Subject
Year
: S1014 / MECHANICS of MATERIALS
: 2008
Introduction
Session 01-02
Introduction to Class’ Rules
Everybody have to :
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Attend the class at least for 10 class session, Tolerance for late students 15 minutes.
Participate in class discussion.
Smoking and sandals in class is NOT allowed
Be an active student
Pay attention about the course material before entering the class session
Search others source to completely the topic ( online reading, browsing the internet,
going to Library )
• Do all the exercises ( IT IS VERY IMPORTANT !! )
• Ready to do assignments/Quiz any time in the class session
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Introduction to Homework’s Rules
• Everybody have to make all home work assignment and give to the
lecturer/ lecturer assistant on the time.
• Whoever doesn’t attend the class without permission, her/his HW
assignment in this session class will not be appraiser
• Do your best for HW Assignment
• Every session has min. 5 additional problems for HW ( from Lecturer
/ Lecturer Assistant ), beside your main HW that you can download
from Binus Maya
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Classification of your HW Assignment
Type :
• Personal
Format :
• There is no a special format but, do your HW systematically & easy
to understand
• If there are instructions to draw the graphics/picture/diagrams
you may use “millimeter block” papers
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Introduction to
MATERIALS
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What are Materials ?
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Common Materials
Common materials are :
Solid
Liquid
Gas
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Solid Material Properties
Solid Material Properties are divided into following categories:
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Physical Properties
Mechanical Properties
Thermal Properties
Electric Properties
Acoustic Properties
Physical properties
• Density
• Melting
• Boiling temperature.
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Mechanical Properties
Including basic mechanical properties, such as
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elastic modulus
shear modulus
Poisson's ratio
mechanical strength properties, i.e., yielding
stress, ultimate stress, elongation
Thermal Properties
• Coefficient of thermal expansion
• Thermal conductivity.
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Electric Properties
• Electric resistivity
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Acoustic Properties
• Compression wave velocity
• Shear wave velocity
• Bar velocity.
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What is elasticity ?
Elasticity is the condition when a material
returns to its original
shape after removing a stress
i.e : rubber bands, wire etc.
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Elastic
Elastic & Inelastic Material Properties
Inelastic
Unstressed Wire
Unstressed Plastic bottle
Apply Compressive stress
Apply Stress
Remove Stress and Material Returns to
Original Dimensions
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Remove compression and Material will
change its shape an dimensions
Compression
Applied stress that squeezes the material
Unstressed Sponge Apply compression Remove Compression and Material
Returns to Original shape
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Compressive Failure
This paper tube was
crushed, leaving an
accordion-like failure
• depends on the cross-sectional
area
• depends on the material
• depends on the length
• depends on the cross-sectional
shape
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Tension
• Applied stress that stretches a
material
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Tensile Failure
• This magnesium test bar is tensile strained until
fracture
• Machine characterizes the elastic response
• Data verifies manufacturing process control
• Frayed rope
• Most strands already failed
• Prior to catastrophic fail
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Force Directions
• AXIAL: an applied force along the length or axis of a material
• TRANSVERSE: an applied force that causes bending or deflection
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Force Direction Examples
Transverse Stress on the Horizontal
Aluminum Rod
Axial Stress on the
Vertical Post
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Yield Stress
The stress point where a
member cannot take any more
loading without failure or
large amounts of deformation.
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Ductile Response
Beyond the yield stress point, the
material responds in a non-linear
fashion with lots of deformation
with little applied force
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Ductile Example
Unstressed Coat Hangar
After Applied Transverse
Stress Beyond the Yield
Stress Point
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Brittle Response
Just beyond the yield stress point, the material immediately fails
Unstressed Stick
Brittle Failure After
Applied Stress Beyond the
Yield Stress Point
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