Elastic and pseudoviscous properties of coal under quasi-static and impact loadings

An investigation of the elastic and viscoelastic properties of Nova Scotia coal was carried out over a wide range of strain rates (quasi-static to impact). High resolution stress–strain diagrams for the coal were obtained from compression tests for the lower and medium strain rates up to [Formula: see text] and with the split Hopkinson bar technique for the high strain rate region up to [Formula: see text].The elastic properties of the coal showed a moderate rate sensitivity at low and moderate strain rates.Above the strain rate [Formula: see text] both Young's modulus and the stress level of microcracking initiation σ f0 isplayed extreme rate sensitivity and was found to be a linear function of strain rate. The associated coefficient of viscosity perpendicular to the bedding plane was η* = 3.08 × 10 4  Pa∙s.The viscoelastic model so determined can be used to assess the elastic properties of coal at even higher strain rates, a situation that is similar to an explosive loading. Keywords: coal, strain rates, dynamic, viscoelastic properties.