Table Of ContentP. Holler· V. Hauk· G. Dobmann
C. O. Ruud . R. E. Green
(Eds.)
Nondestructive
Characterization of Materials
Proceedings of the 3rd International Symposium
Saarbriicken, FRG October 3-6, 1988
Organized by
Deutsche Gesellschaft fur zerstorungsfreie
Priifung e.Y. (DGZiP), Berlin
and
Fraunhofer-Institut fur zerstorungsfreie
Priifverfahren (!ziP), Saarbriicken
With 609 Figures
Springer-Verlag Berlin Heidelberg NewY ork
London Paris Tokyo Hong Kong
Prof. Dr. Paul Holler Prof. Dr. Viktor Hauk
Fraunhofer Institut Institut fUr Werkstoffkunde
fUr zerstorungsfreie Priifverfahren Rhein. Westf. Technische Hochschule
Universitat, Gebaude 37 5100 Aachen
6600 Saarbriicken 11 FRG
FRG
Prof. Dr. Clayton O. Ruud
Dr. G. Dobmann
159 Materials Research Laboratory
Fraunhofer Institut The Pennsylvania State University
fUr zerstorungsfreie Priifverfahren University Park, Pennsylvania 16802
Universitat, Gebaude 37 USA
6600 Saarbriicken 11
FRG
Robert E. Green, Jr.
Center for Nondestructive Evaluation
The Johns Hopkins University
Baltimore, Maryland 21218
USA
ISBN -13: 978-3-642-84005-0 e-ISBN-13 :978-3-642-84003-6
DOl: 10.1007/978-3-642-84003-6
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Preface
Engineering structures for reliable function and safety have to be
designed such that operational mechanical loads are compensated for by
stresses in the components bearable by the materials used. Vhat is
"bearable"? First of all it depends on the properties of the chosen
materials as well as on several other parameters, e.g. temperature,
corrosivity of the environment, elapsed or remaining serviceable life,
unexpected deterioration of materials, whatever the source and nature of
such deterioration may be: defects, loss of strength, embrittlement,
wastage, etc. DEFECTS and PROPERTIES of materials currently determine
loadability. Therefore in addition to nondestructive testing for defects
there is also a need for nondestructive testing of properties.
The third type of information to be supplied by nondestructive
measurement pertains to STRESS STATES under OPERATIONAL LOADS, i.e.
LOAD-INDUCED plus RESIDUAL STRESSES. Residual stresses normally cannot be
calculated; they have to be measured nondestructively; well-approved
elastomechanical finite element codes are available and used for
calculating load-induced stresses; for redundancy and reliability,
engineers, however, need procedures and instrumentation for experimental
checks.
Three quantitative ndt-categories should be available for the
qualification and/or quality assurance of structures during fabrication and
operation:
- ndt for DEFECTS (ndtd)
- ndt for PROPERTIES (ndtp)
- ndt for STRESSES (ndts)
Ndtd and ndts are much further developed and more frequently applied
than ndtp. In addition, the technical communities for ndtd and ndts are
much larger than that for ndtp. National and international ndt conferences
deal far more with ndtd than ndts and ndtp. In November 88 the second
International Conference on Residual Stresses was held in Nancy (less than
60 miles from SaarbrUcken), at which 205 papers were presented and with 280
participants attending. Most contributions dealt with just one
ndts-technique, X-RAY DIFFRACTION. Second place was occupied by relaxation
techniques in which residual stresses are partially released by drilling
holes or machining notches. Releasing strain is measured by arrays of small
strain gauges (rosettes). For shallow bore holes or notches this RELAXATION
TECHNIQUE is at most slightly destructive. Both techniques, X-ray
diffraction and relaxation, measure strains which are directly related to
the stress states to be measured by the second order elastic moduli.
Unfortunately the major mechanical properties describe the nonelastic
i.e. nonreversible -- behaviour of materials, which physically is not
correlated to elastic behaviour; however, only testing in the elastic area
is nondestructive. Consequently, it is due to physical reasons that ndtp is
not possible for MECHANICAL properties in a direct manner as ndtd is for
defects and ndts for stresses. (Nevertheless elastic moduli have become
important ndt quantities; they carry information pertaining to the
stiffness and microstructure of materials. Several papers were presented on
this subject during the symposium). Other physical properties such as
nonelastic mechanical properties -- electric, thermal, magnetic, etc.
can be measured using ndt techniques. They strongly correlate with the
microstructure of materials.
Macroscopic nonelastic properties and behaviour of materials, especially
metals, physically depend on solid solutions (alloys), microstructure
(dislocations, precipitations, etc.) and stresses. Physical metallurgy
deals with these dependencies and will continue research on them as long as
optimization and development of materials exist.
The situation at present: we do not have nd testing methods offering
direct access to macroscopic mechanical properties and describing behaviour
under loads,' however, we do have nd testing technology for microstructure
(and microstresses). Moreover, physical metallurgists have the know-how to
derive macroscopic properties from microstructural data measured
nondestructively.
The scenario described above is illustrated by two diagrams. The first
diagram shows microstructural parameters and defects relevant to strength
VII
and toughness of materials plotted against their linear dimensions,
resulting in the resolution needed for nondestructive materials
characterization. A wide band from 10-10 to 10-2 is covered; the most
important area for metals and ceramics and composites as well is 10-9 to
10-5• In the second diagram ndt techniques are plotted with the same
abscissa. There are more ndt techniques for microstructures and defects
above 10-5 than below; but those below 10-5 already provide access to the
most important microstructures relevant for mechanical properties and early
stages of deterioration.
The nondestructive characterization (ndc) of materials by
electromagnetic techniques was born at least 50 years ago. A few names of
pioneers, for laboratory applications as well as for industrial testing
should be mentioned (in alphabetical order): W.A. Black, F. Forster, W.
Gerlach, W. Jellinghaus, H. Lange. One of these pioneers, F. Forster, has
accepted our invitation to present a paper on the origin of electromagnetic
methods.
It is the merit of C.O. Ruud and R.E. Green that a series of symposia
devoted to nondestructive materials characterization was started in 1983.
This first symposium, held in Hershey Pennsylvania, was a considerable
success. The same holds true for the second symposium, organized by J.F.
Bussiere in Montreal. During a meeting of the organizing committee and the
international advisory board held during the second symposium the
representatives of several countries indicated their willingness and
interest to host and organize the third symposium. The decision was made in
favour of Saarbrlicken, FRG.
The 3rd IS-NDC, organized by the DGZfP and the FhG-IzfP, was conducted
in Saarbrlicken from October 3-6, 1988. 225 scientists from 14 different
countries took part. 81 oral presentations were given, 15 of them were
invited plenary lectures and 37 poster presentations complementing the
comprehensive program. The panel discussion involving P. Adam, G. Nardoni,
H. Schneider, M. G. Seitz, Ch. Thoma, F. TOnolini and R. Zeller was chaired
by D. O. Thompson. R. Sharpe gave an evaluation of the conference in his
concluding speech along with providing an outlook for future objectives and
development trends.
VIII
We would like to especially thank the numerous ladies and gentlemen of
the staffs at the DGZfP, Berlin, and at the Institut fUr zerstorungsfreie
prUfverfahren, SaarbrUcken, for their untiring efforts in helping to
organize and conduct this symposium. We would also like to extend our
thanks to the members of the international advisory board and the
organizing and program committees.
The present proceedings volume contains 103 articles submitted by the
authors. This represents the current level of knowledge in the field of Nne
of materials. The editors would like to thank the authors for adhering to
the restrictions on length imposed. This means that they were forced to
concentrate on essential results, dispense with details and supplementary
work. We would like.to thank Springer Verlag for their efforts in quickly
publishing the volume.
P. Holler V. Hauk G. Dobmann
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Table of Contents
1. Research Programmes
Y.van der Eijk Presentation of the next BRITE-EORAH-Programme
H.Pero (1989-1992) ••.••.•••••••••••••••••••••••••••••.•••••• 3
Y.Faul Materials Research-Programme of the Federal
Ministry for Research and Technology (BMFT) •••••••••• 8
2. Ceramics
H.Schmidt Properties, preparation and requirements to
testing of ceramic materials ••••••••••••••••••••.••• 17
T.Kishi Material characterization of ceramics by
K.Kitadate various nondestructive testing methods .••••••••••••• 26
E.Brinksmeier Requirements on nondestructive testing methods
H.Siemer after machining of ceramics ••••••••••••••••••••••••• 36
H.G.Yobker
P.S.Nicholson Ultrasonic nde of advanced ceramics ••••••••••••••••. 46
J.Goebbels Tomodensitometry with x- and gamma-rays ••••••••••••. 56
H.Heidt
B.Illerhaus
P.Reimers
G.Schlieper Nondestructive density measurements in powder
V.Arnhold metallurgy and ceramics ••••••••••••••••••••••••••••• 65
H.Dirkes
Y.Sachse New developments for the ultrasonic character-
K.Y.Kim ization of materials •••••••••••••••••••••••••••••••• 73
3. Composites
S.Datta Graphite-magnesium elastic constants:
H.Ledbetter Composite and fiber ••••••••••••••••••••••••••••••••• 83
D.Y.Fitting Monitoring of anisotropic material elastic
A.V.Clark properties using ultrasonic receiving arrays •••••••• 91
M.J.Ehrlich Anisotropy measurements and indication of ply
J.Y.Yagner orientation in composite materials using holo
graphic mapping of large amplitude acoustic
waves ••••••••••••••••••••••••••••••••••••••••••••••• 99
