Experimental Study On Fiber Micromechanics

Raman scattering was found by Indian scientist C.V. Raman on the study of light scattering in1928. Raman scattering technique has been widely applied to many fields after a long period of development, including physics, biology, chemistry, materials science. It is mainly used to detect composition, microstructure and defects. In the early1970s, it has been found that Raman peaks are sensitive to mechanical parameters which based on the principle that Raman scattering spectrum can reflect vibration mode of interaction between light and materials, and Raman spectroscopy is used to measure mechanical quantity in recent years, it has been applied on the studies of low-dimensional materials and micro-structure. With the improved spatial resolution and precision, as well as expansion of test object, it relies on the rapid development of related technologies, such as confocal microscopy, Fourier transform Raman spectroscopy, high-quality charge-coupled device (CCD) and electrical control platform.In front part of this paper, based on axial strain measurement method of Kevlar49single fiber which widely used in body armor, a Raman measurement principle of multi-fiber strains in a fiber bundle is established on micro-Raman spectroscopy. The proposed principle for multi-fiber strains measurement shows a consistency with two special cases:single fiber deformation and multi-fiber deformation with same strain. The correctness of multi-fiber strains measurement method is verified using micro-Raman experiments of a double-fiber specimen. And the experiment is performed to verify the feasibility of Raman technique for the multi-fiber strains measurement. Some improved aspects in this part are pointed out.Hair is a natural polymer fiber with complex structure, as one of first fiber reinforced composite materials used in structural engineering. The latter part of this paper focusing on the droplet debonding test, the interface strength, the failure mode and the friction mechanism of human hair were studied as fiber pulled along the growing direction and inverse growing direction, respectively.