A model-based ultrasonic quantitative evaluation method for bonding quality of multi-layered material

Reflection coefficients play an important role in the quantitative evaluation of the bonding quality of the interfaces of the multi-layered composite material. This paper proposes a reflection coefficient-based echo signal model and a new Gaussian model based blind deconvolution method for extracting reflection coefficients of bonding interface. The traditional deconvolution problem can be converted into a parameters estimation process in this model. Moreover, in order to avoid the potential computational burden caused by multiple parameters estimation and the much dependence on the initial parameter values during the estimation process, empirical mode decomposition (EMD) method and an improved Genetic Algorithm are used for parameters estimation. Simulation experiment verified the reliability of this method at different signal-to-noise ratio and with different initial parameter values, and then, reflection coefficients reconstruction of a metal multi-layered composite material specimen is performed through measurement experiment and the result is satisfying. Both the simulation and measurement experiments proved the feasibility and validity of this method.

► A mathematic model developed for reconstruction of reflection coefficients.
► A new Gaussian model based blind deconvolution method is proposed.
► EMD method is adopted in order to avoid the potential computational burden.
► An improved Genetic Algorithm is employed in parameters estimation.