Tearing of knicker fabrics

Area of Science:

• Textile Science
• Forensic Science

Background:

• Sexual assault investigations may rely on physical evidence from damaged apparel.
• Knickers are frequently examined for tears as potential evidence.

Purpose of the Study:

• To characterize the tear behavior of knit fabrics commonly used in knickers.
• To assess the influence of laundering on fabric tear properties.
• To determine if fabric tear patterns are distinctive forensic indicators.

Main Methods:

• Tensile testing using an Instron universal testing machine (Model 4464) to measure fabric tear resistance.
• Evaluation of three knit fabric types: cotton, cotton-rich, and modal-rich with elastane.
• Comparison of tear behavior in new versus laundered fabric specimens.
• Examination of torn fiber ends using Field Emission Scanning Electron Microscopy (FESEM).

Main Results:

• Cotton and cotton-rich fabrics exhibited greater tear resistance than modal-rich fabrics.
• The addition of elastane increased tear initiation time due to fabric extensibility.
• Laundered fabrics required less force to tear compared to new fabrics.
• Torn fiber end morphology under FESEM was not uniquely indicative of tearing damage.

Conclusions:

• Fabric type (cotton vs. modal) and fiber content (elastane) significantly affect tear behavior.
• Laundering reduces the force required to tear fabrics, impacting evidence interpretation.
• Microscopic analysis of torn fiber ends did not provide definitive evidence of tearing damage distinct from other causes.