A new high-performance polyurethane adhesive can prevent crack propagation on wind blades and deliver excellent long-term structural integrity on turbine assemblies. Reportedly the first Germanischer Lloyd (GL)-approved polyurethane adhesive, Macroplast® UK 1340(TM) can cure rapidly at room temperature, reduce production costs, and shorten production cycles by 15-30%. GL requirements primarily relate to an adhesive’s tensile shear strength, resistance to aging, creep behavior and glass transition (Tg) temperature.

The adhesive has reportedly demonstrated a tensile shear strength exceeding 20 MPa at -40 to +80°C and a Tg of 65°C and higher. In addition, it has reportedly shown superior dynamic fatigue strength, which allows wind blades to handle deflection, dynamic load and stress on the adhesive bond line while reducing the risk of stress cracking.

The adhesive passed a four month test conducted by the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in which a 40-m ENERCON blade was subjected for four months to stresses and strains that would normally occur over 20 years. The bonded joints reportedly passed all static and dynamic load tests specified in the IEC 61400-23 standard to determine the rated load and fatigue behavior of the blade. The test criteria specified for approval of wind energy plants were met without any problems, and ENERCON’s specifications were reportedly also satisfied in this test.

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