To measure and understand how materials stretch or change shape, engineers use specific tools and math formulas.

Normal Strain Measurement

• What is Normal Strain?
  Normal strain, often shown as ((\epsilon)), tells us how much a material changes in length compared to its original length.
  The formula for normal strain is:
  (\epsilon = \frac{\Delta L}{L_0})
  Here, (\Delta L) is how much the material got longer or shorter, and (L_0) is the starting length.

• How Do We Measure It?

1. Extensometers: These are tools that measure the distance between two points on a material to see if it has changed.
2. Strain Gauges: These devices measure changes in electrical resistance to detect tiny amounts of strain, as small as 1 microstrain (which is 0.000001).

Shear Strain Measurement

• What is Shear Strain?
  Shear strain, shown as ((\gamma)), measures how a material changes shape when pressure is applied sideways. The formula is:
  (\gamma = \frac{\Delta x}{L})
  In this case, (\Delta x) is how much the material moves sideways, and (L) is its original length in that direction.

• How Do We Measure It?

1. Rotational Strain Gauges: These are useful for measuring twisting or rotation in materials.
2. Digital Image Correlation: This technique uses video to look at the surface of a material and figures out how much it has changed shape.

Analyzing the Data

Engineers also use statistical techniques to look at the information they get from these measurements. This helps them make sure that their findings are correct and reliable. It’s really important for them to do this to design buildings and structures that are safe and work well.