Date of Award
Summer 8-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department/Program
Forensic Science
Language
English
First Advisor or Mentor
Peter Diaczuk
Second Reader
Jack Hietpas
Third Advisor
Andrew Winter
Abstract
Rapid shear is a process that occurs in thermoplastic materials when they interact with a high-velocity impact. In forensics, these interactions would typically be from a bullet interacting with clothing that consisted of synthetic fibers. When the interaction occurs, bulb-like shapes appear on damaged fiber ends, distinguishing them from other kinds of damage. The reason why these shapes occur is varied, but one prevailing factor seems to be the heat generated by the impact.
In prior experiments, the factor of temperature being important to the formation of the phenomenon, different environmental simulations that affected the sample’s temperature were done on nylon, and determined that bulb-like ends formed on each sample. In this experiment, a sample made of a polyester-cotton blend was used, undergoing similar environmental factors with low-velocity projectiles from an air rifle. The sample underwent a control set, two wet sets with different ratios, and a chilled set. Once each set was shot, analysis of the damaged area was done using stereomicroscopy and polarized light microscopy. The fiber’s damaged ends showed that each sample contained bulbed ends in most of the polyester and none in cotton. The absence in polyester fiber can be due to factors such as the velocity of the projectile and even the environmental factors affecting the formation, or both. Quantitative analysis could help further understand the cause of the decreased frequency of the phenomenon appearing, as well as further study of the lower limits at which rapid shear can produce the distinct fiber ends.
Recommended Citation
Oh, Daniel K., "Further Investigation of Environmental Factors on Rapid Shear in Fibers of a Polyester-Cotton Blend" (2025). CUNY Academic Works.
https://academicworks.cuny.edu/jj_etds/365
