Mechanical Properties of Switchgrass and Miscanthus

Abstract. The mechanical properties of energy crops in the longitudinal and transverse directions are necessary for modeling and simulation of biomass stems. Modeling of biomass stems would help in analyzing the interactions between processing equipment and biomass material before building physical systems. While some of the mechanical properties of switchgrass and miscanthus stems are available in the literature, these properties are not complete for modeling and simulation of these materials. Therefore, the objective of this research was to determine the mechanical properties of switchgrass and miscanthus stems by using compressive, tensile, and shearing tests in the longitudinal and transverse directions. Tensile, compressive, and shear strengths and modulus of elasticity of switchgrass and miscanthus tended to decrease with decreasing stem diameter in both the longitudinal and transverse directions. Tensile and compressive strengths of the first internode of switchgrass were 178.0 and 27.3 MPa in the longitudinal direction and 0.7 and 4.1 MPa in the transverse direction. Shear strength for the first internode of switchgrass was 2.2 and 21.1 MPa in the longitudinal and transverse directions. Tensile and compressive strengths of the first internode of miscanthus were 373.1 and 56.9 MPa in the longitudinal direction and 1.8 and 6.3 MPa in the transverse direction. Shear strength for the first internode of miscanthus was 94.4 and 8.7 MPa in the transverse and longitudinal directions. The experimental data collected in this research would be useful for the development of simulation models for investigating the interactions between shearing tools and energy crops and in designing harvest and particle reduction equipment. Further research would be useful for determining the effects of moisture content, growth conditions, and maturity stage on the mechanical properties of these crops. Keywords: Biofuel, Compressive strength, Miscanthus, Shear strength, Switchgrass, Tensile strength.