Consistency evaluation of multilayer metal sheet based on electromagnetic acoustic resonance

With the increasing demand for lightweight electrical equipment, the application scenarios and requirements for metal composite specimens are also expanding. For the consistence of multilayer metal specimens, traditional acoustic detection methods struggle to achieve accurate and rapid online monitoring. A detection method based on electromagnetic acoustic resonance technology is proposed in this paper. A theoretical model is established to calculate the resonance frequencies of a three-layer composite specimen. To measure the detection ability of different-order resonance frequencies for the bonding layer, the concept of resonance frequency shift ratio is proposed in this paper. The resonance frequency shift ratios for changes in bonding layer material parameters at different positions are obtained, and the relationship between the resonance frequency shift ratio and the wave structure is established. Then, ultrasonic resonance detection is performed on a copper-aluminum composite specimen with a thickness of 0.25 mm. Combining theoretical analysis and experimental results, the effects of bonding layer thickness, bonding layer position, and material parameters on resonance frequencies are analyzed.