Influence of moisture content, rate of loading and height regions on tensile strength of alfalfa stems

The objective of this study was to determine tensile strength of alfalfa stems as a function of moisture content, rate of loading and height region. Information on the physical and mechanical properties of alfalfa stem is important for the design of machines such as mowers, balers and choppers. The experiments were conducted at four moisture levels of 10, 20, 40, and 80% w.b., and three rates of loading of 5, 10 and 20 mm min-1. Each alfalfa stem was divided equally into three height regions, as upper, middle and lower. The tensile strength increased exponentially with decrease in the moisture content and towards the lower regions. The values of the tensile strength were within 9.24-26.35, 16.31-32.74, and 28.88-43.82MPa for the upper, middle and lower regions, respectively, at the different moisture contents studied and 10 mm min-1 rate of loading. The tensile strength increased linearly with increases in the rate of loading for all the regions. Its values varied between 9.24-12.27, 16.31-20.46, and 28.80-32.75 MPa for the upper, middle and lower regions, respectively, with increases in the rate of loading from 5 to 20 mm min-1, at the moisture content of 80% w.b.