Simulation sandwich structure ANSYS Mechanical

Your name]In summary, the conversation involved the use of APDL to simulate the behavior of a sandwich structure made of honeycomb and glass fiber under tension. The structure was modeled in CATIA V5 and exported to APDL. Some relevant images were submitted in an attached file. The specimen had a stepped repair, and the type of analysis was static-structural. The load was transmitted through nodes by a piece of Aluminium joined by adhesion to the sandwich structure. The model was divided into smaller volumes and glued back together with Boolean operator VGLUE to obtain a regular mesh. However, the simulation encountered challenges such as a large pivot during the solution and unexpected behavior in the deformed shape. Suggestions were made to check the mesh quality,
  • #1
vanessabrauer
1
0
Hello everyone!
I’m using APDL to simulate the behavior of a specimen in tension with a sandwich structure made of honeycomb and glass fiber. It was modeled in CATIA V5 and exported to APDL in a parasolid file. Only a half of the structure has been modeled because of symmetry condition.
NOTE: Some relevant images are submited in the attached file.

The specimen has a stepped repair, formed by five layers of glass fiber, each of these layers has been modeled individually, with the same directions as the parent material [0-90], and glued together with contacts through MPC approach, the same as the rest of the specimen, everything has been bounded with contacts. The type of analysis is static-structural, the load tension is transmitted through nodes by a piece of Aluminium joined by adhesion to the sandwich structure. The boundary conditions applied in the model are:
The load has been applied on the left edge of the specimen, that is representative of the Aluminium plate, also, all the DOF has been restringed, except for the displacement on the “x” direction which corresponds to the direction of the applied tension load. The other edge has symmetry conditions and a restriction on the “z” direction (transversal direction).

The hole specimen has been modeled with SOLID185, solid and layered elements, furthermore, most of the volumes have been divided with the purpose of get a regular mesh with a low quantity of wedge elements (less than 1%), after that, they were glued again with Boolean operator VGLUE. I have some troubles getting accurate results from the behavior of this model.

There are no relevant warnings before I solve the model, but it always appears a large pivot when I try to get the solution. The behavior of the deformed shape I obtain is totally different as I expect, because it seems that some parts of the laminate have debonded. I’ve checked for overconstraints or an underconstrained model, but all seems to be ok. I also have tried with different approaches for the contact technology such as Lagrangian method or penalty method, but I get the same problem for all of them. I also have applied a first load step with very small displacements to obtain convergence, and for the second step, the enforced displacements have been removed and the force required has been applied, but, even though the displacement at the first load step is very small, there is a pivot in the solution. I found another trouble when I check the behavior of the deformed shape of the model, despite I only applied a tension load, firstly I get compression behavior, followed by tension, and I don’t know why that’s happening.
I’d really appreciate your thoughts on the matter.
 

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  • #2


Hello,

Thank you for sharing your project and the images. It seems like you have put a lot of effort into your simulation and have encountered some challenges. Based on the information you have provided, here are some thoughts and suggestions:

1. Check the mesh quality: Since you have mentioned that you have divided most of the volumes to obtain a regular mesh, it is important to make sure that the mesh quality is good. Poor mesh quality can lead to inaccurate results and can also cause convergence issues. You can use tools like "Mesh Quality" in APDL to check the mesh quality and make necessary adjustments.

2. Check for discontinuities in the model: It is possible that there are some small gaps or overlaps in your model that are causing the debonding behavior. Make sure to check for any discontinuities in the model and fix them before running the simulation.

3. Try different contact formulations: You have mentioned that you have tried both Lagrangian and penalty methods for contact. It might be worth trying other formulations such as augmented Lagrangian or surface-to-surface contact to see if they give better results.

4. Consider using a smaller time step: Sometimes, using a smaller time step can help with convergence issues. You can try decreasing the time step and see if it makes a difference.

5. Check the material properties: Make sure that the material properties of the honeycomb and glass fiber are accurately defined in the model. Incorrect material properties can also lead to unexpected behavior.

I hope these suggestions will help you in resolving the issues you are facing. If you continue to face problems, I would recommend reaching out to ANSYS technical support for further assistance.

Best of luck with your simulation!
 

FAQ: Simulation sandwich structure ANSYS Mechanical

What is a simulation sandwich structure in ANSYS Mechanical?

A simulation sandwich structure in ANSYS Mechanical refers to the process of creating and analyzing a sandwich structure using the simulation capabilities of the software. This involves modeling and simulating the behavior of a sandwich structure made up of multiple layers of different materials, such as a composite material sandwiched between two metal layers.

What are the benefits of using ANSYS Mechanical for simulation sandwich structures?

ANSYS Mechanical offers several benefits for simulating sandwich structures, including the ability to accurately model the behavior of complex structures, the availability of a wide range of material models, and the ability to analyze the effects of different loads and boundary conditions on the structure.

How do you create a simulation sandwich structure in ANSYS Mechanical?

To create a simulation sandwich structure in ANSYS Mechanical, you will need to first create a 3D model of the structure using the software's modeling tools. You can then assign different materials to each layer of the structure and specify the bonding between the layers. Finally, you can set up the simulation and run it to analyze the behavior of the structure.

Can ANSYS Mechanical be used to optimize the design of a sandwich structure?

Yes, ANSYS Mechanical offers design optimization capabilities that can be used to optimize the design of a sandwich structure. By setting up different design variables and constraints, the software can automatically find the optimal design for the given structure under specified loading and boundary conditions.

What types of analyses can be performed on a simulation sandwich structure in ANSYS Mechanical?

ANSYS Mechanical offers a variety of analysis types that can be performed on a simulation sandwich structure, including static structural analysis, modal analysis, thermal analysis, and fatigue analysis. These analyses can provide insights into the structural behavior, strength, and durability of the sandwich structure under different operating conditions.

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