METHOD FOR COMPLEX EVALUATION OF MECHANICAL PARAMETERS OF BENDING AND SHEAR STIFFNESS WHEN TESTING FIBRES FOR BENDING Russian patent published in 2024 - IPC G01N33/36 G01N19/00 

FIELD: textile materials science.

SUBSTANCE: invention relates namely to methods for monitoring quality parameters of fibre or bast of bast crops. It can be used for their qualimetry and standardization. In a method for testing fibres for bending, including sample preparation, its three-point deflection under different test conditions and evaluation of mechanical characteristics, testing a fibre sample of constant mass and length with its width unchanged is carried out in two stages with constant contact of the sample with a bending element in the centre between the supports. At each stage, the deflection is carried out by the same amount, and at the first stage the distance between the centres of the supports is greater than at the second. At the end of the sample deflection at each stage, at the point of contact of the sample with the deflection element, the generated forces are determined accordingly. For each stage, the change in sample thickness at the points of contact with the supports and the bending element is calculated depending on the force, colour of the fibre and its type. The deflection value of the neutral axis of the sample is calculated, and the conditional modulus of longitudinal elasticity in tension is determined using the formula. To estimate the mechanical characteristics of the bending and shear stiffness of bast fibres, the longitudinal elasticity and shear moduli are used, which are determined based on solving a system of equations.

EFFECT: increasing the information content of the analysis by assessing the complex mechanical parameter characterizing the bending and shear stiffness of the analysed bast fibre, as well as reducing the duration of the analysis.

1 cl, 2 dwg