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User Guide
This manual provides detailed information regarding the features, functionality, and simulation methods available in OptiStruct.
Aerospace Applications
Provides an overview of Finite Element Analysis (FEA) for aerospace applications using OptiStruct.
Analysis of Aircraft Fittings
Fittings for aircraft panels are described.

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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.
- 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.
  - Airframe Stress Analysis
  - 1D Beam Modeling
    Different beam cross-sections can be modeled using OptiStruct by specifying the orientation and the cross-section of the beams.
  - Analysis of Aircraft Fittings
    Fittings for aircraft panels are described.
  - Finite Element Model Validation
  - Solution Sequences
    OptiStruct can be use different solution sequences for aircraft analysis.
  - Design Optimization
  - Summary
    This guide provided an overview of the capabilities of OptiStruct for the aerospace industry.
- 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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Analysis of Aircraft Fittings

Fittings for aircraft panels are described.

Fittings involving aircraft panels, the bulkhead, angle, tee, skin and lateral panels are meshed using quadrilateral elements. The fittings are meshed using tetrahedral elements. The fasteners are defined using RBE2 and CBUSH elements.

Figure 1. DFEM Model

The above fitting is analyzed for tensile and compressive loads, in two different load steps.

The details of loading and the boundary conditions for the model are:

Figure 2. Details of Loads and Boundary Conditions

The analysis is performed with different analysis types.

Model Files

Before you begin, copy the file(s) used in this example to your working directory.

Linear Static Analysis

The element forces for the CBUSH elements are then reviewed in the Tension and Compression cases.

Figure 3. DFEM Model Results from Linear Static Analysis

Nonlinear Analysis with Pre-loaded Fasteners

Nonlinear material property is defined using TABLED1 for aluminum and a pre-tension of 6000 lbs. is applied to the fasteners using the DEFORM card.

Figure 4. DFEM Model Results from Nonlinear Static Analysis. (a) before applying an external load; (b) after the application of external load

Large Displacement Nonlinear Analysis with Pre-loaded Fasteners

Large displacement nonlinear analysis can be activated with PARAM, LGDISP in OptiStruct. Figure 5 shows the results from a Nonlinear Large Displacement Analysis.

Figure 5. DFEM Model Results from Nonlinear Large Displacement Static Analysis