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[FAQ]

The only way to get acceleration frequency response in Mechanical APDL is to derive it from the nodal displacements using NSOL and PROD commands in /POST26 (e.g., multiply displacements by 2*pi*freq (i) to get velocity). Velocity and acceleration in harmonic analysis are not stored in the result file, so the user needs to obtain the nodal displacement using the NSOL and PROD commands. The reason we do not store velocities and acceleration in a harmonic analysis is because in Mechanical APDL we would like to be efficient in writing the result file and avoid storing dependent variables to save space. Also, it is just one additional line of code to calculate the velocity or acceleration variable in post26. (In Workbench Mechanical, when acceleration frequency response plot is added in the results, we are just calculating acceleration using nodal displacement post solution.) Additional Note: Since ANSYS performs a smoothing operation on accelerations in a transient analysis, they are stored by the solver (see OUTRES command) and can be obtained using the NSOL command directly.