Identification method of structural defects in glass fiber fabric/epoxy resin laminate
We present the experimental methods proposed for the identification of structural defects of the laminate constituted of 12 layers of glass fiber fabric/epoxy resin. Two techniques of control were used to analyze the principal structural defects (local or global disorientation). The first tech...
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2009
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| Цитувати: | Identification method of structural defects in glass fiber fabric/epoxy resin laminate / A. Naceri // Проблемы прочности. — 2009. — № 6. — С. 119-124. — Бібліогр.: 7 назв. — англ. |
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Naceri, A. 2013-08-20T12:06:44Z 2013-08-20T12:06:44Z 2009 Identification method of structural defects in glass fiber fabric/epoxy resin laminate / A. Naceri // Проблемы прочности. — 2009. — № 6. — С. 119-124. — Бібліогр.: 7 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/48511 539.4 We present the experimental methods proposed for the identification of structural defects of the laminate constituted of 12 layers of glass fiber fabric/epoxy resin. Two techniques of control were used to analyze the principal structural defects (local or global disorientation). The first technique provides a superficial observation (macroscopic analysis) of the superior and lower surfaces of each layer, while the second one ensures internal observation (microscopic analysis) of the different layers after pyrolysis of the matrix (delamination of the laminate). Описано експериментальні методи для ідентифікації структурних дефектів у 12-шаровому ламінаті на основі скловолокнистої тканини й епоксидної смоли. Для аналізу основних структурних дефектів (локальна або глобальна дезорієнтація) використовували два методи. Один метод забезпечує дослідження (макроаналіз) верхньої і нижньої поверхней кожного шару, інший - внутрішнє дослідження (мікроаналіз) кожного шару після піролізу матриці (деламінації ламінату). Описаны экспериментальные методы для идентификации структурных дефектов в 12-слойном ламинате на основе стекловолокнистой ткани и эпоксидной смолы. Для анализа основных структурных дефектов (локальная или глобальная дезориентация) использовались два метода. Один метод обеспечивает исследование (макроанализ) верхней и нижней поверхностей каждого слоя, другой - внутреннее исследование (микроанализ) каждого слоя после пиролиза матрицы (деламинации ламината). en Інститут проблем міцності ім. Г.С. Писаренко НАН України Проблемы прочности Научно-технический раздел Identification method of structural defects in glass fiber fabric/epoxy resin laminate Метод идентификации структурных дефектов в ламинате на основе стекловолокнистой ткани и эпоксидной смолы Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| title |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate |
| spellingShingle |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate Naceri, A. Научно-технический раздел |
| title_short |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate |
| title_full |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate |
| title_fullStr |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate |
| title_full_unstemmed |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate |
| title_sort |
identification method of structural defects in glass fiber fabric/epoxy resin laminate |
| author |
Naceri, A. |
| author_facet |
Naceri, A. |
| topic |
Научно-технический раздел |
| topic_facet |
Научно-технический раздел |
| publishDate |
2009 |
| language |
English |
| container_title |
Проблемы прочности |
| publisher |
Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| format |
Article |
| title_alt |
Метод идентификации структурных дефектов в ламинате на основе стекловолокнистой ткани и эпоксидной смолы |
| description |
We present the experimental methods proposed
for the identification of structural defects of the
laminate constituted of 12 layers of glass fiber
fabric/epoxy resin. Two techniques of control
were used to analyze the principal structural defects
(local or global disorientation). The first
technique provides a superficial observation
(macroscopic analysis) of the superior and lower
surfaces of each layer, while the second one ensures
internal observation (microscopic analysis)
of the different layers after pyrolysis of the
matrix (delamination of the laminate).
Описано експериментальні методи для ідентифікації структурних дефектів у
12-шаровому ламінаті на основі скловолокнистої тканини й епоксидної
смоли. Для аналізу основних структурних дефектів (локальна або глобальна
дезорієнтація) використовували два методи. Один метод забезпечує дослідження
(макроаналіз) верхньої і нижньої поверхней кожного шару, інший -
внутрішнє дослідження (мікроаналіз) кожного шару після піролізу матриці
(деламінації ламінату).
Описаны экспериментальные методы для идентификации структурных дефектов в 12-слойном
ламинате на основе стекловолокнистой ткани и эпоксидной смолы. Для анализа основных
структурных дефектов (локальная или глобальная дезориентация) использовались два метода.
Один метод обеспечивает исследование (макроанализ) верхней и нижней поверхностей
каждого слоя, другой - внутреннее исследование (микроанализ) каждого слоя после пиролиза
матрицы (деламинации ламината).
|
| issn |
0556-171X |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/48511 |
| citation_txt |
Identification method of structural defects in glass fiber fabric/epoxy resin laminate / A. Naceri // Проблемы прочности. — 2009. — № 6. — С. 119-124. — Бібліогр.: 7 назв. — англ. |
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AT naceria identificationmethodofstructuraldefectsinglassfiberfabricepoxyresinlaminate AT naceria metodidentifikaciistrukturnyhdefektovvlaminatenaosnovesteklovoloknistoitkaniiépoksidnoismoly |
| first_indexed |
2025-11-26T13:57:36Z |
| last_indexed |
2025-11-26T13:57:36Z |
| _version_ |
1850623855096233984 |
| fulltext |
UDC 539.4
Identification Method of Structural Defects in Glass Fiber Fabric/
Epoxy Resin Laminate
A. Naceri
Mohammed Boudiaf University, M’sila, Algeria
УДК 539.4
Метод идентификации структурных дефектов в ламинате на основе
стекловолокнистой ткани и эпоксидной смолы
А. Насери
Университет им. Мохаммеда Будиафа, Мейла, Алжир
Описаны экспериментальные методы для идентификации структурных дефектов в 12-слой
ном ламинате на основе стекловолокнистой ткани и эпоксидной смолы. Для анализа основных
структурных дефектов (локальная или глобальная дезориентация) использовались два мето
да. Один метод обеспечивает исследование (макроанализ) верхней и нижней поверхностей
каждого слоя, другой - внутреннее исследование (микроанализ) каждого слоя после пиролиза
матрицы (деламинации ламината).
К л ю ч е в ы е с л о в а : структурный дефект, пластина, композитный материал.
Introduction . The greatest advantage o f com posite materials is strength and
stiffness combined with lightness. Generally, a com posite material is com posed o f
reinforcement (fibers, particles and/or fillers) embedded in a matrix (polymers,
metals or ceramics). The matrix holds the reinforcement to form the desired shape
w hile the reinforcement improves the overall m echanical properties o f the matrix
[1]. According to the form o f reinforcement, com posite materials can be classified
as follows: a) fibers as reinforcement (fibrous composites): random fiber- (short
fiber-) reinforced com posites and continuous fiber- (long fiber-) reinforced
com posites, b) particles as reinforcement (particulate com posites), and c) fillers as
reinforcement (filler com posites).
The microstructural analysis describes the composition and structure (including
defects) o f the material that are significant for study o f its properties. The analysis
o f manufacturing defects o f a com posite is necessary for the control o f the material
quality. Am ong w idely used methods are: optical m icroscope (OM ), transmission
electron m icroscope (TEM) or scanning electron m icroscope (SEM ). The non
destructive testing methods used to verify voids, delaminations and density are
acoustic em ission, radiography and ultrason. The investigations o f the m icro
structure o f fiber-reinforced polym er com posite laminates can be visualized by
means o f optical or acoustic techniques [2, 3].
The structural strength o f laminate is dependent on filament strength, matrix
or resin strength, and fiber orientation. The m echanical strength o f a com posite is
based on the interaction o f fiber and matrix in a process that depends upon ply or
© A. NACERI, 2009
ISSN 0556-171X. Проблемы прочности, 2009, № 6 119
A. Naceri
layer thicknesses and percent o f fiber volum e. In the manufacturing process,
filaments should be tested for tensile strength, elastic m odulus, density, diameter,
and stiffness. Matrix rheology must be characterized through chemical and physical
testing. The preimpregnated material should be tested as to its satisfaction o f
chem ical and thermal requirements. The laminate com posites should be tested for
m echanical strength (com pression, flexion, and shear).
The m echanical behavior o f this type o f w oven structure is very com plex
because o f the particular problem involved in the geom etry o f the fiber network on
w hich depend the structural properties. The significant question w hich arises for
this type o f configuration is the determination, according to each application, o f
the choice o f the fibrous and resinous system , the nature o f adhesion
“renforcement/matrix,” the technique o f implementation, in order to obtain optimal
characteristics. The system o f reinforcement more com m only used for the
developm ent o f the fabrics is the textile glass fiber because o f is excellent ratio:
mechanical performance/price.
The two principal parameters w hich guarantee the quality o f the system o f
w eaving are [4, 5]: surface density (size o f yarns and type o f armour) and counts
(number o f chain yarns and fill yarns).
The w aving o f the yarn in the w oven is a parameter w hich characterizes the
undulation o f the yarn follow ing the selected direction (warp and w eft), it depends
on the follow ing principal factors: number o f yarns and conditions o f weaving.
The w aving o f the yarn in the w oven (K ) is the relation between the length o f
a fabric and the length o f the yarn w hich is necessary to make weaving. Denser
weaving, larger is the embuvage. It is defined by the follow ing expression [6]:
Lf
K (%) = — -100,
L y
where L f is length o f fabric and L y is length o f yarn.
A fabric comprises yarns warp and yarns weft. It is characterized by four
follow ing elements [7]:
(i) the w eave (armour): m ode o f intersection o f yarns between them;
(ii) the account: number o f warp yarns and w eft yarns;
(iii) the nature o f yarns: carbon, kevlar, aramid, and glass;
(iv) density o f yarns before/during weaving.
This study presents the identification approach used for analysis o f manufacture
defects o f laminate (glass fabric fiber/resin epoxy). The results obtained show the
good detection o f defects o f com posite studied. The structural properties o f
laminate depend strongly o f fabrication process and the material microstructure.
E xperim ental D etails. M a te r ia l U sed. The material used was a laminate
constituted o f 12 layers o f glass fiber fabric at taffeta w eave (the warp yarn and
w eft w eaving alternatively) drowned in an epoxy resin. It is delivered in the form
o f plane plates (five plates) o f average size: 350 (w eft direction) X 340 (warp
direction) X 3.2 mm (thickness). The fiber volum e fraction o f the w oven fabric
com posite (glass fiber fabric/epoxy resin) w as approximately 55% and the density
3
was about 1.94 g/cm . The volum e fraction o f fibers w as given according to the
120 ISSN 0556-171X. Проблемы прочности, 2009, N 6
Identification Method o f Structural Defects
method o f calcination and found equal to V f = 30%. The five studied plates
carried numbers 1, 2, 3, 4, and 5 and have 12 layers each.
A n a ly s is o f S tru c tu ra l D efec ts . Initially, the visual observation o f external
surfaces w as used to make a sketch o f the orientation o f the rovings o f the chain
(warp) and w eft o f the two external layers o f the sheet (plate) on a tracing (Fig. 1).
II
PLATE
---------——
—
-
\\ ,\RP
W1 F T
Fig. 1. Orientation defects of layers of the plate (solid lines correspond warp and weft directions of
the superior layer, dashed lines - warp and weft directions of the lower layer).
The control method o f the orientation defects o f rovings used consisted in
measuring the four representative angles o f the defects observed in ten points
distributed in each plate, then the average o f the values obtained was assessed,
whereas the follow ing angles were measured:
a warp is angle measured between the warps o f the layers (superior/lower);
a wef t is angle measured betw een the w efts o f the layers (superior/lower);
a 1warp /weft is angle measured between the rovings o f the warp (chain) and the
w eft for the superior layer (1);
a 12warp/weft angle measured between the rovings o f the warp and the w eft for
the lower layer (12).
R esults and D iscussion. From the results o f the visual observations (Table 1)
one can see that the variation o f the angles a warp, a wef t , a 1warpiwej t , and
a 12warp/Weft o f the layers (superior/lower) is very low for the most plates (Nos. 1 - 4),
except for plate 5 for w hich the variation is very significant. In particular, the
angles a warp (angle measured between the warps o f the layers: superior/lower)
and a wef t (angle measured between the wefts o f the layers: superior/lower) are
definitely larger for plate 5 than for the other plates.
The variation o f the w eaving in the w eft direction is, in general, much more
significant than that observed in the warp direction. This variation is more reduced
for plate 4.
The second phase o f the study im plied the analysis and identification with
precision and a certain degree o f confidence o f the local orientation defects in the
structure o f the layers o f each plate. This requires the pyrolysis o f the matrix
(epoxy resin). Two samples o f 20 mm were studied (Fig. 2) in each plate in the
sides left (sm all white square) and right (sm all black square).
ISSN 0556-171X. npo6n.eubi npounocmu, 2009, № 6 121
A. Naceri
T a b l e 1
Results of the Representative Angles of the Defects Observed
Plates ^ warp •
deg
^ weft•
deg
^Iwarp/weft•
deg
^12warp/weft •
deg
1 0.6 1.5 91.5 89.0
2 0 1.5 90.5 89.5
3 0 1.6 90.5 89.5
4 0 1.0 91.5 88.5
5 1.0 4.0 93.5 88.5
T a b l e 2
Results of the Principal Orientation Defects of the Plates
Plates Samples (t1 warp
deg
a weft •
deg
^warp / weft •
deg
1 Left side 0 0 90
Right side 2.0 2.0 88 to 90
2 Left side 0 2.0 88 to 90
Right side 0 0 88.5 to 90
3 Left side 0 0 90 to 91
Right side 3.5 4.0 86 to 91
4 Left side 0 2.0 88 to 90
Right side 0 2.0 88 to 90
5 Left side 2.0 1.5 87 to 89
Right side 4.0 1.5 84 to 86
350
Fig. 2. Explanatory diagram of the two samples observed on each side (left and right) of the plate.
The study o f visual observation o f the various layers after pyrolysis o f the
matrix required the follow ing steps:
(i) to carbonize the resin, in order to preserve only the separated layers o f the
laminate (taffeta o f glass);
122 ISSN 0556-171X. npo6n.eubi npounocmu, 2009, N 6
Identification Method o f Structural Defects
(ii) to photograph each layer on slide;
(iii) to project these slides, in order to obtain a schematic o f the orientation o f
rovings o f the warp and w eft o f each layer;
(iv) to superimpose the schem atics obtained for the same sample o f the layers
in order to analyze the local orientation defects possibly observed.
For each layer one defines the follow ing angles: a'warp is maximum angle
between the rovings o f the warp relative to a reference, a'wef t is maximum angle
between the rovings o f the w eft relative to a reference, and a'warp /wef t is angle
between the rovings o f the warp and the w eft o f the layer.
Table 2 shows for each plate the maxim um values o f the three defined angles,
those clearly confirm notable confusions o f plate 5 and a good quality o f plates 1
and 2.
C onclusions. The above visual observation method (m acroscopic and m icro
scopic analysis) has permitted us to identify and classify the studied plates, starting
from the results obtained, in three categories w hich are:
- plates 1 and 2 are a priori acceptable to realize tests (light variation o f the
undulation defects w ith a dispersion about 2°);
- plates 3 and 4 are o f average quality but can be used;
- plate 5 is o f poor quality.
Р е з ю м е
Описано експериментальні методи для ідентифікації структурних дефектів у
12-ш аровому ламінаті на основі скловолокнистої тканини й епоксидної
смоли. Для аналізу основних структурних дефектів (локальна або глобальна
дезорієнтація) використовували два методи. Один метод забезпечує дослід
ження (макроаналіз) верхньої і нижньої поверхней кожного шару, інший -
внутрішнє дослідження (мікроаналіз) кожного шару після піролізу матриці
(деламінації ламінату).
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fabrics,” Inst. M ech . E ng. (2004).
2. W. Bai and B. S. W ong, “Evaluation o f defects in com posite plates under
convective environments using lock-in thermography,” M easu r. Sci. Technol.,
12, 142-150 (2001).
3. M. A bu-K housa, W . Saleh, and N . Qaddoum i, “D efect im aging and
characterization in com posite structures using near-field m icrowave non
destructive testing techniques,” C om pos. S tru ct., 62, N o. 3-4, 2 5 5 -2 5 9 (2003).
4. G. Giorleo and C. M eola, “Location and geom etry o f defects in composite
laminates from infrared im ages,” J. M ater. Eng. P erform ., 7, N o. 3, 3 67 -374
(1998).
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(1997).
ISSN 0556-171X. Проблеми прочности, 2009, № 6 123
A. Naceri
6. P. Boisse, B. Zouari, F. Dumont, et A. Gasser, “Assemblage de fibres par
tissage: analyse et simulation du comportement mécanique,” Mécanique &
Industries, 6, 65-74 (2005).
7. K. Buet-Gautier and P. Boisse, “Experimental analysis and modeling of
biaxial mechanical behavior of woven composite reinforcements,” Exp. Mech.,
41, No. 3, 260-269 (2001).
Received 09. 02. 2009
124 ISSN 0556-171X. npoôëeMbi npounocmu, 2009, N 6
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