Relationship between breaking force and structural features of weak places of vortex spun yarn

Weak places are prone to form in the vortex spinning process, owing to uneven fiber wrapping. These structural defects are known to significantly increase weaving breakage rates in subsequent weaving processes. A method is proposed to quantify the structural features of weak places and establish their relationship with breaking force. Sequential yarn images were captured before tensile failure, and images of weak places were collected by matching each failure position with the corresponding image sequence. Structural analysis of weak places reveals that weak places of vortex spun yarn exhibit characteristic features, with elongated morphology and disordered texture. Significant correlations between the breaking force and several indicators within two structural feature categories were demonstrated. For morphological features, aspect ratio showed a negative correlation. Regarding wrapping uniformity features, angular second moment showed a positive correlation, while entropy showed a negative one. Sensitivity analysis under different threshold settings supports the robustness of these relationships. This study provides an effective method for the quantification of structural features of weak places and offers a valuable reference for subsequent spinning process optimization.