# Notches and stress concentrations in composite profiles

Canonical: https://woodplasticcomposite.net/guides/notches-and-stress-concentrations-in-composite-profiles/
Language: en
Updated: 2026-10-15
Version: 1
Review: AI-assisted English editorial draft. Human technical review has not been recorded.

## Summary

A notch, hole or machined corner can change where a WPC component begins to fail. Unnotched specimen data should not automatically be applied to a detailed connection or cut profile.

## Technical context

The local geometry and loading direction influence the stress concentration. Manufacturing damage can add another variable. A smooth laboratory bar may therefore answer a different question from a board with a drilled or routed feature.

https://woodplasticcomposite.net/guides/notches-and-stress-concentrations-in-composite-profiles/#technical-context

## What to measure and document

Test representative details where they are important to the intended use. Record tool condition, hole or notch geometry and edge distances. Distinguish the effect of the design detail from damage introduced during specimen preparation.

https://woodplasticcomposite.net/guides/notches-and-stress-concentrations-in-composite-profiles/#verification-plan

## Implications for development and specification

Do not create universal drilling or routing dimensions from this principle. Use the selected manufacturer's instructions and engineering assessment. A detail is acceptable because the complete arrangement is supported by evidence, not because the base composite has a high nominal strength.

https://woodplasticcomposite.net/guides/notches-and-stress-concentrations-in-composite-profiles/#practical-decision

## Related reading and evidence limits

A finite-element modelling study compared predictions with tests on several WPC products. Use the linked work as related reading. The practical checks above are editorial recommendations, not reported test results or a substitute for product qualification.

https://woodplasticcomposite.net/guides/notches-and-stress-concentrations-in-composite-profiles/#reading-scope

## Key points

The local geometry and loading direction influence the stress concentration.
Test representative details where they are important to the intended use.
Do not create universal drilling or routing dimensions from this principle.

## Comparison

Review step | Evidence to retain
Material and geometry | Exact specimen or product identity
Verification | Method, conditions and individual observations
Decision | Approved scope and documented limitations

## What evidence is needed for notches and stress concentrations in composite profiles?

Test representative details where they are important to the intended use. Record tool condition, hole or notch geometry and edge distances. Distinguish the effect of the design detail from damage introduced during specimen preparation.

## Sources

1. WPC flexure prediction from axial and shear data — https://research.fs.usda.gov/treesearch/53195