Delamination Fracture Behavior of Unidirectional Carbon Reinforced Composites Applied to Wind Turbine Blades

Abstract

One of the materials that is used widely for wind turbine blade manufacturing are fiber-reinforced composites. Although glass fiber reinforcement is the most used in wind turbine blades, the use of carbon fiber allows larger blades to be manufactured due to their better mechanical characteristics. Some turbine manufacturers are using carbon fiber in the most critical parts of the blade design. The larger rotors are exposed to complex loading conditions in service. One of the most relevant structures on a wind turbine blade is the spar cap. It is usually manufactured by means of unidirectional laminates, and one of its major failures is the delamination. The determination of material features that influence delamination initiation and advance by appropriate testing is a fundamental topic for the study of composite delamination. The fracture behavior is studied across coupons of carbon fiber reinforcement epoxy laminates. Fifteen different test conditions have been analyzed. Fracture surfaces for different mode ratios have been explored using optical microscope and scanning electron microscope. Experimental results shown in the paper for critical fracture parameters agree with the theoretically expected values. Therefore, this experimental procedure is suitable for wind turbine blade material characterizing at the initial coupon-scale research level.

A Numerical Method for the Dynamics Analysis of Blade Fracture Faults in Wind Turbines Using Geometrically Exact Beam Theory and Its Validation

“…The results show stress concentration in the bonded joint, with shear stress identified as the primary factor leading to debonding. Focusing on the issue of delamination failure in wind turbine blade wing girder rim strips, Boyano et al [8] used a mixed-mode test setup involving an end-notched flexure test with roller (ENFR) test method to measure and analyze the fracture behavior of carbon fiber-reinforced epoxy laminate specimens. The experimental data aligned with the theoretical values, thus illustrating the validity of the method in composite fracture testing.…”

Analysis of forced vibration of wind turbine blade laminated composites under delamination defects

“…The measured laminate buckling eigenvalues were negatively correlated with the delamination area and positively correlated with the delamination height under the edge-to-edge loading. Boyano et al [9] built a dedicated test rig to simulate the bending loads to which the composites are subjected. Fracture experiments were performed on unidirectional carbon fiber reinforced composite laminates, and the fracture surfaces were observed and studied using optical microscopy and scanning electron microscopy.…”

Simulation of Glass Fiber Reinforced Polypropylene Nanocomposites for Small Wind Turbine Blades

“…In each case, however, there are certain properties to be considered. Glass fibers (GFs), carbon fibers (CFs), and aramid fibers (AFs) are the most widely used in the production of wind turbine blades [14][15][16][17][18][19]. Other examples are nylon, polyester (PE), polytetrafluoroethylene (PTFE), jute, flax, and steel fibers, which are used for specific purposes [4].…”