Module 08
Engineering materials
What a tensile test actually tells you, how the elastic constants connect, and what happens when load is held for years or repeated for millions of cycles.
What this module covers
- Read a stress–strain curve and name what each region means
- Distinguish ductile from brittle behaviour, and nominal from true stress
- Use proof stress for materials with no clear yield point
- Relate E, G, ν and K, and know which two are independent
- Explain creep, relaxation and fatigue, and when each governs
- Calculate thermal strain, restrained thermal stress and impact effects
Lessons
Where E, yield, ultimate strength and ductility actually come from.
Start lesson →E, G, ν and K — why only two of the four are independent.
Start lesson →What happens when load is held for years, or applied a million times.
Start lesson →Why a free member does not care about temperature and a restrained one does.
Start lesson →
Module checkpoint
Check what you have taken in
4 questions
Question 1
On a nominal stress–strain curve for mild steel, what does the drop after the ultimate point represent?
Question 2
A material has E = 70 000 N/mm² and ν = 0.33. What is its shear modulus, in N/mm²?
Question 3
A fully restrained steel member (E = 205 000 N/mm², α = 12 × 10⁻⁶ per °C) is cooled by 40 °C. What is the magnitude of the resulting stress, in N/mm²?
Question 4
Which quantity most directly governs the fatigue life of a welded detail?