A Stress

1. (biology) A physical, chemical, infective agent aggressing an organism.
2. (biology) Aggression toward an organism resulting in a response in an attempt to restore previous conditions.
3. (countable, physics) The internal distribution of force across a small boundary per unit area of that boundary (pressure) within a body. It causes strain or deformation and is typically symbolised by σ or τ.
4. (countable, physics) Force externally applied to a body which cause internal stress within the body.
5. (uncountable) Emotional pressure suffered by a human being or other animal.
6. (countable, phonetics, loosely) A suprasegmental feature of a language having additional attention raised to a sound, word or word group by means of of loudness, duration or pitch; phonological prominence.Synonym: accent
7. (countable, phonetics, strictly) The suprasegmental feature of a language having additional attention raised to a sound by means of of loudness and/or duration; phonological prominence phonetically achieved by means of dynamics as distinct from pitch. Synonym: stress accentAntonyms: pitch, pitch accent
8. (uncountable) Emphasis placed on a particular point in an argument or discussion (whether spoken or written).
9. Obsolete form of distress.
10. (Scotland, law) distress; the act of distraining; also, the thing distrained.

Synonyms

• (phonetics): accent, emphasis
• (on words in speaking): emphasis
• (on a point): emphasis

structural engineering

stress is the internal resistance of a material to deform when subjected to external loads. It is a measure of the internal forces acting within a deformable body, quantified as force per unit area.

The fundamental formula for stress is:

\[\sigma = \frac{F}{A}\]

Where:

• \(\sigma\) = Stress
• \(F\) = Internal resisting force
• \(A\) = Cross-sectional area over which the force acts

Depending on the direction of the internal forces relative to the material's cross-section, stress is divided into two primary categories and several specific sub-types:

1. Normal Stress (\(\sigma\))

(normale spenninger)

Occurs when the internal resisting force acts perpendicular (normal) to the cross-sectional area.

• Tensile Stress: The material is being pulled apart. The forces attempt to elongate the structural member (e.g., a steel cable in a suspension bridge).
• Compressive Stress: The material is being pushed together. The forces attempt to shorten or crush the structural member (e.g., a concrete pillar supporting a roof).

2. Shear Stress (\(\tau\))

(gjennomsnittlige skjærspenninger)

Occurs when the internal resisting force acts parallel to the cross-sectional area, causing layers of the material to slide past one another.

• Direct Shear: Forces slice directly across a cross-section (e.g., a steel bolt being sheared in half by two plates pulling in opposite directions).
• Torsional Shear Stress: Induced when a structural member is twisted around its longitudinal axis (e.g., a rotating drive shaft transmitting torque).

3. Complex Stresses

Most real-world structural elements experience a combination of primary stresses simultaneously.

• Bending Stress: Occurs when a moment (bending force) is applied to a structural member like a floor beam. Bending induces compressive stress on one side of the member's neutral axis and tensile stress on the opposite side simultaneously.
• Bearing Stress: A specific type of localized compressive stress that occurs exactly at the surface of contact between two separate, interacting bodies (e.g., the exact point where a heavy steel beam rests on a brick wall).