SAE J89:2018 pdf free
SAE J89:2018 pdf free.Dynamic Cushioning Performance Criteria for Snowmobile Seats
The missile shall be equipped with an accelerometer system which shall be capable of measuring single impacts of short duration (less than 0.105 seconds) in the 5 to 100 g range with an accuracy of +2% throughout the duration of the pulse.
A penetration measuring device, or some other means, is required to determine the exact starting time of the penetration. A velocity measuring device shall be used for measuring the impacting velocity of the missile if the missile is not totally free to fall under the influence of gravity.
The missile shall be a rigid segment of a hemisphere, the sphere having a radius of 245 mm (9.65 inches) and the segment having a radius of 178 mm (7 inches). (See Figure 3.) The top surface of the missile must be designed to accommodate weights to provide total missile mass capability of 90.7 kg (200 pounds).
The acceleration-time recording equipment should be capable of recording impacts compatible with the accuracy of the accelerometer. Some type of triggering device will be necessary for the recording device.
Any seating system, or component, for which dynamic cushioning data is desired. The number of specimens tested as a sample can vary widely depending upon the intended use of the data. At least two specimens shall be tested for each set of conditions. The specimens shall be conditioned at 21 °C±6 °C (70°F±10 °F) for a minimum of 8 hours prior to testing.
If the test specimen is attached to a gas tank or structure (other than laying flat on a flat tunnel) it needs to be attached to a fixture simulating the identical mounting as it is in the snowmobile it is intended for. If it is attached to a gas tank in the snowmobile, then the fixture needs to include a gas tank. The gas tank used in the fixture needs to be a production gas tank, empty of fluid, and cannot be more than 3 years old.SAE J89 pdf free download.
