Composite News

Determination of shear properties by use of a picture frame approved by DNVGL

The safety and reliability of wind turbines is of the highest priority. To ensure this, DNVGL has developed and published guidelines for the approval of wind turbines that have international significance. As a classification society in the fields of technical consulting, engineering services, certifications and risk management, DNVGL is recognised worldwide.

In December 2015, the newly revised DNVGL standard “Rotor Blades for Wind Turbines” (DNVGL-ST-0376) was published, in which the shear test method using shear frames according to DIN SPEC 4885 is now approved as a test method. This is an important milestone for the shear test method using shear frames and represents progress in the material testing of wind turbine rotor blades. For example, significantly higher material parameters can be achieved with the DIN SPEC 4885 method, as the maximum shear strains are not limited to < 5 % due to the method. This can be of enormous importance for materials that have already been approved and must continue to reliably achieve defined minimum characteristic values.

The innovative shear test method using shear frames is increasingly establishing itself as a reference method, as it offers some significant advantages over existing methods (for example DIN EN ISO 14129 or ASTM D7078). Now the method is not only technically very well suited for use in the wind energy sector, but has also been officially approved by DNVGL with its publication in the new standard for the design of rotor blades.

The test method is standardised as DIN SPEC 4885:2014 and is available free of charge from Beuth-Verlag.