DANSK DS/ISO 18437-4 PDF

1 Scope This part of ISO 18437 presents a direct method for measuring the complex dynamic moduli of elasticity (Young's, shear and bulk moduli, and their respective loss factors corresponding to the tensile, shear and all compressive strains) for polymeric material (rubbery, viscous and polymeric materials and rigid plastics) over a wide frequency and temperature range. The measurements are performed by the dynamic stiffness method, which uses the electric signals from sensors attached to a sample of the material. These signals are proportional to the dynamic forces acting on the test sample and the strains in the test sample due to the effect of these forces. The measurement frequency range is determined by the size of test sample, the accuracy required on the dynamic modulus measurements, the relationship between the stiffness of the oscillation generator and the stiffness of the test sample, and by the resonance characteristics of the test fixture used. The method presented in this standard allows performing the measurements under any static pre-load allowed for the test sample (including the sample having the non-linear characteristics under different static loads), but under the small dynamic (acoustic) strains, i.e. in limits when the linear properties of test material are not distorted. Depending on the pre-load conditions the relation between the moduli will be unique.