Method and apparatus for detecting defects and different-hardness portions of an object with protrusions

摘要: A test object having a plurality of protrusions is inspected for defect and/or different-hardness by applying vibration to the object. Spectral data analyzed based on signals indicative protrusions. energy peaks are then detected in different spectral frequency regions corresponding respectively signals. It determined whether there two separate region each protrusions, thereby determining portion