Raman imaging of residual stress distribution in epoxy resin and metal interface

A method for the distribution analysis of residual stress in epoxy resins by Raman microspectroscopy was developed. By using the uniaxial tensile method, a negative correlation between the peak shift of the aromatic C─H stretching vibration and external stress was obtained. By optimizing the precision of the Raman shift measurement, a reliable stress image was obtained for a bulk epoxy resin. This method was applied to the evaluation of the residual stress distribution in epoxy resin/aluminum bonded materials. Raman spectra imaging revealed that stress concentration strongly occurred in the interface of the cured epoxy resin with aluminum, and it was found that Raman spectra images of the small residual stress of the resin interface were affected by the curing process and physical properties of the epoxy resin. Therefore, Raman spectra imaging would appear to have significant potential as a technique for the evaluation of local thermal residual stress in the interface of multimaterial structures. A method for the distribution analysis of residual stress in epoxy resins by Raman microspectroscopy was developed. By optimizing the precision of the Raman shift measurement, a reliable stress image was obtained for a bulk epoxy resin. Raman spectra imaging revealed that stress concentration strongly occurred in the interphase of the cured epoxy resin with aluminum, and it was found that the residual stress of the interphase were affected by the curing process and physical properties of the epoxy resin.