Low-cycle Fatigue | Online Calculator

Fatigue Calculators







Low-cycle Fatigue

This calculation determines the cyclic strength of parts within 105 loading cycles. To calculate the number of loading cycles to failure N, it is necessary to specify the amplitude of the maximum relative deformations ε obtained under a single static loading, as well as the material area reduction ratio RA.

In the absence of information on the material fatigue strength σ-1, it can be determined based on the ultimate strength σm. The calculated value of the fatigue strength σ-1calc can be used in further calculations.

For the calculation, the elastic modulus E of the part should be specified.

INITIAL DATA

ε - Relative deformations under static loading;


σm - Material ultimate tensile strength;


σ-1 - Material fatigue strength;


E - Young's modulus;


RA - Area reduction ratio of material.

RESULTS DATA

σ-1calc - Calculated fatigue strength of material. It can be applied if the values of fatigue strength for thr material are absent in standards;


N - Number of cycles to failure.

Relative deformations (ε)

Tensile strength (σm)

Fatigue strength (σ-1)

Young's modulus (Е)

Area reduction ratio (RA)

Fatigue strength (σ-1calc)

Number of cycles (N)

BASIC FORMULAS

Ultimate cumulative strain:

ek = 2*ε;

Number of cycles at deformation ε < 0.25Ln(1/[1 - RA]):

ek = C*N-0.6 + 2σ-1 / E;

Number of cycles at deformation ε > 0.25Ln(1/[1 - RA]):

ek = (C - ε)*N-0.6 + 2σ-1 / E;

C = 0.5ln(1/[1 - RA]).

INITIAL DATA

ε - Relative deformations under static loading;


σm - Material ultimate tensile strength;


σ-1 - Material fatigue strength;


E - Young's modulus;


RA - Area reduction ratio of material.

RESULTS DATA

σ-1calc - Calculated fatigue strength of material. It can be applied if the values of fatigue strength for thr material are absent in standards;


N - Number of cycles to failure.

MATERIAL PROPERTIES

Steel

Tensile strength

MPa (psi)

Yield strength

MPa (psi)

Reduction in area

%

Fatigue strength

MPa (psi)

1015

424 (61.5*103)

324 (47*103)

69

217 (31.5*103)

1040

717 (104*103)

490 (71*103)

57

317 (46*103)

4130

758 (110*103)

655 (95*103)

63

304 (44*103)

5140

1000 (145*103)

862 (125*103)

58

380 (55*103)

6150

1434 (208*103)

1331 (193*103)

43

676 (98*103)

OTHER CALCULATORS

AREA MOMENTS OF INERTIA
BEAM CALCULATORS
TORSION OF BARS
CIRCULAR FLAT PLATES
BUCKLING
ELASTIC CONTACT
IMPACT LOADS
NATURAL FREQUENCIES
PRESSURED SHELLS
FLUID DYNAMIC
COMPOSITES
SPRINGS
THREAD CONNECTIONS
SHAFT CONNECTIONS
BEARINGS
DRIVES
FATIGUE
HEAT TRANSFER