Experimental Modal Analysis and Operational Deflection Shape Analysis of a Cantilever Plate in a Wind Tunnel with Finite Element Model Verification

Abstract

This work explores the response of a cantilever plate attached to a cylinder in a wind tunnel under an impact excitation. A detailed computer-aided design (CAD) model and the finite element analysis (FEA) modal simulation of the experimental setup are introduced. Two experimental techniques are thoroughly discussed: an accelerometer-based experimental modal analysis (EMA) method, and a non-contact, full-field, high-speed digital image correlation (DIC)-based operational deflection shape (ODS) analysis method. The experimental and FEA results of the first seven natural frequencies, mode shapes, and ODSs of the cantilever plate are presented and compared. The percent differences between the EMA and FEA natural frequency results are less than 4.8%, and the modal assurance criterion (MAC) values between the EMA and FEA mode shapes are at least 0.845. The percent differences between the ODS analysis and FEA natural frequency results are less than 3.4%, while the MAC values between the ODS analysis ODSs and FEA mode shapes are at least 0.728. The percent differences between the EMA and ODS analysis natural frequency results are less than 3.5%, and the MAC values between the EMA mode shapes and ODS analysis ODSs are at least 0.505. There are two sets of two different mode shapes and ODSs with relatively high correlation. One set is a set of two closely spaced modes and ODSs approximately 20 Hz apart with obvious similarities in shape. The other set is a set of two modes and ODSs approximately 100 Hz apart that share less obvious similarities in shape.