ISO TS 24667-2020 pdf download.Sports and recreational facilities – Impact surfacing testing device. 4.2 Accelerometer The accelerometer can be any type of sensor technology (piezoelectric, piezoresistive, variable capacitance, etc.) as long as it has the following performance specifications: a) minimum design frequency response is 1 Hz to si 000 Hz; b) capable of periodic calibration at 20 Hz, 50 Hz, 100 Hz, 300 Hz, 500 Hz, and 1 000 Hz; c) sensitivity (mV/g) does not deviate from 100 Hz reference frequency by more than ±5 % at all calibration points; d) transverse sensitivity is 1.0 s NOTE Time constant not applicable to MEMS type accelerometers. f) minimum range of all axes is 500g whereg is equal to one gravitation force. 4.3 Data acquisition system 4.3.1 General The data acquisition system shall have the following specifications for all channels: a) 12 bits including sign minimum; b) 20 000 Hz minimum sample rate per channel; c) anti-aliasing filter with – 30 dB at half of the sample rate; d) class 1 000 data channel dynamic accuracy in accordance with ISO 6487; e) record data for minimum 10 ms before and 50 ms after the point on start of impact where acceleration on any axis rises above 5g (total 60 ms record); and f) output all recorded data points in a suitable file format to facilitate post-processing. 4.3.2 Channels The data acquisition system should be configured with enough channels to accommodate the number of accelerometers to be monitored. Single channel missiles as described in 4.1 g) shall be connected to a data acquisition system with at least one channel. . Three-channel missiles as described in 4.1 f) shall be connected to a data acquisition system with at least three channels. 5 Calculation and processing The system will display peak g, Head Injury Criterion (HIC) and HIC interval (2-t1). HIC is calculated with Formula (1). A time interval (dt) of≤50 us will be used. NOTE This ensures that the data collected at a 20 000 sample rate is used (20 000 samples per second equals 0,05 ms per sample). A faster sample rate would give a smaller dt which results in a more accurate HIC calculation.ISO TS 24667 pdf download.
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