BS 960:2006 pdf download – Headforms for use in the testing of protective helmets
2.9
vertical transverse plane
for a given headform, the vertical plane perpendicular to both the vertical longitudinal plane and the referenceplane and located mid-way between the front and rear extremities of the headform
NOTE This corresponds to the coronal plane of the human head.
2.10
basic plane
for a given headform, the horizontal plane located at a vertical distance ‘x’ below and parallel to the referenceplane
NOTE This corresponds to the basic plane of the human head being the longitudinal plane which passes through the lowerlevel of the eye orbits and the upper level of the external opening of the ear canals.
2.11
centre of gravity of the three-quarter headformpoint A
for a given headform, the point on the central vertical axis located at a vertical distance 12,7mm above thereference plane
2.12
centre of gravity of the full headformpoint G
for a given headform, the point on the central vertical axis located at a vertical distance ‘z’ below the referenceplane,as given in Table 1
2.13
geometric centrepoint R
for a given headform, the point on the central vertical axis, located at its intersection with the reference plane
NOTE This point is the datum for all the dimensions given in Annex A.
3Requirements
3.1 Materials and general characteristics
3.1.1 Headforms for shock absorption and penetration tests, with falling headform/helmet assembly
The headforms shall be made of metal and,together with any means for their support,shall exhibit noresonance below a frequency of 2 000 Hz.
Full headforms shall have the following characteristics:
a)the centre of gravity shall be located within a 10 mm radius of point G on the central vertical axis;
b)a facility for attaching an accelerometer shall be incorporated such that, with the headform in any angularorientation, the respective sensitive axes of the accelerometer shall pass within 10 mm of point G;
c)the appropriate mass, if specified in Table 1.
Three-quarter headforms shall have the following characteristics:
i)the centre of gravity shall be located within a 10 mm radius of point A on the central vertical axis;
i)a facility for attaching an accelerometer shall be incorporated within the headform or its means ofsupport,such that,with the headform in any angular orientation,the respective sensitive axes of theaccelerometer shall pass within 10 mm of point A.
NOTE1 For this type of test,full and three-quarter headforms may be specified in the respective helmet standard.
NOTE2 The geometry of the half headform does not facilitate its use for this type of test.
NOTE3 Care should be taken to ensure that the total mass of the headform, when fited with the accelerometer andits means of attachment,falls within any tolerances specified in either this standard or the respective helmet standard, asappropriate.
3.1.2 Headforms for shock absorption and penetration tests, with rigidly mounted (not falling)headform/helmet assembly
The headforms shall be made of a rigid material which does not affect the measurements of shock absorptionor penetration (e.g. wood). The headforms, together with their means of support, shall exhibit no resonancebelow a frequency of 2 000 Hz.
NOTE For this type of test, full, three-quarter and half headforms may be specified in the respective helmet standard.
3.1.3 Headforms for geometric examination or positional marking of the helmet
The headforms shall be made of any suitable material.
3.1.4 Headforms for other tests
When a test requires the headform to be made from a specific material or to possess specific materialcharacteristics (e.g. thermal or electrical conductivity, thermal capacity etc.), these materials and characteristicsshall be as specified in the relevant helmet standard.
3.2Dimensions
The outer surface of each headform shall lie within the locus of the coordinates given in Annex A. Betweencoordinate points, the outer surface of the headform shall be curved and smooth.
NOTE The exact geometry of the surface between the specified coordinates may be determined, for example, by a 5”orderspline function.
3.3Marking
3.3.1 Headforms for geometric examination or positional marking of the helmet shall be marked with:
a)size designation of the headform;
b)reference plane;
c)basic plane;
d)vertical longitudinal plane;
e)vertical transverse plane.
3.3.2 All other headforms shall be marked, at least, with the size designation of the headform.NOTE Other marking may be required by specific helmet standards.