Bending stress, modulus of elasticity, shearing stress and specific shearing energy were determined for
sunflower( Heliantus annus L.) stalk. The bending forces were measured by a cantilever test in the field at
different moisture contents and the bending stress and the modulus of elasticity were calculated from these
data. For measuring the shearing forces, the stalk specimens were severed by using a computer aided cutting
apparatus. The specific shearing energy was calculated by using the area under the shearing force versus
displacement curve. The bending tests were conducted at four different moisture contents. The bending stress
decreased as the moisture content increased. The average bending stress value varied between 3777 and
6209 MPa. The modulus of elasticity in bending also decreased as the moisture content and diameter of stalks
increased. The average modulus of elasticity varied between 125128 and 221089MPa. The shearing stress and
the specific shearing energy were also determined at five moisture contents according to the stalk regions. The
results showed that the shearing stress and the specific shearing energy increased as the moisture content
increased. The maximum shearing stress and specific shearing energy were 107MPa and 1008 mJmm2,
respectively. Both the shearing stress and the specific shearing energy were found to be higher in the lower
region of the stalk due to structural heterogeneity.