Topic 4.1 (Properties of Materials) - IB Design Tech

Physical Properties

Characteristics of materials identified through non-destructive testing

Mass

The amount of matter in a material. It's constant and measured in kilograms (kg), unlike weight, which can change based on location.

Weight

The force resulting from mass and gravity, measured in Newtons.

Volume

The amount of three-dimensional space taken up by a substance, whether solid, liquid, or gas.

Density

Affects how heavy and compact a product is.

Electrical Resistivity

A measure of how well a material conducts electricity; low resistivity indicates good conductivity.

Thermal Conductivity

A measure of the rate at which heat is transferred through a material, given a temperature difference across it.

Thermal Expansion

The increase in dimensions of an object when heated, which can be measured as changes in length, area, or volume.

Hardness

The resistance of a material to penetration or scratching.

Mechanical Properties

Characteristics of a material that describe its behavior under applied forces.

Tensile Strength

The ability of a material to withstand pulling forces without breaking.

Compressive Strength

The ability of a material to withstand being pushed or squashed.

Stiffness

The resistance of an elastic body to deflection when an external force is applied.

Toughness

The ability of a material to absorb energy and undergo plastic deformation without fracturing.

Plasticity

The ability of a material to be changed in shape permanently.

Stress

The force per unit area applied to a material, and it is typically measured in units such as pascals (Pa)

Strain

The extension or change in length per unit length of a material.

Youngs Modulus

A measure of the stiffness of an elastic material and is used to characterize materials.

Smart Materials

Materials that change properties in response to external stimuli.

Photo-chromicity

Refers to a material that changes color reversibly when exposed to light.

Thermoelectricity

generated by devices that convert heat and temperature differences between two materials directly into electrical energy.

Magneto-rheostatic, electro-rheostatic

materials are fluids, which can experience a dramatic change in their viscosity.

Aesthetic Characteristics

Taste, smell, appearance, texture.

Shape memory

Metals that can return to their original shape after deformation due to molecular rearrangement.

Piezo electricity

Electricity generated when a material is deformed.