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User Guide
This manual provides detailed information regarding the features, functionality, and simulation methods available in OptiStruct.
Run OptiStruct
The execution of OptiStruct is described here.
Summary Information
OptiStruct always creates an .out file which contains summary information for the job.

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What's New
View new features for OptiStruct 2024.
Overview
OptiStruct is a proven, modern structural solver with comprehensive, accurate and scalable solutions for linear and nonlinear analyses across statics and dynamics, vibrations, acoustics, fatigue, heat transfer, and multiphysics disciplines.
Tutorials
Discover OptiStruct functionality with interactive tutorials.
User Guide
This manual provides detailed information regarding the features, functionality, and simulation methods available in OptiStruct.
- Run OptiStruct
  The execution of OptiStruct is described here.
  - Environment Variables
    OptiStruct typically tries to avoid the use of environment variables, and instead uses either the defaults file or command line arguments, if possible.
  - Memory Allocation
    Memory is dynamically allocated for a run. The allocation starts with the initial memory (or minimum, memory).
  - Summary Information
    OptiStruct always creates an .out file which contains summary information for the job.
  - Run Options
  - Platforms and Hardware Recommendations
  - Configuration File
    OptiStruct configuration files may be used to establish default settings for OptiStruct.
  - Expanded Error Message File
    OptiStruct Expanded Error Message files may be used to expand the error and warning messages.
  - Memory Handling
  - Requirements for Restarting
    OptiStruct currently supports restart functionality for Nonlinear Analysis and Optimization. The following sections provide specific information regarding the procedure to implement restart.
  - Runtime Monitoring
    OptiStruct currently supports monitoring functionality for Small and Large Displacement Nonlinear static, Large Displacement Nonlinear Transient Analysis, and Fluid-Structure Analysis. Additionally, monitoring is also supported for Nonlinear Optimization runs.
  - Unit Systems
  - Coordinate Systems
    There are various ways in which coordinate systems are defined, applied, and interpreted for an OptiStruct model.
  - Compression Run
    In this special run mode, OptiStruct will simply read the model, compare all material and property data, and remove redundant data.
  - Encryption
    Encryption functionality is available in OptiStruct input files to encrypt confidential information.
- Elements
  Elements are a fundamental part of any finite element analysis, since they completely represent (to an acceptable approximation), the geometry and variation in displacement based on the deformation of the structure.
- Materials
  The different material types provided by OptiStruct are: isotropic, orthotropic, and anisotropic materials. The material property definition cards are used to define the properties for each of the materials used in a structural model.
- High Performance Computing
  High Performance Computing leverages computing power, in standalone or cluster form, with highly efficient software, message passing interfaces, memory handling capabilities to allow solutions to improve scalability and minimize run times.
- Solvers
  OptiStruct includes a variety of in-house and third-party solvers for applications in different engineering and technology fields.
- Contact
  Contact is an integral aspect of the analysis and optimization techniques that is utilized to understand, model, predict, and optimize the behavior of physical structures and processes.
- Structural Analysis
  The Structural Analysis section provides an overview of the following analyses.
- Thermal Analysis
  The Thermal Analysis section provides an overview of the following analyses.
- Electrical Analysis
  An electrical analysis involves calculation of electric potential in structures subject to electrical loads.
- Acoustic Analysis
  The Acoustic Analysis section provides an overview of the following analyses.
- Fluid-Structure Interaction
  OptiStruct and AcuSolve are fully-integrated to perform a Direct Coupled Fluid-Structure Interaction (DC-FSI) Analysis based on a partitioned staggered approach.
- Fatigue Analysis
  Fatigue Analysis is intended for solutions to structures in a large number of loading cycles.
- Aeroelastic Analysis
  Aeroelastic Analysis is the study of the deflection of flexible aircraft structures under aerodynamic loads, wherein the deformation of aircraft structures in turn affect the airflow.
- Multibody Dynamics Simulation
  A multibody system is defined to be an assembly of sub-systems (bodies, components, or sub-structures).
- Rotor Dynamics
  Rotor Dynamics is the analysis of structures containing rotating components.
- Piezoelectric Analysis
  Piezoelectric materials are a class of materials in which structural deformation triggers electrical potential and vice versa.
- NVH Applications and Techniques
  The NVH Applications and Techniques section provides an overview of the following:
- Powertrain Applications
  OptiStruct provides industry-leading capabilities and solutions for Powertrain applications. This section aims to highlight OptiStruct features for various applications in the Powertrain industry. Each section consists of a short introduction, followed by the typical Objectives in the field for the corresponding analysis type.
- Hi-tech Electronic Applications
  This section provides an overview of the capabilities of OptiStruct for the electronics industry. Example problems pertaining to the electronics industry are covered and common solution sequences (analysis techniques) are demonstrated.
- Aerospace Applications
  Provides an overview of Finite Element Analysis (FEA) for aerospace applications using OptiStruct.
- Analysis Techniques
  The Analysis Techniques section provides an overview of the following:
- Loads and Boundary Conditions
  The following boundary conditions are outlined here.
- Output
  OptiStruct generates output depending on various default settings and options. Additionally, the output variables are available in a variety of output formats, ranging from ASCII (for example, PCH) to binary files (for example, H3D).
- Create Output for Third Party Software
  How to create output from OptiStruct for third party programs.
- Design Optimization
  This section provides an overview of the following optimization types.
- Design Interpretation - OSSmooth
  A semi-automated design interpretation software, facilitating the recovery of a modified geometry resulting from a structural optimization, for further use in the design process and FEA reanalysis.
- Debugging Guide
  Guides in identifying and solving commonly encountered errors during the OptiStruct run.
- Error Message Database
  This section is comprised of error messages in ascending numerical order.
- Warning Message Database
  This section is comprised of warning messages in ascending numerical order.
- Build External Libraries
- Legacy Data
- References
Reference Guide
This manual provides a detailed list and usage information regarding input entries, output entries, and parameters available in OptiStruct.
Example Guide
The OptiStruct Example Guide is a collection of solved examples for various solution sequences and optimization types and provides you with examples of the real-world applications and capabilities of OptiStruct.
Verification Problems
This manual presents solved verification models including NAFEMS problems.
Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding OptiStruct.

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Summary Information

OptiStruct always creates an .out file which contains summary information for the job.

This information can be echoed to the screen through the inclusion of the SCREEN I/O Options Entry in the input data or through the use of the -out command line option (Run Options for OptiStruct).

This file also contains memory and disk space estimates. The disk space estimates for eigenvalue analyses (normal modes, linear buckling, modal methods of frequency, transient response, and fluid-structure coupling (acoustics)) are sometimes very conservative and can be three times as much as is truly used. This is because it is not fully predictable how much data needs to be saved to scratch files.

The true usage of memory and disk space is reported at the bottom of the file after the solver has finished.

Should the job be re-run in the same location, the .out file is not overwritten, but is instead moved to _#.out, where # is the lowest available three digit number that creates a unique file name.

For example, if filename.fem were run in a directory already containing filename.out, the existing filename.out would be moved to filename_001.out, and the summary information for the new job would be written to filename.out. Should the job be repeated again, the existing filename.out would be moved to filename_002.out, and the summary information for the latest job would be written to filename.out.

The filename.out is the only file that is saved in this manner. All other results files will be overwritten.

Recommendations

Try running OptiStruct with the default setting first (without specification of the -len or -core options).
Do a check run before submitting large jobs (>500,000 dof) to NQS to make sure sufficient NQS memory is being provided. The -lM option can be used to change the NQS memory. Be sure to include at least 12Mb for the executable in addition to the memory necessary to solve the problem. A check run can also assist in debugging input data without having to wait in a queue.