✓ Sources checked · 10 September 2026 · View verification
Average compressive stress is axial compressive force divided by loaded cross-sectional area. State whether compression is taken as negative or reported as a positive magnitude.
By Matan · Updated
Stress and shortening
For uniform centric loading, magnitude |σ| = F/A. In a small linear elastic uniaxial model, axial strain is σ/E. With tension-positive signs, compression and shortening are negative. Stress has units Pa = N/m². [1]
Worked compressed bar
A 5000 N compressive load acts over 100 mm². Stress magnitude is 50 MPa. With assumed E = 100 GPa and length 0.40 m, strain is −0.00050 and length change is −0.00020 m, or shortening of 0.20 mm.
Crushing and buckling differ
A stocky specimen may fail through material damage, while a slender member can buckle before its average stress reaches material compressive strength. Eccentric loading also introduces bending. Average stress alone cannot establish safety.
Do not confuse strength with force
Compressive strength is a stress under a specified test convention, not just a maximum applied force. Compaction can alter some porous materials, but compression does not universally strengthen every material. The example assumes a uniform bar that remains stable and elastic.
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How this article was checked
Sources checked; calculations checked where shown. The definitions, model assumptions and main explanatory claims were cross-checked against the sources below. Worked-example arithmetic and units were checked separately. These examples are illustrative calculations, not experimental measurements.
Source cross-check and editing assisted by AI. No independent human scientific review is recorded for this revision. The check applies to the version dated 10 September 2026; it is not a guarantee that every possible interpretation is correct.
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Sources and further reading
- OpenStax: Compressive stress and strain — Compressive stress and strain.
- OpenStax: Elastic and plastic response — Elastic and plastic response.
Cite this article
Matan. “Compressive stress.” Your Physicist. Originally published 2023-03-17; updated 2026-09-10. https://your-physicist.com/compressive-stress/
Revision history
: Added a checked stress and shortening calculation; distinguished material strength from member stability. Added linked sources and a transparent verification record.
