Mechanical vibration and shock -- Characterization of the dynamic mechanical properties of visco-elastic materials -- Part 3: Cantilever shear beam method
This part of ISO 18437 defines a cantilever shear beam method for determining from laboratory measurements the dynamic mechanical properties of the resilient materials used in vibration isolators. Common errors due to clamping the specimen are avoided by using fixed ends so there is no rotational motion of the beam at its ends. This part of ISO 18437 is applicable to shock and vibration systems operating from a fraction of a hertz to about 20 kHz. This part of ISO 18437 is applicable to resilient materials that are used in vibration isolators in order to reduce a) transmissions of unwanted vibrations from machines, structures or vehicles that radiate sound (fluid-borne, airborne, structure-borne, or others), and b) the transmission of low-frequency vibrations that act upon humans or cause damage to structures or sensitive equipment when the vibration is too severe. The data obtained with the measurement methods that are outlined in this part of ISO 18437 and further detailed in ISO 18437-2 are used for — the design of efficient vibration isolators, — the selection of an optimum material for a given design, — the theoretical computation of the transfer of vibrations through isolators, — information during product development, — product information provided by manufacturers and suppliers, and — quality control. The condition for the validity of the measurement method is linearity of the vibrational behaviour of the isolator. This includes elastic elements with nonlinear static load deflection characteristics, provided that the elements show approximate linearity in their vibrational behaviour for a given static preload. Measurements using this method are made over two decades in frequency (typically 0,3 Hz to 30 Hz) at a number of temperatures. By applying the time-temperature superposition principle, the measured data are shifted to generate dynamic mechanical properties over a much wider range of frequencies (typically 10-3 Hz to 109 Hz at a single reference temperature) than initially measured at a given temperature. NOTE For the purpose of this part of ISO 18437, the term "dynamic mechanical properties" refers to the determination of the fundamental elastic properties, e.g. the complex Young's modulus as a function of temperature and frequency and, if applicable, a static preload.