Hafifletilmiş zırh optimizasyonu ve tasarımı
Lighted armor optimization and design
Yazar: HALİL İBRAHİM KURT
Danışman: DR. ÖĞR. ÜYESİ ÖZGE ÖZDEMİR
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Savunma Teknolojileri Ana Bilim Dalı / Savunma Teknolojileri Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Uçak Mühendisliği = Aircraft Engineering

Özet:
Plastik matrisli kompozit malzemeler balistik uygulamalarında hafiflik performans oranı sebebi ile en çok kullanılmakta olan malzemelerdir. Pek çok çeşit plastik matris vardır. Örnek olarak; Epoksi, polyester, vinlyester bunların en çok kullanılanlarıdır. Her matris malzemesinin kendine has özellikleri vardır. Epoksi malzemesi daha mukavemetli olmasına rağmen emdirilmesi zordur. Polyester malzemesi ise tam tersi özellikte davranış göstermektedir. Kompozit malzemlerde iyi yada kötü bir özellik yoktur. Optimizasyon ve mühendislik çalışması vardır. Biz hangi özellikleri istiyorsak ona göre bir seçim yapmamız gerekmektedir, Matris malzemesini seçerken kullanılacak alan, üretim prosesi istenecek kuvvet değerleri baz alınmalıdır. Biz savunma sanayi ürünü olması, zırh uygulamasında kullanılması ve takviyre malzemesini aramid olmasından ötürü, matris malzemesi olarak epoksi seçilmiştir.  takviye malzemesinde ise; polimer matrisli kompozit malzemelerde genel olarak 3 temel takviye elemanı kullanılmaktadır. Bunlar; karbon, cam elyaf ve aramid takviye elemanı olarak sıralarsak; bu elemanlar ayrıca kırpıklı, sürekli ve kumaş olmak üzerede belli sınıflara ayrılmaktadır. Her takviye elemanınn kendine has özellikleri vardır. Karbon fiber çok dayanıklı mazleme diye düşünülürken aramid saçaklı yapısı sebebi ile enerji absorbe özelliği daha yüksektir. Bu sebep ile takviye elemanı olarakta aramid seçilerek kompozit malzeme balistik sürece uygun hale getirilmiştir. Çalışma uygun malzemelerin seçimi ve dizilimi ile ilgili optimizasyon çalışması üzerinde durmaktadır. Farklı katlarda plakalar oluşturulup 5 ve 10 metrelik mesafelerde atış yapılmış yapılan atış sonrası geçirgenlik durumu incelenmiştir. İncelemelerde dikkate alınan değerler tabakalı yapıların kurşun geçirgenliğe etkisi ve kumaş örgü tipi etkisi gözlemlenmiştir. Yapılan tesler ve incelemeler göstermiştir ki katman sayısı arrtıkça kurşun geçirgenliği artmış. Geçirgenlik başarılı sonuçlar verirken ağırlık konususunda negatif sonuç vermiştir. Bu yüzden seçim konusunda birinci kriter geçirkenliği sağlayan minimmum değerdeki tabakalı yapı seçilmelidir. Bizim testlerimize göre bu yapı 20 katmalı kompozit yapısıdır. Bunun haricinde fiberlerin örgü yapısıda incelenmiş olup çapraz örgü ve kare örgü özelliklerinin kurşun geçirgenliğine herhangi bir etkisi olmadığı gözlemlenmiştir. Son deneme ise özel bir fiber yapısı ve örgü tipi ile deneme yapılmıştır. Bu yapı katman sayısını 10 kat daha arttırmamıza rağmen ağırlık olarak 20 kat ile aynı değeri vermiştir.

Abstract:
All living things need to protect themselves against attacks from outside world instinctively. And likewise, throughout history human beings not only have taken precautions against environmental factors but also against attacks from enemies. These precautions include precautions against leather, metal and metal derivatives, ditches, city walls and castles. And today, the combination of light fabrics having high resistance and elasticity with polymers forms the basis for ballistic panel and armour production. Investments in the area of ballistics, particularly military investments, as well as academic and military studies, indicate the significance of the issue. This study examines the characteristics of the composites used in ballistic panel and personal protective armour production; the combinations of the protectors made of composite materials and the ballistic tests applied to these protectors. This study which is a collection of the existing studies by examining them will provide literature support for studies on ballistic.
The French word is balistique, is a science that examines the way a bullet reaches the target from a gun (barrel), changes its movement depending on the variables in the shooting environment, absorbs the energy after it hits the target, and deforms / deforms the behavior.
The science of ballistics is divided into three groups: internal ballistics, external ballistics and terminal ballistics. In the inner and outer ballistics, the barrel and air movements of the projectile, and in terminal ballistics, the projectile that hits the target and the deformations occurring in the target are examined.
After all these definitions, armor (protective) design, characteristics and investigation of deformation areas is the subject of terminal ballistics.
Polymer materials have shown significant improvements in the last 25-30 years and have become the materials used in our daily life and in almost every branch of the industry. Polymers are different from steel and other conventional materials due to their structure and their advantages are being expanded by using their advantages.
The main objectives of polymer and polymer composites are to produce at least as robust as steel, as light as possible, resistant to high usage temperatures and economical materials. Today, the automotive sector has undoubtedly the largest share in the use of advanced engineering materials. While the use of various plastic materials in cars is around 10%, plastic composites are unbeatable in some special applications such as buffers.
According to the properties expressed in terms of daily life such as strength, flexibility, lightness, resistance to environmental conditions (humidity, solar rays, etc.), impact resistance, hardness, thermal expansion coefficients, fatigue, cracking and fracture, tensile, bending strength and similar values are sought.
It is extremely rare to find all the desired properties in a single metal, ceramic or polymer material.

Matrix based on composite materials are used in ballistic applications due to their lightness performance ratio. There are many kinds of plastic matrices. For example; Epoxy, polyester, vinlyester are the most commonly used. Each matrix material has its own characteristics. Although the epoxy material is more durable, it is difficult to impregnate. Polyester material has the opposite behavior. 

Composite materials have no good or bad properties. There is optimization and engineering work. We need to make a selection according to which properties we want, the material to be used in the selection of the matrix material, the production process should be based on the force values to be requested. We have chosen epoxy as matrix material because it is a product of defense industry, it is used in armor application and it is aramid reinforcement material. 

In the reinforcing material as polymer matrix composite materials, There are 3 basic reinforcing elements. These; carbon, glass fiber and aramid reinforcing elements; these elements are further cropped, continuous and to be classified into certain classes. Each reinforcing element has its own characteristics. While carbon fiber is thought to be very durable material, its energy absorbing feature is higher due to its aramid fringed structure. For this reason, by choosing aramid as the reinforcing element, the composite material was made suitable for the ballistic process. 

When we examine the production technique, different techniques are used from the production of reinforced plastic composite. The geometrical shape (simple or complex shape), size, resin type and properties of the part to be molded, reinforcing shape (continuous or discontinuous filament, knitting, fabric, felt, etc.), the expected properties of the material are the main factors affecting the process selection. In the production methods using thermoset resin, the curing of the resin at low or high temperatures, fast or slow curing, and the reinforcing form used are separate criteria for process selection.

The impregnation step can be summarized as wetting the fibers with the resin. This creates bonds between the fibers and the resin. In many processes, impregnation is the first step for composite production. Fiber - matrix bond is one of the main factors that affect the mechanical properties of the composite material. For this reason, care must be taken to ensure that the fibers are completely wetted with resin during the impregnation process. It should be ensured that there are no defects such as air gap and moisture that will disrupt the fiber - matrix bond. The deposit is considered as the second step. In this step, the desired thickness is obtained by combining the layers one after the other until reaching the required number of layers for the design. The reinforcing process is performed to remove excess air or air voids between the layers during the depositing process from the system. By this process, defects that will occur between the layers of the laminate structure are eliminated. Solidification is the final step in composite production. The solid resin is solidified to give the composite structure a solid shape. During the solidification, the resin forms a solid phase by forming chemical bonds within itself. This process is called curing. In general, processes such as pressure, vacuum or temperature can be applied during this process.


In this study plastic based on composite materials are used in ballistic applications due to their lightness/performance ratio. Composite material was made suitable for ballistic process by selecting aramid as reinforcing material, epoxy as matrix material. The study focuses on the optimization of the selection and arrangement of suitable materials. Plates were formed on different stacking and then shoting at 5 and 10 meters distances were examined. 

Tests and investigations have shown that lead permeability increased as the number of layers increased. Permeability yielded successful results and negative results in weight. Therefore, the first criterion for selection should be the layered structure of minimmum value which provides the permeability. 

According to our tests, this structure is a 20-layer composite structure. In addition, the weave structure of the fibers was also examined and it was observed that the cross-woven and square-woven properties had no effect on lead permeability. The last experiment was made with a special fiber structure and knitting type. Although this structure increased the number of layers by 10 times, it gave the same value as 20 times by weight.