3 Dynamic seat tests
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Statutory Documents - IMO Publications and Documents - International Codes - HSC 2000 Code - International Code of Safety for High-Speed Craft, 2000 – Resolution MSC.97(73) - Annex 10 - Criteria for testing and evaluation of seats - 3 Dynamic seat tests

3 Dynamic seat tests

  3.1 The requirements of this section are applicable in addition to those in 2.1 for crew and revenue seats in craft having a design collision load of 3g or greater.

  3.2 All seats for which this section applies, the seat supporting structure, the attachment to the deck structure, the lap belt, if installed, and shoulder harness, if installed, shall be designed to withstand the maximum acceleration force that can be imposed upon them during a design collision. Consideration shall be given to the orientation of the seat relative to the acceleration force (i.e. whether the seat is forward-, aft-, or side-facing).

  3.3 The acceleration pulse to which the seat is subjected shall be representative of the collision time-history of the craft. If the collision time-history is not known, or cannot be simulated, the acceleration time-history envelope shown in the figure can be used.

Figure 1 Acceleration time-history envelope

  3.4 In the test frame, each seat unit and its accessories (e.g., lap belts and shoulder harnesses) shall be attached to the support structure similar to the manner in which it will be attached in the craft. The support structure can be a rigid surface; however, a support structure having the equivalent strength and stiffness as the support structure in the craft is preferred. Other seats and/or tables with which an occupant may come in contact during a collision shall be included in the test frame in an orientation and with a method of attachment typical of that in the craft.

  3.5 During the dynamic seat test, a fiftieth percentile anthropomorphic test dummy, suitable for the test being conducted,footnote shall be placed in the seat in an upright seating position. If a typical seating unit is composed of more than one occupant seat, a test dummy shall be placed in each occupant seat in the unit. The dummy, or dummies, shall be secured in the seat unit in accordance with procedures of recognized national standardsfootnote and be secured using only the lap belt and shoulder harness if they are installed. Tray tables and other such devices shall be placed in the position that would cause the greatest potential for an occupant to become injured.

  3.6 The test dummy shall be instrumented and calibrated, in accordance with the requirements of a recognized national standard, so as to permit, as a minimum, calculation of the head injury criterion, calculation of the thoracic trauma index, measurement of force in the femur, and measurement of extension and flexion of the neck.

  3.7 If more than one dummy is used in the tests, the dummy located in the seat having the highest potential for an occupant to be injured shall be the one instrumented. The other dummy or dummies need not be instrumented.

  3.8 The tests shall be conducted and the instrumentation shall be sampled at a rate sufficient to reliably show response of the dummy in accordance with the requirements of a recognized national standardfootnote.

  3.9 The seat unit tested in accordance with the requirements of this section shall be considered acceptable if:

  • .1 the seat unit and tables installed in the seat unit or area do not become dislodged from the supporting deck structure and do not deform in a manner that would cause the occupant to become trapped or injured;

  • .2 the lap belt, if installed, remains attached and on the test dummy's pelvis during the impact. The shoulder harness, if installed, remains attached and in the immediate vicinity of the test dummy's shoulder during the impact. After the impact, the release mechanisms of any installed lap belt and shoulder harness shall be operative;

  • .3 the following acceptability criteria are met:

    • .3.1 the head injury criterion (HIC), calculated in accordance with the formula, does not exceed 500

      where
      = t l and t 2 are the beginning and ending times (in seconds) of the interval in which the HIC is a maximum. The term a(t) is the resultant measured acceleration in the head of the dummy in g;

    • .3.2 the thoracic trauma index (TTI), calculated in accordance with the formula, does not exceed 30g except for periods totalling less than 3 ms

      where
      = g R is the acceleration in g of either the upper or lower rib;
      = g LS is the acceleration in g of the lower spine; and

    • .3.3 neck flexion does not exceed 88 N·m;

    • .3.4 neck extension does not exceed 48 N·m;

    • .3.5 in lieu of the requirements of subparagraphs .3.3 and .3.4 above, a seatback or headrest of at least 850 mm above the seat cushion is acceptable; and

    • .3.6 the force in the femur does not exceed 10 kN, except that it cannot exceed 8 kN for periods totalling more than 20 ms; and

  • .4 loads on the upper torso harness straps do not exceed 7.8 kN or a total of 8.9 kN if dual straps are used.

Parent topic: Annex 10 - Criteria for testing and evaluation of seats
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