Fatigue Trends for Wind Blade Infusion Resins and Fabrics

Abstract

This paper presents recently expanded test data for resin infused glass fiber laminates of interest for wind turbine blades. The new static and fatigue data extend and clarify trends reported in References 3-7 for the relative performance of epoxy, vinyl ester and polyester resins, and various unidirectional (UD) and biaxial (±45) fabrics, and multidirectional (MD) combinations, in standard laminate tests. Significant resin, fabric and process interactions are identified and explored. A second part of the study involves characterizing the performance of the various fabrics and resins in the context of a recently developed complex structured coupon geometry including ply drops. This coupon provides a simplified approach to exploring the relative performance of blade materials in the context of the complex structural details typical of infused blades. This testing approach highlights the significance of resin toughness differences in a representation which can conveniently be applied to blade design as strain knockdown factors.

Hygrothermal aging effects on fatigue of glass fiber/polydicyclopentadiene composites

“…Polydicyclopentadiene (pDCPD) is a potential matrix material for wind turbine blades, offshore oil structures, and automotive parts because of the inherent hydrophobicity and the resistance to chemical corrosion [22e25]. Although the fatigue behavior of preaged pDCPD composites has been reported [26,27], the effect of hygrothermal aging on the fatigue behavior has not been systematically investigated. In this study, we report the effects of aging in deionized water and salt water environments on the tensionetension fatigue behavior of UD glass/pDCPD laminates.…”

Assessment of the mechanical behaviour of glass fibre composites with a tough polydicyclopentadiene (PDCPD) matrix

“…The GIC initiation value found for the composite with the PDCPD formulation used in the present study (1065 J/m², see table 2), is considerably lower, but still in the range typically observed for composites with highly toughened epoxies or highperformance thermoplastics as illustrated in Table 2. The tensile fatigue performance observed in [20][21][22] was similar to that of the epoxy resin composites, while a slightly improved compressive fatigue resistance was observed for the PDCPD laminates. Tests on a complex structured coupon with two ply drops revealed an increase of about 30 % in the static load required to produce large-scale delamination in the PDCPD composite, as well as higher reversed loading fatigue cycles to obtain the same damage length in the complex coupon [22].…”

“…In the framework of the SNL/MSU/DOE project on wind turbine blade materials, however, an extensive experimental program including also some tests on this type of materials has been carried out [20][21][22]. These researchers compared the mechanical properties of PDCPD-glass laminates to that of epoxy-glass counterparts.…”

Creep/Fatigue Behavior of Resin Infused Biaxial Glass Fabric Laminates

“…S-N fatigue lifetime to total failure (defined later) has been characterized for tension-tension, compression-compression, and reversed loading fatigue (R = 0.1, 10 and -1, respectively, where R = min load/max load 1,2 ). Then, concentrating on one typical fabric, a more detailed study of strain accumulation, cyclic stress-strain and residual stress-strain response, stiffness change and creep has been carried out for each R-value.…”