Instantaneous Stiffness
Calculation of stiffness in a linen yarn during high speed mechanical loading identifies the material’s ability to resist deformation during weaving. Dynamic elastic modulus quantifies the ratio of stress to strain under rapid tensioning cycles common in modern air-jet or rapier looms. This value differs from the static modulus because natural fibres exhibit time dependent behavior when loaded at different velocities.
Understanding this property helps spinners produce yarns that maintain their shape under the sudden tug of the picking motion.
Pulse Measurement
Sonic velocity testing provides the most accurate method for determining the modulus without reaching the point of structural failure. A pulse travels through the yarn at a speed determined by the density and the internal tension of the flax strands. By measuring this velocity, laboratory technicians calculate the dynamic elastic modulus using the square of the speed multiplied by the linear density.
Higher values indicate a more rigid yarn that will produce a crisp fabric handle. Low values might suggest excessive moisture or fibre damage during the bleaching process.
Performance Limit
Modulus values remain valid only within the elastic region of the material. Once the yarn reaches its plastic deformation point, the calculation no longer applies.
