*HCF

Keyword type: step

This keyword card is used to consider High Cycle Fatigue (HCF) in a crack propagation calculation. To this end, a modal calculation (*FREQUENCY) must have been performed for the uncracked structure and the resulting stresses must have been stored in a frd-file. Right now, no cyclic symmetry is allowed in this modal calculation. There are three required parameters INPUT, MODE and MISSION STEP and two optional parameters MAX CYCLE and SCALING.

The INPUT parameter is used to denote the frd-file containing the stress results of the modal calculation for the uncracked structure. It must have been performed in a separate calculation. Temperature results are not necessary, since the temperature of the LCF (static) calculation defined on the *CRACK PROPAGATION card is used.

With the MODE parameter the user can select which mode in the modal calculation is to be used. This mode is scaled with the value given by the SCALING parameter (default is 1.) and superimposed on the static step defined by the MISSION STEP parameter.

If HCF crack propagation is not allowed (MAX CYCLE = 0; this is the default) the calculation stops as soon as HCF propagation is detected. If it is allowed (MAX CYCLE 0) HCF calculation is calculated for the actual crack propagation increment and the next increment is started. In that case, no LCF propagation is determined.

First line:

- *HCF
- Enter any parameters and their value

Example: *HCF,INPUT=hcf.frd,MODE=3,SCALING=0.01,MISSION STEP=4

defines high cycle fatigue using the stress results for mode 3 from file hcf.frd, scaling them by 0.01 and superimposing them on the fourth step in the mission. This mission must have been defined using the INPUT parameter on the *CRACK PROPAGATION card.

Example files: crackIIcumhcf, crackIIcumhcf2.