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Electrodynamic shakers or exciters are commonly used in experimental modal analysis. The practical aspects regarding the setup of the shakers, stingers and transducers are often the source of test difficulties and avoidable measurement errors. This paper reviews the basics of shakers as beneficial to modal testing, and common problems associated with setup issues and resulting measurement errors. These include shaker alignment, sensor's considerations, stinger selection, amplifiers, reciprocity assumptions and other test related circumstances.

Resonant Inspection is a non-destructive test technique that measures the structural dynamic signature of an article. By comparing the resulting footprint to expected signatures, anomalous outliers are sorted due to some inherent structural defect, improving quality and consistency of manufactured components. Brake components, such as rotors and drums, are designed with specific structural dynamic properties for desired NVH qualities. Resonant Inspection via the Resonant Acoustic Method (RAM-NDT) provides a proven economical technique with the capacity for accurate, reliable and high-throughput 100% online inspection.

Worldwide emphasis on defect-free manufacturing within the automotive sector has driven manufacturers to seek out cost effective methods of 100% inspection. To achieve zero defect output cost-effectively, manufacturers are making the commitment to move to online, automated nondestructive testing (NDT) methods. This type of online inspection requires accuracy, reliability, and high throughput. The Resonant Acoustic Method of Nondestructive Testing (RAM-NDT) is emerging as a type of resonant inspection that is a very efficient method of structural defect discrimination lending itself well to automated online implementation. This paper presents the fundamental principles of the resonant acoustic method and how it is been applied to testing nodularity in ductile iron brake calipers, rotors and anchors.