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DYNAMIC PROPERTIES OF VISCOELASTIC MATERIALS DURING NONHARMONIC LOADING (STRESSING)
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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Terminology for periodic non-harmonic loading conditions is described and a selection is made for proper characteristics defining the dynamic elasticity and mechanical losses in the material during non-harmonic loading. Expressions were obtained for the dynamic modulus and for the modulus of internal friction of viscoelastic materials, the properties of which are described by a tri-elemental model and a model with continuous relaxation time spectrum. An analysis was made of the nature of stresstime dependencies corresponding to various conditions of non-harmonic change in deformation. Graphic dependencies are given for a series of concrete cases. An analysis was made of the influence of various parameters of the non-harmonic condition duration of intermissions, ratios between duration of intermissions, asymmetry of the cycle with respect to time and sign, magnitude of the plateau and curvature of impulse front on the magnitude of mechanical losses in the material, the properties of which are described by a model with continuous relaxation time spectrum. Author
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