Mechanical Stress: Tensor Components, Stress States, and Analysis

All flashcards

What is mechanical stress?

Mechanical stress describes internal forces that neighboring portions of a material exert on one another, expressed in relation to the area across which they act.

How do stress and strain differ?

Stress concerns internal force per area. Strain measures relative deformation, such as a change in length, shape, or volume.

What are tensile and compressive stress?

Tensile stress pulls material apart and tends to elongate it. Compressive stress pushes material together and tends to shorten it.

What is the SI unit of stress?

The pascal (Pa), where $1\ \text{Pa}=1\ \text{N/m}^2$. The megapascal is often convenient for engineering stresses.

Name two ways stress can arise without an obvious external load.

Built-in stress may remain in materials such as prestressed concrete or tempered glass. Stress can also arise from temperature or chemical changes, or electromagnetic fields.

Quiz questions

1. What does mechanical stress describe within a material?Answer: It describes internal forces distributed across areas between neighboring parts of the material.
2. How does strain differ from stress?Answer: Strain measures relative deformation, whereas stress describes internal force per area.
3. What type of stress tends to elongate a stretched elastic band?Answer: Tensile stress.
4. If the same force acts over a smaller area, what happens to the average stress?Answer: The average stress increases because stress is force divided by area.
5. Which statement about stress is correct?Answer: Stress may be significant even when deformation is negligible, and it can exist as built-in stress without external forces.