Predicted curvature of a glass fiber from the measured curvature of its coating

An analytical stress model is developed to evaluate the elastic curve of a glass fiber whose coating has a constant (measured or imposed) bend radius. It is shown that in order to predict the bending behavior of a coated glass fiber subjected to bending a parameter u should be computed which depends, in addition to Young´s modulus and diameter of the glass fiber itself, also on the length of the curved area and Young´s modulus and outer diameter of the (primary) coating. In the range 0<u<2.365, the maximum curvature of the glass fiber occurs at the midpoint of the curved area. If the calculated u value is greater than (7π/4)=5.50, the curvature of the glass fiber in the midportion of the glass-coating composite is practically not different from the coating curvature. Within the range 2.365<u<5.50, the maximum curvature of the glass fiber is greater than the observed curvature of the coating