Title 49

SECTION 572.217

572.217 Lumbar spine assembly and test procedure.

§ 572.217 Lumbar spine assembly and test procedure.

All assemblies and drawings referenced in this section are contained in Drawings and Specifications, incorporated by reference, see § 572.210.

(a) The lumbar spine and headform assembly for the purposes of the fore-aft lumbar flexion and lateral lumbar flexion qualification tests, as shown in Figures W9 and W10 in appendix A to this subpart, consists of the headform (drawing 020-9050, sheet 2) with angular rate sensor installed (drawing SA572-S58), six-channel neck/lumbar load cell (drawing SA572-S8), lumbar spine assembly (drawing 020-6000), lumbar interface plate (drawing 020-9062) and pendulum interface plate (drawing 020-9051) with angular rate sensor installed (drawing SA572-S58).

(b) When the lumbar spine and headform assembly is tested according to the test procedure in paragraph (c) of this section, it shall have the following characteristics:

(1) Fore-aft lumbar flexion qualification test. (i) Plane D, referenced in figure W9 in appendix A to this subpart, shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal centerline between 47.0 degrees and 58.5 degrees. During the time interval while the rotation is within these angles, the peak moment measured by the neck/lumbar transducer (drawing SA572-S8) shall have a value between 78.2 N-m and 96.2 N-m.

(ii) The decaying headform rotation vs. time curve shall cross the zero angle with respect to its initial position at time of impact relative to the pendulum centerline between 49 to 59 ms after the time the peak rotation value is reached.

(iii) All instrumentation data channels are defined to be zero when the longitudinal centerline of the lumbar spine and pendulum are parallel.

(iv) The headform rotation shall be calculated by the following formula with the integration beginning at time zero:

Headform rotation (deg) = ∫ [(Headform Angular Rate)y−(Pendulum Angular Rate)y] dt

(v) (Headform Angular Rate)y is the angular rate about the y-axis in deg/sec measured on the headform (drawing 020-9050, sheet 2), and (Pendulum Angular Rate)y is the angular rate about the y-axis in deg/sec measured on the pendulum interface plate (drawing 020-9051).

(2) Lateral lumbar flexion qualification test. (i) Plane D, referenced in figure W10, shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal centerline between 46.1 degrees and 58.2 degrees. During the time interval while the rotation is within these angles, the peak moment measured by the neck/lumbar transducer (drawing SA572-S8) shall have a value between 79.4 N-m and 98.1 N-m.

(ii) The decaying headform rotation vs. time curve shall cross the zero angle with respect to its initial position at time of impact relative to the pendulum centerline between 48 to 59 ms after the time the peak rotation value is reached.

(iii) All instrumentation data channels are defined to be zero when the longitudinal centerline of the lumbar spine and pendulum are parallel.

(iv) The headform rotation shall be calculated by the following formula with the integration beginning at time zero:

Headform rotation (deg) = ∫ [(Headform Angular Rate)y−(Pendulum Angular Rate)y] dt

(v) (Headform Angular Rate)y is the angular rate about the y-axis in deg/sec measured on the headform (drawing 020-9050, sheet 2), and (Pendulum Angular Rate)y is the angular rate about the y-axis in deg/sec measured on the pendulum interface plate (drawing 020-9051).

(c) The test procedure for the lumbar spine assembly is as follows:

(1) Soak the lumbar spine assembly in a controlled environment at any temperature between 20.6 and 22.2 °C and a relative humidity between 10 and 70 percent for at least four hours prior to a test.

(2)(i) For the fore-aft lumbar flexion test, mount the lumbar spine and headform assembly, defined in paragraph (a) of this section, on the pendulum described Figure 22 to § 572.33 so that the midsagittal plane of the headform is vertical and coincides with the plane of motion of the pendulum, and with the lumbar spine placement such that the front side of the lumbar spine is closest to the honeycomb material.

(ii) For the lateral lumbar flexion test, the test is carried out in the direction opposing the primary load vector of the ensuing full scale test for which the dummy is being qualified. A right flexion test set-up that is used to qualify the dummy for an ensuing a full scale right side impact is depicted in figure W10 in appendix A to this subpart. A left flexion test set-up would be depicted by a mirror image of all components beneath the pendulum interface plate in Figure W10. Mount the lumbar spine and headform assembly, defined in paragraph (a)(1) of this section, on the pendulum described in figure 22 to § 572.33 so that the midsagittal plane of the headform is vertical and perpendicular to the direction of motion of the pendulum, and with the lumbar spine placement such that the right (or left) side of the lumbar spine is closest to the honeycomb material.

(3)(i) Release the pendulum and allow it to fall freely from a height to achieve an impact velocity of 4.4 ± 0.1 m/s, measured by an accelerometer mounted on the pendulum as shown in Figure 22 to § 572.33 at time zero.

(ii) Stop the pendulum from the initial velocity with an acceleration vs. time pulse that meets the velocity change as specified in table 1 to this section. Integrate the pendulum accelerometer data channel to obtain the velocity vs. time curve beginning at time zero.

(iii) Time zero is defined as the time of initial contact between the pendulum striker plate and the honeycomb material.

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