Dairesel delikli kompozit levhalarda gerilme yığılmalarının incelenmesi

Yıl 2016, Cilt: 7 Sayı: 1, 113 - 128, 01.06.2016

Serdar Karakılçık Mahmut Özbay Hamit Adin

Öz

Bu çalışmada, tek eksenli gerilmeye maruz düzlemsel olarak yüklenmiş ve ortasında dairesel delik bulunan
kompozit levhalarda delik kenarlarında meydana gelen gerilme yığılmaları hesaplanmıştır. Hesaplamalarda
dört tabakalı Grafit/Epoksi kompozit levha kullanılmıştır. Gerilme yığılması hesaplamaları Sonlu Elemanlar
Analizi kullanılarak yapılmıştır. Sonlu Elemanlar Analizi ANSYS(v.12.01) yazılımı kullanılarak
gerçekleştirilmiştir.
Gerilme yığılmalarını doğru olarak hesaplayabilmek için ağ yapısının etkinliği yakınsama testi yapılarak
belirlenmiştir. Delik çevresindeki etkin eleman sayısı belirlenerek ağ yapısı her bir model için
oluşturulmuştur. Maksimum gerilme bulunmuş ve ortalama gerilmeye bölünerek gerilme yığılma faktörü
hesaplanmıştır. Bulunan sonuçlar literatürde yer alan sonuçlar ile karşılaştırılmıştır. Ayrıca, fiber takviye
açısının ve levha genişliğinin gerilme yığılmalarına olan etkisi incelenmiştir. Fiber açısının 450 civarında
tutulması, gerilme yığılması açısından büyük avantaj sağlamıştır. Sonuçta, takviye açısı ve levha
genişliği/delik çapı oranı arttıkça gerilme yığılmasının azaldığı görülmüştür. Gerilme yığılması azalırken,
çekme eksenindeki Elastisite Modülü de düştüğünden dolayı malzemenin mukavemeti azalmıştır.

Anahtar Kelimeler

Kompozit malzemeler, Gerilme, Gerilme yığılması, Fiber takviye açısı, Ansys

The investigation of the stress concentration in composite plates with a circular hole

Öz

In this study, the stress concentrations of composite
plate have been investigated numerically by static
tensile test. The stress concentrations that occurred
at the vicinity of the hole that centered on a
laminated composite plate which is exposed to one
axial load have been calculated. Four layered
Grafite / Epoxy composite plates have been used in
calculates. In order to calculate of stress
concentrations was by using Finite Element
Analysis. The Finite Element Analysis was executed
with ANSYS (v.12.01) software program. In
modeling, Shell 99 elements were used.
The analysis on the different diameter of the plate
(10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70
mm, 80 mm and 90 mm) has been examined for 9
different types in the stress concentrations. Effects of
the fiber reinforcement angle has been investigated
for the plate with layer 00, 50, 100, 150, 200, 250
, 300,350, 400, 450, 500, 550, 600, 650, 700, 750
, 800, 850 and 900
. The fiber direction of 00 was adopted to parallel
the axis of the samples. Uniaxial tensile stress was
performed to applying to each model 1 MPa. Effects
of the hole diameter and fiber reinforcement angle
has been investigated for concentrations of stress.
In order to calculate accurately of the stress
concentrations have been determined by the
convergence test of effectiveness of the mesh. Then,
for each model has been created by determining the
number of active mesh elements around the hole.
The number of active elements in the around holes
was found to as 200. Thus, the maximum stresses
formed in the material were found and the factor of
stress concentration is calculated by dividing to the
average tensile. These values are compared with the
values calculated by Lekhnitski (1968) analytical
method.
The obtained results were compared the studies
available in the literature. Besides, the effects of
fiber orientation angle and plate’s width on the
stress concentration have been analyzed. As a result,
the stress concentration was found to be decreased
with the increase of the ratio between fiber
orientation angle and plate’s width to the diameter
of the hole.
The results showed that we need different
approaches to improve the stress concentrations. To
get the higher performance, more effective methods
should be improved. In the future work, we focused
on this problem.
As a continuation of this work was seen that instead
of a single hole on the composite plate of two
adjacent holes the smaller diameter will change to
the extent to which strength what would be the most
appropriate level of distance between the centers of
hole and what can be done in the case of the
analytical solution is not possible, and can be done
in the case of the analytical solution is not possible.

Anahtar Kelimeler

Composite Materials, Stress, Stress Concentration, fiber orientation angle, Ansys.