Prof. Yu's Research Group in the Cloud

With the increasing demand and needs for composite materials in many fields of industry, analysis and simulation of composite materials are becoming more and more important and challenging. In theory, one can use the finite element analysis (FEA) to conduct a direct numerical simulation (DNS) for composite structures. But a fine enough mesh is required to capture all the microstructural details of a heterogeneous composite structure, which occupies too much computation time and power. An alternative method is multiscale modeling approach.

Common multiscale modeling approaches usually apply a two-step approach (TSA). The first step is to conduct a micromechanical analysis. The original heterogeneous material is replaced by an imaginary homogeneous material. This imaginary homogeneous material has a set of effective properties computed by a micromechanics model. One such micromechanics model is Representative Volume Element (RVE) analysis. The effective properties obtained in the first step can be applied to construct a structural model for the macroscopic structural analysis.

Mechanics of Structure Genome

Recently, Professor Wenbin Yu at Purdue University introduced Mechanics of Structure Genome (MSG) for multiscale modeling, which represents a unified approach for constitutive modeling for all types of composite structures including beams, plates/shells, and 3D structures. MSG uses the principle of minimum information loss (PMIL) to minimize information loss between the original heterogeneous structure and the final homogeneous structure. MSG is a new multiscale theory which assures the best models at a given level of efficiency to capture both anisotropy and heterogeneity of composites at the microscopic scale or any other scale of user’s interest. Users can choose any Structure Genome (SG), defined as the smallest mathematical building block of a structure, based on the characteristics of the structures and their experiences.

SwiftComp^TM

Based on the theory of MSG and the concept of SG, the companion software SwiftComp^TM provides an efficient and accurate approach for modeling composite materials and structures. It can be used either independently as a tool for virtual testing of composites or as a plugin to power conventional FEA codes with efficient high-fidelity multiscale modeling for composites. SwiftComp^TM enables engineers to model composites as an effective homogeneous continuum, capturing details as needed and affordable. To facilitate the use of SwiftComp^TM for ANSYS users, a simple graphic user interface (GUI) based on ANSYS Mechanical APDL platform called ANSYS-SwiftComp GUI is developed.

ANSYS-SwiftComp GUI Overview

ANSYS-SwiftComp GUI is a graphic user interface integrated into the Main Menu of ANSYS, which can use the preprocessing and postprocessing capability of ANSYS as a user-friendly GUI for SwiftComp^TM. The newly added functions specific for SwiftComp^TM are in the Preprocessor menu and the Solution menu in ANSYS as shown in Figure 1.  

Figure 1 Customized menu structure for ANSYS-SwiftComp GUI

The first level menu of ANSYS-SwiftComp GUI composes of three major parts: Preprocessor, Solution and General Postproc.

Preprocessor

• Material Props: Users can define isotropic, orthotropic or general anisotropic materials properties under this menu by using Material Models function.
• Modeling: Users can build their own models by elementary entities which contain all basic geometry elements (e.g. point, line, surface, and volume).
• Common SGs: Users can create their model through Common SGs, which provides several common fundamental building blocks of composite materials and structures.
• Mesh: Generate mesh per the geometry of model, and users can choose different mesh algorithms to meet their needs.

Solution

• Homogenization: Users can invoke SwiftComp™ to compute the effect properties for different structural models (beams, plates/shells or 3D solids).
• Dehomogenization: Providing the global behavior, users can invoke SwiftComp™ to compute the local fields including displacements, stresses and strains, and contour plots will be automatically generated after the calculation is completed.

General Postproc

• Plot Results: After Dehomogenization, users can choose different contour plots (displacements, stresses and strains) in this menu to visualize the results.

ANSYS-SwiftComp GUI provides a convenient way to create some common SG models. Engineers can easily create the geometry and mesh of these models, and invoke SwiftComp™ to perform homogenization and dehomogenization for different composites with arbitrary fundamental building blocks (aka SGs).

Currently, ANSYS-SwiftComp GUI provides the following common SGs:

• 1D SGs: layered materials, laminates.
• 2D SGs: square pack microstructures (with interphase region), hexagonal pack microstructures (with interphase region).
• 3D SGs: square pack microstructures, spherical inclusion microstructures.

Users can also create their own user-defined SGs according to the microstructure they are analyzing. The capabilities of ANSYS-SwiftComp GUI include but not limited to

• Compute 3D effective properties (including through-the-thickness properties) of composite laminates (elastic, thermal, piezoelectric, magnetic).
• Carry out general-purpose micromechanics analysis, which is an efficient alternative to the RVE analysis.
• Compute effective structural properties for beams (any structure has one dimension much larger than two other dimensions), plates/shells (any structure has two dimensions much larger than the third dimensions such as sandwich structures, stiffened structures, corrugated structures, lattice structures, etc.

Example Problem

ANSYS-SwiftComp GUI in principle can be used for multiscale constitutive modeling of any structures. We are using a simple example to demonstrate some of its features. As shown in Figure 2, an artificial, unidirectional fiber reinforced composite is made of graphite fiber and epoxy matrix. The fiber can be assumed to be transversely isotropic with E1 = 276 GPa, E2 = E3 = 19.5 GPa, G12 = G13 = 70 GPa, ν12 = ν13 = 0.28, ν23 = 0.70. The epoxy matrix can be assumed to be isotropic with E = 4.76 GPa and ν = 0.37. A laminate is made of a 0-degree ply on the bottom and a 90-degree ply on the top. Assuming the bottom layer contains 10 fibers and the top layer contains 50 fibers. The microstructure can be assumed as square packing with fiber volume fraction equal to 60%. Note the lines between unit cells in Figure 2 are artificial and they are used to show the unit cell. The length of the laminate is 25 mm, and the width is 5 mm, and the thickness of each layer is 0.5 mm. It is clamped at one end and free at the other end. It is subject to 100 Pa pressure on the top surface.

Figure 2 Example problem

ANSYS-SwiftComp GUI is used to solve this problem. There are two ways to attack this problem by MSG and its companion code SwiftComp^TM: Classical Plate Model and Classical Beam Model. For each way, the detail steps of modeling and analysis are given.

Classical Plate Model:

Using MSG, the original problem is decoupled, as shown in Figure 3, into a constructive modeling over a 3D SG (left) and a structural analysis of a plate (right).

Figure 3 3D SG and structural analysis for classical plate model

The detailed steps are given in the following:

First, create the 3D SG.

Then, use ANSYS-SwiftComp GUI to performed homogenization: Solution → Homogenization → Plate/Shell Model. Use default parameter. A screen slot is shown in Figure 4.

Figure 4 Homogenization for Plate/Shell Model

Next, create plate model and read result from homogenization to perform the plate analysis

Next, use ANSYS-SwiftComp GUI to performed dehomogenization: Solution → Dehomogenization → Plate/Shell Model. Input global response from the previous step. A screenshot is shown in Figure 5.

Figure 5 Dehomogenization for Plate/Shell Model

The contour plot for the nodal solution of Von Mises stress result is shown in Figure 6.

Figure 6 Contour Plot of Nodal Von Mises Stress

Classical Beam Model:

Using MSG, the original problem is decoupled, as shown in Figure 7, into a constructive modeling over the 3D SG (left) and a structural analysis of a beam (right).

Figure 7 3D SG and structural analysis for classical beam model

The detailed steps are given in the following:

First, create the 3D SG.

Then, use ANSYS-SwiftComp GUI to performed homogenization: Solution → Homogenization → Beam Model. Use default parameter. A screenshot is shown in Figure 8.

Figure 8 Homogenization for Beam Model

Next, create beam model and read the result from homogenization to perform global beam analysis.

Next, use ANSYS-SwiftComp GUI to performed dehomogenization: Solution → Dehomogenization → Beam Model. Input global response from the previous step. A screenshot is shown in Figure 9.

Figure 9 Dehomogenization for Beam Model

The contour plot for the nodal solution of Von Mises stress result is shown in Figure 10.

Figure 10 Contour Plot of Nodal Von Mises Stress

Results and Discussion

The comparisons of stress sigma11 , sigma22 and sigma33  (along path (12.75, 0.25, x3) in DNS) are shown from Figure 11 to Figure 13.

Figure 11 Comparison of  sigma11 along path (12.75, 0.25, x3)

Figure 12 Comparison of  sigma22 along path (12.75, 0.25, x3)

Figure 13 Comparison of sigma33 along path (12.75, 0.25, x3)

As we can see, both MSG plate and MSG beam agree very well with DNS.

Note, the current model for DNS has around 8 million DOFs, which needs 1 day for calculation with 16 CPUs. However, both MSG plate and MSG beam only take less than a minute for computation.

Getting access to ANSYS-SwiftComp GUI

ANSYS-SwiftComp GUI is available for download free of charge from cdmHUB: https://cdmhub.org/resources/1136.

Please be advised that what you download is the GUI only. You have to fill the form at https://analyswift.com/software-trial/  to request SwiftComp from AnalySwift LLC for performing the analysis. 

Manual and the source codes for the interface can be found in the Supporting Documents. If you want a quick start, please watch our ANSYS-SwiftComp GUI Tutorial Video Series:  https://www.youtube.com/playlist?list=PLGwp8OYDfmxEA66ggKyNwUM470fZh_b08

Please ask your question inside the Forum of Prof. Yu's Research Group:

https://cdmhub.org/groups/yugroup/forum.

1. ANSYS-SwiftComp GUI
2. Mechanics of Structure Genome
3. Multiscale Modeling