A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures
In the Institute of Strength Problems of the Academy of Sciences of the Ukrainian SSR using a KM-50 test machine as a base, a machine with increased rigidity has been built making it possible to conduct crack resistance tests of double cantilever beam specimens up to 20 mm thick.
Збережено в:
| Дата: | 1985 |
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| Автори: | , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Інститут проблем міцності ім. Г.С. Писаренко НАН України
1985
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| Назва видання: | Проблемы прочности |
| Теми: | |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/182898 |
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures/ Yu.A. Kashtalyan, V.M. Torop // Проблемы прочности. — 1985. — № 8. — С. 1181-1184. — Бібліогр.: 6 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
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irk-123456789-1828982022-01-23T01:27:19Z A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures Kashtalyan, Yu.A. Torop, V.M. Production section In the Institute of Strength Problems of the Academy of Sciences of the Ukrainian SSR using a KM-50 test machine as a base, a machine with increased rigidity has been built making it possible to conduct crack resistance tests of double cantilever beam specimens up to 20 mm thick. 1985 Article A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures/ Yu.A. Kashtalyan, V.M. Torop // Проблемы прочности. — 1985. — № 8. — С. 1181-1184. — Бібліогр.: 6 назв. — англ. 0556-171X http://dspace.nbuv.gov.ua/handle/123456789/182898 539.4 en Проблемы прочности Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| language |
English |
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Production section Production section |
| spellingShingle |
Production section Production section Kashtalyan, Yu.A. Torop, V.M. A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures Проблемы прочности |
| description |
In the Institute of Strength Problems of the Academy of Sciences of the Ukrainian SSR using a KM-50 test machine as a base, a machine with increased rigidity has been built making it possible to conduct crack resistance tests of double cantilever beam specimens up to 20 mm thick. |
| format |
Article |
| author |
Kashtalyan, Yu.A. Torop, V.M. |
| author_facet |
Kashtalyan, Yu.A. Torop, V.M. |
| author_sort |
Kashtalyan, Yu.A. |
| title |
A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures |
| title_short |
A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures |
| title_full |
A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures |
| title_fullStr |
A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures |
| title_full_unstemmed |
A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures |
| title_sort |
machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| publishDate |
1985 |
| topic_facet |
Production section |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/182898 |
| citation_txt |
A machine for determination of the characteristics of crack resistance in the crack arrest stage at normal and low temperatures/ Yu.A. Kashtalyan, V.M. Torop // Проблемы прочности. — 1985. — № 8. — С. 1181-1184. — Бібліогр.: 6 назв. — англ. |
| series |
Проблемы прочности |
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2025-07-16T02:10:05Z |
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2025-07-16T02:10:05Z |
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1837767658872766464 |
| fulltext |
PRODUCTION SECTION
A MACHINE FOR DETERMINATION OF THE CHARACTERISTICS
OF CRACK RESISTANCE IN THE CRACK ARREST STAGE AT
NORMAL AND LOW TEMPERATURES
Yu. A. Kashtalyan and V. M. Torop UDC 539.4
The method recommendations on determination of the characteristics of fracture toughness
(crack resistance) in the crack arrest stage establish certain requirements for test machines
and above all else for their rigidity [i]. It is desirable that the rigidity of the machine
be an order of magnitude greater than the rigidity of the specimen. The capacity of the
test machine to fix the specified external displacement regardless of what load is required
for this is also important [2]. Based on this it is possible to conclude that mechanical
machines are preferable to hydraulic.
From Fig. i, which gives the rigidities of various test machines according to the data
presented in [3], it follows that the rigidity of the majority of the machines is insufficient
even for 20-mm-thick double cantilever beam type specimens, which are the most commonly used
in crack arrest tests.
Double cantilever beam specimens are loaded by various methods including through pins
(off-center tension) [i], by a wedge parallel or transverse to the specimen (compression [4,
5], or by a thrust screw (torsion) [i]. Since each of these methods possesses both advant-
ages and disadvantages it is desirable that the machine permit use of all of these forms of
loading.
In the Institute of Strength Problems of the Academy of Sciences of the Ukrainian SSR
using a KM-50 test machine as a base, a machine with increased rigidity has been built making
it possible to conduct crack resistance tests of double cantilever beam specimens up to 20
mm thick. On it it is possible to load in tension, compression, and torsion. Figure 2 shows
the general plan of the machine, which uses the base i of the KM-50 machine with the drive
mechanism mounted on it and also the fastened steel columns 2. The remaining assemblies and
parts were specially developed for the machine built.
The columns 2 are fastened to each other by the upper crosspiece 5. The feed screw 14
is rotated through a reducer by an electric motor or manually. The feed nut 13 is rigidly
connected to the feed screw and rotation of it causes movement of the lower load rod 12.
This rod is located in the guide sleeve Ii, which is fastened to the lower crosspiece 3.
The tensile or compressive force is transmitted through the rod to the lower clamp I0 and
then to the specimen 9. The upper clamp 8 is connected through the rod 7 with the spherical
bearing 6 to the upper crosspiece. The upper and lower crosspieces are fastened to each other
by the short thrust columns 4.
The specimen is centered by the double cylindrical hinge formed by the joints of the
clamp with the specimens and the clamp with the rod. This method of loading makes it pos-
sible to provide off-center tension of double cantilever beam specimens.
On the machine it is possible to test double cantilever beam specimens with loading of
them with a wedge. In this case the wedge 2 (Fig. 3) is placed in the upper crosspiece i in
place of the upper load rod. The test specimen 3 rests on its end on the lower load rod 5
through the ball 4.
The machine also makes it possible to load the specimen with the use of a thrust screw.
For this the crossbeam and the upper i and lower 4 clamps of the KM-50 test machine are used.
Into the clamps are inserted the thrust screws 3 holding the specimen 2 (Fig. 4).
Institute of Strength Problems, Academy of Sciences of the Ukrainian SSR, Kiev. Trans-
lated from Problemy Prochnosti, No. 8, pp. 121-123, August, 1985. Original article submitted
October 30, 1984.
0039-2316/85/1708-1181509.50 �9 1986 Plenum Publishing Corporation 1181
I !1 I [ I " . ' , 1 -~ I il I / I / I I ' ,
-%- - I - / . . . . . -.- I "
0,05 RIO 0.15 020 32~ a?,mrn
F i g . 1. The r i g i d i t y o f t e s t m a c h i n e s and d o u b l e
cantilever beam specimens: i) the load frame of
a machine for crack resistance testing; 2) the
same with added rods; 3) TsD-40 test machine; 4)
TsD-10 test machine; 5) load frame of a machine
for crack resistance testing with added rods and
studs; 6) 20-mm-thick double cantilever beam
specimen; 7) TsD-4 test machine; 8) TsDMI-30
test machine; 9) 10-mm-thlck double cantilever
beam specimen; i0) Instron TTK-25 test machine.
5 /
a ~
7 8
VA I V/Z '. i I
i
I
i . . -4"--0
1"- '44_11 I I
lk',,~. I ~1"--t-- in
/
Fig. 2. General plan of the machine for
determination of the crack resistance
characteristics in the crack arrest stage.
Increased rigidity of the machine is provided by the fact that the upper and lower
crosspieces (Fig. 2) were produced by welding of thick plates and have a H-shaped cross
section. They are connected to each other by short, heavy thrust columns. The crosspieces
and the columns form the load frame, the rigidity of which is greater than that shown in
Fig. 1 for all of the other test machines. Connection of the load rods to the load frame
reduces the rigidity of the whole system insignificantly. The least rigid element is the
pins with which the clamps are fastened. To a significant degree the presence of the pins
reduces the rigidity of the load system of the machine, which follows from the characteris-
tics presented in Fig. i.
Figure 5 shows the plan of recording the forces and displacements in off-center tension
testing of double cantilever beam testing specimens. The force transmitted to the specimen
is recorded with the use of the strain gauges 6 cemented to the upper load rod 5 connected
to the clamp 4. After amplification in the strain gauge amplifier 7 the signal from the
1182
J
5
F i g . 3
L .......
Fig. 4
Fig. 3. Loading of a specimen with the use of a
wedge.
Fig. 4. Loading of the specimen with the use of
a thrust screw.
Nitrogen ~ 0
1 ," I
Fig. 5. Plan of measurement of the forces,
displacements, and temperature and the de-
vice for cooling the specimen.
T, oE
O -
- L t O -
- 8 0 -
-12C
- #60 -
- 206
I
......... : .... 4 _ _ _ . . . .
Fig. 6. The temperature distribution
along the length of a 20-mm-thick double
cantilever beam specimen.
1183
strain ~auges is supplied to the two-coordinate recorder 8. The displacements on the line
of action of the force are recorded with the use of the bracket 3 on which are cemented the
resistance strain gauges 2. After amplification in the strain ~au~e amplifier 7 the signal
from them is also supplied to the two-coordinate recorder 8. The recorder records the load--
displacement curve.
The specimen I is cooled with two contact coolers i0 to which nitrogen in the Raseous
or liquid state is supplied from a Dewar vessel, and the rate of supply is regulated by a
special device [6].
The specimen temperature is recorded with the copper--constantan thermocouples 9 and
their junctions are welded in the groove along which the crack advances. The surfaces of
the specimen not covered with the coolers are thermally insulated with foam plastic.
The temperature distribution along the length of a specimen is shown in Fi~. 6. With
insignificant cooling (to--40~ the specimen temperature is practically the same over the
whole length while with more thorough cooling the portion of the specimen located near the
clamps has a higher temperature. Selection of the proper length of the original crack makes
it possible to conduct tests under isothermal conditions.
LITERATURE CITED
I. Calculations and Tests for Strength. Methods of Mechanical Tests of Metals. Determina-
ation of the Characteristics of Fracture Toughness (Crack Resistance) in the Crack
Arrest Stage. Method Reco~endations MR71-82 [in Russian], Gosstandart, Moscow (1982).
2. S. Swenson, "The influence of test machine inertia on the validity of fracture tough-
ness values," in: The Fracture Toughness of High Strength Materials [Russian trans-
lation], Metallurgiya, Moscow (1973), pp. 47-55.
3. A.A. Lebedov, V. P. Lamashevskii, and P. T. Alflmov, "An investigation of the influence
of test machine rigidity on the rules of deformation and failure of structurally in-
homogeneous materials," Probl. Prochn., No. 7, 64-67 (1982).
4. R. Hoagland, A. Rosenfield, and D. Hahn, "A method of measurement of Klm , KID , an~ Kla
in retarding of a crack," in: Fracture Mechanics. Rapid Fracture and Crack Arrest
[Russian translation], Mir, Moscow (1981).
5. D. Hahn, A. Rosenfield, K. Marshall, et al., "The concept of crack arrest and its use,"
in: Fracture Mechanics. Rapid Fracture and Crack Arrest [Russian translation], Mir,
Moscow (1981), pp. 222-253.
6. V.P. Yasnil, "A method and certain results of investigation of the rules of fatigue
crack development in plane bending under high-temperature conditions," Probl. Prochn.,
No. 5, 78-81 (1980).
1184
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