Dynamic Hysteresis Loops in High Speed Flax Shedding and Moisture Adjusted Invoice Settlements
Dynamic flax shedding causes thermal moisture desorption, requiring invoice adjustments based on ISO 6741 oven-dry mass plus standard regain.
Yarn Viscoelastic Dissipation
Energy Absorption
Energy losses within a material during cyclic loading occur when the work done during deformation is not fully recovered upon unloading. In the processing of linen, yarn viscoelastic dissipation refers to the conversion of mechanical energy into heat due to the internal friction of the flax fibers.
Thermal Effect
Repeated stretching of the yarn on the loom leads to an accumulation of heat within the fiber bundles. If the yarn viscoelastic dissipation is high, the temperature rise can alter the effectiveness of the sizing agents. This change in the surface coating can lead to increased lint shedding and yarn degradation.
Laboratory tests measure this dissipation by recording the area of the hysteresis loop in a stress and strain diagram.
Mechanical Consequence
Control of this energy loss is achieved by maintaining optimal humidity levels in the weaving shed to facilitate heat removal. While yarn viscoelastic dissipation provides some damping against sudden tension shocks, excessive loss indicates a potential for premature fiber fatigue. This behavior is documented during the yarn qualification phase to ensure the material can withstand the intended mechanical environment.
The final data assists in determining the maximum safe operating speed for the spinning or weaving line, allowing the mill to maximize throughput without compromising the structural integrity of the linen thread.