Envelope Plots

Envelope plotting can be used to plot either the minimum, maximum or the absolute maximum data values within a range of states.

In addition to plotting the minimum or maximum values, the times of the states that the values occurred at can also be plotted.

If envelope plotting is turned on for an element-based data component (e.g. strain), then element averaging is automatically turned off (see Averaging).

When envelope plotting is turned on, Line Contours are only available for node-based data components (e.g. velocity).

Envelope plotting may also be used with the WRITE option (see WRITE Listing Numerical Data to Screen and/or File) but it is not available during ANIMATION (see Animation How to Display, Control, Store and Retrieve Animation Sequences) or when the REFERENCE_STATE option (see REFERENCE STATE/MODEL) is being used.

Saving and Retrieving Envelopes

You can save computed envelope plots to a file and retrieve them later. This is typically useful for large models where envelope calculation may take an increased amount of time and you would like to view that envelope data later without having to wait for the calculation again.

Saving an Envelope

Saving an envelope occurs when you press the Calculate and Write button. For all windows selected in the Data Panel, D3PLOT will loop over each window and for each model in that window automatically calculate and write out an envelopes.h5 file within the respective model's directory. Multiple writes will append that information to the same HDF5 file and there's currently no limit to the number of envelopes that you can save in a file other than the size of the disk on your system.

Various information is written to the Envelope file, including:

• Model Metadata: 
  • The model's file path from which the envelope was original saved
  • The number of elements (e.g. the number of shells, solids, beams etc...)
  • The model's title
• Envelope Metadata:
  • Component name
  • On-plan and through-thickness integration point
  • Number of states and which states are selected
  • Reference frame
• Envelope Data:
  • The actual data to be read into D3PLOT

The Model Metadata is used to validate that the envelope you are trying to retrieve matches the model on which you're trying to map the data. 

The Envelope Metadata is used to give you context about the data you saved, and repopulates the Data Panel when you retrieve the envelope later.

You can also write envelopes as a batch process – see Valid D3PLOT Command Line Arguments.

Writing to network drives

If you experience issues writing the envelope file to a network drive, this will typically be due to the type of network drive system being used, the timing of different files being written, and also file locking behaviour on that system.

If you receive any HDF5 warnings regarding:

H5Fopen(): unable to synchronously open file

then you may find success setting the HDF5_USE_FILE_LOCKING environment variable to FALSE. 

Retrieving an Envelope

Clicking Retrieve from File will bring up an option to select a previously written envelopes.h5 file. Selecting a file will then populate the following panel:

Envelopes can currently only be retrieved one envelope plot at a time. The selected envelope will be mapped (applied) to any valid model you select, across all the active windows as specified at the top of the Data Panel. Information about the envelope can be seen by hovering over the "Data Component" to provide more context about what was saved prior to retrieval.

Retrieval can only occur if the model which you are trying to map onto matches the model from which the envelope was originally created. This means that you won't be able to map any envelope to any model and you won't be able to create an envelope from a model and map it onto the same model with fewer parts created via PTF Cut for instance.

When you right-click the mapping list, you will get a list of the currently loaded in models in D3PLOT. Select a valid model for the envelope and then press the Apply button to retrieve it.

If a model you have selected is not compatible with the envelope you're trying to read in you will receive one of the following warnings:

This warning indicates that the envelope is incompatible for reading and you will not be able to read the envelope data.

This warning indicates that the envelope is compatible. However, the file path from which you saved the envelope now differs from where you are reading it from.

This can occur when you move the model directory with the envelope file to another directory. We still allow reading to continue as the model could still be valid for retrieval.