l3 - CIVE 2700 Civil Engineering Materials, Winter 2007...

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CIVE 2700 – Civil Engineering Materials, Winter 2007 1 Mechanical Properties II Professor George Hadjisophocleous, Ph.D., P.Eng. Carleton University Department of Civil and Environmental Engineering Ottawa, Ontario CIVE 2700, Civil Engineering Materials, Winter 2007 2 Outline • True stress-strain • Compression • Bending • Torsion • Hardness CIVE 2700, Civil Engineering Materials, Winter 2007 3 True Stress and Strain • During elastic deformation, dimensional changes in the material are negligible. • Definitions of stress and strain based on the initial cross sectional area and initial length are adequate. • These stresses are known as engineering or conventional stress and strain. CIVE 2700, Civil Engineering Materials, Winter 2007 4 True Stress and Strain • During plastic deformation length and area change appreciably. • True stress and strain are based on the instantaneous dimensions of the specimen during the course of a test. CIVE 2700, Civil Engineering Materials, Winter 2007 5 True Stress and Strain True stress and strain are defined using the actual area and length of the test specimen. CIVE 2700, Civil Engineering Materials, Winter 2007 6 True Strain ! " ! " # $ % $ % % % ( ) * * + , % % - 1 ln 1 1 ln T o o o o o T o d ! ! ! ! ! ! ! ! ! ! ! ! !
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CIVE 2700 – Civil Engineering Materials, Winter 2007 2 CIVE 2700, Civil Engineering Materials, Winter 2007 7 True Strain • Measurement of minimum area in the necked region provides a basis for determining the true strain ) ln( A A A A A A o T o o o o % % % # ! ! ! ! occurs change volume no If CIVE 2700, Civil Engineering Materials, Winter 2007 8 True Stress and Strain • These equations are valid only up to the onset of necking • Beyond this point actual load and A and gauge length measurements should be used ! " ! " . $ % $ % 1 ln 1 T T CIVE 2700, Civil Engineering Materials, Winter 2007 9 True Stress and Strain 530MPa K and 0.26 n : steel carbon Low 1) ( component hardening strain - n : where % % / % n T T K CIVE 2700, Civil Engineering Materials, Winter 2007 10 True Stress and Strain CIVE 2700, Civil Engineering Materials, Winter 2007 11 Tensile Test • A tensile tests is a method for determining the behaviour of materials under axial stretch loading. • Data from test are used to determine: – elastic limit, – elongation, – modulus of elasticity, – proportional limit, – reduction in area, – tensile strength, – yield point, – yield strength and other tensile properties. CIVE 2700, Civil Engineering Materials, Winter 2007 12 Tensile Test • Tensile tests at elevated temperatures provide creep data. • Procedures for tensile tests of metals are given in ASTM E-8. • Methods for tensile tests of plastics are
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This note was uploaded on 11/13/2011 for the course CIVE 2*** taught by Professor - during the Spring '11 term at Carleton CA.

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l3 - CIVE 2700 Civil Engineering Materials, Winter 2007...

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