Equivalent initial flaw size model for fracture strength prediction of optical fibers with indentation flaws

This work presents an equivalent initial flaw size (EIFS) model for indentation flaws to quantify the fracture strength of optical fibers. Three geometry parameters of the indentation flaws, namely, the total projection length, the average crack length and the total flaw depth are used to establish the EIFS model. Indentation flaws of different dimensions are made using a Berkovich indenter by adjusting the load force. A stereo microscopic imaging system is employed to acquire the geometry parameters of the indentation flaws. Tensile testing is then performed using 16 commercial optical fiber specimens. A groove fixture is employed to ensure the reliability of data acquisition. The experimental data are used for model development and performance validation. Furthermore, the proposed model is compared with existing models to demonstrate the effectiveness of the method. The proposed EIFS model gives more accurate prediction of fracture strength in current investigation.