Simulation and measurement of in-plane vibrations of an ultra lightweight membrane using a newly designed 6DOF laser scanning head performing conical scan measurements

This paper presents a novel measurement technique for measuring in-plane vibrations of a clamped circular ultra lightweight membrane. This work is divided in two parts a (i) modelling and an (ii) experimental part. The modelling part focuses both on construction of an FE model of an ultra-thin membrane and the simulation of an LDV output time signal using conical spiral scan method. The experimental part focuses on the design and manufacturing of a mechanism for performing spiral conical scan and, eventually, concludes with in-plane measurements of the membrane using a Scanning LDV and 6DOF Scanning LDV measurement methods. This experimental work follows the development of a novel laser scanning head which was designed for measuring up to 6 degrees of freedom using continuous scanning measurement methods. For this specific test case a spiral conical scan method had to be developed. Test results are presented and discussed here. keywords: in-plane vibrations, Scanning 6DOF LDV system, continuous laser Doppler vibrometry, modal testing.