1、Designation: E2001 08E2001 13Standard Guide forResonant Ultrasound Spectroscopy for Defect Detection inBoth Metallic and Non-metallic Parts1This standard is issued under the fixed designation E2001; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This guide describes a procedure for detecting defects in metallic and non-metallic
3、 parts using the resonant ultrasoundspectroscopy method. The procedure is intended for use with instruments capable of exciting and recording whole body resonantstates within parts which exhibit acoustical or ultrasonic ringing. It is used to distinguish acceptable parts from those containingdefects
4、, such as cracks, voids, chips, density defects, tempering changes, and dimensional variations that are closely correlated withthe parts mechanical system dynamic response.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.
5、3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Docum
6、ents2.1 ASTM Standards:2E1316 Terminology for Nondestructive ExaminationsE1876 Test Method for Dynamic Youngs Modulus, Shear Modulus, and Poissons Ratio by Impulse Excitation of VibrationE2534 Practice for Process Compensated Resonance Testing Via Swept Sine Input for Metallic and Non-Metallic Parts
7、3. Terminology3.1 DefinitionsThe definitions of terms relating to conventional ultrasonics can be found in Terminology E1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 resonant ultrasonic spectroscopy (RUS), na nondestructive examination method, which employs resonant ultrasoundmethodo
8、logy for the detection and assessment of variations and mechanical properties of a test object. In this procedure, wherebya rigid part is caused to resonate, the resonances are compared to a previously defined resonance pattern. Based on this comparisonthe part is judged to be either acceptable or u
9、nacceptable.3.2.2 swept sine method, nthe use of an excitation source to create a transient vibration in a test object over a range offrequencies. Specifically, the input frequency is swept over a range of frequencies and the output is characterized by a resonantamplitude response spectrum.3.2.3 imp
10、ulse excitation method, nstriking an object with a mechanical impact, or electromagnetic field (laser and/or EMAT)causing multiple resonances to be simultaneously stimulated.3.2.4 resonant inspection (RI), nany induced resonant nondestructive examination method employing an excitation force tocreate
11、 mechanical resonances for the purpose of identifying a test objects conformity to an established acceptable pattern.4. Summary of the Technology (1)34.1 Introduction:1 This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommitt
12、ee E07.06 on Ultrasonic Method.Current edition approved July 1, 2008Dec. 1, 2013. Published July 2008January 2014. Originally approved in 1998. Last previous edition approved in 20032008 asE2001 - 98E2001 - 08.(2003). DOI: 10.1520/E2001-08.10.1520/E2001-13.2 For referencedASTM standards, visit theAS
13、TM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The boldface numbers in parentheses refer to the list of references at the end of this guide.This docu
14、ment is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as
15、appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
16、 States14.1.1 In addition to its basic research applications in physics, materials science, and geophysics, Resonant UltrasoundSpectroscopy (RUS) has been used successfully as an applied nondestructive testing tool. Resonant ultrasound spectroscopy incommercial, nondestructive testing has a few reco
17、gnizable names including, RUS Nondestructive Testing, Acoustic ResonanceSpectroscopy (ARS), and Resonant Inspection. Early references to this body of science often are termed the “swept sine method.”It was not until 1990 (2) that the name Resonant Ultrasound Spectroscopy appeared, but the two techni
18、ques are synonymous.Additionally, impulse methods, like the striking of a rail car wheel with a hammer, and listening for the responses, have been usedfor over 100 years to detect the existence of large cracks. RUS based techniques are becoming commonly used in the manufactureof steel, ceramic, and
19、sintered metal parts. In these situations, a part is vibrated mechanically, and defects are detected based onchanges in the pattern of resonances or variations from theoretically calculated or empirically acceptable spectra. RUS measuresall resonances, in a defined range, of the part rather than sca
20、nning for individual defects. In a single measurement, RUS-basedtechniques potentially can test for numerous defects including cracks, chips, cold shuts, inclusions, voids, oxides, contaminants,missed processes or operations, and variations in dimension, hardness, porosity, nodularity, density, and
21、heat treatment. Since theRUS measurement yields a whole body response, it is often difficult to discriminate between defect types. The technique iseffective for detecting parts with structural anomalies, but less effective for diagnosing the exact location or cause of an anomalywithin a part. Nevert
22、heless, on certain types of parts, it can be accurate, fast, inexpensive and require no human judgment, making100 % examination possible in selected circumstances. Many theoretical texts (3) discuss the relationship between resonances andelastic constants and include the specific application of RUS
23、to the determination of elastic constants (4). The technology receiveda quantum increase in attention when Migliori published a review article, including the requisite inexpensive electronic designsand procedures from which materials properties could be measured quickly and accurately (5). The most
24、recent applicationsinclude studies in ultrasonic attenuation, modulus determinations, thermodynamic properties, structural phase transitions,superconducting transitions, magnetic transitions, and the electronic properties of solids.Acompendium of these applications maybe found in the Migliori (1) te
25、xt. Resonant ultrasound spectroscopy also found use in the study of the elastic properties of theApollo moon rocks (6).4.1.2 This guide is intended to provide a practical introduction to RUS-based nondestructive test (NDT), highlighting successfulapplications and outlining failures, limitations, and
26、 potential weaknesses. Vibrational resonances are considered from theperspective of defect detection in 4.2. In 4.3 and 4.4, a review of some of the types of RUS measurements are given and 4.6examines the common practice of using the impulse excitation method. In 4.6, some example implementations an
27、d configurationsof RUS systems and their applications are presented. Finally, the guide concludes with a discussion of constraints, which limit theeffectiveness of RUS.4.2 Mode Shapes and Defects:4.2.1 Resonant ultrasound spectroscopy/NDT techniques, operate by driving a part at given frequencies an
28、d measuring itsmechanical response (Fig. 1 contains a schematic one embodiment of a RUS apparatus). The process proceeds in small frequencysteps over some previously determined region of interest. During such a sweep, the drive frequency typically brackets a resonance.When the excitation frequency i
29、s not matched to one of the parts resonance frequencies, very little energy is coupled to the part;that is, there is little mechanical vibration. At resonance, however, the energy delivered to the part is coupled generating muchlarger mechanical vibrations. A parts resonance frequencies are determin
30、ed by the standard dynamic equations of motion, whichinclude variables for mass, stiffness, and damping. From a materials perspective, this is affected by its dimensions (to include theshape and geometry) and by the density and the elastic constants of the material. The required frequency window for
31、 a scandepends on the size of the part, its mechanical rigidity, and the size of the defect being sought.FIG. 1 Schematic of the Essential Electronic Building Blocks to Employ RUS in a Manufacturing EnvironmentE2001 1324.2.2 Vibrational resonances produce a wide range of distortions. These distortio
32、ns include shapes, which bend and twist. It isknown that increasing the length of a cylinder will lower some resonant frequencies. Similarly, reducing the stiffness, that is,reducing the relevant elastic constant, lowers the associated resonant frequency for most modes; thus, for a given part, the r
33、esonantfrequencies are measures of stiffness, and knowledge of the mode shape helps to determine what qualities of the part affect thosefrequencies. If a defect, such as a crack, is introduced into a region under strain, it will reduce the effective stiffness, that is, theparts resistance to deforma
34、tion, and will shift downward the frequency of resonant modes that introduce strain at the crack. Thisis one basis for detecting defects with RUS-based techniques.4.2.3 The torsional modes represent a twisting of a cylinder about its axis. These resonances are easily identified because theirfrequenc
35、ies remain constant for fixed length, independent of diameter. A crack will reduce the ability of the part to resist twisting,thereby reducing the effective stiffness, and thus, the frequency of a torsional mode. A large defect can be detected readily by itseffect on the first few modes; however, sm
36、aller defects have much more subtle effects on stiffness, and therefore, require higherfrequencies (high-order modes) to be detected. Detection of very small defects may require using the frequency corresponding tothe fiftieth, or even higher, mode. Some modes do not produce strain in the end of the
37、 cylinder, therefore, they cannot detect enddefects. To detect this type of defect, a more complex mode is required, the description of which is beyond the scope of thisspecification. A defect in the end will reduce the effective stiffness for this type of mode, and thus, will shift downward thefreq
38、uency of the resonance. In general, it must be remembered that most modes will exhibit complex motions, and for highlysymmetric objects, can be linear combinations of several degenerate modes, as discussed in 4.3.2.4.3 General Approaches to RUS/NDT:4.3.1 Test Evaluation Methods (1)Once a fingerprint
39、 has been established, for conforming parts, numerous algorithms can beemployed to either accept or reject the part. For example, if a frequency 650 Hz can be identified for all conforming parts, thedetection of a peak outside of this boundary condition will cause the computer code to signal a “test
40、 reject” condition. The code,rather than the inspector, makes the accept/reject decision. The following sections will expand on some of these sorting criteria.4.3.2 Frequency Shifts:4.3.2.1 Resonant ultrasound spectroscopy measurements generally produce strains (even on resonance) that are well with
41、in theelastic limit of the materials under test, that is, the atomic displacements are small in keeping with the “nondestructive” aspect ofthe testing. If strains are applied above the elastic limit, a crack will tend to propagate, causing a mechanical failure. Note thatcertain important engineering
42、 properties, for example, the onset of plastic deformation, yield strength, etc., generally are notderivable from low-strain elastic properties. Sensitivity of the elastic properties of an object to the presence of a crack depends onthe stiffness and geometry of the sample under test. This concept i
43、s expanded upon under 4.4.3.4.3.2.2 Fig. 2 shows an example of the resonance spectrum for a conical ceramic part. Several specific types of modes arepresent in this scan, and their relative shifts could be used to detect defects as discussed above; however, the complexity is suchthat, for NDT purpos
44、es, some selections must be made so that only a portion of such a large amount of information is used. ForFIG. 2 Typical Broad-Spectrum ScanE2001 133simple part geometries, the mode type and frequency can be calculated, and selection of diagnostic modes can be based on theseresults. For complex geom
45、etries, empirical approaches have been developed to identify efficiently diagnostic modes for specificdefects. In this process, a technician measures the spectra for a batch of known good and bad parts. The spectra are compared toidentify diagnostic modes whose shift correlates with the presence of
46、the defect.The key is to isolate a few resonances, which differfrom one another, when known defects are present in the faulty parts.4.3.3 Peak SplittingOne of the techniques employed for axially symmetric parts is identified in texts on basic wave physics(7). Some test procedures are based on simple
47、 frequency changes while others include the recognition that symmetry is brokenwhen a defect is present in a homogeneous, isotropic symmetrical part. These techniques employ splitting of degeneracies orsimply “splitting.” A cylinder actually has two degenerate bending modes, both orthogonal to its a
48、xis. The bending stiffness forboth of these modes, and therefore their resonance frequency, is proportional to the diameter of the cylinder. Because the part issymmetric, both modes have the same stiffness, and therefore, the same frequency (the modes are said to be degenerate and appearto be a sing
49、le resonance). When the symmetry is broken by a chip, however, the effective diameter is reduced for one of theorthogonal modes. This increases the frequency for that mode, so both modes are seen. In addition, a crack or inclusion affectsthe symmetry. This splitting of the resonances is illustrated in Fig. 3, which shows spectra for a good part and two defective parts.The part is a steel cylinder. Fig. 3 also demonstrates a useful feature of this particular technique, that is, the size of the splittingis proportional to the size of the defect. It is important to reco
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