Commission Regulation (EC) No 631/2009Show full title

Appendix I Certification of Impactors U.K.

1. Certification requirements U.K.

1.1. The impactors that are used in the tests detailed in Part II and Part IV are required to comply with appropriate performance requirements. U.K.

The requirements for the lower legform impactor are specified in Section 2; the upper legform impactor requirements are specified in Section 3 and the adult, child and child/small adult headform impactor requirements are specified in Section 4.

2. Lower legform impactor U.K.

2.1. Static tests U.K.

2.1.1. The lower legform impactor shall meet the requirements specified in point 2.1.2 when tested as specified in point 2.1.4 and the impactor shall meet the requirements specified in point 2.1.3 when tested as specified in point 2.1.5. U.K.

For both tests the impactor shall 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 shall be 20 ± 2 °C.

The CAC response values, as defined in ISO 6487:2002, shall be 50° for the knee bending angle and 500 N for the applied force when the impactor is loaded in bending in accordance with point 2.1.4, and 10 mm for the shearing displacement and 10 kN for the applied force when the impactor is loaded in shearing in accordance with point 2.1.5. 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.

2.1.2. When the impactor is loaded in bending in accordance with point 2.1.4 the applied force/bending angle response shall be within the limits shown in Figure 1. Also, the energy taken to generate 15,0° of bending shall be 100 ± 7 J. U.K.

2.1.3. When the impactor is loaded in shearing in accordance with point 2.1.5 the applied force/shearing displacement response shall be within the limits shown in Figure 2. U.K.

2.1.4. The legform 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 3. The rotational axis of the impactor knee joint shall be vertical. To avoid friction errors, no support shall 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), shall not exceed 25 Nm. U.K.

A horizontal normal force shall 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 shall be recorded. The load shall be increased such that the rate of increase of the angle of deflection of the knee is between 1 and 10°/s until the angle of deflection of the knee is in excess of 22°. Brief excursions from these limits due, for instance, to the use of a hand-pump shall be permitted.

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.

2.1.5. 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 and restrained at 2,0 m from the centre of the knee joint, as shown in Figure 4. U.K.

A horizontal normal force shall be applied to the femur at a distance of 50 mm from the centre of the knee joint and the resulting knee shearing displacement shall be recorded. The load shall be increased such that the rate of increase of the shearing displacement of the knee is between 0,1 and 20 mm/s until the shearing displacement of the knee is in excess of 7,0 mm or the load is in excess of 6,0 kN. Brief excursions from these limits due, for instance, to the use of a hand-pump shall be permitted.

2.2. Dynamic tests U.K.

2.2.1.

The lower legform impactor shall meet the requirements specified in point 2.2.2 when tested as specified in point 2.2.4. U.K.

2.2.1.1. The foam flesh for the test impactor shall be stored for a period of at least four hours in a controlled storage area with a stabilised humidity of 35 ± 10 percent and a stabilised temperature of 20 ± 2 °C prior to impactor removal for calibration. The test impactor itself shall have a temperature of 20° ± 2 °C at the time of impact. The temperature tolerances for the test impactor shall apply at a relative humidity of 40 ± 30 percent after a soak period of at least four hours prior to their application in a test. U.K.

2.2.1.2. The test facility used for the calibration test shall have a stabilised humidity of 40 ± 30 percent and a stabilised temperature of 20 ± 4 °C during calibration. U.K.

2.2.1.3. Each calibration shall be completed within two hours of when the impactor to be calibrated is removed from the controlled storage area. U.K.

2.2.1.4. The relative humidity and temperature of the calibration area shall be measured at the time of calibration and recorded in the calibration report. U.K.

2.2.2. When the impactor is impacted by a linearly guided certification impactor, as specified in point 2.2.4, the maximum upper tibia acceleration shall be not less than 120 g and not more than 250 g. The maximum bending angle shall be not less than 6,2° and not more than 8,2°. The maximum shearing displacement shall be not less than 3,5 mm and not more than 6,0 mm. U.K.

For all these values the readings used shall 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 shall be so arranged that the arresting phase does not overlap in time with the initial impact. The arresting system shall not cause the transducer outputs to exceed the specified CAC.

2.2.3. The instrumentation response value CFC, as defined in ISO 6487:2002, shall be 180 for all transducers. The CAC response values, as defined in ISO 6487:2002, shall 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. U.K.

2.2.4. Test procedure U.K.

2.2.4.1. The impactor, including foam covering and skin, shall 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 5a. It shall 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 shall have the intended orientation about its longitudinal axis, for the correct operation of its knee joint, with a tolerance of ± 2°. The impactor shall meet the requirements of point 3.4.1.1 Chapter II of Part II with the attachment bracket(s) for the wire ropes fitted. U.K.

2.2.4.2. The certification impactor shall 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 shall be as specified in Figure 5b. The face of the certification impactor shall be made of aluminium, with an outer surface finish of better than 2,0 micrometers. U.K.

The guidance system shall 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 lower legform impactor. The guides shall prevent motion in other directions including rotation about any axis.

2.2.4.3. The impactor shall be certified with previously unused foam. U.K.

2.2.4.4. The impactor foam shall not be excessively handled or deformed before, during or after fitting. U.K.

2.2.4.5. The certification impactor shall be propelled horizontally at a velocity of 7,5 ± 0,1 m/s into the stationary impactor as shown in Figure 5a. The certification impactor shall 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. U.K.

3. Upper legform impactor U.K.

3.1.

The upper legform impactor shall meet the requirements specified in point 3.2 when tested as specified in point 3.3. U.K.

3.1.1. The foam flesh for the test impactor shall be stored for a period of at least four hours in a controlled storage area with a stabilised humidity of 35 ± 10 percent and a stabilised temperature of 20 ± 2 °C prior to impactor removal for calibration. The test impactor itself shall have a temperature of 20 ± 2 °C at the time of impact. The temperature tolerances for the test impactor shall apply at a relative humidity of 40 ± 30 percent after a soak period of at least four hours prior to their application in a test. U.K.

3.1.2. The test facility used for the calibration test shall have a stabilised humidity of 40 ± 30 percent and a stabilised temperature of 20 ± 4 °C during calibration. U.K.

3.1.3. Each calibration shall be completed within two hours of when the impactor to be calibrated is removed from the controlled storage area. U.K.

3.1.4. The relative humidity and temperature of the calibration area shall be measured at the time of calibration and recorded in the calibration report. U.K.

3.2. Requirements U.K.

3.2.1. When the impactor is propelled into a stationary cylindrical pendulum the peak force measured in each load transducer shall 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 shall not be more than 0,10 kN. Also, the peak bending moment measured by the strain gauges shall 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 shall not be more than 20 Nm. U.K.

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

3.2.2. The instrumentation response value CFC, as defined in ISO 6487:2002, shall be 180 for all transducers. The CAC response values, as defined in ISO 6487:2002, shall be 10 kN for the force transducers and 1 000 Nm for the bending moment measurements. U.K.

3.3. Test procedure U.K.

3.3.1. The impactor shall be mounted to the propulsion and guidance system, by a torque limiting joint. The torque limiting joint shall 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 675 ± 25 Nm. The guidance system shall 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. U.K.

3.3.2. The impactor mass shall 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. U.K.

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

3.3.4. The impactor shall be certified with previously unused foam. U.K.

3.3.5. The impactor foam shall not be excessively handled or deformed before, during or after fitting. U.K.

3.3.6. The impactor with the front member vertical shall be propelled horizontally at a velocity of 7,1 ± 0,1 m/s into the stationary pendulum as shown in Figure 6. U.K.

The pendulum tube shall have a mass of 3 ± 0,03 kg, an outside diameter of 150 mm ^{+ 1 mm}/- _{4 mm} and a wall thickness of 3 ± 0,15 mm. Total pendulum tube length shall be 275 ± 25 mm. The pendulum tube shall 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 shall 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 shall be clean and dry. The pendulum tube shall 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.

4. Headform impactors U.K.

4.1. Performance criteria U.K.

The headform impactors shall meet the requirements specified in Section 4.2 when tested as specified in Section 4.4.

4.2. Requirements U.K.

4.2.1. When the headform impactors are dropped from a height of 376 ± 1 mm in accordance with point 4.4. the peak resultant acceleration measured by one triaxial (or three uniaxial) accelerometer (accelerometers) in the headform impactor shall be: U.K.

(a)

for the child/small adult headform impactor not less than 245 g and not more than 300 g;

(b)

for the adult headform impactor not less than 225 g and not more than 275 g.

The acceleration time curves shall be uni-modal.

4.2.2. The instrumentation channel frequency class (CFC) response values and channel amplitude class (CAC) for each accelerometer shall be 1 000 Hz and 500g respectively as defined in ISO 6487:2002. U.K.

4.2.3. Temperature conditions U.K.

The headform impactors shall have a temperature of 20 ± 2 °C at the time of impact. The temperature tolerances shall apply at a relative humidity of 40 ± 30 percent after a soak period of at least four hours prior to their application in a test.

4.3. After complying with the certification test, each headform impactor can be used for a maximum of 20 impact tests. U.K.

4.4. Test procedure U.K.

4.4.1. The headform impactor shall be suspended from a drop rig as shown in Figure 7. U.K.

4.4.2. The headform impactor shall be dropped from the specified height by means that ensure instant release onto a rigidly supported flat horizontal steel plate, over 50 mm thick and over 300 x 300 mm square which has a clean dry surface and a surface finish of between 0,2 and 2,0 micrometers. U.K.

4.4.3. The headform impactor shall be dropped with the rear face of the impactor at the following angle from the vertical: U.K.

(a)

50° ± 2° for the child headform impactor;

(b)

65° ± 2° for the adult headform impactor;

4.4.4. The suspension of the headform impactor shall be such that it does not rotate during the fall. U.K.

4.4.5. The drop test shall be performed three times, with the headform impactor rotated 120° around its symmetrical axis between tests. U.K.

Figure 1

Force versus angle requirement in static lower legform impactor bending certification test

Figure 2

Force versus displacement requirement in static lower legform impactor shearing certification test

Figure 3

Top view of test set-up for static lower legform impactor bending certification test

Figure 4

Top view of test set-up for static lower legform impactor shearing certification test

Figure 5a

Test set-up for dynamic lower legform impactor certification test (side view top diagram, view from above bottom diagram)

Figure 5b

Details of dynamic lower legform certification impactor face

Notes: U.K.

1.

Saddle may be made as a complete diameter and cut as shown to make two components.

2.

The shaded areas may be removed to give the alternative form shown.

3.

Tolerance on all dimensions is ± 1,0 mm.

Material: aluminium alloy.

Figure 6

Test set-up for dynamic upper legform impactor certification test

Figure 7

Test set-up for dynamic headform impactor certification test