La. Admin. Code tit. 55 § III-1116

Current through Register Vol. 50, No. 9, September 20, 2024

Section III-1116 - Test Conditions

A. Impact Attenuation Test. Impact attenuation is measured by determining acceleration imparted to an instrumented test headform on which a complete helmet is mounted as specified in §1114, when it is dropped in guided free fall upon a fixed hemispherical anvil and a fixed flat steel anvil.

B. Each helmet shall be impacted at four sites with two successive identical impacts at each site. Two of these sites shall be impacted upon a flat steel anvil and two upon a hemispherical steel anvil as specified in §1116. I and §1116. J The impact sites shall be at any point on the area above the test line described in Paragraph §1113 C, and separated by a distance not less than one-sixth of the maximum circumference of the helmet in the test area.

C. Impact testing at each of the four sites, as specified in §1116 B, shall start at two minutes, and be completed by four minutes, after removal of the helmet from the conditioning environment.

1. The guided free fall drop height for the helmet and test headform combination onto the hemispherical anvil shall be such that the minimum impact speed is 17.1 feet/second (5.2 m/sec). The minimum drop height is 54.5 inches (138.4 cm). The drop height shall be adjusted upward from the minimum to the extent necessary to compensate for friction losses.

2. The guided free fall drop height for the helmet and test headform combination onto the flat anvil shall be such that the minimum impact speed is 19.7 ft./sec (6.0 m/sec). The minimum drop height shall be 72 inches (182.9 cm). The drop height shall be adjusted upward from the minimum to the extent necessary to compensate for friction losses.

D. Test headforms for impact attenuation testing shall be constructed of magnesium alloy (K-1A), and exhibit no resonant frequencies below 2,000 Hz.

E. The monorail drop test system shall be used for impact attenuation testing.

F. The weight of the drop assembly, as specified in Table 1, shall be the combined weight of the test headform and the supporting assembly for the drop test. The weight of the supporting assembly shall not be less than 2.0 lbs. and not more than 2.4 lbs. (0.9 to 1.1 kg). The supporting assembly weight for the monorail system shall be the drop assembly weight minus the combined weight of the test headform, the headform's clamp down ring, and its tie down screws.

G. The center of gravity of the test headform shall be located at the center of the mounting ball on the supporting assembly and lie within a cone with its axis vertical and forming a 10 degree included angle with the vertex at the point of impact. The center of gravity of the drop assembly shall lie within the rectangular volume bounded by x = -0.25 inch (-0.64 cm), x = 0.85 inch (2.16 cm), y = 0.25 inch (0.64 cm), and y = -0.25 inch (-0.64 cm) with the origin located at the center of gravity of the test headform. The rectangular volume shall have no boundary along the z-axis. The x-y-z axes shall be mutually perpendicular and shall have positive or negative designations in accordance with the right-hand rule (see §1131. F Figure 5). The origin of the coordinate axes shall also be located at the center of the mounting ball on the supporting assembly (see §1131. K -M.Figures 6, 7, and 8). The x-y-z axes of the test headform assembly on a monorail drop test equipment shall be oriented as follows: From the origin, the x-axis shall be horizontal with its positive direction going toward and passing through the vertical centerline of the monorail. The positive z-axis shall be downward. The y-axis shall also be horizontal and its direction will be decided by the z- and x-axes, using the right-hand rule.

H. The acceleration transducer shall be mounted at the center of gravity of the test headform with the sensitive axis aligned to within 5 degrees of vertical when the test headform assembly is in the impact position. The acceleration data channel shall comply with SAE Recommended Practice J211 JUN 80, Instrumentation for Impact Tests, requirements for channel class 1,000.

I. The flat anvil shall be constructed of steel with a 5-inch (12.7 cm) minimum diameter impact face, and the hemispherical anvil shall be constructed of steel with a 1.9 inch (4.8 cm) radius impact face.

J. The rigid mount for both of the anvils shall consist of a solid mass of at least 300 pounds (136.1 kg), the outer surface of which shall consist of a steel plate with minimum thickness of 1 inch (2.5 cm) and minimum surface area of 1 ft² (929 cm²).

K. The drop system shall restrict side movement during the impact attenuation test so that the sum of the areas bounded by the acceleration-time response curves for both the x- and y-axes (horizontal axes) shall be less than 5 percent of the area bounded by the acceleration-time response curve for the vertical axis.

La. Admin. Code tit. 55, § III-1116

Promulgated by the Department of Public Safety and Corrections, Office of State Police, LR 27:64 (January 2001).

AUTHORITY NOTE: Promulgated in accordance with R.S. 32:190.