HIN File

Use the HIN file to specify the fatigue loading history.

As with any fatigue algorithm, knowledge of the load history must be supplied to accurately predict the fatigue life of a composite material. In contrast to many fatigue algorithms, however, knowledge of the time history is also necessary when predicting the fatigue life of composite structures. To facilitate specification of the load history with the fatigue feature, Helius PFA requires a HIN file (.hin) to describe the analysis step of the fatigue loading and the load history of the fatigue loading.

For this problem we will add a single block loading to be repeated twice that defines the load history of the fatigue step. By specifying the load as a fraction of the maximum load at three points in time, a saw-toothed fatigue load history can be represented. See the Helius PFA User's Guide for further detail (Specify a Load History for Fatigue).

Open a notepad editor
Add the required *FATIGUE and *BLOCK keywords as shown below:
```
*FATIGUE, STEP=2
*BLOCK, REPEATS=2
0.1, 0.0
1.0, 0.1
0.1, 0.13
```
The load history specified represents the fatigue loading shown below.
Save the HIN file using the same name as the tutorial with a .hin extension.
```
Tutorial_4.hin
```