Unit 1 (A1 Properties of Materials) Flashcards
What is the definition of Mass?
Measure of how much matter there is within an object
Mass is not affected by gravity.
What is the definition of Density?
The amount of Mass in an object per a certain amount of volume.
Water has a density of 1000kg per meter cubed. (Kg/m³)
What is Strength/Stress?
The force per unit area
What is the formula for calculating Strength/Stress?
Stress = Force / Cross sectional area (N/m²)
Pascals
What are the SI units for Density?
(Kg/m³)
What are the SI units for Strength/Stress?
Pascals.
N/m²
What is the definition for compressive strength?
The maximum compressive load an object can bear prior to failure, divided by its cross sectional area.
Name a material with good compressive strength
- Concrete
2. Ceramics
What is the definition of tensile strength?
The maximum tensile load an object can withstand before failure, divided by its cross sectional area.
Name a material with good tensile strength
Glass
Kevlar
Carbon fibre
What is the definition of shear strength?
The maximum shear load an object can withstand before failure, divided by its cross sectional area.
What is the definition of bending strength?
The ability to resist deformation under load.
What is the definition of hardness?
Ability of a material to resist deformation, which is determined by a standard test where the surface resistance to indentation is measured.
What is the definition of toughness?
The ability of a material to absorb energy without fracturing.
What is the definition of malleability
The property of a metal to deform under compression and take on a new shape
Give and example of a malleable metal
- Gold
- Silver
- Aluminium
- Copper
What is the definition of workability?
Ease of placement
What is the definition of stiffness
resistance to elastic deformation when a load is applied.
What is the definition of fatigue ?
Where structures fail when subjected to a cyclic load. Cyclic load is when loads are applied, removed and then re-applied
What is the definition of creep?
The tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses
What is the definition of fire resistance ?
The property of materials that prevents or retards the passage of excessive heat, hot gasses or flames
Quantified by fire resistance rating
What is the definition of electrical conductivity ?
The measure of how easily electricity flows through a material
Give an example of a material that has high electrical conductivity
Copper
Aluminium
Gold
Silver
What is the definition of thermal conductivity ?
(often denoted by k or λ)
Refers to the ability of a material to transfer or conduct heat.
Thermal conductivity occurs through molecular agitation.
Heat moves along a temperature gradient, from an area of high temperature and high molecular energy to an area with a lower temperature and lower molecular energy.
This transfer will continue until thermal equilibrium is reached.
Give an examples of materials with high and low thermal conductivity
High:
Metals such as Copper, Aluminium, Brass
Low:
Wood
Rubber
Resistance to Moisture Penetration
Rain, particularly when driven by strong winds, can penetrate the thickest masonry walling, typically at mortar joints, through stones and defective or dirty wall ties.
Damaged or blocked gutters and downpipes, provide another source of penetrating moisture
Moisture may penetrate a wall by absorption of water from the ground that is in contact with foundation walls or through rain falling on the wall.
Resistance to Vapour Penetration
Water vapour spreads more easily inside structures, when a gradient of pressure and temperature is established between the sides of the material
The water vapour modifies the behaviour of the insulator, increasing the thermal conductivity value and thus increasing the energy losses and the risk of condensations.
By their nature, all materials, except glass and metals, are permeable to water vapour.
A good insulator must avoid the penetration of water vapour.
Resistance to Degradation
Allbuilding materialscan suffer from deterioration and decay if they are not protected and maintained correctly.
Commonreasons for thedegradation of construction materialsinclude:- Naturalagents, Moisture, Shrinkage, Exposureconditions, Corrosioninmetals, Loading and Chemical.
Embedded Energy
Embodied energyis the sum of all theenergyrequired to produce any goods or services, considered as if that energy was incorporated or ‘embodied’ in the product itself.
The concept can be useful in determining the effectiveness of energy-producing orenergy savingdevices, or the “real” replacement cost of a building, and, because energy-inputs usually entailgreenhouse gasemissions, in deciding whether a product contributes to or mitigatesglobal warming.
Recycling Potential
Recyclingis the process of converting waste materials into new materials and objects.
Recyclingcan prevent the waste ofpotentiallyuseful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution (from incineration), and water pollution (from landfilling).
