Intrinsic features (eigenproperties) of the Cauchy stress tensor are discussed. Novelty notions of isotropy and skewness mode angles are introduced for the improved parametric description of spherical (isotropic) and deviatoric (anisotropic) components of stress tensor. The skewness angle is defined with pure shear employed as a comparison reference mode upon observing that pure shear states can be interpreted as elementary (atomic) blocks of any macroscopic deviatoric stress state. An original statistical-physical interpretation of the stress tensor orthogonal invariants is provided. A micromechanical explanation for observed decrease of the stress tensor anisotropy factor values, measured in terms of the tensor orbit diameter, with stress deviator diverging from pure shear mode, is proposed. Explicit reasons explaining why biaxial experimental layouts (simple shear and/or planar shear) are insufficient for the comprehensive characterization of materials properties submitted to complex stress states loadings are presented. New explicit formulas for the triaxiality factor valid for biaxial stress states are delivered.
W artykule przedstawiono metodę obliczania wartości wypadkowej siły tnącej na głowicy struga węglowego, niezbędnej do urabiania węgla. Podstawą wyznaczania tej siły są wyniki pomiarów parametrów mechanicznych węgla, wykonywanych specjalnie do tego celu zaprojektowanym przyrządem. Metoda składa się z dwóch etapów: obliczeń teoretycznych oraz określania współczynników dopasowania przybliżających wyniki tych obliczeń do wyników eksploatacji.
EN
In the article a method of calculating the resultant cutting powers on the head plane coal was presented, essential to extract coal. Results of measurements of mechanical parameters of coal made on the device especially at this target designed are a ground for appointing this power. This method consists of two stages: of theoretical calculations and determining rates of fitting theoretical calculations giving an approximation of the score to conditions of real exploitations.
Cutting as the most important component of polymer grinding process, especially for elastomers and porous materials was presented. The model investigation of porous materials quasi-cutting were performed using the punching die of movable parts different geometry.
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