There are 2 file types use the .PCH file extension:
1. Nastran Punch Output File
Output file created by MSC Nastran, a structural analysis program that enables you to test the integrity of different structures such as spacecraft or buildings; contains different types of data output depending on the card (similar to a command) that is run.
An example of a card is XYPUNCH, which will create an output of the X and Y-axis data, e.g., magnitude vs. frequency. The contents of the PCH file created from this card would consist of two types of data. The first type would resemble the .F06 file, with mode shapes, static displacements, and grid point stress data, but in alternate format from the F06 file. The second type of output would display magnitude vs. frequency, which helps plot the response curve in a spreadsheet.
Updated: December 13, 2013
2. Precompiled Header File
Contains programming code referenced by a source code file, often using an #include preprocessor directive; may reference other header (.H) files and other resources.
PCH files are used by Microsoft Visual C++ and other software development programs, such as Apple Xcode. PCH files used by Xcode are called Prefix Header files and are typically named "[name]_Prefix.pch."
Updated: March 4, 2015