ARC281 Lecture 6 Notes

Lecture 6 - Stress and Strain
Type Lecture

Date @October 12, 2023

Materials https://www.youtube.com/watch?v=lxlIPlE9bYc

Reviewed


Principals of Stress and Strain
Types of Forces

Stress and Strain - What are they?

Stress

Strain

Modulus of Elasticity

Stress Strain Curves

Definitions

Stress Strain Curves - Concrete and Steel

Shear Stress

Bending Stress


Types of Forces
Axial (Tension/Compression)

Shear

Bending

Torsion




Lecture 6 - Stress and Strain 1

, Axial Shear Bending Torsion
Moment
A force tending to A force acting in The twisting of an
elongate or shorten a direction A force that acts object due to an
a member parallel to a to bend a applied force
surface or to a component
planar cross putting one side
section of a body of the part in
tension and the
opposite side in
compression




kN, N, kPa and MPa
225 lb = 1 kN
1 kN = 1000 N
1 kPa = 1 kN/m^2

1 MPa = 1N/mm^2
1 MPa = 1000 kPa


Strength
Factored Load < Reduced Capacity

α Load < Φ Capacity
Xf (Pf, Vf, Mf, Tf, Cf) < Xr (Pr, Vr, Mr, Tr, Cr)

Subscript f means it has Subscript r means it has
been factored been reduced




Lecture 6 - Stress and Strain 2

, Stress and Strain - An Introduction
Stress and strain are to are to a material what force and deflection are to an object.

They are the effects on the material of an object subjected to applied loads.


Stress → Force
Strain → Deflection


Best to learn with Axial forces


Stress vs Force Stress vs Deformation




Stress
Stress is defined as force per unit area

σ = P /A

σ = Stress (N/mm^2 or MPa)

P = Force (N)

A = Cross Sectional Area (mm^2)


Stress - Illustrated


Lecture 6 - Stress and Strain 3