Appendix 1 Impactor certification

The impactors used in the tests specified in Part II must comply with appropriate performance requirements.

The lower legform impactor must meet the requirements specified in paragraph 2.1.5 when tested in accordance with paragraph 2.1.7 and the requirements specified in paragraph 2.1.6 when tested in accordance with paragraph 2.1.8.

For both tests the impactor must have the intended orientation about its longitudinal axis, for the correct operation of its knee joint, with a tolerance of ± 2 °.

The stabilised temperature of the impactor during certification must be 20° ± 2 ° C.

The CAC response values, as defined in ISO 6487:2000, must be 50° for the knee bending angle and 500 N for the applied force when the impactor is loaded in bending in accordance with paragraph 2.1.7, and 10 mm for the shearing displacement and 10 kN for the applied force when the impactor is loaded in shearing in accordance with paragraph 2.1.8. For both tests low-pass filtering at an appropriate frequency is permitted, to remove higher frequency noise without significantly affecting the measurement of the response of the impactor.

When the impactor is loaded in bending in accordance with paragraph 2.1.7, the applied force/bending angle response must be within the limits shown in Figure 16. The energy taken to generate 15° of bending must be 100 ± 7 J.

When the impactor is loaded in shearing in accordance with paragraph 2.1.8, the applied force/shearing displacement response must be within the limits shown in Figure 17.

The impactor, without foam covering and skin, shall be mounted with the tibia firmly clamped to a fixed horizontal surface and a metal tube connected firmly to the femur, as shown in Figure 18. To avoid friction errors, no support may be provided to the femur section or the metal tube. The bending moment applied at the centre of the knee joint, due to the weight of the metal tube and other components (excluding the legform itself), must not exceed 25 Nm.

A horizontal normal force must be applied to the metal tube at a distance of 2,0 ± 0,01 m from the centre of the knee joint and the resulting angle of knee deflection must be recorded. The load must be increased until the angle of deflection of the knee exceeds 22°.

The energy is calculated by integrating the force with respect to the bending angle in radians, and multiplying by the lever length of 2,0 ± 0,01 m.

The impactor, without foam covering and skin, must be mounted with the tibia firmly clamped to a fixed horizontal surface and a metal tube connected firmly to the femur and restrained at 2,0 m from the centre of the knee joint, as shown in Figure 19.

A horizontal normal force must be applied to the femur at a distance of 50 mm from the centre of the knee joint and the resulting knee shearing displacement must be recorded. The load must be increased until the shearing displacement of the knee is in excess of 8,0 mm or the load exceeds of 6,0 kN.

The impactor must meet the requirements specified in paragraph 2.2.3 when tested in accordance with paragraph 2.3.

The stabilised temperature of the impactor during certification must be 20° ± 2 °C.

When the impactor is impacted by a linearly guided certification impactor, as specified in paragraph 2.3.2, the maximum upper tibia acceleration must be not less than 120 g and not more than 250 g. The maximum bending angle must be not less than 6,2° and not more than 8,2°. The maximum shearing displacement must be not less than 3,5 mm and not more than 6,0 mm.

For all these values the readings used must be from the initial impact with the certification impactor and not from the arresting phase. Any system used to arrest the impactor or certification impactor must be so arranged that the arresting phase does not overlap in time with the initial impact. The arresting system must not cause the transducer outputs to exceed the specified CAC.

The instrumentation response value CFC, as defined in ISO 6487:2000, must be 180 for all transducers. The CAC response values, as defined in ISO 6487:2000, must be 50° for the knee bending angle, 10 mm for the shearing displacement and 500 g for the acceleration. This does not require that the impactor itself be able to physically bend and shear to these angles and displacements.

The impactor, including foam covering and skin, must be suspended horizontally by three wire ropes of 1,5 ± 0,2 mm diameter and of 2,0 m minimum length, as shown in Figure 20. It must be suspended with its longitudinal axis horizontal, with a tolerance of ± 0,5°, and perpendicular to the direction of the certification impactor motion, with a tolerance of ± 2 °. The impactor must have the intended orientation about its longitudinal axis, for the correct operation of its knee joint, with a tolerance of ± 2 °. The impactor must meet the requirements specified in paragraph 3.1 of Chapter III, Part II, with the attachment bracket(s) for the wire ropes fitted.

The certification impactor must have a mass of 9,0 ± 0,05 kg, this mass includes those propulsion and guidance components which are effectively part of the certification impactor during impact. The dimensions of the face of the certification impactor must be as specified in Figure 21. The face of the certification impactor must be made of aluminium, with an outer surface finish of better than at least 2,0 micrometers.

The guidance system must be fitted with low friction guides, insensitive to off-axis loading, that allow the impactor to move only in the specified direction of impact, when in contact with the vehicle. The guides must prevent motion in other directions including rotation about any axis.

The impactor must be certified with previously unused foam.

The impactor foam must not be excessively handled or deformed before, during or after fitting.

The certification impactor must be propelled horizontally at a velocity of 7,5 ± 0,1 m/s into the stationary impactor as shown in Figure 20. The certification impactor must be positioned so that its centreline aligns with a position on the tibia centreline of 50 mm from the centre of the knee, with tolerances of ± 3 mm laterally and ± 3 mm vertically.

The upper legform impactor must meet the requirements specified in paragraph 3.3 when tested in accordance with paragraph 3.4.

The stabilised temperature of the impactor during certification must be 20° ± 2 °C.

When the impactor is propelled into a stationary cylindrical pendulum the peak force measured in each load transducer must be not less 1,20 kN and not more than 1,55 kN and the difference between the peak forces measured in the top and bottom load transducers must not be more than 0,10 kN. The peak bending moment measured by the strain gauges must not be less than 190 Nm and not more than 250 Nm on the centre position and not less than 160 Nm and not more than 220 Nm for the outer positions. The difference between the upper and lower peak bending moments must not be more than 20 Nm.

For all these values the readings used must be from the initial impact with the pendulum and not from the arresting phase. Any system used to arrest the impactor or pendulum must be so arranged that the arresting phase does not overlap in time with the initial impact. The arresting system must not cause the transducer outputs to exceed the specified CAC.

The instrumentation response value CFC, as defined in ISO 6487:2000, must be 180 for all transducers. The CAC response values, as defined in ISO 6487:2000, must be 10 kN for the force transducers and 1000 Nm for the bending moment measurements.

The impactor must be mounted to the propulsion and guidance system, by a torque limiting joint. The torque limiting joint must be set so that the longitudinal axis of the front member is perpendicular to the axis of the guidance system, with a tolerance of ± 2 °, with the joint friction torque set to a minimum of 650 Nm. The guidance system must be fitted with low friction guides that allow the impactor to move only in the specified direction of impact, when in contact with the pendulum.

The impactor mass must be adjusted to give a mass of 12 ± 0,1 kg, this mass includes those propulsion and guidance components which are effectively part of the impactor during impact.

The centre of gravity of those parts of the impactor which are effectively forward of the torque limiting joint, including the extra weights fitted, must lie on the longitudinal centreline of the impactor, with a tolerance of ± 10 mm.

The impactor must be certified with previously unused foam.

The impactor foam must not be excessively handled or deformed before, during or after fitting.

The impactor with the front member vertical must be propelled horizontally at a velocity of 7,1 ± 0,1 m/s into the stationary pendulum as shown in Figure 22.

The pendulum tube must have an outside diameter of 150 ⁺¹ _-4 mm, a wall thickness of 3 ± 0,15 mm and a mass of 3 ± 0,03 kg. Total pendulum tube length must be 275 ± 25 mm. The pendulum tube must be made from cold finished seamless steel (metal surface plating is permissible for protection from corrosion), with an outer surface finish of better than 2,0 micrometers. It must be suspended on two wire ropes of 1,5 ± 0,2 mm diameter and of 2,0 m minimum length. The surface of the pendulum must be clean and dry. The pendulum tube must be positioned so that the longitudinal axis of the cylinder is perpendicular to the front member (i.e. level), with a tolerance of ± 2 °, and to the direction of impactor motion, with a tolerance of ± 2 °, and with the centre of the pendulum tube aligned with the centre of the impactor front member, with tolerances of ± 5 mm laterally and ± 5 mm vertically.

The child/small adult headform impactor must meet the requirements specified in paragraph 4.3 when tested in accordance with paragraph 4.4.

The stabilised temperature of the impactor during certification must be 20° ± 2 °C.

When the child/small adult headform impactor is impacted by a linearly guided certification impactor, as specified in paragraph 4.4, the peak resultant acceleration measured by one tri-axial (or three uni-axial) accelerometer in the headform must be not less than 290 g and not more than 350 g. The resultant acceleration time curve must be uni-modal.

The instrumentation response value CFC, as defined in ISO 6487:2000, must be 1000. The CAC response value, as defined in ISO 6487:2000, must be 1 000 g for the acceleration.

The headform impactor must be suspended as shown in Figure 23. The headform impactor must be suspended with the rear face at an angle between 25° and 90° with the horizontal, as shown in Figure 23.

The certification impactor must have a mass of 1,0 ± 0,01 kg. This mass includes those propulsion and guidance components which are effectively part of the impactor during impact. The linear guidance system must be fitted with low friction guides which do not contain any rotating parts. The diameter of the flat impactor face must be 70 ± 1 mm, while the edge must be rounded by a 5 ± 0,5 mm radius. The face of the certification impactor must be made of aluminium, with an outer surface finish of better than 2,0 micrometers.

The certification impactor must be propelled horizontally at a velocity of 7,0 ± 0,1 m/s into the stationary child/small adult headform impactor as shown in Figure 23. The certification impactor must be positioned so that the centre of gravity of the headform is located on the centre line of the certification impactor, with tolerances of ± 5 mm laterally and ± 5 mm vertically.

The test must be performed on three different impact positions on the headform impactor. Previously used and/or damaged skin must be tested in those specific areas.