques is applied using rigid bodies for most body segments, but describing the thorax as a flexible structure.

Mathematical modelling is widely used for crash-safety research and design. However, most occupant models used in crash simulations are based on crash dummies and thereby inherit their apparent limitations. Several models simulating parts of the real human body have been published, but only few describe the entire human body and these models were developed and validated only for a limited range of conditions. This paper describes a human body model for both frontal and rearward loading. A combination of modelling techniques is applied using rigid bodies for most body segments, but describing the thorax as a flexible structure. The skin is described in detail using an arbitrary surface. Static and dynamic properties of the articulations have been derived from literature. The RAMSIS anthropometric database has been used to define a model representing a 50th percentile male.

In the past, muscle activation has been identified as having an important effect on the head-neck response in dynamic conditions. However, this claim has been largely based on global observations, and not by accurate analysis. In this study, the influence of muscle activation on the head-neck response is investigated by mathematical modeling. The detailed mathematical head-neck model presented by De Jager is improved by modeling the neck muscles in more detail. A multi-segment muscle description is applied in which the muscles curve around the vertebrae, resulting in realistic muscle lines of action. The model is validated with human volunteer responses to frontal and lateral impact at several severities. The model response with maximum muscle activation to high severity frontal and lateral impacts agrees well with volunteer responses, whereas a submaximum activation level or a larger reflex delay provides better results for the low severity impacts.

Ongoing developments in crash safety research, regulations and product enhancements have indicated the need for a review on child dummy design philosophies. Late 1991, the TNO Crash-Safety Research Centre started a research program including a review on child anthropometry, a literature study on biomechanical properties of children and a study on scaling techniques. The objective of this research program is to establish sets of requirements for basic child dummy “design characteristics”. The main design characteristics covered in this paper are anthropometry and biofidelity. The anthropometry study resulted in a new TNO database on child anthropometry and includes published data on more than 75 parameters. The database's background and construction are explained and the main parameters for child dummy design are presented. The literature study on biomechanical properties of children revealed a limited set of data on material properties.