35 Years with Structural Measurements at Brüel & Kjær

Abstract

Both Gade & Herlufsen started working for Brüel and Kjær Company, when the modern era of structural measurements began in the early 1980s. In (Brown and Allemang, Sound Vib Mag 19–25, January 2007), it is even argued that the modern era of Experimental Modal Analysis already started one or maybe two decades earlier. In 1982 we participated at IMAC I, the first international modal analysis conference at Hyatt Orlando, USA—the time considered when modal analysis changed from being a pure scientific concept to be a practical engineering tool. Many tests were at that time limited to Single Input/Single Output, SISO measurements. In 1983, we were involved in the release of Brüel and Kjær’s first Dual Channel Signal analyzer. Today Dual channel FFT analysis is the established method of performing Frequency Response Function measurements used for what we might call classical mobility based modal testing and analysis. Over the years, we have seen progress and development in all fields of the measurement chain from the input vibration transducers via the signal conditioning to the analog to digital conversion, real time- and post-processing of functions followed by modal parameter estimation and applications of the modal model. This paper will deal with what we see (and we both have been involved with from a Brüel & Kjær perspective) as some of the most important/biggest steps achieved in this progress. Today it is not unusual that modal analysis is performed using several hundreds of high dynamic range measurement channels connected to dedicated smart modal accelerometers (with build-in Transducer Electronic Data Sheets (TEDS)) doing Multiple Input Multiple Output measurements with automated modal parameters estimation and model correlation with large Finite Element models.