QCAA Engineering EA flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Engineering design process

A cyclical method moving from problem definition through research, concept generation, analysis, prototyping, testing and evaluation, with documentation and iteration at every stage until requirements are met.

Design brief versus specification

A brief states the client need, purpose and constraints in general terms; a specification converts these into measurable, testable requirements with tolerances and acceptance criteria.

Weighted decision matrix

A selection tool scoring each concept against weighted criteria, multiplying score by weight and summing totals; the highest total is preferred, subject to sensitivity checks.

Young's modulus

The slope of the linear elastic portion of a stress–strain curve, equal to stress divided by strain; it measures stiffness and is largely independent of component geometry.

Ductile versus brittle

Ductile materials undergo large plastic strain before fracture, giving warning and absorbing energy; brittle materials fracture with little plastic deformation and almost no warning.

Thermoplastic versus thermoset

Thermoplastics soften when reheated and can be remoulded and recycled; thermosets cross-link permanently, cannot be remelted and are difficult to recycle.

Toughness

The energy a material absorbs before fracture, represented by the total area under the stress–strain curve; it combines strength and ductility rather than either alone.

Moment of a force

The turning effect of a force about a point, calculated as force multiplied by the perpendicular distance from the point to the force's line of action, in newton-metres.

Static equilibrium conditions

A rigid body at rest satisfies the sum of horizontal forces, sum of vertical forces and sum of moments about any point all equalling zero.

Two-force member

A structural member with forces applied at only two points and no applied moment, so the resultant forces act along the line joining those points, in tension or compression.

Second moment of area

A geometric property describing how area is distributed about an axis, equal to bh³/12 for a rectangle about its centroid; larger values reduce bending stress.

Newton's second law

The net force on a body equals its mass times acceleration (F = ma); force and acceleration are in the same direction and weight is the special case W = mg.

Conservation of energy

Energy is neither created nor destroyed but converted between forms; in a closed system the total remains constant, though friction converts mechanical energy to heat.

Mechanical advantage

The ratio of load force to effort force in a machine; efficiency equals mechanical advantage divided by velocity ratio, expressed as a percentage.

Centripetal force

The net inward force required to keep a mass moving in a circular path, equal to mv²/r, directed toward the centre of rotation.

Third-angle projection

An orthographic arrangement where the top view appears above the front view and the right-side view appears to the right, as if the object sits in a glass box unfolded.

Geometric tolerancing

A symbolic system controlling form, orientation, location and runout of features relative to datums, independent of the size tolerance specified for the feature.

Parametric CAD modelling

A modelling approach where geometry is driven by dimensions and constraints, so changing a parameter updates the model and all derived drawings and assemblies.

Critical path

The longest sequence of dependent tasks in a project network, determining the minimum project duration; tasks on it have zero float, so delay there delays completion.

Design for manufacture and assembly

A design approach reducing part count, simplifying handling and standardising fasteners so products are cheaper and easier to make and assemble with fewer defects.

Process capability index

Cp compares specification width to six standard deviations of process variation; Cpk also accounts for centring, so a process can be capable yet off-centre.

Life cycle assessment

A method quantifying environmental impacts across a product's life, from raw material extraction through manufacture and use to end-of-life disposal or recycling.

Hierarchy of control

A ranked order for reducing risk: eliminate the hazard, substitute, apply engineering controls, then administrative controls, with personal protective equipment last and least effective.

Circular economy

An economic model keeping materials in use through repair, reuse, remanufacture and recycling, replacing the linear take-make-dispose approach and reducing waste and resource depletion.

Factor of safety

The ratio of a material's failure stress to the allowable working stress; values above one provide margin for uncertainty, overload and material variability.

Shear force diagram

A graph of internal shear along a beam, stepping by each point load and sloping under distributed loads; bending moment is the area under it.

Impulse and momentum

Impulse is force multiplied by the time it acts and equals the change in momentum; total momentum is conserved in collisions with no external net force.

Projectile motion

Motion under gravity alone, analysed by separating constant horizontal velocity from vertical motion with constant downward acceleration g; time of flight depends on vertical displacement.

Bill of materials

A structured list of every component, quantity and specification needed to build a product, linking design data to purchasing, costing and assembly instructions.

Embodied versus operational energy

Embodied energy is consumed in making and delivering a product; operational energy is used during its service life; total lifecycle energy is their sum.

Section view

A drawing where part of the object is imagined removed to reveal internal features, with cut material shown by hatching and hidden lines generally omitted for clarity.

Stress and strain

Stress is force per unit area in pascals; strain is change in length divided by original length, dimensionless; their ratio in the elastic region gives Young's modulus.