Damage development in pultruded composites for optical telecommunications cables under tensile and flexural fatigue

This paper investigates the long-term behaviour of pultruded glass-fibre composites, which are used as load-bearing components in optical telecommunications cables. Both flexural and tensile fatigue tests were conducted using the materials in their commercial product forms. Fatigue damage progression was monitored on-line by the acoustic emission technique. Damage accumulation was quantified by the stiffness loss evaluated from the change of resonance frequency in a free vibration test. The resonance measurement is able to determine modulus degradation to an accuracy of 0.01%. A definition of fatigue failure under tensile and flexural fatigue is proposed. Fatigue damage development is discussed and is found to be dependent on stress level and stress history. (C) 2003 Elsevier Ltd. All rights reserved.