Abstract
Strain Modal Testing (SMT), based on strain sensors signal processing, is an unconventional approach to perform Experimental Modal Analysis which is typically based on data measured by accelerometers. SMT is still mainly restricted to academia and requires additional investigation for a successful transition towards industry. This paper critically reviews why the automotive sector can benefit from this relatively new approach for a variety of reasons. Moreover, a case study representative of the automotive field is analyzed and discussed. Specifically, an SMT methodology is applied to evaluate the modal properties of a reinforced composite roof belonging to a racing solar powered vehicle. In the experimental activity, signals from Fiber Bragg Grating (FBG) sensors, strain gauges, and accelerometers were simultaneously acquired and further processed. The advantages of using optical fibers were discussed, together with their weaknesses and ongoing challenges. The FBG results were compared with the conventional analysis performed with the accelerometers, emphasizing the main similarities and discrepancies.
Highlights
Nowadays, Experimental Modal Analysis (EMA) is still a fundamental tool in the design development [1]
The ultimate aim of the study is to investigate how Strain Modal Testing (SMT) compares to Displacement Modal Testing (DMT) and understand if Fiber Bragg Grating (FBG) can be conveniently embedded in automotive applications, to monitor the modal parameters and their potential variations, possibly enabling global vibration-based Structural Health Monitoring (SHM) for early fault detection
The similarity in the results suggests the consistency of the FBG coupling with the structure, which can be undermined by a not adequate strain transfer
Summary
Experimental Modal Analysis (EMA) is still a fundamental tool in the design development [1]. It permits the assessment of the numerical model accuracy, the understanding of the vibration response level under operational conditions and the determination of certain material properties when the structure is subjected to dynamic loading [2]. In DMT, modal parameters are estimated by means of the receptance matrix, namely the system Frequency Response Function (FRF) [2,3,4,5]. In the assessment of the modal parameters, the FRF is replaced by the Strain Frequency Response Function (SFRF)
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