인장시험 - ram.cau.ac.kr

1 1 Tension TestHMLeeStrength Evaluation Group TestHMLeeStrength Evaluation Group (1) (2) (Load cell, LVDT, Extensometer, Grips) (1) (2) (3) (4) (5) 3 Tension TestHMLeeStrength Evaluation Group 1. Tensile Testing, Edited by J. R. Davis and Davis & Associates, 2ndEdition. ASM International, 20042. The Testing of Engineering Materials, H. E. Davis, G. E. Troxelland G. F. W. Hauck, 4thEdition, McGraw-Hill, Inc., 19823. Mechanical Metallurgy, G. E. Dieter, 2ndEdition, McGraw-Hill, Inc., 19764. Mechanical Testing, Edited by J. R. Davis, Metals Handbook, 9thEdition, Volume 8, American Society for Metals, 19854 Tension TestHMLeeStrength Evaluation Group (1) (2) (Load cell, LVDT, Extensometer, Grips) (1) (2) (3) (4) (5)

2 5 Tension TestHMLeeStrength Evaluation Group * 6 Tension TestHMLeeStrength Evaluation Group -- 22 -- -- 7 Tension TestHMLeeStrength Evaluation Group Fish-Bone Diagram of Sources of Variabilityin Mechanical-Test ResultsMetal systemFerrousAluminumCopperOthersMethod of processingRolledForgedOthersForm of productSheetBarTubularOthersHomogeneityS ampling procedureType of testTension testBend testHardness testOthersTest method followedConformanceDesign of the experimentPreconditioningISOKSASTMO thersTest-piece locationTest-piece orientationMaterialsMethodologyTrainingE xperiencePrecision/sensitivityElectronic sFilteringBand factorsEquipmentAmbient conditionsOn-going trainingJudgment requiredManagementOthersTest Variation8 Tension TestHMLeeStrength Evaluation GroupElements of Mechanical TestingSpecimensProceduresTesting MachinesPersonnelStandards (KS, ISO, ASTM, etc.)

3 Lab. Accreditation (KOLAS, ILAC, etc)CalibrationProficiency TestRound Robin Test9 Tension TestHMLeeStrength Evaluation Group (1) (2) (Load cell, LVDT, Extensometer, Grips) (1) (2) (3) (4) (5) 10 Tension TestHMLeeStrength Evaluation GroupExtension, L (mm)Force,P (N)Strain, (%)Stress, (MPa) offset YS UTS (%)100)(00 ==LLMPaAP Before the TestA0: cross-sectional area(mm2)LO LLDuring the TestPmaxDetermination of Tensile Properties11 Tension TestHMLeeStrength Evaluation Group (1)( ) , ( ) ( ) (force/load) N( ; newton) . ( )1 kgf N .12 Tension TestHMLeeStrength Evaluation Group (1901 3 ).

4 , . m/s2 .F = ma = mg1 N = 1 kg 1 m/s2 kgf : = : N : kg : m/s213 Tension TestHMLeeStrength Evaluation Group (2)( ) (deformation) . 14 Tension TestHMLeeStrength Evaluation Group (3)( ) (stress) ( ) . MPa .( )1 MPa = 1 106Pa = 1 106N/m2= 1 kgf/mm2 MPa .FFArea, AFStress = F/A15 Tension TestHMLeeStrength Evaluation Group (4)( ) (strain) [ ] .LFFL LStrain = L/L( ) (reduced section).

5 16 Tension TestHMLeeStrength Evaluation Group (5)( ) (gage length) , .( ) (engineering stress) ( E) (P) (A0) . E= P/A0 Reduced SectionGage Length17 Tension TestHMLeeStrength Evaluation Group (6)( ) (engineering strain) ( E) ( L) (L0) . E= L/L0( ) (true stress) . (A) ( , T) . T= P/A18 Tension TestHMLeeStrength Evaluation Group (7)( ) (true strain) . ( ) ( T) . T= L1/L1 + L2/L2 + L3/L3+ = dL/L = ln(L/L0 )( ) - (stress-strain curve).

6 LL019 Tension TestHMLeeStrength Evaluation Group (8) - (Stress-strain curve) AA BB CC , , , , 20 Tension TestHMLeeStrength Evaluation Group (9) , , (Brittle) (Ductile) 21 Tension TestHMLeeStrength Evaluation Group (10)BeforeAfterPlastic DeformationSlipStrainStressPlasticElasti c ( )AL=A0L0 Necking , (work hardening strain hardening) 22 Tension TestHMLeeStrength Evaluation Group (11) - : (E, elastic modulus) (yielding): Plastic ElasticOAB QPStress (or Load)StrainYETotal23 Tension TestHMLeeStrength Evaluation Group (12)Curve 1 Curve 2 Curve 3 Curve 1 : High C steelCurve 2 : Medium C steelCurve 3 : Low C steelStrongest : Curve 1 Toughest : Curve 2 Most ductile.

7 Curve 3 StrainStress24 Tension TestHMLeeStrength Evaluation Group (1) (2) (Load cell, LVDT, Extensometer, Grips) (1) (2) (3) (4) (5) 25 Tension TestHMLeeStrength Evaluation Group (1) , ( ) (1) (2) (3) 26 Tension TestHMLeeStrength Evaluation Group (2) (1) (Ultimate Tensile Strength)(2) (Yield Strength)(3) (Elongation)(4) (Reduction of Area)(5) (Proportional Limit)(6) (Poisson s Ratio)(8) (Modulus of Elasticity) 27 Tension TestHMLeeStrength Evaluation Group (3) - - - - - - 28 Tension TestHMLeeStrength Evaluation Group (1) (2) (Load cell, LVDT, Extensometer, Grips) (1) (2) (3) (4) (5) 29 Tension TestHMLeeStrength Evaluation Group.

8 (Ultimate Tensile Strength) . - (Proportional Limit)- (Elastic Limit)- (Yield Point) (Yield Strength) . - (Elongation)- (Reduction of Area) . (Elastic Modulus) (Poisson s Ratio) . - Strain-Hardening Exponent (n) & Strength Coefficient (K) = K pn30 Tension TestHMLeeStrength Evaluation Group Strain, (%)Stress, (MPa)Specified offset YS UTS Elastic limitProportional limit(MPa)AP UTS0max=31 Tension TestHMLeeStrength Evaluation Group Accuracy lowAccuracy highStress, ksi10020304050 Strain, inch/inch Low accuracyStrain, inch/inch High TestHMLeeStrength Evaluation GroupUpper yieldStrengthSlope: E Lower yieldStrengthStrainStressSlope: E StrainStressYield Strength( Offset)E : Elastic Modulus or Young s ModulusYield Strength( EUL) * Proof StrengthYoung's Modulus (GPa) Yield Strength (MPa)110115120125130135140 Mean : MPaZ = 2 ( MPa)Z = -2 ( MPa) GPaFinal Report of Proficiency Test Metallic Materials.

9 Tensile Testing at Ambient Temperature, Organized by IfEP(Institut f r Eignungspr fung), Dec. 2002 (# of Participants: 126)Measurement Uncertainties Declared by Most Participants < 20% !!!!! at least: Questionable StressStrainStressStrain, E1: , E2: StressStrainE1E2 Elastic Modulus, EE 200 GPa (for steel)E 70 GPa (for Al alloy) 35 Tension TestHMLeeStrength Evaluation Group 100 AA - A RA(%)100 LL - L (%) Elong0f000f = = 36 Tension TestHMLeeStrength Evaluation Group : x = y xMetal : : (2) Strain-Hardening Exponent (n) & Strength Coefficient (K) = K pn y(1) Poisson s Ratio37 Tension TestHMLeeStrength Evaluation Group (1) : A0L0= ALA0/A = L/L0 E= (L-L0)/L0= L/L0-1yxy = xy = ln(1+x) T= P/A = (P/A0) (A0/A)= (P/A0) (L/L0 )L/L0= 1 + E T= E(1 + E) T= dL/L = ln(L/L0 ) LL0 T= ln(1 + E) True Stress True Strain38 Tension TestHMLeeStrength Evaluation Group (2) T= E(1 + E) T= ln(1 + E) True Stress : True Strain : necking ( ).

10 A0L0= ALA0/A = L/L0 E= (L-L0)/L0= L/L0-1L/L0= 1 + E T= P/A T= = ln(A0/A) = ln[( D02/4)/( D2/4)] = ln(D0/D)2 = 2 ln(D0/D)dL/L = - LL0dA/A AA039 Tension TestHMLeeStrength Evaluation Group StressStrainStressStrainStressStrainStre ssStrainHigh-carbon steelMedium-carbon steelLow-carbon steel(most ductile)Medium-carbon steel(toughest)Low-carbonsteelHigh-carbo n steelHigh-carbon steel(strongest)Medium-carbon steelLow-carbon steelCast iron40 Tension TestHMLeeStrength Evaluation Group (1) (2) (Grips, Load cell, LVDT, Extensometer)(3) (1) (2) (3) (4) (5) 41 Tension TestHMLeeStrength Evaluation Group - (Load unit)-Controller(- Hydraulic Power Supply)- - - (UTM.)