Mermi-zırh etkileşiminin analizi
Analysis of projectile-armour interaction
Yazar: HÜSEYİN EKREM DEMİRTAŞ
Danışman: PROF. DR. CELALETDİN ERGUN
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2015
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
İnsanlık tarihi boyunca zırh sistemleri çok önemli bir konuma sahip olmustur. Çünkü
devletler yıllarca birbirleriyle mücadele içerisinde olmus ve sürekli silah anlamında
kendilerini gelistirmek durumunda kalmıslardır. Silah konusunda yasanan bu
gelismelere paralel olarak savunma anlamına gelen zırhlarda gelisim göstermek
mecburiyetinde kalmıstır. Đlkel çağlarda zırh malzemesi olarak daha çok çelik ve
telden olusan sistemler kullanılırken günümüzde teknolojinin sağlamıs olduğu
avantajlarla birlikte zırh sistemlerinde de önemli bir gelisme kaydedilmistir.
Bu çalısmada amaç olarak Al2O3/Al2024 malzemelerden olusan kompozit zırhın
optimum kalınlığı simülasyon yöntemi kullanılarak belirlenmeye çalısılmıstır. İlk
olarak hangi parametlerin kullanılacağı belirlenmistir. Elde edilen parametre
sonuçları yorumlanmıs ve sonuçlara göre modellemeye geçilmiştir.
İlk olarak parametleri belirlenen parametler analiz programında karsılastırılmıstır.
Parametre olarak sınır sartları, ısıl islem durumu, yapıstırıcı etkisi ve katman sayısı
gibi faktörlerin sistem üzerindeki etkileri incelenmis, elde edilen sonuçlara göre
ikinci asama olan seramik/alüminyum oranı hesaplanmıstır.
İlk parametre olan sınır sartları durumu için iki farklı sınır sartı incelenmistir. İlk
olarak sistemin üç eksende hareket etmesi engellenmistir. İkinci durumda ise
merminin gelis yönünde hareketi engellenip diğer yönlerde hareket etmesine izin
verilmistir. Böylece sistemde ön gerilme olusturulduğu düsünülerek bu gerilmelerin
etkisi değerlendirilmis ve çalısmadaki sını sartına karar verilmistir.
İkinci parametre olarak ısıl islem durumunun zırh sistemine etkisi incelenmistir. Bu
çalısmada alüminyum, T3 fazındaki alüminyum malzeme ile T4 fazındaki
alüminyum malzeme karsılastırılmıstır. Böylece verilecek yapılacak çalısmada
kullanılacak alüminyum malzeme belirlenmistir.
Üçüncü parametre olarak ise yapıstırıcı kullanılarak çalısma yapılmıstır. Bu
çalısmada üç farklı durum incelenmistir. İlk durum olarak yapıstırıcı kullanılmamıs,
ikinci durumda 1 mm kalınlığında yapıstırıcı kullanılmıs ve üçüncü durum olarak 2
mm kalınlığında yapıstırıcı kullanılmıstır. Elde edilen sonuca göre zırhda yapıstırıcı
kullanılmalı mı, kullanılacaksa bu kalın mı yoksa ince katmanlı mı olmalı sorusunun
cevabı belirlenmistir.
Son parametre olarak da aynı kalınlıktaki malzemeyi tek ve katman katman ayırarak
katman sayısının zırh üzerinde etkisi incelenmistir. Üç farklı çalısma
gerçeklestirilmistir. Tek katmanlı, iki katmanlı ve üç katmanlı olmak üzere üç farklı
durum incelenmistir. Bu parametrenin incelenme amacı ise katman sayısının
malzeme üzerinde etkisi olup olmadığı anlasılmaya çalısılmıstır.
Bu çalısmada steel 4340 çelik malzemeden yapılmıs mermi ile atıslar
gerçeklestirilmistir. Mermi için malzeme modeli olarak Johnson-Cook dayanım
modeli ve Johnson-Hasar modeli kullanılmıs ve teroik olarak bu modeller
açıklanmıstır.
Seramik levha malzemesi olarak Al2O3 malzemesi seçilmistir ve bu malzeme içinde
Johnson-Holmquist dayanım modeli ve Johnson-Holmquist kırılma modeli modeli
kullanılmıs ve teorik olarak bu model açıklanmıstır.
Alüminyum malzeme olarak T4 fazına ısıl islem görmüs Alüminyum 2024 malzeme
seçilmistir.

Abstract:
Fighting and wars between societies throughout human history have occurred many
times in history, and it does appear that the various sections of humanity will
continue to occur as there are. They heard about the need to defend themselves in
these struggles, people and technology, to the extent permitted time have developed a
variety of methods. This is the first centuries protection is ok, like the bow and the
sword of war against vehicles, while the invention of gunpowder and explosives with
the new requirements have emerged that require different protection technologies.
For example, at first, as the armor material used in a variety of metals and steel,
along with the development of technology today, Al2O3, SiC, B4C composite
structures containing hard ceramic layers are widely used. At the moment, the more
durable, and lighter armor that makes it possible to produce composite structures,
tanks, helicopters, aircraft, warships, such as the production of armor for military
vehicles and personnel protection they deem a wide range of applications.
This armor structures, the outer parts of the ceramic plate, consists of layers of
composite or metal on the inside. Ceramic layers with high hardness and
compressive strength, due to erosion and fragmentation of the bullets that hit them
and they perform a task in the form of the destruction of ballistic impacts. Therefore,
the bullet taken from the first pulse, his head has been destroyed, and a large part of
the energy of the initial phase of the projectile after absorbing side of the ceramic
plate are blocked through the composite layer. In addition, due to much lower
densities much lighter than steel structures forms. However, the major disadvantages
of ceramics is that they are fragile, so it can not be used alone. Be supported in a
layer of metal or composite. Thus, a very hard and tough outer plate, elastic and
shock-absorbing inner layer of a composite structure consisting of a more functional
is concerned. The lower layer, the remaining energy of the bullet as well as to
support the absorption of the ceramic plate, ceramic plate breakage caused by
collision fragments carries out a task as keeping.
Bullet / armor interaction will be examined more closely if the bullet end portion of
the first stage have been destroyed without penetration of the ceramic plate can be
seen. During this process, pressure shock waves caused by the impact is moving
towards the back of the ceramic plate. This is caused by stress waves at the back of
the plate and the ceramic cone-shaped broken. This cone angle varies depending on
the properties of materials and the bullet at the beginning of the bullet due to erosion
of the ceramic plate and ceramic particles of jamming coup against the tip of the
bullet shows in real-time rigid behavior and excessive plastic deformation reveals the
failure.
In the second stage, the bullet enters the cone-shaped armor progression of the
broken pieces of ceramic parts, leads to the spread sideways. Meanwhile armor
begins to be deformed elastically.
In the third stage, the seramic has been fully broken and bullet has been contacted
with aluminum supporter block. The aim of this block is support to seramic. When
bullet contact with seramic, ceramic begin the broken and the same time bending to
backside. This block challenge to bending moment. Mechanical properties of block
should be strong.
The last stage, bullet penetrate through armor system if bullet energy higher then
aluminum damping properties. Chosen backing plate material is ductile material.
Since it is not broken and it is act spring.
The aim of this thesis has been investigated to optimum armour thickness which is
composed of Al2O3/seramic material using simulation aspect. Firstly, used
parameters have been defined. According to parameters results, armour model has
been created.
Firstly, specified parameters have been compared AUTODYNA programme.
Specified parameters are boundry conditions, heat treatment affect, adhesive
thickness affect and layers number ( in this parameter, thickness has not been
changed, only material has been divided two and three layers, recpectively). In this
stage, effect of parameters have been invastigated on the armour system. Secondly,
according to parameters results, armour model has been created and optimum
Al2O3/seramic thickness has been attained.
Parameter which chosen firstly is boundary conditions. In this stage, two boundary
conditions have been chosen. First condition, movement of armor system has been
restricted to three axis. Second condition, only one direction movement has been
restricted and other two directions have been moved freely. The main goal of this
parameter, on the armor has been created to pre-stress. Pre-stress affect has been
investigated. As a result of analysis, boundary condition has been chosen.
As second parameter, heat treatment condition has been chosen and affect of heat
treatment condition has been investigated. Two different heat treatment condition
which is T3 phase and T4 phase aluminum plate has been preferred. Aim of this
parameter investigate to answer of question of how does affect strength of support
plate. After analysis results, backing plate material condition has been decided.
The another parameter is adhesive thickness. In this stage, three different conditions
have been defined. First step no adhesive was used, second step 1 mm thickness
ashesive was used and the last step 2 mm thickness adhesive was used. The aim of
chosen this parameter, to determine whether or not adhesive is required or if
required, should it thick or thin.
The last prameter to chosen, layers status. In this and last stage three different layers
effect has been investigated. Backing plate thickness has not been changed. But
backing plate has been diveded two and three layer, respectively. Three different
which is composed of one layer, two layers and three layers model has been cretaed.
Analysis results has been compared and according to result backing plate layer has
been determined.
Designated bullet diameter is 6.17 mm, length is 27,4 mm. Bullet material has been
chosen hard core steel in AUTODYNA library. The 7.62 mm APM2 Bullet compose
of brass jacket, an end cap, lead filler, and hard steel core. Because the brass jacket
and lead filler had a relatively small effect on the perforation process, jacket and
filler was ignored and only hard steel core designated. For bullet, Johnson-Cook
strength model and Johnson-Cook damage model has been used. Models have been
clarified as therotical. Bullet has been designated to quarter model at ANSYS
Workbench programme.
For front material, Al2O3 seramic material has been chosen. Because this material
both has a lower density and cheap and find easily. For parameter conditions seramic
thickness has not been changed; however, to find optimum thickness ratio thichness
has been varied 9 to 12 mm thickness. For Al2O3 seramic front plate Johnson-
Holmquist strength model and Johnson-Holmquist failure model has been used.
Models have been clarified as therotical. Seramic plate has been designated as
quarter model at AUTODYNA programme. Material has been chosen AUTODYNA
library.
Chosen last material is aluminum. Aluminum 2024-T4 phases has been used for
backing plate. Aluminum material has been heat treated up to T4 phase. Al2024-T4
material has been designated as quarter model at AUTODYNA programme. Material
has been chosen AUTODYNA library.