Problem

I have 16 fatigue load cases (FTCASE) defined in my fatigue input. Why does my fatigue analysis stop with the error:

ERROR - FATIGUE LOAD CASE 14 HAS 0 VALUES IN TRANSFER FUNCTION

 

Answer

This error occurs when the fatigue solver cannot find any transfer function (RAO) values for a defined fatigue load case during the fatigue analysis.

A common cause of this error is an incorrect setting in the FTOPTGB line of the fatigue input.

The parameter defining the Number of Additional Postfiles controls how many additional postfiles are read during fatigue analysis.

If the number of postfiles specified is smaller than the number of fatigue cases requiring transfer function data, some fatigue load cases will not have transfer function values available.

For example:

The model defines 16 FTCASE fatigue cases

The FTOPTGB option is set to B, which instructs SACS to read 11 additional postfiles

In this situation, the solver cannot retrieve transfer function data for fatigue load cases beyond the available postfiles resulting in the error.

As the resolution,

Ensure that the Number of Additional Postfiles parameter is sufficient to read all postfiles required by the fatigue cases defined in the model.

Update the FTOPT 'B' line so that the Number of Additional Postfiles matches the required number of postfiles. 

After correcting the Number of Additional Postfiles setting and rerunning the fatigue analysis, the solver is able to read the required transfer function data for all fatigue load cases, and the analysis completes successfully without errors. 

 

When defining fatigue cases, ensure that:

• The Number of Additional Postfiles parameter is consistent with the number of fatigue load cases.
• All required postfiles containing transfer function data are available for the fatigue analysis.

This will prevent missing transfer function data and avoid interruptions during the fatigue run.