1. Chapter 2 - Strain
Figure: 02-00CO

2. Chapter 2 - Strain
Normal Strain – Elongation (or contraction) of a line segment per unit length.
Upon Loading, structure will experience stress as well as strain.
Example:
Undeformed (before Loading) P
Deformed (after Loading)

3. BEFORE LOADING:
AFTER LOADING:
Figure: UN01

4. Definition of Normal Strain:
Definitions:
Ds’
Ds = Initial length
Ds’ = Final length
= deformation = change in length
= Ds’ - Ds Ds d
Normal Strain = e = d/Ds = (Ds’ – Ds)/Ds
Units = in/in or mm/mm or M/M, etc….

5. Definition of Normal Strain:
Normal Strain = e = d/Ds = (Ds’ – Ds)/Ds
Example: A shaft which is ” in initial length grows to ” after loading. Determine deformation and strain.
Answer:
d = ” – ” = 0.005”
e = 0.005”/ = E-6 in/in = min/in

6. Definition of Shear Strain:
Figure: 02-02a
Shear Strain = g = p/2 - q’ units = rad

7. Seismic mounts (tested in pairs) shown at 4. 5” displacement
Seismic mounts (tested in pairs) shown at 4.5” displacement. What is the shear strain if the rubber thickness is 3.3” per mount??