EXAM: Structures & Mechanisms (THEORY)

This is a difficult lesson, so you're going to take 2 exams:

• (1) THEORY [20th February 2018]
• (2) PRACTICE [12th March 2018]

STRUCTURES (theory)

What is the mission of a structure? Definition.

Natural and man-made structures. Definition. Identify drawings.

FORCES AND LOADS

Forces. Static effect=deform. Dynamic=move/stop. Parameters: Intensity, direction, trajectory, point of application.

Loads. Definition. Types (Fixed or permanent) and (variable). They produce stress on the structure of a body.

STRESS

Traction, compression, bending, torsion, shearing or cutting. Identify definitions, identify drawings, draw arrows and put real examples (from the student’s book).

MAN MADE STRUCTURES

Identify definitions & drawings. 

• Massive structures and lintels. 
• Vaulted structures 
• STONES->COMPRESSION. 
• Triangular structures. 
• Suspended structures 
• CABLES->TRACTION. 
• Reinforced concrete structures.
• CONCRETE+STEEL -> COMPRESSION+TRACTION. 
• Laminated structures. 
• Pneumatic structures. 
• Spatial and geodesic

STRUCTURAL CONDITIONS

Stability. Centre of gravity must be centred over its base and close to the ground. Ways of achieving stability (pictures).

Resistance. Depends on the material, quantity of material and the shape of the structure.

Rigidity. Avoid deforming considering:

• Shape. Chosen to resist compression (avoid buckling), traction and bending stress
• Rigid joints. What is corbelling useful for?
• Using triangular structures & crossbracing.

STRUCTURAL ELEMENTS

Match structural elements with their corresponding pictures (columns, pillars, lintels, arches (KEY STONE), vaults, buttresses, flying buttresses, load bearing wall, retaining wall, joists and blocks, foundations with footings, foundations with piles, suspenders and tension rods, bracing).

MECHANISMS (theory)

What is the mission of a mechanism? Definition, comparison with structures.

LINEAR TRANSMISSION

Levers, Pulleys, Fixed Pulley, Movable Pulley, Compound pulley systems.

Description, equation.

Identify drawings and give examples (from the student’s book).

ROTARY TRANSMISSION

Wheels & belts, friction wheels, pulleys with belts, interlocking gears, sprockets with chains.

Description, equation.

Driver & Driven wheel concept

Identify drawings and put real examples (from the student’s book).

TRANSFORMATION OF MOTION

Winch and crank, rack and pinion, crank and rod

Description, equation.

Identify drawings and put real examples (from the student’s book).