Determination of vibrational properties of Shahroudiʹʹs almond stem

ABSTRACT: Iran is one of the biggest almond’s producers in the world and like the most fruits, almond harvesting is done mechanically by hand. According to the shape of the branches and also their stiffness, it is supposed that using vibration is an appropriate method to harvest almond. Therefore, this research has been performed in order to obtain the vibrational characteristics of the branches of Shahroudialmondʹs stem. Due to the various vibrational characteristics of the stem branches in different directions, experiments have been performed in three different directions and vibrational properties such as Modulus of Elasticity (E), Stiffness (K), Damping constant (C), and Mass (M) have been obtained. By using the above information, natural frequency of the branches (?n) was calculated in two models; 1-D and 2-Dmodels. In the 1-D model, the average stiffness and the average natural frequency of branches were obtained 113.4 KN/m and 19.88 Hz, respectively. In 2-D model, the average of branches stiffness were obtained 118.9 and 101.8 KN/m and the first and the second natural frequencies were obtained 18.84 and 28.80Hz, respectively. Also in the bending test according to ASTM standard with bending test machine (Instron; Model 20 Santam STM), average modulus of elasticity and bending strength of Shahroudiʹs almond stem brancheswere obtained 5406.62 MP and 82.31 MP, respectively.