Chapter 6 Notes

Chapter 6 Notes - Chapter 6 Notes Mechanical Properties of...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 6 Notes Mechanical Properties of Metals Introduction- Important mechanical properties are strength, hardness, ductility, and stiffness- Mechanical properties of materials are ascertained by performing carefully designed laboratory experiments- The role of structural engineers is to determine stresses and stress distributions within members that are subjected to well-defined loads. This may be accomplished by experimental testing techniques and/or theoretical and mathematical stress analyses. Concepts of Stress and Strain- There are three ways in which a load may be applied: tension, compression, and shear- One of the most common mechanical stress-strain tests is performed in tension- The tension test can be used to ascertain several mechanical properties of materials that are important in design. - A specimen is deformed with gradually increasing tensile load that is applied uniaxially along the long axis of a specimen - The output of a tensile test is recorded as load or force vs. elongation- To minimize these geometrical factors, load, and elongation are normalized to the respective parameters of engineering stress and engineering strain.- Engineering stress, = F / A - The units of engineering stress are MPa- Engineering strain, = l i l / l i - L is the original length before any load- Compression stress/strain tests may be conducted if in-service forces are of this type- The specimen contracts along the direction of the stress- Tensile tests are more common because they are easier to perform- Compressive tests are used when a materials behavior under large and permanent strains is desired, as in manufacturing applications, or when the material is brittle in tension- Shear strain = tan - Shear stress t = F/A- GEOMETRIC CONSIDERATIONS OF STRESS STATE (need to know this?) Stress-Strain Behavior- The degree to which a structure deforms or strains depends on the magnitude of an imposed stress- For most metals that are stressed in tension and at relatively low levels, stress and strain are proportional to each other through = E - Modulus of elasticity = E- Deformation in which stress and strain are proportional is called elastic deformation, a plot of stress vs. strain results in a linear relationship- Modulus = stiffness or a materials resistance to elastic deformation- Elastic deformation is nonpermanent, which means it returns to its original shape- On an atomic scale, a macroscopic elastic strain is manifested as small changes in the interatomic spacing and stretching of interatomic bonds - The magnitude of the modulus of elasticity is a measure of the resistance to separation...
View Full Document

Page1 / 8

Chapter 6 Notes - Chapter 6 Notes Mechanical Properties of...

This preview shows document pages 1 - 3. Sign up to view the full document.

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