Unit 1 Topic: Engineering I. Reading skills Pre-reading tasks

Mechanical Properties of Materials
In both manufacturing and construction, mechanical engineers develop methods for making products. They need to know the properties of materials to be used.
Mechanical properties have to do with how a material reacts to loads and forces. Testing can determine mechanical properties. By means of testing, the best material for a product can be chosen.
Ductility
If a material has high ductility, its shape can be changed without breaking it. Aluminum is very ductile. This is why it is used in foils, such as food wraps, that are meant to be shaped or folded.
Elasticity
If a material is elastic, it can be pulled or pushed out of shape, but it will return to its original shape.
Brittleness
When a force is applied to brittle materials, they break easily.
Hardness
A hard material cannot be scratched or dented easily.
Tensile strength
Tensile strength is the ability of a material to resist being pulled apart. Materials with tensile strength are usually very dense or compact.
Compressive strength
Compressive strength is the opposite of tensile strength. It is the ability of a material to resist being crushed.
Shear strength
Shearing is pushing a material in opposite directions at the same time. This is what happens when you tear a sheet of paper in half. You pull one half toward you and the other half away from you.
Fatigue strength
When you’re fatigued, you’re tired. Fatigue strength is the ability to carry a load over and over again without wearing out. The metal used to make airplanes must have fatigue strength. Otherwise, over time the plane will develop fatigue cracks.
Torsion strength
Torsion is a kind of twisting action. A material that has high torsion strength cannot be twisted easily.
Impact strength
Impact strength is the ability of a material to withstand a sudden blow.
Creep. It is a time-dependent permanent strain under stress.