The Acoustic Emission Characteristic Of Coated Sheet Metal Deformation

The Acoustic Emission (AE) technique has become one kind of important non-destructive inspection and evaluation method, because the AE technique has many advantages such as non-destructive, real-time, on-scene, simple equipment and so on. Nickel plated steel sheet is one kind of high performance battery material. In its production, nickel coating may dehiscence in the processing and use process. It is very important to test this expiration behavior. AE technique is an effective method to solve this problem.This article first synthetically introduces the elaboration nickel plated steel sheet, AE technique and the AE technique for coated sheet metal. Then the AE characteristic of nickel plated steel sheet was studied. The main contents and the results are as follows:(1) The AE characteristic from tensile deformation of nickel plated steel sheet was studied. The testing plan was designed for tensile testing and acoustic emission monitoring. An RG2000 universal testing machine was used to perform the tensile test. The PAC-â…¡AE inspection was used to gathering AE transmitting signal. The results showed that the change of AE parameters and the damage evolutionary process of nickel plated steel sheet test specimen was consistent. The AE signal obviously increases when the plastic deformation of nickel plated steel sheet test specimen occurs. The neck stage AE signal peak-to-peak value to distribute mostly in 43-79 dB scopes. The nickel plating steel belt AE signal's frequency centroid probably distributes in 150 KHz either 230 KHz or 270 KHz.(2) The AE characteristic of indentation process for nickel plated steel sheet was studied. The indentation experiments were conducted the HVS?30 type hardness measurement system. The results show that there is a relationship between the AE parameter and the indentation diagonal line length. The noise of AE signal may carry on the effective filtration through the wavelet distortion. From the five level of wavelet decomposition, the substrate sound transmitting message frequency mainly concentrates in 128?256 KHz. However, nickel plated steel sheet frequency mainly to concentrate in 128?256 KHz and 256?512 KHz.(3) The application of the Fourier transform in the AE signal of nickel plated steel sheets deformation was studied. One fast processing AE signal STFT method and frequency centroid was designed based on the LabVIEW. The frequency resolution of the STFT program was higher than that of AE signal. The AE signal frequency centroid can supply more frequency information than the AEwin frequency spectrum transformation.In this article, the AE characteristic from coated sheet metal deformation and the indentation can be obtained. The results have some values to AE examination of the metal coated steel.