Accuracy verification examples

Contains accuracy examples which you can use to verify correct calculation results using Fusion simulation.

Introduction

This Help section was written to assure customers that the Fusion software performs consistently and accurately within its defined scope. It contains a number of Accuracy Verification Examples (AVEs), which compare analysis results with analytical solution for cases taken from NAFEMS benchmark publications. Other examples are taken from theoretical sources, such as Roark's Formulas for Stress and Strain. Each AVE page specifies the source of the reference benchmark. The software should produce results that are consistent with the material presented in this Help section.

Differences in Results

Minor result differences are to be expected for any examples in this Help section for one or more of the following reasons:

• The Fusion analyses are performed with different mesh settings and element types relative to the NAFEMS computations. For example:
  • Solid element NAFEMS examples are often based on structured brick (hexahedral) elements as opposed to the automatically generated tetrahedral mesh generated in Fusion.
  • Many NAFEMS examples are based on planar (shell, 2D, or membrane) elements, which are not currently available in Fusion. Shell elements support rotational degrees of freedom not supported for solid elements. In addition, a finer mesh and multiple elements through the thickness are required to accurately capture flexural deformation and stresses when using solid elements.
  • Many NAFEMS examples are based on line (beam) elements, which are currently only supported as Bolt Connectors in Fusion. Beam elements support all six degrees of freedom (three translations and three rotations), whereas solid elements support only the translational DOF.
• Careful attention to the way a model is constrained is required to properly duplicate or approximate the behavior of planar and line element models when using solid elements.

To obtain the best accuracy of results, the setup parameters require fine-tuning. For example, a tetrahedral mesh will somewhat exaggerate the stiffness of a structure relative to a hexahedral mesh. To obtain the same level of accuracy, the tetrahedral mesh must be somewhat finer than the hexahedral mesh to which it is being compared. For example, assume that all other parameters are identical (such as the element order, inclusion of midside nodes, and whether element edges are curved or straight). A typical tetrahedral mesh might need to have an element size approximately 75% of the hexahedral element size to most closely match the results.

Model Datasets

Datasets for the Accuracy Verification Examples are available from the Data Panel in Fusion.

1. If the Data Panel is not currently shown, click Show Data Panel at the top of the screen. The Data Panel appears at the left side of the program window.
2. The top level (home view) of the Data Panel is divided into two subsections: PROJECTS and SAMPLES. Scroll to the bottom of the PROJECTS list, if necessary, to see the SAMPLES list.
3. Locate the Simulation Samples entry under SAMPLES and double-click it. The Data Panel now displays a list of the folders containing various types of simulation sample models.
4. Double-click the 2 – Accuracy Verification Examples folder. The list of available verification models appears.
5. Double-click the desired verification model to open it.