🔩 STRESS AND STRAIN
PAGE 1 OF 5, FORCE PER AREA
THE LOAD TEST
WHAT IS STRESS?
Hang a heavy crate from a steel rod and the rod feels squeezed and pulled from the inside. Stress is how engineers describe that internal push or pull spread across the material. It equals the force applied divided by the cross-sectional area carrying that force. A thin wire and a thick bar may carry the same weight, but the thin wire feels far more stress because the same force is packed into a smaller area. Stress is measured in pascals (Pa), or often megapascals (MPa) and gigapascals (GPa) for tough metals. Higher stress means the material is working harder to hold the load.
🔩 STRESS FORMULA
Stress (σ) = Force ÷ Area. Units: pascals (Pa), or N/m². Same total force on a smaller area means higher stress.
PUSH!
THIN VS THICK
📏 Thin wire: same force, tiny area
⚠️ Stress shoots up fast
💥 Easier to snap under load
⚠️ Stress shoots up fast
💥 Easier to snap under load
SPREAD THE LOAD
🏗️ Wide I-beam spreads force
✅ Lower stress for same weight
🌉 Why bridges use thick steel
✅ Lower stress for same weight
🌉 Why bridges use thick steel