composite materials iad 232 ass. prof. dr. işıl duman
TRANSCRIPT
COMPOSITE MATERIALSIAD 232 Ass. Prof. Dr. Işıl DUMAN
WHAT ARE THEY?
Through ages, man have become more innovative in discovering new materials, cost reduction techniques aiding life to exist far more better.
A combination of dissimilar materials which retain their individual characteristics yet achieve performance that surpasses the combined performance of the individual materials.
The constituent materials work together yet remain in their original physical forms and chemical compositions, they are not chemically combined
WHAT IS A COMPOSITE MATERIAL? Often shortened to composites or called
composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or microscopic scale within the finished structure.
two materials in which one of the materials, called the reinforcing phase, is in the form of fibers, sheets, or particles, and is embedded in the other materials called the matrix phase. The reinforcing material and the matrix material can be metal, ceramic, or polymer. Composites are used because overall properties of the composites are superior to those of the individual components.
COMPOSİTE MATERİALS
Definition: any combination of two or more different materials at the macroscopic level.
OR Two inherently different materials that when
combined together produce a material with properties that exceed the constituent materials.Reinforcement phase (e.g., Fibers)
Binder phase (e.g., compliant matrix)
Advantages High strength and stiffness Low weight ratio Material can be designed in addition to the structure
Wattle and daub is one of the oldest manmade composite materials, at over 6000 years old. Concrete is also a composite material, and is used more than any other man-made material in the world. As of 2006, about 7.5 billion cubic metres of concrete are made each year—more than one cubic metre for every person on Earth.
A wattle and daub panel in need of repair
1940s and 1950s, aerospace industry looked at high performance composites as replacement for steel .Early materials were glass fiber and polyester resin.
Limited to non-structural applications. Resin and fibers developed and material
systems matured.During the 1960s new fiber systems were
developed for structural componentsHigh strength glass fibers (S-901),
Aramid(Kevlar 49), carbon and graphite systems
WHY COMPOSITES?
High specific strength (strength/density) • High specific modulus (modulus/density) • Fatigue resistance • Creep and creep rupture resistance • Low, tailorable coefficient of thermal
expansion • High temperature capability • Wear resistance • Corrosion resistance • Tailorable electrical conductivityVery low
to very high
WHY COMPOSITES?
Tailorable thermal conductivity very low to extremely high
• Tailorable mechanical and thermal properties • Unique combinations of properties • Great design flexibility • Formable to complex shapes • Low cost (some) • Enabling technology for many applications,
e.g.Lightweight vehicle and aerospace structures
High-performance thermal management Lightweight optical systems Infrastructure repair
TYPES OF COMPOSITES
Particle-reinforced composites
Fiber-reinforced composites
Structural composites
PARTICLE-REINFORCED COMPOSITES* Used in particle reinforcing- ceramics, glasses (small mineral particles)- metal particles (aluminium, and amorphous
materials ) polymers and carbon black
Particles are used to increase the modulus of the matrix, to decrease the permeability of the matrix, to decrease the ductility of the matrix and also used to produce inexpensive composites.
EXAMPLE:CONCRETE where the aggregtes ( sand and
gravel) are the particles and cement is the matrix. Particle reinforced composites support higher tensile, compressive and shear stresses.
FIBER-REINFORCED COMPOSITES Fiber-reinforced Composites are made
of:- metals, ceramics, glasses, or polymers that
have been turned into graphite and known as carbon fibers.
- Fibers increase the modulus of the matrix material. (strong covalent bonds along the fiber's length gives them a very high modulus in this direction because to break or extend the fiber the bonds must also be broken or moved )
USES OF FIBER-REINFORCED COMPOSITES sports equipment, such as a time-trial racing bicycle
frame which consists of carbon fibers in a thermoset polymer matrix. Body parts of race cars and some automobiles are composites made of glass fibers (or fiberglass) in a thermoset matrix
Fiber orientation in fiber reinforced composites.
STRUCTURAL COMPOSITES
The properties of structural composites depend on:
- Constituents - Geometrical design
COMMON COMPOSITE MATERIALS< ASPHALT
FIBER GLASS >
< CEMENT
PLYWOOD>