Variability of simulants used in recreating stab events.

Area of Science:

• Forensic Science
• Materials Science
• Biomechanics

Background:

• Forensic investigators use fabric and simulant materials to recreate stab damage for evidence analysis.
• Previous research has not systematically compared simulant types for their effect on stab severance morphology and variability.

Purpose of the Study:

• To investigate the influence of simulant type and knife blade geometry on stab severance morphology.
• To assess the variability of different simulants in forensic stab event reconstruction.

Main Methods:

• Three simulants (pork, gelatine, expanded polystyrene) and two knife types (carving, bread) were tested.
• A laboratory impact apparatus generated consistent impact velocities for stab simulations.
• Severance morphology, force-time, and energy-time data were analyzed for apparel fabric (single jersey) and a skin simulant (Tuftane).

Main Results:

• Both simulant and knife type significantly impacted critical forensic measurements, including severance length in fabric and skin simulants.
• Expanded polystyrene (EPS) exhibited the lowest data variability among the tested simulants.
• Severances in fabric and Tuftane using EPS more accurately reflected the dimensions of the impacting knife blades.

Conclusions:

• Simulant material choice critically influences the accuracy and reliability of forensic stab analysis.
• Expanded polystyrene (EPS) is a promising simulant for stab event reconstruction due to its low variability and accurate representation of knife dimensions.
• Findings provide crucial data for selecting appropriate simulants in forensic investigations.