Çentikli kompozit levhaların hasar davranışlarının incelenmesi

Yıl 2015, Cilt: 6 Sayı: 2, 73 - 82, 01.12.2015

Abdullah Çelik Kadir Turan

Öz

Bu çalışmada, çentikli kompozit levhaların hasar davranışları statik çekme testleriyle deneysel olarak
araştırılmıştır. Sekiz tabakalı örgülü cam elyaf takviyeli epoksi reçine matrisli kompozit levhalar
kullanılmıştır. Levhaya kenarlarından ve ortasından açılan çentiklerin ve fiber takviye açısı değişiminin
levhanın çekme mukavemeti üzerine etkileri incelenmiştir. Fiber takviye açısının etkileri [0o]8, [15o ]8, [30o]8, ve
[45o]8, tabaka dizilimine sahip levhalar için araştırılmıştır. Çentik türü değişimi ise levha ortasında
radyal delik (Tip 1), levha kenarında yarım daire çentik (Tip 2), levha merkezinde dairesel delik (Tip 3) ve
levha kenarında u çentik (Tip 4) olmak üzere 4 farklı çentik türü için incelenmiştir. Fiber takviye açısına
bağlı olarak tüm çentik türleri için hasar yüklerinin azaldığı gözlemlenmiştir. Buna ek olarak çentik türü
değişiminin hasar yükleri üzerinde oldukça etkili olduğu deneysel çalışma sonuçlarından görülmektedir.

Anahtar Kelimeler

Tabakalı kompozit levhalar, hasar analizi, çentik etkisi.

Investigation of Failure Behaviors of Notched Composite Plates

Öz

In this study, the failure behavior of notched
composite plate has been investigated
experimentally by static tensile test. Eightlayered
woven glass fiber reinforced epoxy
resin matrix composite plates have been used.
Notch opened on the middle and by the side of
plates and their effects on the tensile strength
of the fiber reinforcement plate angle changing
has been examined. Effects of the fiber
reinforcement angle has been investigated for
the plate with layer [0o
]8, [15o
]8, [30o
]8, and
[45o
]8. Radial hole in the middle plate (Type
1), semicircular notch on the plate edge (Type
2), a circular hole in the plate center (Type 3)
and U notch on the plate edge (Type 4) has
been examined for 4 different notch types.
Reducing of the failure loads has been
observed for all notch types depending upon
the fiber reinforcement angle reducing. In
addition, that notch type changing is quite
effective on failure loads have been seen from
the experimental results.
3 samples has been produced in the laboratory
and they has been used for each parameter. All
samples has been fixed to the jaws of 100
kNInstron 8800 tensile machine and tests has
been carrying out under the room temperature
conditions. Tensile test speed has been applied
as 1 mm / min. While testing, failure loads and
elongations have been recorded to the
computer automatically and this data has been
used in the desired graphics. Failure loads has
been reducing depending on the reducing of
fiber reinforcement angle, whereas the
elongation rate has been increasing
significantly. Elongation rate has been
decreasing because of effect notch. [0o
]8 plates
has been breaking suddenly without significant
elongation but failure has been incurring with
elongation for the other angels. Alongation to
the other supplements has been realized with a
sudden breakage occurs with prolonged
failure.
The maximum failure load value were
measured as 7297.32 N for [0o
] 8 Type3 notch
type. The minimum failure load was measured
as 1475.50 N for [45o
]8 Type1 notch. Notches
on the composite plates led to a decline as
varying from 78% to 40.4 % rates. If we make
a generalization; Type1 in terms of all fiber
reinforcement angels provides the largest
decline according to the reduction of failure to
the loads and the decrease in load failure is
seen to range between 75.5% and 78% . Type4
failure reduction rate is close to the value of
Type1 , but less than Type 1. Type3 has 50%
average reduction on failure loads. Type1 and
type4 have the maximum reducing rate. the
change of the fiber reinforcement angle is the
most important parameter to determine the
failure loads.
General results from this study; Failure loads
have been decreasing due to the fiber
reinforcement angle increasing. It has been
observed that elongation increased due to the
fiber reinforcement angle increasing. The first
failure of the material has been occurring
earlier due to fiber reinforcement angle
increasing and after resin hardens
immediately, failure progressing time has been
increasing. That changes of notch types are
important on the failure loads has been seen.
Elongation has increased depending on the
notch geometry. Sudden breakages carry out at
[0o
]8plates, these type breakages are unwanted
conditions in terms of types in the structures
because of sudden. Ductile fracture has been
carrying out in the angled plate and there has
been an significant increasing in the
elongation before complete breakage. Type1
equals to Type4; Type2 equals to Type3 about
geometric dimensions. Different notches
locations cause to different failure load values.
Failure load of a circular hole in plate center
(Type 3) is bigger than plate edge semicircular
notch (Type 2). This result is already expected
because of central notch performance. U notch
on the plate edge (Type 4) is bigger than
semicircular notch on the plate edge (Type 2).

Anahtar Kelimeler

Laminated composite, failure analysis, notch effect.