Ch6_2 - Chapter 6 Mechanical Properties of Metals By Dr....

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 6 Mechanical Properties of Metals By Dr. Taleb H. Ibrahim Chemical Engineering Program
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ISSUES TO ADDRESS. .. Stress and strain : What are they and why are they used instead of load and deformation? Elastic behavior: When loads are small, how much deformation occurs? What materials deform least? Plastic behavior: At what point does permanent deformation occur? What materials are most resistant to permanent deformation? Toughness and ductility : What are they and how do we measure them? Chapter 6: Mechanical Properties
Background image of page 2
Mechanical Properties of Metals How do metals respond to external loads? Stress and Strain - Tension - Compression - Shear - Torsion Elastic deformation Plastic Deformation - Yield Strength - Tensile Strength - Ductility - Toughness - Hardness Not tested: true stress-true stain relationships, resilience, details of the different types of hardness tests, variability of material properties
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Introduction To understand and describe how materials deform (elongate, compress, twist) or break as a function of applied load, time, temperature, and other conditions we need first to discuss standard test methods and standard language for mechanical properties of materials.
Background image of page 4
• Typical tensile specimen 9 • Other types of tests: --compression: brittle materials (e.g., concrete) --torsion: cylindrical tubes, shafts. gauge length (portion of sample with reduced cross section) = • Typical tensile test machine load cell extensometer specimen moving cross head Adapted from Fig. 6.2, Callister 6e. Adapted from Fig. 6.3, Callister 6e. (Fig. 6.3 is taken from H.W. Hayden, W.G. Moffatt, and J. Wulff, The Structure and Properties of Materials , Vol. III, Mechanical Behavior , p. 2, John Wiley and Sons, New York, 1965.) STRESS-STRAIN TESTING
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tension Compression Shear Torsion (twisting) Load can be applied as
Background image of page 6
Tensile stress, σ : Shear stress, τ : Area, A F t F t σ = F t A o original area before loading Area, A F t F t F s F F F s τ = F s A o Stress has units: N/m 2 or lb/in 2 ENGINEERING STRESS
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Concepts of Stress and Strain (tension and compression) To compare specimens of different sizes, the load is calculated per unit area. Engineering stress : σ = F / Ao F is load applied perpendicular to speciment cross-section; A 0 is cross-sectional area (perpendicular to the force) before application of the load. Engineering strain : ε = l / l o ( × 100 %) l is change in length, l o is the original length. These definitions of stress and strain allow one to compare test results for specimens of different cross-sectional area A 0 and of different length l 0 . Stress and strain are positive for tensile loads, negative for compressive loads
Background image of page 8
Simple tension: cable o σ = F A Simple shear: drive shaft A o = cross sectional Area (when unloaded) F F σ σ o τ = F s A τ Ski lift (photo courtesy P.M. Anderson) COMMON STATES OF STRESS M M A o 2R F s A c
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Canyon Bridge, Los Alamos, NM 6 Simple compression: A
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 54

Ch6_2 - Chapter 6 Mechanical Properties of Metals By Dr....

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online