Ch students per table 2.Workbook & Textbook 3.Pencil / Pen 4.Start when quiet

Ch. 12: Materials 1.Constraints & Deformations 2.Properties 3.Degradation and Protection

Text / Work Books Text Book - p. 386 Work Book - p. 197 Copy the following definitions

A CONSTRAINT Describes the effect of external forces on a material (p. 387)

Compression A material subjected to forces that tend to crush it is undergoing compression (p. 387)

Example of Compression

Tension A material subjected to forces that tend to stretch it is undergoing tension.

Example of Tension

Torsion A material subjected to forces that tend to twist it in undergoing torsion.

Example of Torsion

Deflection (bending) A material subjected to forces that tend to bend it is undergoing deflection.

Examples of Bending

Shearing A material subjected to forces that tend to cut it is undergoing shearing.

Example of Shearing

3 Types of Deformation

Elastic - p. 387 The constraint leads to temporary change in the shape or dimensions of the material. When the constraint is removed, the material returns to its original form.

Plastic The constraint leads to a permanent change in the shape or dimensions of the material. Even when the constraint is removed, the material remains deformed.

Fracture The constraint is so intense that the material breaks.

Constraints Lab 1.Work with table groups 2.Write ALL names on hand-out 3.Hand in at the end of lab

Objective To illustrate such types of constraints and deformations as compression, tension, torsion, deflection, shearing, elastic, plastic and fracture.

Procedure Perform a compression, tension, torsion, deflection and shearing test on the materials provided at each station. Complete the following table by ranking the materials from 1-3, where 1 represents the material that reacts the least to the constraint and 3 represents the material that reacts the most to the constraint.

Homework Work Book - p