ALTANA SPI Modifi ed Impact Tester - Manual (Page 12)


0RINCIPLE¬OF¬/PERATION
4HE¬UNITS¬USED¬IN¬MEASURING¬IMPACT¬ARE¬UNITS¬
OF¬ENERGY¬4HE¬ENERGY¬POSSESSED¬BY¬THE¬FALLING¬
WEIGHT¬AT¬THE¬INSTANT¬OF¬IMPACT¬IS¬KINETIC¬ENERGY¬
4HIS¬IS¬EQUAL¬TO¬THE¬ENERGY¬USED¬TO¬RAISE¬THE¬WEIGHT¬
TO¬THE¬HEIGHT¬OF¬DROP¬)T¬IS¬THE¬POTENTIAL¬ENERGY¬
POSSESSED¬BY¬THE¬WEIGHT¬THE¬INSTANT¬IT¬IS¬RELEASED¬
3INCE¬THE¬POTENTIAL¬ENERGY¬IS¬EXPRESSED¬AS¬THE
PRODUCT¬OF¬WEIGHT¬MULTIPLIED¬BY¬HEIGHT ¬THE¬GUIDE¬
TUBE¬IS¬MARKED¬WITH¬A¬LINEAR¬SCALE¬OF¬INsLB¬SHOWING¬
THE¬IMPACT¬RANGE¬OF¬THE¬INSTRUMENT¬)T¬IS¬ASSUMED¬
THAT¬ANY¬ENERGY¬LOSS¬DUE¬TO¬FRICTION¬IN¬THE¬TUBE¬OR¬
TO¬MOMENTARY¬ACCELERATION¬OF¬THE¬PUNCH¬AT¬IMPACT¬
IS¬NEGLIGIBLE
4HE¬PURPOSE¬OF¬IMPACT¬TESTING¬IS¬TO¬lND¬THE¬
AMOUNT¬OF¬ENERGY¬NECESSARY¬TO¬CAUSE¬FAILURE¬OF¬
A¬SPECIMEN¬TYPE¬AND¬TO¬ESTABLISH¬A¬STANDARD¬FOR¬
IMPACT¬RESISTANCE¬AND¬TO¬TEST¬SAMPLES¬OF¬A¬PRODUCT
AGAINST¬THE¬ESTABLISHED¬STANDARD¬4HE¬NATURE¬OF ¬
AND¬THE¬EXTENT¬OF ¬IMPACT¬DAMAGE¬THAT¬CONSTITUTES¬
FAILURE¬MUST¬BE¬ESTABLISHED¬BY¬THE¬USER¬3UCH¬
VARIABLES¬AS¬MATERIAL¬THICKNESS ¬SHAPE¬OF¬SPECIMEN¬
AND¬END¬USE¬OF¬PRODUCT¬ARE¬FACTORS¬IN¬THIS¬
EVALUATION
/NCE¬THE¬FAILURE¬POINT¬HAS¬BEEN¬DElNED ¬THE¬ACTUAL¬
TESTING¬PROGRAM¬CAN¬BE¬DEVELOPED ¬THAT¬IS ¬HOW¬
MANY¬SPECIMENS¬ARE¬TO¬BE¬IMPACTED¬AND¬WHAT¬
ENERGY¬TO¬USE¬WITH¬EACH¬IMPACT¬4HESE¬CHOICES¬
WILL¬DEPEND¬ON¬THE¬EXPENDABILITY¬OF¬SPECIMENS¬AND¬
WHETHER¬THE¬OBJECTIVE¬IS¬lNDING¬THE¬AVERAGE¬ENERGY¬
REQUIRED¬TO¬CAUSE¬FAILURE ¬OR¬TESTING¬TO¬ASSURE¬THE¬
ABILITY¬TO¬PASS¬A¬SELECTED¬LEVEL¬OF¬IMPACT
0RINCIPLE¬OF¬/PERATION