WACE MDT ATAR cheat sheet

Design process sequence: identify need → define brief → research → generate concepts → develop and refine → prototype/test → evaluate against brief → document and communicate.

A design brief must state the problem, target user, constraints, and success criteria; constraints are fixed limits, criteria are measurable goals used to judge solutions.

Functional analysis decomposes a product into sub-functions (e.g. transmit force, store energy) so each can be solved independently before recombination.

Ergonomic design rule: anthropometric data should be applied at the 5th percentile for reach limits and the 95th percentile for clearance, never the mean alone.

Design for manufacture and assembly (DFMA) reduces part count; fewer parts typically lowers assembly time, cost, and failure points.

Aesthetics principles: proportion, balance, unity, rhythm, contrast, and emphasis; each can be evaluated but not measured on a single absolute scale.

Intellectual property: a patent protects a new functional invention (typically up to 20 years), a design registration protects appearance, and copyright protects original expression automatically.

Life cycle assessment (LCA) stages: raw material extraction, manufacture, distribution, use, and end-of-life; impacts are summed per functional unit for comparison.

Human-centred design uses observation and user testing rather than assumption; iterative prototyping cycles shorten the feedback loop between user and designer.

Stress σ = F/A (N/mm² or MPa); strain ε = ΔL/L₀ (dimensionless); Young's modulus E = σ/ε in the linear elastic region.

Yield strength marks the end of elastic behaviour; ultimate tensile strength is the maximum stress before necking; failure occurs at fracture stress.

Hardness, toughness, and ductility are distinct: toughness is energy absorbed before fracture, ductility is plastic strain before failure.

Ferrous alloys: increasing carbon raises hardness and strength but lowers ductility and weldability; stainless steels gain corrosion resistance from chromium (>10.5%).

Thermoplastics soften on reheating and are recyclable; thermosetting polymers cross-link permanently and cannot be remelted.

Composites combine matrix and reinforcement; specific strength and stiffness exceed most metals, but properties are anisotropic and recycling is difficult.

Material selection uses property charts: plot two properties logarithmically, apply performance index lines, then filter by cost, availability, and process compatibility.

Corrosion prevention methods: barrier coating, cathodic protection, alloying, and design that avoids trapped moisture and dissimilar-metal contact.

Wood is anisotropic: strength along the grain exceeds strength across it; moisture content changes cause shrinkage and swelling.

Casting: molten material fills a mould cavity; sand casting suits complex low-volume ferrous parts, die casting suits high-volume non-ferrous parts with fine detail.

Forming processes conserve material: rolling, forging, extrusion, and pressing reshape material plastically; forging aligns grain flow and improves fatigue strength.

Machining is subtractive: turning uses a rotating workpiece, milling uses a rotating cutter, drilling produces holes; feed and speed determine surface finish and tool life.

Joining: welding fuses material, brazing and soldering use a filler with a lower melting point, and adhesives distribute stress but need surface preparation.

Injection moulding requires draft angles (typically 1–2°), uniform wall thickness, and radii to avoid warping and ejection damage.

Additive manufacturing builds parts layer by layer; it suits low-volume complex geometry but has slower cycle times and anisotropic strength.

Lean production targets the seven wastes (overproduction, waiting, transport, over-processing, inventory, motion, defects); takt time = available time / customer demand.

Quality control: tolerance is the permitted deviation from nominal; go/no-go gauges check limits quickly, and statistical process control plots sample means against control limits.

Automation trade-off: higher capital cost is justified when volume is high and product variety is low; flexible manufacturing suits mid-volume, high-variety output.

Project management phases: initiation, planning, execution, monitoring and control, and closure; each phase produces defined deliverables.

Critical path method: the critical path is the longest-duration path through the network; any delay on it delays project completion, and its float is zero.

Float (slack) = latest start − earliest start; activities with positive float can be delayed without affecting the project end date.

Gantt charts show activity duration against calendar time; network diagrams show logical dependencies, so the two are complementary tools.

Work breakdown structure decomposes deliverables hierarchically until each work package can be estimated, scheduled, and assigned.

Cost estimating types: bottom-up is accurate but slow, analogous uses past similar projects, and parametric uses a cost-per-unit relationship.

Risk management cycle: identify, assess likelihood and consequence, treat (avoid, reduce, transfer, accept), then monitor and review.

Quality management uses the plan–do–check–act cycle; specifications define requirements and inspection verifies conformance.

Break-even quantity = fixed costs / (unit price − variable cost per unit); it identifies the output at which total revenue equals total cost.