Stress and Deformation Analysis

# Stress and Deformation Analysis - Stress and Deformation...

This preview shows pages 1–4. Sign up to view the full content.

1 Stress and Deformation Analysis Material in this lecture was taken from chapter 3 of Mot , Machine Elements in Mechanical Design, 2003 Representing Stresses on a Stress Element ± One main goals of stress analysis is to determine the point within a load-carrying member that is subjected to the highest stress level. ± The orientation of the stress element is critical, and it must be aligned with specified axes on the member, usually called x, y, and z. Representing Stresses on a Stress Element con’t ± Tensile and compressive stresses, called normal stresses, act perpendicular to the opposite faces of the stress element. ± Tensile stresses pull on the element. ± Compressive stresses crush the element.

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

View Full Document
2 Stress Elements for 3 Types of Stresses Mot , Machine Elements in Mechanical Design, 2003 Representing Stresses on a Stress Element con’t ± Shear stresses are created by direct shear, vertical shear in beams, or torsion. ± There is a tendency to cut the element by exerting a stress downward on one face while simultaneously exerting a stress upward on the opposite, parallel face. Sign Convention for Shear Stresses ± Positive shear stresses rotate the element in a clockwise direction. ± Negative shear stresses rotate the element in a counterclockwise direction. ± A double subscript notation is used to denote shear stresses in a plane. For example, drawn for the y-z plane, the pair of shear stresses, τ yz , indicates a shear stress acting on the element face that is perpendicular to the y-axis and parallel to the z-axis. ± So, τ yx acts on the face that is perpendicular to the y- axis and parallel to the x-axis. In this example, τ yz is positive and τ yx is negative.
3 Direct Stresses: Tension and Compression ± Stress = the internal resistance offered by a unit area of a material to an externally applied load. Normal stresses ( σ ) can be tensile (positive) or compressive (negative). ± The magnitude of the stress can be calculated from the direct stress formula: ± σ = force / area = F/A ± (US Units) lb / in 2 = psi ; (SI Units) N / m 2 = pascal = Pa Mot , Machine Elements in Mechanical Design, 2003 Direct Stresses: Tension and Compression con’t ± The conditions on the use of the previous equation are as follows: 1. The load-carrying member must be straight 2. The line of action of the load must pass through the centroid of the cross-section of the member

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 13

Stress and Deformation Analysis - Stress and Deformation...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online