Topic 4.1 properties of materials

Define physical properties

They are the characteristics of a material that can be identified through testing that is considered to be non-destructive. Hardness is often catergorized as a mechanical property

Definition of Mass

The amount of matter contained in a specific material, and it is a constant where every you measure it.

definition of weight

Weight relies on mass and gravitational forces to provide measurable value

Definition of Volume

Volume is the quantity of a three dimensional space that is enclosed by some closed boundry.

Definition of density

It is the mass per unit volume of a material, important when looking at the weight and size of a product

definition of electrical resistivity

The measure of how well a material conducts electricity, the lower the resistivity the more it conducts electricity.

Thermal conductivity

The measure of how fast a material can conduct heat within a slab of material given a specific temperature

Thermal expansion

A measure of the degree of the increase in dimension when a object is heated

Hardness

Resistance a material offers to penetration or scratching

Definition of Mechanical properties

Mechanical Properties describe how a material reacts to external forces like pushing, pulling or twisting

Tensile strength

Ability of material to withstand pulling force, important when selected ropes and cables

Compressive strength

The capacity of a material to withstand loads tending to reduce size

Stiffness

The resistance of a elastic body to be deflected by an applied force, important when maintains shape is crucial for design.

Toughness

The ability of a material to resists the transmission of cracks.

Ductility

The ability of materials to be extruded or drawn out into wires or other extended shapes (stretched out)

Malleability

The ability for materials to be shaped easily

Youngs modulus

A measure that shows the stiffness of an elastic material and is a quantity used to characterize materials.

X axis- strain

Y axis - stress

Point A elastic region (can go back to original shape)

Point B- yield point (can’t go back to original shape)

Point A to C strain increases faster (length will increase faster her than in any other point)

Stress= force / cross sectional area

Strain = change in length / original length

Aesthetic characteristic

Make them more appealing, hard to quantify as this is subjective.

• Taste: detect flavor

• Smell: detect odor

• Appearance:how something looks

• Texture:sensation by touching

• Color: visual perception

Smart materials

Materials that have two or more properties that can dramatically change

Types of smart materials

• Piezoelectricity- pressure acting on material give of a small electrical discharge which can increase size (airbags for example)

• Shape memory alloy- makes material durable and harder to break ( like glass frames)

• Photochromicity- and it’s when products change color when exposed to light