1. Reference problem

1.1. Geometry

Analysis consists of determining the damage suffered by a part at a point at which the loading history is provided.

To test the calculation of damage by the Wöhler method, we consider the history of stress loading and we extract the elementary cycles by a cycle counting method, which in this test is the method of RCCM. Then the elementary damage due to each elementary cycle is calculated, by interpolation on the Wöhler curve of the material.

The Wöhler curve is provided as a point by point function, which gives the value of the number of cycles at break as a function of the alternating stress \(\mathrm{Salt}=\frac{\Delta \sigma }{2}\).

Interpolation is of the logarithmic type on the abscissa and the ordinate and it is allowed to extend this function linearly to the right and to the left.

Three different calls to operator POST_FATIGUE make it possible to take into account or not the average constraint of each elementary cycle.

The correction adopted is that of the Haigh diagram, either along the Goodman line or following the Gerber parabola [R7.04.01].

Total damage is determined by Miner’s linear accumulation rule.

To test the calculation of damage by the Manson-Coffin method, the history of deformation loading is considered and the elementary cycles are extracted by a cycle counting method, which in this test is the RCCM method. Then the elementary damage due to each elementary cycle is calculated, by interpolation on the Manson-Coffin curve of the material.

The Manson-Coffin curve is provided in the form of a point by point function, which gives the value of the number of cycles at break as a function of \(\frac{\Delta \varepsilon }{2}\).

Total damage is determined by Miner’s linear accumulation rule.

1.2. Material properties

The Wöhler curve of the material, which gives the value of the number of cycles at break as a function of the alternating stress, is defined point by point by:

\(\mathit{Salt}\)
\(N\)		500,000.		100,000.	50,000.

\(\mathrm{Su}\) = material breakage limit = 850.

Charging history

\(t\)
\(\sigma (t)\)				—500.

The Manson-Coffin curve of the material, which gives the value of the number of cycles at break as a function of \(\frac{\Delta \varepsilon }{2}\), is defined point by point by:

\(\frac{\Delta \varepsilon }{2}\)
\(N\)		500,000.		100,000.	50,000.

Charging history

\(t\)
\(\varepsilon (t)\)				—500.