Structures and Mechanisms

Structure or Mechanism? Can you identify a Structure within this bicycle? Can you name a mechanisms on this bicycle? Frame = Structure Chain and Sprocket = One example of a mechanism

Bridge Supporting Roadway Introduction Structures can be seen all around us in our everyday lives. High Rise Building Vehicle Frame Bridge Supporting Roadway Residential Dwelling

Introduction Tractor Drill Car Luas Exercise Bicycle Machinery is a central part of life today. How many can you identify? Tractor Drill Car Luas Exercise Bicycle

Introduction All these machines have working parts called –Mechanisms Rack and Pinion Pulley Wheels Cam and Follower

Introduction 2. Wheelbarrow Look at the following items. 1. Bicycle 3. Wrench 4. Entrance Can you identify and name the mechanisms and/or structure in each of these items?

Mechanisms, Motion and Force A system of moving parts that performs some function. Collins Dictionary Motion The process of continual change in the position of an object “movement” Collins Dictionary

Motion and Force Force “Strength or Power” What input is needed for a drill to work? Exertion or the use of exertion against a person or thing that resists. Collins Dictionary Input: The lever of the drill is pulled down Output: The chuck of the drill moves down

Motion There are four main types of motion. Linear motion – Train Pendulum There are four main types of motion. Linear motion – Train Oscillating Motion – Pendulum of a clock Reciprocating Motion – Hacksaw Rotary Motion - Shaft Train Shaft

Motion – movement in a straight line Linear motion A train on its tracks moves in a linear motion Can you give other examples of linear motion?

- backwards and forwards movement Motion Reciprocating Motion - backwards and forwards movement The engine pistons and valves above move up and down (reciprocate) continuously. Can you suggest other examples?

Motion Rotary Motion The wheels of a bike move in a rotary fashion. Motion in a circular direction, which can also be called circular motion . Forward and backward movement in an arc The wheels of a bike move in a rotary fashion. Oscillating Motion The pendulum of a clock or a child on a swing are examples of oscillating motion.

Force There are five main types of force: Compression Tension Shear Bending Torsion Shear forces Columns in Compression A rope in Tension Torsion forces Pipe Bending

Force Can crushed by compression Compressive and Tensile Forces Can crushed by compression This is where a load presses or squashes objects together Spring in Tension, this is where a load pulls an object apart.

Force Torsion and Shearing forces This is where the load causes an object to twist This is where loads push at right angles to the surface of the object. E.g. scissors Torsion force

Force Bending and Static Forces This is where the load causes an object to Bend A piece of metal Dynamic Load – a car which is not fixed to any one specific point, e.g. a car travelling along a road Bending a piece of metal Static Load – a load which is fixed at one point, e.g. a building