What is stress concentration factor Kt?

Kt is the ratio of maximum local stress to nominal stress at a geometric discontinuity. Kt = σ_max / σ_nom. It depends only on geometry, not material. A circular hole in a wide plate under tension has Kt ≈ 3.0.

What causes stress concentrations?

Any abrupt change in geometry: holes, notches, fillets, keyways, threads, grooves, changes in cross-section. The stress flow lines crowd together at these features, increasing local stress.

How does Kt affect fatigue life?

Stress concentrations dramatically reduce fatigue life because fatigue cracks initiate at the point of highest stress. The fatigue notch factor Kf ≤ Kt accounts for material sensitivity: Kf = 1 + q(Kt-1), where q is the notch sensitivity factor.

How can stress concentrations be reduced?

Use generous fillet radii, avoid sharp corners, use gradual transitions, add relief grooves near shoulders, polish surfaces at critical points, and use shot peening to introduce beneficial compressive residual stress.

What is Peterson's Stress Concentration Factors?

Peterson's is the definitive reference book containing charts and equations for Kt values for hundreds of geometric configurations. It provides Kt as a function of geometric ratios (r/d, D/d, etc.) for tension, bending, and torsion loading.

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Calculadora del Factor de Concentración de Tensiones

Busque Kt para geometrías comunes: agujero en placa, radio de transición en escalón, entalla en U, utilizando datos simplificados de los gráficos de Peterson’s.

Gráficos de Peterson’sBúsqueda de Kt#173

Resultados

Factor de Concentración de Tensiones Kt

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Tensión local máxima σ_max

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Relación geométrica

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Factor de Concentración de Tensiones

Valores típicos de Kt

Geometría	Rango de Kt
Agujero central en placa ancha	~3.0 (d/W pequeño)
Radio de transición en escalón (D/d=2, r/d=0.1)	~1.8–2.5
Entalla en U	~1.5–3.5
Surco circunferencial	~1.5–3.0

⚠️ Nota: Estos son valores aproximados obtenidos de ecuaciones de ajuste de curvas simplificadas. Para valores precisos, consulte Peterson’s Stress Concentration Factors o realice un análisis por elementos finitos (FEA). Kt es solo para análisis elástico.