GB2309814A

GB2309814A - Head and neck model

Info

Publication number: GB2309814A
Application number: GB9601921A
Authority: GB
Inventors: Sandra Jane Bell; David John Townend; Simon Stuart Balistrari
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1996-01-31
Filing date: 1996-01-31
Publication date: 1997-08-06
Also published as: GB9601921D0

Abstract

A model of the human head comprises a shell filled with a material having substantially similar physical properties to that of the human head and internal and external instrumentation for the sensing of impacts and/or movement. Optionally the model further comprises an artificial neck which allows resilient movement of the head in relation to the neck in one or more degrees of freedom.

Description

Head and Neck Model The invention relates to an anthromorphic model of a human head and neck.

In many applications such as in the boxing, defence, automotive and equestrian industries it is desirable to analyse the effect of impacts to the head and consequential effect to the neck, vertebrae and torso. The problem of studying the effect of impact in vivo is limited to the data following the onset of injury which may take some time and also to results of cadaver experiments which apart from the obvious ethical problems; there is a different response between live and dead tissues.

These problems are overcome by the invention which provides a fully instrumented anthropomorphic model of the head and neck and allows the full spectrum of injury mechanisms to be determined. Additionally the model allows analysis of power and accuracy of punches for training purposes in sports such as boxing.

According to the invention is provided a model of the human head comprising a shell filled with a material having substantially similar physical properties to human flesh, including sensing means to assess movement and/or impact of said model.

The attenuation or transmittance of pressure waves is dependant substantially on physical properties of the material through which the pressure waves move. Said physical properties include mechanical and dynamic properties. To allow more realistic modelling of impact to the human head, preferably the acoustic impedance and/or density and/or complex moduli and/or, loss tangent and/or complex phase velocity are substantially the same as that of human tissue. This allows transmitted stresses to be accurately mimicked. Such flesh simulant material is preferably a polyurethane material.

The shell optimally mimics the human skull in terms of the physical properties. The transmittance of impact and pressure wave to the brain in real life is dependant not only on the physical properties of the brain material, mainly acoustic impedance, but also of that of the skull through which obviously the pressure waves must pass. In addition the relative value or mismatch between impedance values of a composite layer is a highly important factor in overall transmissibility of the impact.

Similarly the head model may preferably have a thin coating around the shell of a material having similar mechanical properties to that of skin. Again incorporation of a third layer would further enhance the accuracy of modelling impact to the human head.

In order to provide data of the impact to the model head for analysis it is envisaged that pressure or acceleration sensing means are located on the outside and more importantly on the inside of the shell, including within the filler material. Acceleration sensing means would includes sensors such as accelerometers which may be single or multiaxal. In addition pressure sensors may also be provided again on the outside of the shell or within the shell including in the within the flesh simulant.

In order to provide analysis of the effect of impact on the head has to the neck and vertebrae, the model head may be mounted in an articulated fashion onto a model neck which may in its simplest form be a solid base. The articulation or joint between the head and the neck may allow one or more degrees of freedom and would also be resilient. By resilient is meant that the joint has means to urge the head into a neutral position with respect to the neck after displacement consequential to impact. The neck may also comprise a number of vertebra each having one or more degrees of freedom with relation to one another. These will preferably comprise sensors for e.g. strain pressure torsion , acceleration that will allow the effect of impact to the head on the human vertebrae to be assesses.

These vertebrae may also be connected in a similar fashion to a model of the human torso. Vertebrae may be modelled from a material having similar physical properties to human bone and may optionally be capped at both ends with a material having similar physical characteristics to human cartilage.

The invention will now be explained with reference to the following figures by way of example only Figure 1 shows an anthropomorphic model of a human head (2) and neck (3) comprising artificial vertebrae 3a, 3b, 3c, 3d. Some of the artificial vertebrae may also be connected to a torso component 12 by resilient means. Figure 2 shows a cross section through the head of figure 1. The model head comprises a shell 4, preferably having the same physical material properties as human skull material.

Importantly the shell is filled with a material 5 having the same mechanical properties of human flesh, e.g. acoustic impedance. Within this filler material as well as on the inner or outer surface of the shell, are located one or more sensors 6, 7, 8 which can be pressure sensors or accelerometers. The invention however is not limited to these types of sensors and the person skilled in the art would readily contemplate using further sensors which enable the characteristics of an impact to the head to be analysed. The sensors are operationally connected by suitable means e.g. wire to a suitable data processing device, having print-out means. It may be programmable so as to provide all types of statistical data which are particularly suitable to assess impact injury. The shell is optionally covered in a layer of soft pliant material 9 having similar mechanical properties to human skin e.g. Young's modulus, density or acoustic impedance. The skin may also comprise sensors 10 on the outside similar to those described above.

The model head may also comprise a neck portion 3 comprising one or more artificial vertebrae, again having similar mechanical properties to human flesh. The vertebrae are connected to one another and the head by resilient means which are not shown in the figures for clarity, and have one or more degrees of freedom in their relative movement. They may be homogenous or altematively be made of a composite structure, preferably comprising a core of material having similar mechanical properties to bone material and being capped at both ends by a more pliant material having the same mechanical properties as human cartilage. One or more of the vertebrae may also be connected to a torso 12. Sensors are provided on or within the vertebrae, torso and also between adjacent vertebrae so as to provide information regarding pressure, stress, strain, torsion, etc.

Claims

1. A model of the human head comprising a shell filled with a material having substantially similar physical properties to human flesh, including sensing means to assess movement and/or impact of said model.

2. A model of the human head as claimed in claim 1 wherein said physical properties are acoustic impedance and/or density and/or complex moduli and/or, loss tangent and/or complex phase velocity.

3. A model of the human head as claimed in claims 1 or 2 wherein said material is a polyurethane material.

4. A model of the human head as claimed in claims 1 to 3 wherein said shell has similar mechanical properties to human skull material.

5. A model of the human head as claimed in claims 1 to 4 wherein said shell has similar acoustic impedance to human skull material.

6. A model of the human head as claimed in any of the above claims in that said sensing means comprises means for measuring acceleration and/or pressure located within the shell or outside of the shell.

7. A model of the human head as claimed in any of the above claims additionally comprising a thin layer of material on the outside of the shell having substantially similar mechanical properties of human skin.

8. A model of the human head as claimed in any of the preceding claims additionally comprising a connection at the base of the head to an artificial neck which allows resilient movement of the head in relation to the neck in one or more degrees of freedom.

9. A model of the human head as claimed in claim 8 wherein said neck comprises more than one vertebra each being resilently connected to each other and having one or more degrees of freedom relative adjacent vertebrae.

10. A model of the human head as claimed in claim 9 wherein each vertebra comprises one or more pressure, strain, torsion or acceleration sensors.

11. A method of assessing impact injury comprising assessing data provided by analyses of sensing means located on a model of the human head as claimed in any of the preceding claims.