Prediction of long-term creep behavior of blade by time-stress superposition principle(TSSP) modeling

Abstract

Rotor blades are vulnerable portion of wind turbine. Researches have shown the delamination of composite due to fatigue and creep lead to failure of wind turbine rotor1. Besides, According to the DNV GL standard related to design the wind turbine, creep failure mode at a T-bolt in the root joint is one of the failure mechanism that may occur in wind turbine blades2. Even if the creep fracture does not occur, slow creep deformation lead to decrease the effective performance of the structure in the long time. Therefore, the investigation of long-term creep behavior of the FRP composites is an important subject to design the wind turbine blades. Long-term creep tests are impractical3 and need high cost. Therefore researchers prefer to use the modeling methods. Time-stress superposition principle (TSSP) is the main model that was used to predict long term creep behavior of linear viscoelastic polymers4.