Section 572.21 - Test conditions and instrumentation(a)(1) The test probe used for head and thoracic impact tests is a cylinder 3 inches in diameter, 13.8 inches long, and weighing 10 lbs., 6 ozs. Its impacting end has a flat right face that is rigid and that has an edge radius of 0.5 inches.(2) The head and thorax assembly may be instrumented with a Type A or Type C accelerometer. (i) Type A accelerometer is defined in drawing SA-572 S1.(ii) Type C accelerometer is defined in drawing SA-572 S2.(b)Head accelerometers. Install one of the triaxial accelerometers specified in § 572.21(a)(2) on a mounting block located on the horizontal transverse bulkhead as shown in the drawings subreferenced under assembly SA 103C 010 so that the seismic mass centers of each sensing element are positioned as specified in this paragraph, relative to the head accelerometer reference point located at the intersection of a line connecting the longitudinal centerlines of the transfer pins in the side of the dummy head with the midsagittal plane of the dummy head. (1) The sensing elements of the Type C triaxial accelerometer are aligned as follows: (i) Align one sensitive axis parallel to the vertical bulkhead and coincident with the midsagittal plane, with the seismic mass center located 0.2 inches dorsal to, and 0.1 inches inferior to the head accelerometer reference point.(ii) Align the second sensitive axis with the horizontal plane, perpendicular to the midsagittal plane, with the seismic mass center located 0.1 inches inferior, 0.4 inches to the right of, and 0.9 inches dorsal to the head accelerometer reference point.(iii) Align the third sensitive axis so that it is parallel to the midsagittal and horizontal planes, with the seismic mass center located 0.1 inches inferior to, 0.6 inches dorsal to, and 0.4 inches to the right of the head accelerometer reference point.(iv) All seismic mass centers are positioned with ±0.05 inches of the specified locations.(2) The sensing elements of the Type A triaxial accelerometer are aligned as follows: (i) Align one sensitive axis parallel to the vertical bulkhead and coincident with midsagittal planes, with the seismic mass center located from 0.2 to 0.47 inches dorsal to, from 0.01 inches inferior to 0.21 inches superior, and from 0.0 to 0.17 inches left of the head accelerometer reference point.(ii) Align the second sensitive axis with the horizontal plane, perpendicular to the midsagittal plane, with the seismic mass center located 0.1 to 0.13 inches inferior to, 0.17 to 0.4 inches to the right of, and 0.47 to 0.9 inches dorsal of the head accelerometer reference point.(iii) Align the third sensitive axis so that it is parallel to the midsagittal and horizontal planes, with the seismic mass center located 0.1 to 0.13 inches inferior to, 0.6 to 0.81 inches dorsal to, and from 0.17 inches left to 0.4 inches right of the head accelerometer reference point.(c)Thorax accelerometers. Install one of the triaxial accelerometers specified in § 572.21(a)(2) on a mounting plate attached to the vertical transverse bulkhead shown in the drawing subreferenced under assembly No. SA 103C 030 in drawing SA 103C 001, so that the seismic mass centers of each sensing element are positioned as specified in this paragraph, relative to the thorax accelerometer reference point located in the midsagital plane 3 inches above the top surface of the lumbar spine, and 0.3 inches dorsal to the accelerometer mounting plate surface.(1) The sensing elements of the Type C triaxial accelerometer are aligned as follows: (i) Align one sensitive axis parallel to the vertical bulkhead and midsagittal planes, with the seismic mass center located 0.2 inches to the left of, 0.1 inches inferior to, and 0.2 inches ventral to the thorax accelerometer reference point.(ii) Align the second sensitive axis so that it is in the horizontal transverse plane, and perpendicular to the midsagittal plane, with the seismic mass center located 0.2 inches to the right of, 0.1 inches inferior to, and 0.2 inches ventral to the thorax accelerometer reference point.(iii) Align the third sensitive axis so that it is parallel to the midsagittal and horizontal planes, with the seismic mass center located 0.2 inches superior to, 0.5 inches to the right of, and 0.1 inches ventral to the thorax accelerometer reference points.(iv) All seismic mass centers shall be positioned within ±0.05 inches of the specified locations.(2) The sensing elements of the Type A triaxial accelerometer are aligned as follows: (i) Align one sensitive axis parallel to the vertical bulkhead and midsagittal planes, with the seismic mass center located from 0.2 inches left to 0.28 inches right, from 0.5 to 0.15 inches inferior to, and from 0.15 to 0.25 inches ventral of the thorax accelerometer reference point.(ii) Align the second sensitive axis so that it is in the horizontal transverse plane and perpendicular to the midsagital plane, with the seismic mass center located from 0.06 inches left to 0.2 inches right of, from 0.1 inches inferior to 0.24 inches superior, and 0.15 to 0.25 inches ventral to the thorax accelerometer reference point.(iii) Align the third sensitive axis so that it is parallel to the midsagital and horizontal planes, with the seismic mass center located 0.15 to 0.25 inches superior to, 0.28 to 0.5 inches to the right of, and from 0.1 inches ventral to 0.19 inches dorsal to the thorax accelerometer reference point.(d) The outputs of accelerometers installed in the dummy, and of test apparatus specified by this part, are recorded in individual data channels that conform to the requirements of SAE Recommended Practice J211a, December 1971, with channel classes as follows:(1) Head acceleration-Class 1000.(2) Pendulum acceleration-Class 60.(3) Thorax acceleration-Class 180.(e) The mountings for accelerometers have no resonance frequency less than cut-off 3 times the cut-off frequency of the applicable channel class.(f) Limb joints are set at the force between 1-2g, which just supports the limbs' weight when the limbs are extended horizontally forward. The force required to move a limb segment does not exceed 2g throughout the range of limb motion.(g) Performance tests are conducted at any temperature from 66 °F to 78 °F and at any relative humidity from 10 percent to 70 percent after exposure of the dummy to these conditions for a period of not less than 4 hours.(h) For the performance tests specified in §§ 572.16 , 572.18 , and 572.19 , the dummy is positioned in accordance with Figures 16, 17, and 18 as follows: (1) The dummy is placed on a flat, rigid, clean, dry, horizontal surface of teflon sheeting with a smoothness of 40 microinches and whose length and width dimensions are not less than 16 inches, so that the dummy's midsagittal plane is vertical and centered on the test surface. For head tests, the seat has a vertical back support whose top is 12.4 ±0.2 inches above the seating surface. The rear surfaces of the dummy's shoulders and buttocks are touching the back support as shown in Figure 16. For thorax and lumbar spine tests, the seating surface is without the back support as shown in Figures 17 and 18, respectively.(2) The shoulder yokes are adjusted so that they are at the midpoint of their anterior-posterior travel with their upper surfaces horizontal.(3) The dummy is adjusted for head impact and lumbar flexion tests so that the rear surfaces of the shoulders and buttocks are tangent to a transverse vertical plane.(4) The arms and legs are positioned so that their centerlines are in planes parallel to the midsagittal plane.(i) The dummy's dimensions are specified in drawings No. SA 103C 002, sheets 22 through 26.(j) Performance tests of the same component, segment, assembly or fully assembled dummy are separated in time by a period of not less than 20 minutes unless otherwise specified.44 FR 76530, Dec. 27, 1979, as amended at 45 FR 82267, Dec. 15, 1980; 55 FR 30468, July 26, 1990