Ricerca CERCA

Metasurface-based Interferometers on Life Prediction on Interface Debonding of Laminated Structures under Cyclic Loading

estero Tesi all'estero


Descrizione This project aims to explore, develop, and validate a low-cycle life prediction model of debonding/delamination at the interface of two parts in laminated structures and a debonding interferometer enabling the measurement of relative displacements at micrometer level. The model is established following the stress-based fatigue life prediction of metals with the MinerˇŻs rule for crack initiation and the Paris law for crack growth. It will be applied into practice by using the equivalent number of constant-amplitude stress cycles from arbitrary loading spectra measured by debonding interferometers, using the rainflow counting method. Each interferometer consists of a lead-in optical fiber, a frequency-selective metasurface sensing element in a plane perpendicular to the optical fiber, and a cavity between them. The fiber longitudinal displacement from a metasurface is measured by the interferometer cavity length change, while the fiber transverse displacements are resolved through the identification of the spatially-distributed metasurfaces. Each metasurface and the corresponding lateral displacement can be identified by its unique resonant frequency at which the amplitude of a Fabry¨CP¨¦rot interference decreases to a minimum due to low reflectivity. Three optical fibers can be bundled together to form with the metasurface sensing element a tri-interferometer for both linear and angular displacement measurements. The proposed interferometer is calibrated with a precision three-axis stage (0.5 ¦Ěm sensitivity). The mechanism of debonding is examined with the microstructural view of failed interfaces. Both the interferometer/tri-interferometer and the dedonding life model are validated experimentally with PVC-confined reinforced concrete (RC) beams.

Conoscenze richieste English speaking

Scadenza validita proposta 26/04/2020      PROPONI LA TUA CANDIDATURA

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