Citation: VAN LOPIK, D.W. and ACAR, M., 2007. Development of a multibody computational model of human head and neck. Proceedings of the IMechE, Part K: Journal of Multi-body Dynamics, 221 (2), pp. Additional Information:• This is an article from the journal, Proceedings of the IMechE, Abstract: Experimental studies using human volunteers are limited to low acceleration impacts while whole cadavers, isolated cervical spine specimens, and impact dummies do not normally reflect the true human response. Computational modelling offers a cost effective and useful alternative to experimental methods to study the behaviour of the human head and neck and their response to impacts to gain insight into injury mechanisms.This article reports the approach used in the development of a detailed multi-body computational model that reproduces the head and cervical spine of an adult in the upright posture representing the natural lordosis of the neck with mid-sagittal symmetry. The model comprises simplified but accurate representations of the nine rigid bodies representing the head, seven cervical vertebrae of the neck, and the first thoracic vertebra, as well as the soft tissues, i.e. muscles, ligaments, and intervertebral discs. The rigid bodies are interconnected by non-linear viscoelastic intervertebral discs elements in flexion and extension, non-linear viscoelastic ligaments and supported through frictionless facet joints. Eighteen muscle groups and 69 individual muscle segments of the head and neck on each side of the body are also included in the model. Curving the muscle around the vertebrae and soft tissues of the neck during the motion of the neck is also modelled. Simulation is handled by the multi-body dynamic software MSC.visuaNastran4D. Muscle mechanics is handled by an external application, Virtual Muscle, in conjunction with MSC.visuaNastran4D that provides realistic muscle properties. Intervertebral discs are modelled as non-linear viscoelastic material in flexion and extension but represented by 'bushing elements' in Visual Nastran 4D, which allows stiffness and damping properties to be assigned to a joint with required number of degrees of freedom of the motion. Ligaments are modelled as non-linear viscoelastic spring-damper elements.As the model is constructed, the cervical spine motion segments are validated by comparing the segment response to published experimental data on the load-displacement behaviour for both small and large static loads. The response of the entire ligamentous cervical spine model to quasi-static flexion and extension loading is also compared to experimental data to validate the model before the effect of muscle stiffening is included. Moreover the moment-generating capacity of the neck muscle elements has been compared against in vivo experimental data.The main and coupled motions of the model segments are shown to be accurate and realistic, and the whole model is in good agreement with experimental findings from actual human cervical spine specimens. It has been shown that the mode...

Abstract.A complete three-dimensional multi-body dynamic computational model of the human head and neck has been developed and validated using human volunteer experimental data. The complete head-neck model has been used to simulate 15g frontal and 8.5g rear-end impacts with the resulting motion compared against response corridors derived from sled acceleration tests using human volunteers. This paper reports an original work, a further development of the model that incorporates a finite element analysis of the intervertebral discs subjected to the loading conditions determined by the multi-body dynamic model of the head and neck complex.

A multi-body computational model of the human head and neck was previously shown to be in good agreement with experimental findings from actual human cervical spine specimens. The model segments were tested in three directions of loading showing main and coupled motions to be accurate and realistic.The model's ability to predict the dynamic response of the head and neck, when subjected to acceleration pulses representing frontal, lateral, and rear-end impacts, is verified using experimental data derived from sled acceleration tests with human volunteers for 15 g frontal and 7 g lateral impacts and from isolated cervical spine specimen tests for rear-end impacts. Response corridors based on sled acceleration tests with human volunteers for frontal and lateral impacts are used to evaluate the model and investigate the effect of muscle activation on the headneck motion. Firstly, the impacts are simulated with both passive and active muscle behaviour. Secondly, the local loads in the soft-tissue elements during the frontal impact are analysed. For rear-end impact simulation experiments using ligamentous isolated cervical spine specimens are used to evaluate the model performance before investigating the effects of muscle tensioning.Good agreement with human volunteer response corridors resulting from frontal and lateral impacts, and isolated cervical spine specimen sled test rear-end impact experiments is demonstrated for the model, highlighting the important role the muscles of the neck play in the head-neck response to acceleration impacts. The model is shown to be able to predict the loads and deformations of the cervical spine components making it suitable for injury analysis.

A computational model of the human head and neck system for the analysis of whiplash motion Abstract -This paper presents the development and validation of a three-dimensional multi-body model of the human head and neck for the study of whiplash motion. The model has been validated against experimental data for small and large static loading conditions. The resulting main and coupled displacements of the individual motion segments have been shown to be accurate and the moment generating capacity of the neck muscle elements realistic. The model has been used for the dynamic simulation of impacts in frontal, lateral and rear-end directions. For rear-end impacts the characteristics of 'whiplash' motion have been accurately reproduced in terms of head and vertebral kinematics The model results with active musculature suggest that, for rear-end impact, the influence of active muscle response is unable to significantly alter the head and neck kinematics of an initially unaware occupant but will affect the forces developed in the cervical soft-tissues.

This paper presents the development and validation of a three-dimensional computational model of the human head and neck. The model has been produced to study the mechanics of the human cervical spine in response to automobile impacts. The complete head-neck model has been used to simulate 15g frontal and 7g lateral impacts with the resulting motion compared against response corridors derived from sled acceleration tests using human volunteers. The effect of passive and fully active muscle behaviour has been investigated and it is shown that for both impact directions the inclusion of active muscle tensioning results in closest agreement with the experimental data. Good agreement is seen for both impact directions. An analysis of the local loads in the soft-tissue components is also presented for the 15g frontal impact case.