ASTM E3397-23 pdf free download – Standard Practice For Resonance Testing Using The Impulse Excitation Method.
This standard outlines a general procedure for utilizing the Impulse Excitation Method (IEM) to measure natural frequencies and identify defects as well as material variations in both metallic and non-metallic components. This testing technique is also referred to by various names, including Impulse Excitation Technique (IET), Acoustic Resonance Testing (ART), ping testing, and tap testing. IEM is categorized under Resonance Ultrasound Spectroscopy (RUS) methods. The approach involves applying an impulse load to a component, which excites it and allows for the recording of its resonance frequencies. These frequencies are then compared against a reference dataset or within specific subgroups of similar components, as well as modeled frequencies.
Variations in absolute frequency, resonance damping, and resonance patterns can be utilized to differentiate between acceptable components and those exhibiting material inconsistencies or defects. Such defects may include cracks, voids, porosity, variations in material elastic properties, and residual stress. IEM is applicable to components produced through various manufacturing processes, including, but not limited to, powdered metal sintering, casting, forging, machining, composite layup, and additive manufacturing (AM).
This practice is designed for use with instruments that can excite, measure, record, and analyze multiple mechanical vibration resonance frequencies across acoustic or ultrasonic frequency ranges, or both. While this standard does not set specific acceptance criteria for inspections, it does address the procedures for establishing such criteria related to impulse testing. These criteria encompass acceptable frequency ranges for absolute frequency shifts, scoring systems for statistical analysis methods (such as Z-scores), Gage Repeatability & Reproducibility (R&R) assessments for diagnostic resonance modes, and adjustments to inspection criteria to account for variations in manufacturing processes and environmental conditions.
