Stress and strain

What this module covers

• Explain why stress matters more than force when comparing members
• Calculate direct stress, direct strain and axial extension
• Use Hooke's law and Young's modulus correctly
• Distinguish material stiffness, member stiffness and strength
• Say where simple stress theory stops being reliable

Lessons

1. 7.1

   Stress and strain

   Why engineers divide by area, and what strain actually measures.

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2. 7.2

   Hooke's law, stiffness and strength

   The elastic relationship, and three ideas that are constantly confused.

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3. 7.3

   Shear strain and the Poisson effect

   The second kind of stress, and why stretching one way shrinks the others.

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4. 7.4

   Pressure vessels and shared load paths

   Two places where direct stress alone answers the whole question.

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