Research On Chinese Chestnut's Cracking Mechanism Of Flexible Rubbing And Analysis With FEA

Chinese chestnut has a high nutritional value and officinal value. The cracking of Chinese chestnut becomes a problem when output increased. Although there are some shelling equipments, shelling efficiency, full amount and capability compare price can't satisfy requirement. So research of mechanics characteristic and shelling mechanism can provide some theoretical and technical parameters.There are four parts in this paper, dryness test, mechanics characteristic test, cracking performance test and FEA analysis. Single factor and Multi-factors methods are used to research the influences of size, moisture, loading velocities and space to cracking force of Chinese chestnut in the mechanics characteristic test. Single factor and double factors methods are used to research influences of loading velocity, moisture and space to cracking rate and crushing rate in shelling performance test. On the base of the above researches, stress and strain of Chinese chestnut's shell are analyzed with ANSYS. Main conclusions as follows:1) There are few alterative Chinese chestnuts on 65℃, except for some C grade Chinese chestnut after 75min dryness time. So, the right dryness Conditions are 65~C and 75min.2) Mechanics characteristic test indicates that size, moisture and loading velocities are the factors which influence cracking force, while size and moisture are the main factors; cracking force increases when size grade increased and moisture decreased; the influence of loading velocities is small and space have no influence. The function between cracking force, size grade, moisture and loading velocity are got.3) Cracking performance test indicates that Chinese chestnut's cracking rate increases and crushing rate decreases when moisture decreased; cracking rate and crushing rate increase when loading velocity increased, but increase trend of crushing rate is bigger than cracking rate obviously when loading velocity is high than 20mm/min; cracking rate is high when space is small, and crushing rate is high when space is too big or too small; optimal space and loading velocity are 17.4mm and 20mm/min to Chinese chestnut which the range of thickness is 17.5-18.5mm and the average thickness is 18.1mm. 4) ANSYS is used to establish the model of Chinese chestnut on the base of physics parameters. Finite element model of Chinese chestnut is got after choosing element type, meshing and creating contact manager.5) The type of rubbing is loading on the direction of Z in XZ plane in this test. ANSYS is used to analyze stress and strain. The result indicates that stress and strain are mainly on the top of Chinese chestnut's bend plane, where shell cracks first.6) On the base of Chinese chestnut's model, other two loading type are analyzed. There are loading on the direction of Y in YZ plane and loading on the direction of Z in YZ plane. Comparing the results of this three loading type, the result indicates that cracking effect of loading on direction of Y and Z in YZ plane are better than the type of loading on the direction of Z in XZ plane, but the shell can all be cracked. The maximal stress and strain are on the different place of shell for the three loading types, it means that cracking place of shell is different.