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Preface

You can encounter several types of problems when working with large files:

• Problems with large SOLIDWORKS models (many large part and assembly files)

• Problems with large meshes

• Problems creating large result files

• Problems reading large result files
• Problems displaying mesh or results.

The typical difficulty when working with large files is usually poor performance.

This document explains the problems that can arise with large files and proposes solutions. Keep in mind the following three ideas, which constitute a high-level summary of the document:

• Anticipate potential problems by using good modeling practices
• Use the Result Options PropertyManager to save only the results you need only.
• Work locally (SOLIDWORKS and result files)

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Problems With Large SOLIDWORKS Models

A large SOLIDWORKS model is a model that contains many large parts and assembly files.

For this first type of problem, the solution is to implement best practices for SOLIDWORKS that concern the use of appropriate hardware, and the proper settings and procedures for working with large assemblies. Consider following the recommendations in the SolidPractices document Best Practices for Managing Large Assemblies. See the Dassault Systèmes Knowledge Base (KB) QA00000122358.

The use of large assemblies for simulation also calls for a change of paradigm. That is, modeling the geometry with simulation (instead of manufacturing) in mind. Consider the following:

• With what type of element will you use to mesh each component?
• Will global bonding take care of most bonded contact situations?
• What components can you replace with connectors?
• Any other considerations.

These considerations are not the topic of this SolidPractice. Look for tips in the Dassault Systèmes KB. For example:

• QA00000109908 - Meshing and modeling tips and tricks
• QA00000105159 - Preparing a solid model for mixed meshing
• QA00000105124 - Solid modeling guidelines for solid meshing
• QA00000105324 - How to model and mesh a frame structure made of beams
• QA00000105058 - Where can I find an example of Surface geometry creation that explains the procedure from from solid to meshable surface geometry.
• QA00000109909 - When should I not use Beam elements?
• And many more…

Problems With Large Meshes

There is no limitation for the number of nodes and elements SOLIDWORKS Simulation can generate in a mesh. There used to be a limitation in the number of degrees of freedom (DOFs) for some solvers. This limitation disappeared in version 2021 and the Intel Direct Sparse solver can nowadays handle linear static and nonlinear studies with more than 4 million equations.

The only real limit is the amount of data that your computer can handle. This depends on the operating system, the amount of RAM, the available disk space, etc.

If creating a large mesh is typically not a problem in itself, the very large result files you obtain can cause performance problems.

In general, do not use the full amount of RAM on your systems to size an analysis upward. For example, if you have 64 GB of RAM, do not assume that the right mesh for your model is a mesh that uses the full amount of RAM.

Larger meshes cause more than larger result files. They also cause longer analysis time. This is especially true for linear dynamic studies and for nonlinear studies. In addition, the response time of the user interface (UI) can suffer from delays. For example, when you display results, or when you zoom, pan, or rotate a result plot.

Whenever you run a study with time or frequency steps (transient thermal, nonlinear, dynamic, etc.), be aware that the size of the result files are proportional to the number of saved steps.

To limit the severity of performance issues caused by large result files, always optimize your mesh. You can make many adjustments to a simulation to shorten the analysis time and reduce the file size. Some of these adjustments include:

• Using modeling techniques to:
  • Suppress components that do not participate in the structural behavior of the structure.
  • Replace components with connectors, loads, or fixtures.
  • Simplify the geometry by removing details.
  • Plan the type of element that you want to use to mesh each remaining body, irrespective of the default element type. Create the appropriate supporting geometry to have the mesh you want. When appropriate for some components, use idealization with 1D and 2D elements such as beams, trusses, and shells. Remember that the total number of degrees of freedom (DOF) in a mesh depends on the number of and the type of nodes. Solid elements have 3 DOF per node. Shell and beam elements have 6 DOF per node.
  • Whenever appropriate, split bodies to ensure two elements across thickness for thin solid parts so that you can use a larger element size. See QA00000111602.
• Taking advantage of symmetry (planar, axial, and circular).
• Using the Mesh Control PropertyManager to adjust the element size according to the requirements, and not using too many elements where not required.
• Using adaptive solution techniques to refine the mesh only where accuracy of the results requires it.
• Effective with the release of SOLIDWORKS Simulation 2020, the application includes an improved mesh formulation for linear static studies that allows both draft and high-quality solid elements to coexist in a single mesh definition. This can help reduce the number of degrees of freedom. For more information, click here.

Problems Creating Large Result Files

You typically encounter problems creating large result files only with analysis types that create results sets for multiple steps. These include:

• Dynamic analysis
• Nonlinear analysis
• Drop test
• Transient thermal analysis

In general, in case of large result files, you need enough disk space and a high reading/writing speed on the drive that stores the files.

Available Disk Space

Problems occur when you there is insufficient disk space.

1. For all solvers

SOLIDWORKS Simulation needs an available disk space that is at least twice the size of the result file set. This is because when the solver creates the result files, both the CWR format file and the individual result files are present. For example, assume that the available disk space before performing the mesh and analysis is 10 GB, and that the analysis creates result files (such as .STE, .STR, .OUT, .CLD, .GEN files) of 6 GB in size. Consequently, the program cannot create the .CWR file. Indeed, the creation of the .CWR file would require 6 GB. This is impossible with only 4 GB remaining.

When there is sufficient disk space, SOLIDWORKS Simulation can handle very large files. On a 64-bit machine, you can expect the program to work well with .CWR format files as large as 30 GB.

1. Special case of the Large Problem Direct Sparse solver

A unique feature of the Large Problem Direct Sparse solver is that this solver uses disk space to generate temporary files during run-time instead of trying to use RAM. The solver deletes these files after completion of the study. The file names follow the convention [MODEL_NAME]-[STUDY_NAME].XXX where XXX is a numerical value that usually starts at 096 and increases in increments with the creation of each new temporary file. This can go as high as 130 and more as shown in the following image:

Currently, the solver does not verify that there is enough disk space when you start the simulation.

See the SPR 1104995: “Enhancement Request: for the Large Problem Direct Sparse (LPDS) solver, Perform an estimation of the required disk space, compare with available disk space and inform user if disk space is insufficient”.

1. High Read/Write Speed On The Drive That Stores The Files

Achieving a high read/write speed for the result files is typically not possible when the result files exist on a network drive.

You can expect to encounter major performance problems when writing files on a network drive. For more information, see section 7: “Is it advisable to have the results folder on a network location?”

Be aware that the same type of problems are also present when reading these large CWR files.

Better performance happens when the result files exist on a local drive. Additional considerations include using a solid-state drive (SSD) rather than a spindle drive.

Use of a real-time scanning antivirus program may interfere with both the performance and success of writing and reading very large files.

Reducing CWR File Size Without Changing The Mesh

A good workaround to reduce the size of CWR files for transient thermal and dynamic analysis is to split the analysis into several studies.

For example, consider a transient thermal analysis with a time step of 10 seconds and a duration of 10,000 seconds. This analysis creates 1000 file sets. You can split the analysis in a first study with a time step of 10 seconds, and a duration of 500 seconds, and then use the final time step of that study as the initial condition for a second study that lasts another 500 seconds. This way, you have only 50 result sets per CWR file, which makes each file half as large.

You can also edit the options in the Result Options PropertyManager to specify not to save certain result quantities that are not useful for the analysis.

• For Static studies, SOLIDWORKS Simulation 2013 introduced a new option to not store the stress and strain results in the result file (*.CWR) for static studies. To activate this option, in the Result Options PropertyManager, clear the Stresses and strains option under Quantities to Save into File. Only displacement and body force results will be calculated and stored in the results file.
• In Nonlinear analysis, you can use the result options to save results for only every other calculation time steps (for example), reducing the result file size by 2.
• For thermal transient studies, SOLIDWORKS Simulation 2013 introduced new result options to allow saving results only for selected solution steps. In the Result Options PropertyManager, select For specified solutions steps. Define the Start and End solution step, and the step increment for the solution step set you want.
• For drop test analysis, the solution is to reduce the number of saved plots in the Result Options PropertyManager.
• For Dynamic studies, you have the option to save Nodal von Mises stress only (Faster) results. This reduces file size and accelerates the display of von Mises stress plots.

Problems Reading Large Result Files

Problems reading large result files are similar to those you encounter when writing the same files. You need enough disk space and a high read/write speed on the drive that stores the files.

1. Problems Displaying The Mesh Or Results

The rendering of stress and strain plots for simulations that have more than 10 million elements could appear patchy.

This is an active area of enhancement for the software. If you encounter any problem, test with the latest SOLIDWORKS version and service pack.

Is It Advisable To Have The Simulation Results Folder On A Network Location?

No, this is not a recommendation. Such a configuration might work fine if the network is very fast, the files are small, and the network antivirus does not cause problems. However, such a setup causes problems in many cases.

In general, one of the biggest issues may be performance. During meshing and while an analysis is running, SOLIDWORKS Simulation creates many temporary files in the results folder. The results folder needs constant and immediate read/write access. The size of these files is often much bigger than the results (.CWR) file. Transferring all of these files across a network location might not only slow down the network, but it can also significantly increase run times.

Network reliability can also be an issue because if the network goes down even momentarily, it can interrupt an analysis and cause a loss of data or even some software instability.

Antivirus software can also affect the performance because such software can block the reading and writing of temporary files that are used for meshing or solving. This can cause unusual behavior, which is not reproducible when you run the analysis on a local hard drive.

In addition, as with local hard drive locations, permissions come into play, especially if the network location has additional policy restrictions set by an administrator.

The best way of handling simulations in a shared or network environment is to:

1. Copy the files over from the network to a local hard drive before meshing and running an analysis.
2. Specify a local folder as the results folder location in the study properties.
3. Move the SOLIDWORKS model along with the respective CWR files to a network location for sharing purposes.

It is also a best practice to copy the CWR file to a local hard drive for the purpose of viewing results. This is true even when not remeshing or rerunning a completed analysis. This is because such files are often large and performance suffers if the program reads the result file across a network.

It is important to check the result folder location (at the bottom of the study's Properties dialog box) before running an analysis if you previously copied the SOLIDWORKS files. This is because the former result file location is still stored in the study's Properties. If you copied the files on your local C: drive, the files may still point to a remote location. Running the analysis (or creating a mesh) with the result folder pointing to a remote location drastically reduces performance. When this occurs, it is advisable to stop the analysis, change the result folder, and rerun the analysis locally.

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