Engineering Notes — Fundamentals of Stress and Strain + 6 more topics

$\sigma = F / A$

There are a few types of stress you'll encounter:
* Normal Stress: Acts perpendicular to the surface. It can be tensile (pulling apart) or compressive (pushing together).
* Shear Stress: Acts parallel to the surface, like when you try to tear a piece of paper.

• Normal Strain: Measures the change in length ($\Delta L$) divided by the original length ($L_0$). It's how much something stretches or compresses.
  $\epsilon = \Delta L / L_0$
• Shear Strain: Measures the angular distortion of an object. Imagine a square becoming a parallelogram.

Ceramics are inorganic, non-metallic materials processed at high temperatures. Their properties are directly tied to the types of atomic bonds present, which are primarily ionic and/or covalent.

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Composite materials are engineered materials made from two or more constituent materials with significantly different physical or chemical properties. When combined, they produce a material with characteristics superior to the individual components. Think of them as team players where each material brings its strengths to the table.

You'll generally find composites made of two main parts:

The reinforcement is what gives the composite its strength and stiffness. Think of it as the "muscle." It's usually in the form of fibers (like glass, carbon, or Kevlar) or particles. These fibers are incredibly strong in tension.

The matrix is the "glue" that holds the reinforcement in place and transfers loads between the fibers. It protects the fibers from environmental damage and abrasion. Common matrix materials are polymers (like epoxy, polyester, or vinyl ester resins), but you can also have metal or ceramic matrices for high-temperature applications.

You use these methods during material selection, design validation, quality control, and failure analysis. They're essential for understanding a material's true limits, which is vital for safety-critical applications like aerospace, automotive, and structural engineering.