Introduction Session Subject: S1014 / MECHANICS of MATERIALS Year: 2008

Bina Nusantara Introduction to Class’ Rules Everybody have to : 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

Bina Nusantara 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

Bina Nusantara 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

Bina Nusantara Introduction to MATERIALS

Bina Nusantara What are Materials ?

Bina Nusantara Common Materials Common materials are : Solid Liquid Gas

Bina Nusantara Solid Material Properties Solid Material Properties are divided into following categories: Physical Properties Mechanical Properties Thermal Properties Electric Properties Acoustic Properties

Bina Nusantara Physical properties Density Melting Boiling temperature.

Bina Nusantara Mechanical Properties Including basic mechanical properties, such as elastic modulus shear modulus Poisson's ratio mechanical strength properties, i.e., yielding stress, ultimate stress, elongation

Bina Nusantara Thermal Properties Coefficient of thermal expansion Thermal conductivity.

Bina Nusantara Electric Properties Electric resistivity

Bina Nusantara Acoustic Properties Compression wave velocity Shear wave velocity Bar velocity.

Bina Nusantara 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.

Bina Nusantara Elastic & Inelastic Material Properties Unstressed Wire Apply Stress Remove Stress and Material Returns to Original Dimensions Inelastic Elastic Unstressed Plastic bottle Apply Compressive stress Remove compression and Material will change its shape an dimensions

Bina Nusantara Compression Applied stress that squeezes the material Unstressed Sponge Apply compression Remove Compression and Material Returns to Original shape

Bina Nusantara 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

Bina Nusantara Tension Applied stress that stretches a material

Bina Nusantara Tensile Failure Frayed rope Most strands already failed Prior to catastrophic fail This magnesium test bar is tensile strained until fracture Machine characterizes the elastic response Data verifies manufacturing process control

Bina Nusantara Force Directions AXIAL: an applied force along the length or axis of a material TRANSVERSE: an applied force that causes bending or deflection

Bina Nusantara Force Direction Examples Axial Stress on the Vertical Post Transverse Stress on the Horizontal Aluminum Rod

Bina Nusantara Yield Stress The stress point where a member cannot take any more loading without failure or large amounts of deformation.

Bina Nusantara Ductile Response Beyond the yield stress point, the material responds in a non-linear fashion with lots of deformation with little applied force

Bina Nusantara Ductile Example Unstressed Coat Hangar After Applied Transverse Stress Beyond the Yield Stress Point

Bina Nusantara Brittle Response Just beyond the yield stress point, the material immediately fails Unstressed Stick Brittle Failure After Applied Stress Beyond the Yield Stress Point