Akustik och vibration - Laboratoriemätningar av vibro-akustiska överföringsegenskaper hos elastiska element - Del 4: Dynamisk styvhet vid rätlinjig rörelse hos andra element än vibrationsisolatorer (ISO 10846-4:2003)
This part of ISO 10846 specifies two methods for determining the dynamic transfer stiffness for translations of resilient elements other than resilient supports. Examples are resilient bellows, shaft couplings, power supply cables, hoses and pipe hangers (see Figure 1). Elements filled with liquids, such as oil or water, are excluded. NOTE 1 Pipe hangers are extensionally deflected, as opposed to elastic supports which are compressed. Therefore, the test conditions are different from those described in ISO 10846-2 and ISO 10846-3. The methods are applicable to resilient elements with flat flanges or flat clamp interfaces. It is not necessary that the flanges be parallel. Resilient elements which are the subject of this part of ISO 10846 are those that are used to reduce a) the transmission of audiofrequency vibrations (structure-borne sound, 20 Hz to 20 kHz ) to a structure which may, for example, radiate unwanted sound (airborne, waterborne or other), and b) the transmission of low-frequency vibrations (typically 1 Hz to 80 Hz), which may, for example, act upon human subjects or cause damage to structures of any size when the vibration is too severe. In practice, the size of the available test rig(s) determines restrictions for very small and for very large resilient elements. Measurements for translations normal and transverse to the flanges or clamp interfaces are covered in this part of ISO 10846. Annex A provides guidance for the measurement of transfer stiffnesses that include rotatory components. The direct method can be applied in the frequency range from 1 Hz up to a frequency that is usually determined by the lowest resonance frequency of the test arrangement frame (typically 300 Hz for test rigs with dimensions of the order of 1 m). NOTE 2 In practice, the lower frequency limit depends on the dynamic excitation system.