Bicycle Unit: Materials Testing

ACTIVITY HEADER

 

 

 

Name of Activity

Bicycle Unit: Materials Testing

Author

STOMP

Keywords

material choices, strengths, weaknesses, materials, static load, dynamic load, friction, physical properties, chemical properties, mechanical properties, elasticity, yield strength, ultimate strength

Subject

Non-LEGO

Grade Level

K, 1, 2, 3, 4, 5, 6

Time

1 Hour Total

Brief Description

Students will learn about different materials that bikes are made out of. Students will learn about different factors, material strength, flexibility, cost, weight etc. that affect an engineers decision when choosing a material to use in constructing a prototype/real thing.

To apply this information, students will test and rate the strength of different types of materials. They will record the strengths on a chart and compare the different materials. Students will discuss the factors that affect an engineer’s choice of materials.

Lesson Objectives:

- To explore the factors that affect material choices for a design.

- To compare strengths and weaknesses of different materials.

Materials Needed:

- Hot glue sticks.

- Popsicle sticks.

- Plastic spoons.

- Wire.

- Metal Rods (e.g. thin nail).

- Activity Worksheet.

Preparation and Set Up:

- Print out enough worksheets for the class (either one per group or per student)

- Optional: Set up large version of real bike materials sheet.pdf or make copies for each group to look at.

- Arrange students into groups.

- Distribute materials and worksheets.

Necessary Background

Engineers need to keep a lot of things in mind when choosing what material they will use in their designs.

A bike will have two types of loads. The Static Load – the bike frame must support itself – and the Dynamic Load – the bike frame must support changing forces of a cyclist’s weight, forces of pedaling and breaking, road’s surface (bumps, holes)

Friction – or the resistance of the road’s surface. This factor affects the engineers decision on what a tire should be made out of and how it should be designed. Road bikes want to reduce friction for faster movement v. mountain bikes, which want wide tires for increase friction to reduce falls.

Materials that engineers choose for their designs must withstand all of these forces. There are three categories of material properities that enable bikes to function to suit different purposes

Physical: Density, color, electrical conductivity

Chemical: Reactivity, rust resistance, solubility, reaction to heat.

Mechanical: hardness, stiffness, expansion, toughness

Different tests of mechanical strength are:

Elasticity: When a material can be bent and come back to its original shape.

Yield Strength: The point at which a material is bent and it keeps the new shape.

Ultimate Strength: The point at which a material is bent and it breaks.

Vocabulary:

Static load

Dynamic load

Friction

Physical properties

Mechanical properties

Elasticity

Yield Strength

Ultimate Strength

Chemical properties

Procedure

  1. Explain the concepts mentioned in the Teacher Background section. Tell students about the things that engineers must keep in mind when choosing a material.
    1. Go over Static and Dynamic Loads, and discuss the differences.
    2. Go over friction on tires – when you might want more friction (mountain bikes) and when you might not (racing road bikes).
    3. Talk about physicalmechanical and chemical properties (e.g., physical – weight of the bike for easy of carrying; mechanical – the amount of weight the bike must hold without breaking; chemical – rust resistance for a long-lasting frame).
    4. Talk about elasticityyield strength, and ultimate strength and how these strengths are different and necessary (e.g., a bike frame should have a high ultimate strength but should not be easily bent, even if it does return to it’s original shape).

  • Discuss why engineers choose certain materias and why they avoid others. Remind students that there are reasons other then strength. Talk about costs, looks, availability, appearance, durability, aerodynamics etc.
  • Page 1 of 2 | Next page