Simulations have become more of an integral part of the product design and development process. For a large complex system like an excavator, simulation is used not only to evaluate structural integrity, but also to learn many insights of a systems’ performance.

We asked Biswanath Nandi, 3DEXPERIENCE Technical Solutions Manager with SIMULIA who developed this workflow, to provide answers to some common questions.

Q. Why does this workflow need to be analyzed?

A. Analysts often spend a lot of time building a simulation-ready finite element model (FEM) before carrying out a simulation. This involves modeling with multiple levels of assemblies starting from a full system model, to sub-assemblies, to component level assemblies, to individual components. Such a model could easily have thousands of connections to create and manage. Also, nobody wants to build these models manually, as these tasks are non-value added tasks for the analyst.

This workflow demonstrates how different meshing tools available on the 3DEXPERIENCE platform can be utilized to minimize the time required for building such a complex, multilevel finite element model. The workflow also focuses on the tools available for carrying out structural simulations with different load cases. Finally, it shows how to compare simulation results with the experimental data.

Q. Describe the workflow.

A.  The following image shows an overview of the excavator simulation workflow (click to enlarge).

This workflow contains the following four (4) major steps:

1. Meshing and Modeling

• As a first step, the CAD model of the excavator was imported into the 3DEXPERIENCE platform for meshing. Note that the CAD data can be developed natively on the platform or it can be from any major third party CAD tool.
• The model has about 450 parts with four major sub-assemblies, chassis, upper body, boom and arm and bucket. This large model with multi-level assemblies was meshed using automated modeling tools in a collaborative environment. A meshing dashboard was also created to manage the meshing. Meshes were generated using rule-based meshing feature.
• Connections between different parts were created on the CAD features.
• Section properties and materials were assigned to each part.

2. Structural Simulations

• Different structural analyses were carried out to evaluate the structural integrity of the entire system.
• A digging load sequence was analyzed.
• Rollover protection on the cabin structure was also analyzed (see image).

3. Multiscale Systems Simulations

• A logical-physical co-simulation was carried out to evaluate the performance of the arm-bucket actuation systems. The hydraulic system was modeled using Dymola and the structural parts were modeled using Abaqus.
• The Multiscale Experiement Creator app was used to author the co-simulation. The co-simulation was also executed using the same app. After the execution, the co-simulation results were reviewed using 3DPlay.

4. Virtual + Real

• Strain gauges were created on the cabin structure model. Finite element model of the strain gauge was assembled with the rollover protection model.
• Rollover protection model was analyzed with strain gauge output.
• Strain history output was stored in the platform.
• Experimental data was also stored in the platform.
• Simulation data was compared with the experimental data using Metrics Reader app.

Q. What are the key simulation goals?

A. The objectives of the excavator simulation workflow are manifolds such as:

• Evaluate structural integrity of the system under critical operating conditions
• Evaluate rollover protection strength of the cabin structure
• Evaluate hydraulics systems of the arm-bucket actuator assembly
• Evaluate the reliability of the simulation by comparing simulation and experimental data
• Reduce product development time by evaluating structural strength at early stages of product design
• Use automated tools to reduce model building time
• Get more insights of the product performance which are not possible by carrying out experiments

Q. Which SIMULIA solutions did you use?

A. The following 3DEXPERIENCE Simulation roles were used to complete this workflow:

• 3DEXPERIENCE Finite Element Modeling Specialist (SFM) Role was used to build the entire finite element model. Automated Modeling tools are a feature of this role.
• 3DEXPERIENCE Mechanical Analyst (SMU) Role was used for the structural analysis load cases in the rollover protection.
• 3DEXPERIENCE Multiscale Systems Specialist ( MCK) Role was used for carrying out logical physical co-simulation for the arm-bucket actuation system.
• In addition to the above Roles, Simulation Tokens (SET) were used for solving the structural analysis load cases as well as the co-simulations.

Q. What were the benefits of using simulation on the 3DEXPERIENCE platform?

A. The 3DEXPERIENCE platform provides many benefits for carrying out excavator simulations. Here are some of them:

1. There are many tools or options available on the platform for building a large FE model such as:
   • Collaborative modeling
   • Automated modeling and users procedures with rule-based meshing
   • Dashboard capability for managing meshing activities
   • Assembly of Meshes concept
   • Connection manager for managing a large number of connections
   • Meshes and connections are associated with the CAD data. When the CAD data are updated, the FE model gets updated automatically
   • Supports orphan meshes
2. A material app for creating and storing material models which can be accessed by all users across the organization.
3. User friendly Mechanical Scenario app for creating simulation scenarios
   • Data model allows creating simulations on the entire excavator model as well as on any sub-assembly like cabin structure.
4. An web-based app (Multiscale Experiment Creation) for authoring and executing co-simulations with best-in-class, drag-and-drop users experience.
5. Offers both high-performance and lightweight versions of result visualization tools.