Evaluation of Mechanical Parameters of Pellets

Abstract

The paper dealt with the evaluation of mechanical properties of the cylinder wheat straw, rapeseed straw and 50/50 % mixed wheat and rapeseed straw pellet samples. The pellets were made by the granulating machine MGL 200 (Kovonovak). The compressive loading curves of dependencies of stress on strain were realised by the test stand Andilog Stentor 1000 (Andilog Technologies, Vitrolles, France). Certain mechanical parameters were determined, namely the initial force (force at 10 % of compress strain), force in maximum of loading curve, strain in maximum of loading curve, initial stress (stress at 10 % of compression strain), stress in maximum of loading curve and modulus of elasticity. Mean value of the initial force was maximal for mixed straw pellet samples 52.49 N. Mean values of the initial force of the wheat straw samples and the rapeseed straw samples were smaller and almost identical 43.58 N and 43.12 N. Mean values of the initial stress of loading curve, of the wheat straw samples reached 1.46 MPa, the rapeseed straw samples reached value 1.40 MPa and the mixed straw samples reached value 1.63 MPa. Mean value of the force in maximum of loading curve was also maximal for mixed straw pellet samples 213.26 N. Mean values of the force in maximum of loading curve of the wheat straw samples reached 178.11 N. The rapeseed straw samples reached value 95.95 N and the mixed straw samples reached value 213.26 N. Mean values of the stress in maximum of loading curve, of the wheat straw samples reached 5.93 MPa, the rapeseed straw samples reached value 3.11 MPa and the mixed straw samples reached value 7.10 MPa Mean values of the modulus of elasticity, of the wheat straw samples reached 18.27 MPa, the rapeseed straw samples reached value 13.08 MPa and the mixed straw samples reached value 14.97 MPa. Significant correlations of the mechanical parameters pellet samples were observed among initial force and initial stress and modulus of elasticity. Significant correlations of force in maximum with stress and strain in the maximum were observed.