Modal analysis of wind turbine blades with different test setup configurations

Abstract

Modal testing of large structures such as wind turbine blades poses several challenges. Applied test setup configuration, test specimen mounting and measurement equipment are known to affect the test results. This paper presents a comparison study of the modal tests of nominally identical 14.3 m long blades. Blade A was supported in free-free boundary conditions and tested with the Experimental Modal Analysis using accelerometers. Blade B was clamped to a concrete block and tested with Operational Modal Analysis and strain gauges. The modes and corresponding natural frequencies obtained from both test cases were compared and correlated with the numerical models of the blades.