Stress and strain are basic ideas in how materials work. They help us understand how materials react when we put different forces on them.

What is Stress?

• Stress is like how much force is being pushed on a certain area.
• We measure stress in a few different ways:
  • Pascals (Pa) in the metric system: 1 Pa is the same as 1 newton per square meter (N/m²).
  • Megapascals (MPa): 1 MPa is 1 million Pascals (10⁶ Pa).
  • Pounds per square inch (psi) in the imperial system: 1 psi is about 6895 Pascals.

What is Strain?

• Strain shows how much something bends or stretches compared to its original size.
• We usually write it as a ratio or a percentage:
  • Normal strain (we use the symbol ε) can be calculated like this: ε = ΔL/L₀, where ΔL is how much the length changes, and L₀ is the original length.

Why Does This Matter in Engineering?

• It’s really important to measure stress and strain correctly. This helps engineers choose the right materials, design safe structures, and check if things are safe to use.
• Engineers rely on these numbers to make sure materials can handle the expected forces. This helps prevent accidents and keeps structures strong and safe, no matter what they’re used for.