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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.
Size (Parameter) Optimization
OS-E: 0905 Spot Weld Fatigue Analysis and Size Optimization of a Frame Structure
Demonstrates Spot weld fatigue optimization using OptiStruct.

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What's New
View new features for OptiStruct 2024.1.
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.
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.
- Nonlinear Small Displacement Analysis
  This section presents nonlinear small displacement analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Nonlinear Large Displacement Analysis
  This section presents nonlinear large displacement analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Nonlinear Transient Analysis
  This section presents nonlinear transient analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Frequency Response Analysis
- Normal Modes Analysis
  This section presents normal modes analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Complex Eigenvalue Analysis
  This section presents complex eigenvalue analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Thermal and Heat Transfer Analysis
  This section presents thermal and heat transfer analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Analysis Techniques
  This section presents analysis technique examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Topology Optimization
- Size (Parameter) Optimization
  - OS-E: 0900 Seam Weld Fatigue Analysis and Size Optimization of a Frame Structure
    Demonstrates Seam weld fatigue optimization using OptiStruct.
  - OS-E: 0905 Spot Weld Fatigue Analysis and Size Optimization of a Frame Structure
    Demonstrates Spot weld fatigue optimization using OptiStruct.
  - OS-E: 0910 Shell Cantilever
    Demonstrates how size optimization can be used.
  - OS-E: 0915 Cantilever Beam using Equations
    Demonstrates how to use the equation utility to define cross-sectional properties in a size (parameter) optimization.
  - OS-E: 0920 Ten Bar Truss
    Demonstrates how size (parameter) optimization can be used.
  - OS-E: 0925 Solve an Optimization Problem Not Defined by a Finite Element Model
    This example involves the optimization of a box defined entirely by equations (there is no finite element model in the solution).
  - OS-E: 0930 Optimization Using Compose Function for DRESP3 Response
    This example deals with a size optimization of a radar stiffened panel, where the response used as objective is an external response (DRESP3) using a function defined in Compose.
- Free-shape Optimization
- Shape Optimization
  This section presents shape optimization example problems, solved using OptiStruct. Each example uses a problem description, execution procedures and results to demonstrate how OptiStruct is used in shape optimization.
- Topography Optimization
  The examples in this section demonstrate how topography optimization generates both bead reinforcements in stamped plate structures and rib reinforcements for solid structures.
- ESLM Optimization
  The examples in this section demonstrate how the Equivalent Static Load Method (ESLM) can be used for the optimization of flexible bodies in multibody systems.
- Multiphysics
  This section presents multiphysic examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Rotor Dynamics
- Response Spectrum
  This section presents response spectrum examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Nonlinear Explicit Analysis
  This section presents nonlinear explicit analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
- Piezoelectric Analysis
  This section presents piezoelectric analysis examples generated using OptiStruct. Each example uses a problem description, execution procedures, and results to demonstrate how OptiStruct is used.
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.

OS-E: 0905 Spot Weld Fatigue Analysis and Size Optimization of a Frame Structure

Demonstrates Spot weld fatigue optimization using OptiStruct.

Model Files

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

spotweld_cbar_opt.fem

Model Description

Objective here is to minimize the fatigue life of the structure using size optimization, by using fatigue life and mass as response (Figure 1).

Figure 2. Size Optimization Plot and Fatigue Life Plot

FE Model
Elements Types: CBAR; CQUAD; RBE2

The linear material properties are:

MAT1
Young’s Modulus: 2.1E5 MPa
Poisson's Ratio: 0.3
Density: 7.9E-9

Results

The final design of the fatigue analysis and size optimization of the frame has improved the fatigue life from 91% to 100%.

Figure 3. Fatigue Life Optimization of the Frame Observations