ASTM E3213-19

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E3213 − 19
Standard Practice for
Part-to-Itself Examination Using Process Compensated
Resonance Testing Via Swept Sine Input for Metallic and
Non-Metallic Parts
This standard is issued under the fixed designation E3213; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope deformation, corrosion, and fatigue. This practice is intended
for use with instruments capable of exciting, measuring,
1.1 This practice covers a general procedure for using the
recording, and analyzing multiple, whole body, mechanical
Process Compensated Resonance Testing (PCRT) via swept
vibration resonance frequencies in acoustic or ultrasonic fre-
sine input method to perform Part-to-Itself (PTI) examination
quency ranges, or both.
on populations of newly manufactured and in-service parts.
PCRT detects resonance pattern differences in metallic and 1.2 Units—The values stated in inch-pound units are to be
non-metallic parts. Practice E2534 for Defect Detection with regarded as standard. The values given in parentheses are
PCRT and Practice E3081 for Outlier Screening with PCRT mathematical conversions to SI units that are provided for
cover the development and application of PCRT sorting mod- information only and are not considered standard.
ules that inspect a part at a single point in time.These methods
1.3 This standard does not purport to address all of the
use the resonance frequency spectra recorded from test parts
safety concerns, if any, associated with its use. It is the
and perform different statistical analyses to compare test parts
responsibility of the user of this standard to establish appro-
to reference populations.These comparisons include, and must
priate safety, health, and environmental practices and deter-
compensatefor,thenormalgeometric,material,andprocessing
mine the applicability of regulatory limitations prior to use.
variations present in any population of parts. In many
1.4 This international standard was developed in accor-
applications,however,theusermayneedtoevaluatetheeffects
dance with internationally recognized principles on standard-
of a single processing step or in-service load in isolation from
ization established in the Decision on Principles for the
other sources of variation. For example, a manufacturer may
Development of International Standards, Guides and Recom-
want to perform process monitoring and control on a heat
mendations issued by the World Trade Organization Technical
treatment or hardening process. A maintainer may want to
Barriers to Trade (TBT) Committee.
evaluate the effect of service cycles in an engine.APCRT PTI
examination measures the resonance frequency spectrum of a 2. Referenced Documents
part at two points in time, such as before and after a 2
2.1 ASTM Standards:
manufacturing process step, and calculates the change in
E1316 Terminology for Nondestructive Examinations
resonance frequencies to evaluate the effect of the intervening
E2001 Guide for Resonant Ultrasound Spectroscopy for
process. Control limits can be set on the frequency change to
Defect Detection in Both Metallic and Non-metallic Parts
fieldaPTIPASS/FAILinspectioncapability.Thelimitsmaybe
E2534 Practice for Process Compensated ResonanceTesting
based on training populations of parts with acceptable and
Via Swept Sine Input for Metallic and Non-Metallic Parts
unacceptable levels of change, model predictions of the effects
E3081 Practice for Outlier Screening Using Process Com-
of part changes, or criteria derived from process control
pensated Resonance Testing via Swept Sine Input for
practices. Manufacturing processes and in-service loads that
Metallic and Non-Metallic Parts
can be evaluated with a PCRT PTI inspection include, but are
not limited to heat treatment, hot isostatic pressing (HIP), shot
3. Terminology
peening, induction hardening, carburization, coating, thermal
3.1 Definitions—The definitions of terms relating to con-
history changes, residual stress changes, creep, plastic
ventional ultrasonic examination can be found in Terminology
E1316.
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.06 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Ultrasonic Method. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 1, 2019. Published June 2019. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
E3213-19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3213 − 19
3.2 Definitions of Terms Specific to This Standard: frequencies, or both, for the identification of acceptable varia-
3.2.1 broadband, n—the range of frequencies, excitation tions in the physical characteristics of test parts in production
parameters, and data collection parameters developed specifi- environments.
cally for a particular part type. 3.2.11.1 Discussion—BasicRUS (1) wasoriginallyapplied
in fundamental research applications in physics and materials
3.2.2 classification, n—thelabelingofateachingsetofparts
science. Other recognizable names include acoustic resonance
as acceptable or unacceptable.
spectroscopy, acoustic resonant inspection, and resonant in-
3.2.3 diagnostic resonance mode, n—a resonance mode of
spection. Guide E2001 documents RUS extensively. In this
vibration that is sensitive to the change in material state
procedure an isolated, rigid component is excited, producing
produced by a manufacturing process or in-service damage.
oscillation at the natural frequencies of vibration of the
3.2.4 false negative, n—part failing the sort but deemed by
component. Diagnostic resonance frequencies are measured
other method of post-test/analysis to have acceptable or con-
and compared to resonance frequency patterns previously
forming specifications.
defined as acceptable. Based on this comparison, the part is
judged to be acceptable or, if it does not conform to the
3.2.5 false positive, n—part passing the sort but exhibiting a
established pattern, unacceptable.
flaw (either inside the teaching set of flaws or possibly outside
the teaching set range of flaws) or nonconforming to specifi-
3.2.12 sorting module, n—for PCRT PTI applications, a
cation.
software program that records diagnostic resonance modes in
two or more material states of a part, calculates the frequency
3.2.6 margin part, n—a single part representative of a part
changes for those modes between the material states, compares
type that is used to determine measurement repeatability and
the frequency changes to acceptability limits, and classifies a
for system verification.
part as acceptable or unacceptable.
3.2.7 Part-to-Itself (PTI) examination, n—a PCRT PTI ex-
3.2.13 teaching set, n—for PCRT PTI applications, a group
amination uses the resonance spectrum recorded for a part in
of parts identical to normal production or in-service parts (with
two different states, such as before and after a manufacturing
normal part-to-part variation) subjected to the process or
process like heat treatment or hardening, or after the accumu-
in-service load(s) of interest to identify diagnostic resonance
lation of in-service loads/damage.
modes and quantify the frequency changes produced by the
3.2.7.1 Discussion—The change in resonance frequencies is
material state changes resulting from the process or loads.
used to evaluate the change in material state. The frequency
3.2.13.1 Discussion—An effective teaching set includes ex-
changes can be compared to acceptability limits to evaluate
amples of acceptable and unacceptable material state changes.
manufacturing processes and the effects of accumulated in-
service damage.
3.2.14 work instruction, n—stepwise instructions developed
for each examination program detailing the order and applica-
3.2.8 Process Compensated Resonance Testing (PCRT),
tion of operations for PCRT examination of a part.
n—PCRT is a nondestructive examination method that en-
hances RUS with pattern recognition capability.
4. Summary of Practice
3.2.8.1 Discussion—PCRT effectively discriminates reso-
4.1 Introduction:
nance frequency shifts due to unacceptable conditions from
4.1.1 Many variations on resonance testing have been ap-
resonance frequency shifts due to normal, acceptable manufac-
plied as nondestructive examination tools to detect structural
turing process variations. The process employs the measure-
anomalies that significantly alter component performance. The
ment and analysis of acoustic or ultrasonic resonance fre-
details of this basic form of resonance testing are outlined in
quency patterns, or both. PCRT pattern recognition tools
Guide E2001.
identify the combinations of resonance patterns that most
4.1.2 Process Compensated Resonance Testing (PCRT) is a
effectively differentiate acceptable from unacceptable compo-
progressive development of the fundamental principles of
nents. In PTI applications, the change in resonance frequencies
RUS, and can employ various methods for enhancing the
for diagnostic modes is used to evaluate the material state
discrimination capability of RUS. Throughout the 1990s,
changeproducedbymanufacturingprocesses,repairprocesses,
application of RUS for production NDT led to better under-
or in-service loads/damage and determine whether a part is
standing of the challenges associated with differentiating
acceptable.
resonance variations caused by structural anomalies from
3.2.9 quality factor (Q factor), n—dimensionless property
resonance variations from normal and acceptable process
of resonance peak that describes the peak shape, that is, width
variation in mass, material properties and dimensions (2, 3).
at full width at half maximum (FWHM) divided into the peak
PCRT first became commonly used in the production exami-
center frequency; peaks with higher Q factor values are
nation of metal and ceramic parts in the late 1990s (4). By the
narrower and sharp.
early 2000s, PCRT had essentially developed into the robust
3.2.10 resonance spectra, n—the recorded collection of
NDT capability it is today (5).
resonance frequency data, including frequency peak locations
4.1.3 PCRT is a comparison technology using a swept sine
and the characteristics of the peaks, for a particular part.
wave to excite the components through a range of resonance
3.2.11 Resonant Ultrasound Spectroscopy (RUS), n—RUS
is a nondestructive examination method that employs the
The boldface numbers in parentheses refer to a list of references at the end of
measurement and analysis of acoustic or ultrasonic resonance this standard.
E3213 − 19
frequencies determined by the mass, geometry, and material sificationofapart.Somebasicexplanationsofresonances,and
properties of the part. In Part-to-Itself (PTI) applications, the the effects of anomalies on them, are found in 4.2. Some
resonance spectrum for a part is recorded for the part in two or successful applications and general description of the equip-
more different material states. The resonance spectrum re- mentnecessarytosuccessfullyapplyPCRTforclassificationof
corded at each material state is stored in a database organized production parts are outlined in 5.1 and 5.2, respectively.
by component serial number. For non-serialized components, a Additionally, some constraints and limitations are discussed in
temporary serialization scheme is implemented to track parts 5.3.Thegeneralprocedurefordevelopingapart-specificPCRT
through a manufacturing or repair process. The PCRT mea- application is laid out in 6.1.
surement yields a whole-body response, finding structurally-
4.2 Resonances and the Effect of Anomalies:
significant material state variations anywhere within the part,
4.2.1 The swept sine method of vibration analysis operates
but it is generally not capable of determining the type or
by driving a part at given frequencies (acoustic through
location of the anomaly.
ultrasonic, depending on the part characteristics) and measur-
4.1.4 PCRT PTI examination can be applied to new parts in
ingitsmechanicalresponse.Fig.1containsaschematicforone
the manufacturing environment, to parts currently in service in
embodiment of a PCRT apparatus. The swept sine wave
a maintenance environment, or in a combined program in
proceedsinsmallfrequencystepsoverapreviouslydetermined
which PTI examinations are conducted from new manufacture
broadband frequency range of interest. When the excitation
throughoutthepartservicelife.Inamanufacturingapplication,
frequency is not matched to one of the resonance frequencies
material state changes resulting from manufacturing processes
ofthepart,verylittleenergyiscoupledtothepart;thatis,there
can include heat treatment, hot isostatic pressing (HIP), induc-
is essentially no vibration. At resonance, however, the energy
tion hardening, carburization, and many others. The change in
delivered to the part is coupled, generating much larger
frequency of diagnostic resonance modes is used to evaluate
vibrations. The resonance frequencies of a part are determined
the change in the material state of the part. This evaluation can
by the geometry, density, and material elastic constants (me-
include a comparison of the frequency changes to acceptability
chanically equivalent to mass, stiffness, and damping) of the
limits for monitoring and control of the manufacturing process
material. An example of the resonance spectra for a part is
and for nondestructive testing (NDT) of 100 % of the part
shown in Fig. 2 for reference.
population to determine whether the final parts are acceptable.
4.2.2 Material state changes from a manufacturing process,
In a maintenance application, material state changes resulting
accumulated damage, or a repair process will change the
from the accumulation of in-service loads and damage are
effective stiffness of a part. That is, the resistance of the part to
evaluatedbymeasuringthefrequencychangesbetweenservice
deformation will change and will shift the resonance frequen-
intervals. The frequency changes are compared to limits to
cies of resonance modes that are sensitive to that material state
determine if the accumulated damage has rendered the part
change. In general, any change to a part that alters the
unserviceable, enabling a condition-based maintenance ap-
structural integrity, changes a geometric feature, or affects the
proach. A second maintenance application is the evaluation of
material properties will alter its natural resonance frequencies.
repair processes that change the part material state. The
Graphic examples of the effects of various anomalies on
changes in frequencies measured before and after the repair
resonances are presented in Guide E2001.
process are compared to acceptability limits to determine if the
4.2.3 For example, the resonance mode for a turbine blade
repair process was performed to specification, and for NDT of
shown in Fig. 3 features significant bending deformation in the
100 %ofthepost-repairpopulationtodetermineiftherepaired
airfoil section. Material state changes that affect the airfoil
parts are acceptable. One example of a PCRT PTI manufac-
section, such as a diffusion heat treatment in a coating process,
turing application is induction hardening of steel gears. The
will cause frequency changes in airfoil-centric modes that
gears are measured before and after induction hardening, and
correlate to the magnitude of the material state change. In the
the frequency change is calculated and compared to accept-
case of diffusion heat treatments during coating, this will tend
ability limits to determine if the case depth and hardness are
to reduce the overall stiffness of the airfoil material, producing
within specification. An example of a maintenance PTI appli-
a decrease in frequency for mode shapes that feature airfoil
cation is an aircraft engine turbine blade at an engine overhaul
deformation.Otherresonancemodeswithdeformationinareas
facility. Blades are measured in the as-new condition when
that are masked during the coating and heat treatment process,
they are purchased as spares, again when the blades return to
like the fir tree, will be affected much less or not at all.
overhaulafteraserviceinterval,andfinallyafterarejuvenation
4.2.4 Anotherexampleisinductionhardeningofsteelgears.
repairprocess.Theas-newtoserviceintervalfrequencychange
The induction hardening process reduces the stiffness of the
is used to determine if a part has accumulated unacceptable
material in the case-hardened region, typically the gear teeth
levels of damage. The frequency change from the repair
(6). The reduction in stiffness causes a decrease in resonance
processisusedtodetermineiftherepairhasbeenperformedto
frequencies. The magnitude of the decrease correlates to the
specification.
case depth and hardness of the hardened region.
4.1.5 Thispracticeisintendedtoprovideapracticalguideto
the application of PCRT PTI examination of metallic and
5. Significance and Use
non-metallic parts. It highlights the steps necessary to produce
robust and accurate test applications and outlines potential 5.1 PCRT Applications and Capabilities—PCRT PTI ex-
weaknesses, limitations, and factors that could lead to misclas- amination has been applied successfully to a wide range of
E3213 − 19
FIG. 1 PCRT System Schematic
(b) Additively manufactured components
(c) Steel mechanical components
(d) Industrial gas turbine blades
(2) Induction hardening and carburization (both case-
hardened and through-hardened parts):
(a) Gears
(b) Ballnuts
(3) Hot Isostatic Pressing (HIP):
(a) Gas turbine engine components (blades, vanes, disks)
(b) Additively manufactured components
(4) Shot peening:
(a) Steel mechanical components
FIG. 2 Resonance Spectra (50 kHz to 120 kHz)
(5) In-service thermal history, aging, creep damage, fa-
tigue:
(a) Gas turbine engine components (blades, vanes, disks)
(b) Industrial gas turbine blades
(c) Aircraft landing gear wheels
(6) Maintenance repair/rejuvenation processes:
(a) Gas turbine engine components (blades, vanes, disks)
(b) Industrial gas turbine blades
(c) Aircraft landing gear wheels.
FIG. 3 Airfoil Bending Mode for Turbine Blade
5.2 General Approach and Equipment Requirements for
PCRT via Swept Sine Input:
parts in manufacturing and maintenance environments. Ex-
5.2.1 PCRT systems comprise hardware and software ca-
amples of manufacturing processes, repair processes, and
pable of inducing vibrations, recording the component re-
in-service damage mechanisms evaluated with PTI are dis-
sponse to the induced vibrations, and analyzing the data
cussed in 1.1. PCRT has been shown to provide cost effective
collected. Inputting a swept sine wave into the part has proven
and accurate PTI-based NDT, process monitoring, and life
to be an effective means of introducing mechanical vibration
monitoring in many industries including automotive,
and can be achieved with a high-quality signal generator
aerospace, and power generation. Examples of successful
coupled with an appropriate active transducer in physical
applications currently employed in commercial use include,
contact with the part. Collection of the part’s resonance
but are not limited to:
response is achieved by recording the signal received by an
(1) Heat treatment operations:
appropriatepassivevibrationtransducer.Thesoftwarerequired
(a) Aerospace gas turbine engine components (blades,
vanes, disks) to analyze the available data may include a variety of suitable
E3213 − 19
statistical analysis and pattern recognition tools. Measurement 6. Procedure
accuracy and repeatability are extremely important to the
6.1 Successful PCRT application development and imple-
application of PCRT.
mentation follows a standard flow. The stepwise functions
5.2.2 Hardware Requirements—A swept sine wave signal
required in the flow are:
generatorandresponsemeasurementsystemoperatingoverthe
(1) Collection of a teaching set of components,
desired frequency range of the test part are required with
(2) Design and fabrication of a test nest or appropriate
accuracy better than 0.002 %. The signal generator should be
fixturing,
calibrated to applicable industry standards. Transducers must
(3) Understanding the effects of temperature on the reso-
be operable over same frequency range. Three transducers are
nance spectra,
typically used; one Drive transducer and two Receive trans-
(4) Specification of resonance broadband data collection
ducers. Transducers typically operate in a dry environment,
parameters,
providing direct contact coupling to the part under examina-
(5) Evaluation of system measurement repeatability and
tion. However, noncontacting response methods can operate
reproducibility (similar to Gauge R and R) with respect to
suitably when parts are wet or oil-coated. Other than fixturing
mounting parameters,
and transducer contact, no other contact with the part is
(6) Collection of the baseline resonance data from the
allowed as these mechanical forces dampen certain vibrations.
teaching set of parts,
For optimal examination, parts should be placed precisely on
(7) Application of manufacturing process, repair process,
the transducers (gen
...