Physical Properties of Human Hair: Evaluation of Bending Stress by Measuring the Major and Minor Axis of Human Hair
TLDR The cuticle significantly contributes to hair stiffness, making up about 60% of the total bending stress.
The study evaluated the bending stress of human hair by measuring its major and minor axes and assessing its stiffness using Young's modulus. A laser-based device was developed to measure hair diameter accurately. The hair was modeled as a two-layer structure consisting of the cuticle and cortex, each with different Young's moduli. The cuticle was found to be approximately 4 times stiffer than the cortex. The contribution of the cuticle to the overall bending stress was significant, accounting for about 60% of the total, indicating its crucial role in hair stiffness.
