The Resonance Acoustic Method (RAM) is a long-standing nondestructive test (NDT) that measures the structural responses of a part. These responses are a set of unique and measurable natural frequency (resonance) data. This data is known as the fingerprint of the component, derived from a part’s unique material properties and geometry. RAM is an NDT technique that collects and measures all the structural characteristics of a part in a single and rapid test.
RAM is a volumetric approach and evaluates the whole part, both for internal and external structural flaws, metallurgical deviations, and consistency. Governed by ASTM E2001, the method is also known as resonant ultrasound spectroscopy (RUS). The results are objective and quantitative and provide either: 1) test results of parts against a control set of known parts to screen for processing differences and/or defects, 2) measuring a population’s statistical variation and assessing individual part positions in relation to said variation, or 3) to verify a part’s actual natural frequencies to compare to or validate a 3D model or digital twin.