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non-destructive testing NDT
non-destructive examination NDE
non-destructive evaluation NDE
non-destructive inspection NDI
zerstrungs-freie prfung ZfP
...strani nazivi:
nerazorna ispitivanja (HZN, TO 135)
kontrola bez razaranja
ispitivanja bez razaranja
defektoskopija
...HR nazivi:
NDE karakterizacija materijala
ZAVOD ZA KVALITETU
KATEDRA ZA
NERAZORNA ISPITIVANJA
Prof.dr.sc. Damir Markui
Nerazorna ispitivanja
U svrhu pronalaenja nepravilnosti
su vrlo znaajna za praenje kvalitete
u proizvodnjizavarivanje, odljevci, otkivci,
strojne i toplinske obradbe, ...
i posebno tijekom
eksploatacijepetrokemijska i energetskapostrojenja, nuklearna
postrojenja, pomorski objekti,
transport,
posude pod tlakom, ...
volumnih i
planarnih,
. nastalih uslijed tehnolokih ili eksploatacijskih uvjeta.
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Metode i tehnike nerazornih ispitivanja
a obzirom na specifinosti naina provedbe ispitivanja na
TEHNIKE nerazornih ispitivanja
Obzirom na fizikalne principe/naela, nerazornaispitivanja dijelimo na
METODE nerazornih ispitivanja,
PRINCIP ispitna struktura METODA TEHNIKE
elektromagnet-
ski valoviX i zraenje
RT
radiografska
(radijacijska)
radiografija,
radioskopija,
gamagrafija, XRD, XRF
vidljivi dio
spektra
VT
vizualnadirektna, RVI
IR valoviIR
termografska
termovizija,
lock-in termografija
mikrovaloviGPR
radarska
niskofrekventna
polja
ET
(EC, vrtlone struje)RFEC, ACPD, ACFM, ..
magnetsko poljeMT
magnetska
magnetskim esticama,
MFL, Barkhausen
elastini valovi ultrazvuni valoviUT
ultrazvuna
tehnike odjeka (PE),
difrakcije (TOFD), ...
akustiki valoviAC, AE
akustika
akustika emisija,
Impact Echo (IE)
kontaktpenetrant
(kapilarni efekt)
PT
penetrantska
ovisno o vrsti
penetranta...
inertni plin
(propusnost)
LT
ispitivanje propusnostivacuum, helij
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Metode i tehnike nerazornih ispitivanja
Ovisno o primijenjenom fizikalnom principu i ispitnim
parametrima (npr. osjetljivost, razluivost) moe se govoriti
Stoga se nerazorna ispitivanja primjenjuju u cilju
i o odzivu materijala (strukture).
pronalaenja nepravilnosti (pogreaka) i
karakterizacije materijala
Detekcija nepravilnosti temelji se na
odreenom odzivu od nepravilnosti.
Pobuda odzivi
ispitivana
cjelina
izvorprobe analizatorprobe
proba
okolina
PRINCIP
Razina odziva od nepravilnosti i
od materijala.
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Ispitivanje ultrazvukom (UT) - osnove
Propagacija impulsa kroz medij - interakcija
brzina propagacije
ultrazvunog impulsa
relevantna (akustika) svojstva medija
akustika impedancija Z = v
pojave na granici dva (akustiki razliita) sredstva
Snellov zakon loma
konverzija
koeficijentirefleksije i transmisije
(Ri T)
Ispitivanje ultrazvukom (UT) - osnove
Propagacija impulsa kroz medij - interakcija
konvencionalna granica detekcije u ispitnom materijalu proizlazi
iz frekvencije odabrane sonde i brzine propagacije UZ impulsa:
v = * f
detektibilnost: /2 = d npr. d = 0,3 mm
f: od 2 do 10 MHz (1-20 MHz) v: od 2000 do 6500 m/s
slabljenje energije impulsa guenje
koef. priguenja
gubici uslijed: apsorpcije, rasprenja,
geometrije UZ polja
iznos ovisi o odabranoj frekv.,
odnosno o odnosu
veliine zrna d i (valne duljine)
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UT - frekvencijske karakteristike
UT - frekvencijska analiza
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UT - primjeri karakterizacije
Karakterizacija amplitudnih odziva - priguenje
UT - primjeri karakterizacije
Karakterizacija materijala u kontaktu
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UT - primjeri karakterizacijehttp://www.olympus-ims.com/en/ndt-application/183-id.209715263.html
Measuring Nodularity in Cast Iron
Application: Measuring degree of nodularity
in cast iron, or distinguishing nodular iron from
gray iron.
Problem: Carbon in the form of graphite is
often used as an additive in the production of
cast iron, amounting to 2 to 4 percent by
weight or 6 to 10 percent by volume in typical
castings. The microstructure of graphite within
cast iron has major effects on the casting's
mechanical properties. When graphite
arranges itself as thin flakes the result is grayiron, which is hard and brittle. When graphite
takes the form of spherical nodules the result
is nodular iron, which is soft and malleable.
UT - primjeri karakterizacijehttp://www.olympus-ims.com/en/ndt-application/183-id.209715270.html
Elastic Modulus Measurement
Application: Measurement on Young's
Modulus and Shear Modulus of Elasticity, and
Poisson's ratio, in nondispersive isotropicengineering materials.
Problem: Young's Modulus of Elasticity is
defined as the ratio of stress (force per unit
area) to corresponding strain (deformation) in
a material under tension or compression.
Shear Modulus of Elasticity is similar to the
ratio of stress to strain in a material subjected
to shear stress.
Poisson's Ratio is the ratio of transverse strain
to corresponding axial strain on a materialstressed along one axis.
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UT - primjeri karakterizacijehttp://www.mendeley.com/research/dependence-ultrasonic-velocity-
porosity-pore-shape-sintered-materials/#
Dependence of ultrasonic velocity on porosity
and pore shape in sintered materials Abstract:A new approach to predict the longitudinal and
transverse ultrasonic velocities in porous materials is presented. The
model is based on a previously derived Young's modulus-porosity
correlation assuming spheroidal geometry of the pores. It is also
assumed that the Poisson's ratio of porous materials does not change
significantly with porosity. The longitudinal and transverse ultrasonic
velocities are given as functions of the Young's modulus, Poisson's
ratio, density of the pore-free material and of the porosity and axial
ratio (z/x) of the spheroidal pores. Experimental data drawn from the
literature on different porous sintered materials including SiC, Al2O3,
YBa2Cu3O7-x, porcelain, sintered iron, Si3N4, and sintered tungsten,
were used to verify the model. A strong relationship between pore
shape and the slope of the ultrasonic velocity-porosity curve was
confirmed. In general, the calculated values are in fairly goodagreement with the experimental data. When the actual shape (axial
ratio) of the pores was known, the approach was shown to predict the
experimental data better than a similar model derived by Phani. It is
suggested that the present approach, coupled with the measurement
of the ultrasonic velocity, may constitute a simple nondestructive
technique to gain knowledge of the morphology of the porosity in
sintered materials.
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UT - primjeri karakterizacije
Mjerenje tvrdoe
http://www.ndt.net/ndtaz/content.php?id=178
Ultrasound is used for the measuring of hardness
or elastic material properties under loads by
the ultrasonic contact-impedance (UCI)method, in which a rod-shaped resonator , one
end holding an indentation body, is pressed
against a test specimen with a given test force,
so that the indentation body penetrates the
specimen, and the resulting change of df in the
frequency f of the resonator is measured. The
probe usually contains a Vickers diamond
(136 pyramid) and due to conversion scales
the reading can be performed in HV, HB, HRC,
HRB and HS.
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UT - primjeri karakterizacije
Scanning Acoustic Microscope (SAM)
http://www.sv.vt.edu/comp_sim/sam/sam.html
Our goal in this study is to investigate how a SAM can be used to evaluate elasticproperty gradients that exist near a fiber-matrix interface. Unlike images from
a reflecting microscope, a SAM image can highlight differences in elastic
properties. For example look at this SAM image of a [0/90] glass/epoxy fiber-
reinforced composite laminate [Briggs, 85]..
UT - primjeri karakterizacije