340 CHAPTER 10 Materials
Fig.10.7
Izod impact test.
Fig.10.8
Charpy impact test.
Impacttestsmeasuretheabilityofmaterialstowithstandshockloadsandprovideanindicationoftheir
toughness.Twomaintestsareinuse:theIzodandtheCharpy.
Bothtestsrelyonastrikerorweightattachedtoapendulum.Thependulumisreleasedfromafixed
height,theweightstrikesanotchedtestpiece,andtheanglethroughwhichthependulumthenswingsisa
measureofthetoughnessofthematerial.ThearrangementfortheIzodtestisshowndiagrammatically
in Fig. 10.7(a). The specimen and the method of mounting are shown in detail in Fig. 10.7(b). The
Charpytestissimilarinoperationexceptthatthetestpieceissupportedinadifferentmanner,asshown
intheplanviewinFig.10.8.
10.7.2 Stress–Strain Curves
Weshallnowexamineindetailthepropertiesofthedifferentmaterialsfromtheviewpointoftheresults
obtainedfromtensileandcompressiontests.