AS ISO 7096:2021 pdf free download – Earth-moving machinery -Laboratory evaluation of operator seat vibration

AS ISO 7096:2021 pdf free download – Earth-moving machinery -Laboratory evaluation of operator seat vibration.
1.1 This document specifies, In accordance with ISO 10326-1:2016, a laboratory method for measuring and evaluating the effectiveness of the seat suspension in reducing the vertical whole-body vibration transmitted to the operator of earth-moving machines at frequencies between 1 Hz and 20 Hz. It also speafies acceptance criteria for application to seats on different machines.
1.2 This document is applicable to operator seats used on earth-moving machines as defined in ISO 6165.
1.3 This document defines the input spectral classes required for the following earth-moving machines.
Each cbss dufines a group of machines having similar vibration characteristics:
— rigid-frame dumpers >4500 kg operating mass;
— articulated-frame dumpers;
— scrapers without axle or frame suspension’);
— wheeled loaders >4 500 kg operating mass;
— graders;
— wheeled dozers;
— soil compactors;
— backhoe loaders;
— crawler dumpers;
— crawler loaders;
— crawler-dozers 50 000 kg operating mass2);
— compact dumpers 4 500 kg operating mass;
— wheeled compact loaders s4 500 kg operating mass;
— skid-steer loaders, wheeled 4 500 kg and tracked 6 000 kg operating mass.
1.4 The following machines Impart sufficiently low vertical vibration Inputs at frequencies between
1 Hz and 20 Hz to the seat during operation that these seats do not require suspension for the attenuation
of transmitted vibration:
— excavators, including walking excavators and cable excavators3); trenchers;
The seat shall be loaded with an inert mass of 75 kg and then excited by a sinusoidal vibration In the range from 0,5 to 2 times the expected resonance frequency of the suspension. The inert mass shall, If necessary, be secured to the seat In order to prevent the mass from moving on the seat or from falling off it.
Bags filled with lead shot or other material with similar density should be used as Inert mass.
To determine the resonance frequency, the frequency range shall be investigated with either a linear frequency sweep or in maximum steps oF 0,05 Hz. With either method, the frequency should be varied from a lower frequency (equal to 0.5 times the expected resonance of the suspension) to an upper frequency (equal to 2 times the expected resonance frequency of the suspension) and back again to the lower frequency. The frequency sweeping shall be made over a duration of at least 80 s at a constant peak to peak displacement of the platform that is equal to 40 % of the total suspension travel (stroke) specified by the seat manufacturer, or 50 mm. whichever is the smaller.
The damping test and the calculation of the transmissibility HJ) at resonance shall be performed according to ISO 10326-1:2016,9.5. In all cases, the damping test itself at the resonance frequency shall be carried out with a peak to peak displacement of the platform of 40% of the total suspension travel even if the 40 %value exceeds 50mm.
Only one measurement needs to be carried out at the resonance frequency of the seat’s suspension.
5.5.3 Damping test for active and semi-active suspension systems
For active and semi-active suspension systems, the simulated Input vibration test shall be performed as for passive systems. The damping test shall be performed at the frequency of highest response in the range of (0.1 to 10) Hz. The frequency of highest response can be different than the suspension’s resona lit frequency.
5.6 Tolerances on input vibration
5.6.1 General
See In ISO 10326.1:2016,9.3.
The input excitation for the seat as defined in 5.5.1 can only be created on a simulator in an approximate manner. In order to be valid the test input shall comply with the Following requtrrnwnts.
5.6.2 Distribution function
Under the condition that the acceleration on the platform shall be sampled at a minimum of 50 data points per second and analyzed into amplitude cells of not greater than 20 % of the total true rms acceleration, the probability density function must he within ±20 % of’ the ideal Gaussian function between ±200 % of the total true rms acceleration, and with no data exceeding ±350 % of the total true rms acceleration. For the purposes of this requirement, the total true rms acceleration is 0p12 as defined in Table 4.
5.6.3 Power spectral density and rrns values
The power spectral density of the acceleration measured on the platform is considered to be representative of GpfJ ii, and only if.