Engineering Drawing, CAD and Applied Mechanics
Core concepts
Understand orthographic projection, first- and third-angle projection, sectioning, auxiliary views, dimensioning, tolerances, and surface finish symbols. Know isometric and oblique views and the conventions for threads, welds, and gears. Study CAD fundamentals: layers, blocks, coordinates, drawing and editing commands, and plotting. In applied mechanics, understand force systems, equilibrium, moments, couples, centroids, and second moments of area. Learn stress, strain, Hooke's law, bending moments, shear force diagrams, torsion, and beam deflection. Understand friction and simple machines.
Common traps
Questions often confuse first-angle and third-angle projection symbol placement. Watch for the difference between a moment and a couple. Stress is force per unit area; strain is dimensionless. Bending stress is maximum at the extreme fibre, not at the neutral axis. CAD layers control visibility and properties, not physical size.
Worked example
A simply supported beam of span 4 m carries a central point load of 10 kN. Maximum bending moment = WL/4 = 10 × 4/4 = 10 kN·m. Rule of thumb: for a central point load, maximum moment is WL/4; for a uniformly distributed load, it is wL²/8.
Study approach
Practise drawing views and sections by hand and in CAD. Solve equilibrium and beam problems step by step, always drawing the free-body diagram first.