Section B

Static load

Does not move

dynamic load

e.g. Book dropping

does move

Tension

• When a pulling force is applied to either end of a material

• Object becomes stretched as it tries to resist being pulled apart

tensile strength

the ability of a material to resist being pulled apart

Compression

occurs when pushing force is applied to either end of material

compressive strength

ability of a material to resist being compressed or squashed

Torsion

occurs when a material is being twisted

Torsional strength

ability of a material to resist being twisted out of shape

bending

Both tension and compression on either side of its neutral axis

stiffness

Ability to resist being bend out of shape

shear force

Acts on an object in a direction perpendicular to its length

Reinforcement

adding a material to an object to improve ability to withstand force and stress e.g. reinforced concrete which has more flex than concrete alone so less prone to failure

webbing

strong fabric woven into strips from yarns. Used for belts (car seat belts, climbing equipment, furniture)

methods of stiffening materials

• laminating

• Interfacing

• Folding

• Bending

Laminating

bonding two or more materials to improve product’s strength, stability, aesthetics and flexibility e.g. paper - becomes waterproof, more durable and less prone to tearing. Retains flexibility

Fabric interfacing

• additional layer in specific areas where extra structure, shape or support is required

• Fusible uses heat to bond it to the surface of a fabric

• Sew in is placed between layers of fabric and held in place with stitching

• Eg. Baseball cap to keep peak rigid

folding

allows material to hold more weight while holding its shape

Bending

• curves, arches and tubes add strength while using a minimum amount of material

• Some can be manipulated by hand, some need specialist equipment

ecological footprint

measures the impact of a person’s life on the environment

social footprint

measure of the impact that a company’s social policies have on its employees, partners or subcontractors and on society as a whole

factors of social footprint

• flexible work hours policy for parents

• Understanding that a parent has to stay home because a child is sick

• Fair wages

• Health and safety of employees

• Appropriate training schemes

Safe working conditions

• Health and Safety executive is an organisation which looks after the welfare of employees and enforces the Health and safety work act

• Employers have to consider health and safety of workers

• Fairtrade

ecological issues

• harvesting raw materials

• Refining processes can be detrimental to the environment

• Deforestation - slash and burn to convert forests to farmland. Shrinking habitats, extinction. Does not grow back

• Desertification

• Mining e.g. soil erosion, sinkholes

• Drilling

• Farming

• Product miles

the 6 Rs

• reduce

• Refuse

• Reuse

• Rethink

• Repair

• Recycle

reduce

• miniaturisation of products

• Motion sensitive lighting to reduce energy use

Scales of production

• one off

• Mass

• Batch

• Continuous

batch production

• a certain number of identical products

• Higher level of automation

• Machines use templates, jigs, patterns

• Specialist tools and equipment

• Short lead time to get products to market