Sıcaklık Etkisindeki Metal Matrisli Kompozit Dönen Diskteki Isıl Gerilmelerin Analizi
Öz
Bu çalışmada, ortasında dairesel delik bulunan bir kompozit disk modellenmiştir. Kompozit malzeme,
alüminyum matrise sahiptir ve çelik fiberlerle takviye edilmiştir. Çözüm için sonlu elemanlar metodu (FEM)
tercih edilmiştir. Sonlu elemanlar metodu son zamanlarda çeşitli alanlardaki birçok mühendislik
probleminin çözümünde tercih edilen bir yöntemdir. Bu amaçla, modelleme ve analizler için ANSYS yazılımı
kullanılmıştır. Kompozit disk önceki çalışmalardan farklı olarak, üç boyutlu olarak oluşturulmuştur. Üç
boyutlu kompozit disk modeli üzerine çeşitli sınır şartları, uniform sıcaklıklar (60, 90, 120, 150, 180, 210,
240 ve 270 °C) ve açısal dönmeler (10, 20, 30, 40 rad/sn) uygulamıştır. Daha önceki çalışmalarda genel
olarak, tek bir yük nedeniyle oluşan gerilmeler ve dolayısıyla tek bir yükün yapı üzerine etkisi incelenmiştir.
Bu çalışmada ise sıcaklık ve açısal hız birlikte uygulanmak suretiyle, kompozit disk üzerinde oluşan
gerilmelere, iki yükün birden etkisi incelenmiştir. Meydana gelen ısıl gerilmelerin miktarları hesaplanmış ve
disk üzerindeki dağılımları elde edilmiştir. Radyal, teğetsel ve z-yönlerinin hepsi için gerilmelerin değerleri
ve dağılımları elde edilmiştir. Farklı yükleme durumlarına göre elde edilen sonuçlar, birbiriyle
karşılaştırılmıştır. Elde edilen sonuçlara göre, ısıl gerilmelerin değerleri ve dağılımlarının, uygulanan
uniform sıcaklık ve açısal hız değişimine bağlı olarak değişim gösterdiği anlaşılmıştır.
Anahtar Kelimeler
Analysis of Thermal Stresses in Metal Matrix Composite Rotating Disc Exposed Temperature
Abstract
The goal of this study analysis of thermal stresses in
a metal matrix composite rotating disc that was
exposed temperature.
The composite material was aluminum matrix and it
was reinforced by steel fibers, curvilinearly. The
material properties provided from earlier studies
(Çallıoğlu vd., 2006; Altan ve Topçu, 2010).
These researchers have produced this composite
material and they measured mechanical
properties of it via experimental techniques.
The finite element method (FEM) was preferred for
solution. Since, it is known that FEM is a powerful
tool for solving of many engineering problems
recently. A lot of previous studies pointed out that
the FEM results were in a good agreement with
experimental results and analytical results.
ANSYS software was used for both modeling and
analyses of rotating composite disc. Because, many
researchers and designers have preferred this
program for thermal stress problems and etc.
The metal matrix composite disc was created as
three dimensional as a difference from previous
studies. This was an innovation for solving the
composite disc problem. Since modeling and solving
of this problem were very difficult for researchers
using analytical methods, especially. FEM and
ANSYS were supplied to solve this problem as three
dimensional easily.
The ¼ part of the composite disc was modeled
because of the symmetry condition. It is an
advantage of FEM solution. Therefore, symmetry
boundary conditions were applied on three
dimensional composite disc. A circular hole was
also created in center of disc.
Mapped mesh was created on three dimensional
disc. It is known that the designing of a structure
with mapped mesh is very difficult if structure have a
circular hole and circular dimensions. When the
structure is three dimensional, creating of mapped
mesh is also very hard.
Various boundary conditions were performed on
three dimensional composite disc. Firstly, some
uniform temperatures were applied on it as 60, 90,
120, 150, 180, 210, 240 ve 270 °C. And then
angular velocities were carried out as 10, 20, 30, 40
rad/s. It is mean that ecah uniform temperature were
applied on disc when one of the angular velocity was
also peformed.
Briefly, stresses of the three dimensional composite
disc were determined for both temperature effect
and rotation in the same time. Analyses were done
for all uniform temperatures and angular velocities.
It is said that only one loading condition was
applied on the disc in many previous studies.
Because, appliying of two loading condition were
difficult.
The magnitudes of thermal stresses were calculated
and its distributions were obtained on the disc. The
obtained results were compared with each other.
According to different loading conditions mentioned
as uniform temperature effect and rotation, values
and distributions of thermal stresses were changed
by changing magnitudes of uniform temperatures
and angular velocities.
The highest values of stresses were calculated when
270 °C uniform temperature applying and 40 rad/s
angular velocity. The lowest values of stresses were
calculated when 60 °C uniform temperature
applying and 10 rad/s angular velocity.
The magnitudes of stresses for tangential and radial
directions were higher than z-direction. The
distributions of stresses on the disc were seen as
similar for radial and tangential directions, whereas
distributions of stresses were very different for zdirection.
Both tensile and compressive stresses were occurred
on the three dimensional disc. It was understood that
the anisotropic material properties of composite disc
caused this case. Different thermal expansion
coefficients related to directions of composite were
important occurring, magnitudes and distributions
of stresses.
Keywords
