Optimizes degree-of-freedom usage in a coupled acoustic model.
APDL Command: ECPCHG
The ECPCHG command converts uncoupled acoustic element types to coupled acoustic element types that are attached to the fluid-structure interaction interface. Or it converts coupled acoustic element types to uncoupled acoustic element types that are not attached to the fluid-structure interaction interface. Issuing ECPCHG can dramatically reduce the size of the Jobname.EMAT file, compared to the model fully meshed with the coupled acoustic elements.
Performing the ECPCHG conversion on meshed volumes can create circumstances in which more than one element type is defined for a single volume.
If the acoustic elements are coupled with shell elements (SHELL181 or SHELL281), you must set the fluid-structure interaction (FSI) flag by issuing the SF,,FSI command before the ECPCHG command.
ECPCHG may add new element types to your model, or it may change the element type for existing acoustic elements. You should verify the defined element types with ETLIST and the element attributes with ELIST after using this command.