Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions
An experimental study of static and dynamic fracture properties of a spheroplastics (SPH) that has a matrix of polyester resin containing a filler of glass microspheres was conducted. Crack propagation was investigated under loading conditions generated by pulse magnetic field. Microstructure featur...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2002
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| Zitieren: | Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions / S.A. Atroshenko, S.I. Krivosheev, Yu.A. Petrov, A.A. Utkin, and G.D. Fedorovskii // Проблемы прочности. — 2002. — № 3. — С. 92-95. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-467962013-07-06T21:32:22Z Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions Atroshenko, S.A. Krivosheev, S.I. Petrov, Yu.A. Utkin, A.A. Fedorovskii, G.D. Научно-технический раздел An experimental study of static and dynamic fracture properties of a spheroplastics (SPH) that has a matrix of polyester resin containing a filler of glass microspheres was conducted. Crack propagation was investigated under loading conditions generated by pulse magnetic field. Microstructure features of dynamic fracture were analyzed. Проведено экспериментальное исследование статического и динамического разрушения композиционного материала (сферопластика), состоящего из матрицы (полиэстер) с наполнителем в виде стеклосфер. Распространение трещины исследовано при нагружении импульсным магнитным полем. Проанализированы микроструктурные особенности динамического разрушения. Проведено експериментальне дослідження статичного і динамічного руйнування композиційного матеріалу (сферопластик), що складається з матриці (поліестер) з наповнювачем у вигляді скляних сфер. Поширення тріщини досліджувалося при навантаженні імпульсним магнітним полем. Проаналізовано мікроструктурні особливості динамічного руйнування. 2002 Article Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions / S.A. Atroshenko, S.I. Krivosheev, Yu.A. Petrov, A.A. Utkin, and G.D. Fedorovskii // Проблемы прочности. — 2002. — № 3. — С. 92-95. — Бібліогр.: 3 назв. — англ. 0556-171X http://dspace.nbuv.gov.ua/handle/123456789/46796 539.4 en Проблемы прочности Інститут проблем міцності ім. Г.С. Писаренко НАН України |
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Научно-технический раздел Научно-технический раздел Atroshenko, S.A. Krivosheev, S.I. Petrov, Yu.A. Utkin, A.A. Fedorovskii, G.D. Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions Проблемы прочности |
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An experimental study of static and dynamic fracture properties of a spheroplastics (SPH) that has a matrix of polyester resin containing a filler of glass microspheres was conducted. Crack propagation was investigated under loading conditions generated by pulse magnetic field. Microstructure features of dynamic fracture were analyzed. |
| format |
Article |
| author |
Atroshenko, S.A. Krivosheev, S.I. Petrov, Yu.A. Utkin, A.A. Fedorovskii, G.D. |
| author_facet |
Atroshenko, S.A. Krivosheev, S.I. Petrov, Yu.A. Utkin, A.A. Fedorovskii, G.D. |
| author_sort |
Atroshenko, S.A. |
| title |
Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions |
| title_short |
Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions |
| title_full |
Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions |
| title_fullStr |
Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions |
| title_full_unstemmed |
Investigation of Fracture of Spheroplastics under Static and Dynamic Loading Conditions |
| title_sort |
investigation of fracture of spheroplastics under static and dynamic loading conditions |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| publishDate |
2002 |
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Научно-технический раздел |
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http://dspace.nbuv.gov.ua/handle/123456789/46796 |
| citation_txt |
Investigation of Fracture of Spheroplastics under Static and Dynamic
Loading Conditions / S.A. Atroshenko, S.I. Krivosheev, Yu.A. Petrov, A.A. Utkin, and
G.D. Fedorovskii // Проблемы прочности. — 2002. — № 3. — С. 92-95. — Бібліогр.: 3 назв. — англ. |
| series |
Проблемы прочности |
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| first_indexed |
2025-07-04T06:16:59Z |
| last_indexed |
2025-07-04T06:16:59Z |
| _version_ |
1836696052555579392 |
| fulltext |
UDC 539.4
Investigation of Fracture of Spheroplastics under Static and Dynamic
Loading Conditions
S. A. Atroshenko, S. I. Krivosheev, Yu. A. Petrov, A. A. Utkin, and
G. D. Fedorovskii
St. Petersburg State University, St. Petersburg, Russia
УДК 539.4
Исследование разрушения сферопластика при статическом и
динамическом нагружении
С. А. Атрошенко, С. И. Кривошеев, Ю. А. Петров, А. А. Уткин,
Г. Д. Федоровский
Санкт-Петербургский госуниверситет, Санкт-Петербург, Россия
Проведено экспериментальное исследование статического и динамического разрушения
композиционного материала (сферопластика), состоящего из матрицы (полиэстер) с на
полнителем в виде стеклосфер. Распространение трещины исследовано при нагружении
импульсным магнитным полем. Проанализированы микроструктурные особенности динами
ческого разрушения.
Ключевые слова: сферопластик, разрушение, импульс, инкубационное время.
Introduction. The effect of pulse loading on heterogeneous porous medium
is not studied in full, although shock compression of porous matters is widely used in shock wave physics. Interest in porous materials is caused by the
necessity to describe their behavior within the framework of the thermonuclear
synthesis and, moreover, with the needs of creation of new materials for damping
of pulse loads. Porous heterogeneous materials containing glass microspheres are
of great practical interest. Such materials show good constructional and dielectric
properties, as well as high resistance to shock loads. Dynamic strength of
materials containing 42% of glass microspheres by volume or 27.7% by weight
with epoxy binder was analyzed in [1] and assessed as 0.24 GPa. Due to the reinforcement of plastic binder by glass microspheres, density of the new material
decreases significantly, while the damping properties are improved as well.
Addition of microspheres is a proper method to creation of heterogeneous materials with controlled properties.
An approach based on the notion of incubation time [1] and a new testing
method were used to evaluate the dynamic crack resistance of the material.
According to the applied approach, the principal parameter responsible for critical
characteristics of dynamic fracture is the incubation time r, which has to be determined individually for each material and can be found from tests on
macrocracked specimens.
Material and Experimental Technique. The specimens were manufactured as square plates 120 X120 X (9 — 16) mm containing a precracked notch that was
loaded on its faces by a controllable uniform pulse pressure with semi-sinusoidal
© S. A. ATROSHENKO, S. I. KRIVOSHEEV, Yu. A. PETROV, A. A. UTKIN, G. D. FEDOROVSKII, 2002
92 ISSN 0556-171X. Проблемы прочности, 2002, N 3
Investigation o f Fracture o f Spheroplastics
history. The controllable impact loading was provided by an installation [2], based
on the pulse current generator, so that the magnetic field produced a mechanical
pressure, which generated dynamic stress waves, fracture and crack propagation
processes. In the present paper, the basic principles and characteristics of the above installation, which is able to produce controllable pulses of the order of
1 GPa with duration of the order 1 is, are described.
The material under investigation was spheroplastics (SPH) that has a
matrix of polyester resin containing a filler of glass microspheres. In different
specimens, the size of spheres varied in intervals from 6-60 /im and also from
12-60 fim with average diameters of 21-31 im. The SPH density was
p = (0.79± 0.01)-103 kg/m3.
The static characteristics of the material are established on the basis of data
obtained by a standard static testing machine. The elastic modulus obtained from
a standard test is E = 2400 ± 50 MPa. The material ultimate strength turned out to
be equal o c = 12.4 ± 0.9 MPa. The critical value of the stress intensity factor (or
static fracture toughness) obtained from static tensile tests on specimens
containing central cracks is Kic = 0.52 ± 0.03 MPaVm. The longitudinal wave
velocity is c± = 2450 m/s.
Results and Discussion. Two values of pulse duration T were considered:
2.76 is and 4.4 is. The basic characteristic taken from experiments is threshold
amplitude of pulse that turned out to be equal 16.8 MPa and 11.2 MPa
correspondingly for the above durations. The incubation time of the SPH, that
was found from values of threshold amplitudes according to the method described
in [1, 2], is r = 5.0 ± 0.3 is.
In compliance with the incubation time approach, two material constants
KIc and r describe static and dynamic crack resistance of the material on the
given scale level, respectively. The critical parameters of the external loading for
the given construction, which is loaded symmetrically (regarding the crack line)
can be evaluated by means of the criterion [1, 2]:
t
f Ki(s)ds < rKIc,t-r
where Ki( t) is the stress intensity factor as a function of time, which is to be found from the solution of the appropriate dynamic boundary problem.
The dynamic fracture toughness Kw = KI( t*), where t* is time to fracture,
can be considered as a calculated parameter that generally is not needed for
solving a fracture problem. Within the framework of the incubation time theory,
the dynamic fracture toughness is an unstable characteristic depending on the
history of loading and other conditions of problem. The same is confirmed by
numerous experimental observations. In our particular case for the above
threshold pulses, we got: Kw = 0.7KIc for T = 2.76 is, and Ku = 0.74KIc for
T = 4.4 is. It is important that for the threshold pulses the fracture occurs in the stage of decreasing of the stress intensity factor at the crack tip.
The SPH fracture mainly took place in-between glass microspheres. Crack
propagated along the binder rounding spheres. Only in separate cases, it crossed
sphere as illustrated in Fig. 1. Uneven grains of filler can be seen in this figure.
ISSN 0556-171X. npo6n.eubi npounocmu, 2002, N 3 93
S. A. Atroshenko, S. I. Krivosheev, Yu. A. Petrov, et al.
T a b l e 1
Crack Length and Filler Size
Specim en C rack length, m m Filler size,
fimFirst crack Second crack
1 24.0 27.0 48.5
3 9.6 11.9 35.1
4 7.0 11.0 21.1
6 9.0 11.2 30.5
Fig. 1. C rack propagation in the com posite m aterial filled w ith glass m icrosheres.
Two cracks, as a rule, propagate
from the notch tip in specimens: one
goes along the notch, another - under
some angle to the notch. Their sizes
vary in the range of 7-27 mm
depending on the loading conditions.
The crack abruptly changes the
direction of its propagation in different
specimens at the distance 2 or 4 mm
from the fracture starting to deviate
from the previous one at the angle of
8-10°. Then crack changes its direction
once again approximately at the same
distance and under the same angles. A
summary of fractographic SPH
investigations is given in Table 1.
As it follows from the results
given in Table 1, the smaller filler
grain size, the smaller crack length. It
can be explained in the following way:
higher quantity of glass spheres creates
more barriers for crack movement.
More detailed microstructure is
shown in Fig. 2. Traces of plastic flow of binder and microcracks can be seen in
some places around glass spheres. Under more magnification binder deformation
can be seen with pronounced features of hackle or parabolic fracture.
Fig. 2. M icrostructure o f the fracture surface
o f the com posite m aterial filled w ith glass
m icrosheres.
94 ISSN 0556-171X. npo6neMbi npouHocmu, 2002, № 3
Investigation o f Fracture o f Spheroplastics
C o n c l u s i o n s
1. A new testing method was proposed, which allows qualitative and
quantitative evaluation of the dynamic crack resistance of materials.
2. A new approach was developed, according to which the principal
parameter controlling the critical characteristics of dynamic fracture is the
incubation time r that is to be determined individually for each material and can
be found from tests on macrocracked specimens.
3. It has been found that for threshold pulses, the fracture event occurs at the
stage of decreasing of the stress intensity factor Ki(t) at the crack tip.
4. Comparison of fracture properties of various materials demonstrates that
the heterogeneous composite material such as a composite material filled with
glass microspheres has similar characteristics as PMMA.
5. The peculiarities of dynamic crack propagation in the composite materials
filled with glass microsphere and the microstructural aspects of their fracture were
defined:
• The smaller filler grain size, the smaller crack length. This can be
attributed to the fact that more quantity of glass microspheres creates more
barriers for the crack propagation.
• Two cracks, as a rule, propagate from the specimen notch: the first one
propagates along the notch, while the second - under some angle to the
notch. Their sizes change in the range of 7-27 mm depending on the
loading conditions.
Acknowledgements. The work was supported by the RFBR (Grants 99-01-00718, 97-01-05009, 00-01-00484), the Federal Special Program
“Integration,” and the Educational Fundamental Research Center (Grant
97-0-4.3-28).
Р е з ю м е
Проведено експериментальне дослідження статичного і динамічного руйну
вання композиційного матеріалу (сферопластик), що складається з матриці
(поліестер) з наповнювачем у вигляді скляних сфер. Поширення тріщини
досліджувалося при навантаженні імпульсним магнітним полем. Проаналі
зовано мікроструктурні особливості динамічного руйнування.
1. L. J. Weirick, “Shock characterization of epoxy - 42 volume percent glass
microballoons,” in: Shock Compression of Condensed Matter, Elsevier
Science Publishers B.V. (1992), pp. 99 - 102.
2. N. Morozov and Yu. Petrov, Dynamics of Fracture, Springer-Verlag.
Berlin-Heidelberg-New York (2000).
3. S. I. Krivosheev and Yu. A. Petrov, Experimental Unit and the Method of
Investigation of Threshold Fracture Loads for Macrocracked Specimens
under Impact Loading Produced by Pulse Magnetic Field [in Russian],
IPME, St. Petersburg (1997).
R eceived 14. 11. 2001
ISSN 0556-171X. Проблеми прочности, 2002, № 3 95
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