top of page

Group

Public·8 Art and Sustenance Partners
Ray Krishnamurthy
Ray Krishnamurthy

[PATCHED] How to Simulate Mode I Dominant Fatigue Crack Growth in Ansys Workbench


[PATCHED] Crack Growth Ansys Workbench Tutorials




Crack growth is a phenomenon that occurs when a material is subjected to cyclic or dynamic loading, causing a pre-existing flaw or defect to propagate and eventually lead to failure. Crack growth can have serious consequences for the safety, performance, and reliability of engineering structures, especially in aerospace, automotive, civil, and nuclear industries. Therefore, it is essential to understand and predict the behavior of cracks under various loading conditions and environments.




[PATCHED] Crack Growth Ansys Workbench Tutorialsl



Ansys Workbench is a powerful simulation platform that integrates various Ansys products and enables engineers to perform complex multiphysics analyses. One of the capabilities of Ansys Workbench is to simulate crack growth using the extended finite element method (XFEM) and the SMART Crack Growth feature. These tools allow engineers to model arbitrary cracks without remeshing, calculate accurate stress intensity factors (SIFs), simulate mode I dominant fatigue or static crack growth, and visualize the crack evolution.


In this article, we will provide a comprehensive tutorial on how to perform crack growth simulation in Ansys Workbench using SMART Crack Growth feature. We will cover the following topics:



  • Crack growth modeling: We will introduce the basic concepts and equations for crack growth modeling, discuss the different types of crack growth models and how to choose them, and highlight the challenges and limitations of crack growth modeling.



  • Crack growth simulation in Ansys Workbench: We will show how to set up a crack growth simulation in Ansys Workbench using SMART Crack Growth feature, define the geometry, mesh, loads, boundary conditions, and material properties for crack growth simulation, select the crack growth model, parameters, and criteria for crack growth simulation.



  • Crack growth results and postprocessing: We will demonstrate how to run the crack growth simulation and monitor the progress and convergence, visualize and analyze the crack growth results using Ansys Workbench tools, validate and verify the crack growth results using experimental data or other methods.



By the end of this article, you will have a clear understanding of how to perform crack growth simulation in Ansys Workbench using SMART Crack Growth feature, as well as the benefits and applications of crack growth simulation in engineering design and analysis.


Crack growth modeling




Crack growth modeling is the process of developing mathematical equations that describe how a crack grows under cyclic or dynamic loading. The main purpose of crack growth modeling is to predict the size, shape, direction, rate, and life of a crack under various loading conditions and environments.


The most common approach for crack growth modeling is based on linear elastic fracture mechanics (LEFM), which assumes that the material behavior around the crack tip is linear elastic and that the plastic deformation is negligible. LEFM uses the concept of stress intensity factor (SIF) to characterize the stress state at the crack tip. The SIF depends on the applied stress, the geometry of the structure, and the size and shape of the crack. The SIF can be calculated analytically for simple configurations using geometry factors or numerically for complex configurations using finite element methods.


The relationship of the capabilities of Ansys Workbench is to simulate crack growth using the extended finite element method (XFEM) and the SMART Crack Growth feature. These tools allow engineers to model arbitrary cracks without remeshing, calculate accurate stress intensity factors (SIFs), simulate mode I dominant fatigue or static crack growth, and visualize the crack evolution.


In this section, we will show how to set up a crack growth simulation in Ansys Workbench using SMART Crack Growth feature. We will use a simple example of a center-cracked plate under tensile loading to illustrate the steps and procedures. The geometry, mesh, loads, boundary conditions, and material properties for this example are shown in Figure 1.



Figure 1: Geometry, mesh, loads, boundary conditions, and material properties for the center-cracked plate example


The steps for setting up a crack growth simulation in Ansys Workbench using SMART Crack Growth feature are as follows:



  • Create a new project in Ansys Workbench and drag and drop a Static Structural analysis system from the toolbox to the project schematic.



  • Double-click on the Geometry cell to open the DesignModeler application. Create or import the geometry of the structure with the initial crack. In this example, we create a rectangular plate with a center crack using sketching and extruding tools.



  • Double-click on the Mesh cell to open the Meshing application. Generate a mesh for the structure using appropriate meshing methods and controls. In this example, we use a mapped face meshing method with biasing controls to create a finer mesh near the crack tip.



  • Double-click on the Setup cell to open the Mechanical application. Define the loads, boundary conditions, and material properties for the structure. In this example, we apply a uniform tensile load of 100 MPa on the right edge of the plate, fix the left edge of the plate, and assign a linear elastic material with Young's modulus of 200 GPa and Poisson's ratio of 0.3 to the plate.



  • Right-click on the Model branch in the outline tree and select Insert > SMART Crack Growth. This will create a new branch for crack growth simulation under the Model branch.



  • Right-click on the SMART Crack Growth branch and select Insert > Crack Definition. This will create a new branch for defining the crack geometry and orientation.



  • Select the Crack Definition branch and go to the Details view. Under the Definition Method section, select Face Selection as the method to define the crack faces. Under the Face Selection section, select both faces of the initial crack as the crack faces. Under the Crack Orientation section, select Normal To Face as the method to define the crack normal direction. Under the Normal To Face section, select any face of the initial crack as the reference face for defining the crack normal direction.



  • Right-click on the SMART Crack Growth branch and select Insert > Crack Growth Parameters. This will create a new branch for defining the crack growth model, parameters, and criteria.



  • Select the Crack Growth Parameters branch and go to the Details view. Under the Crack Growth Model section, select Mode I Dominant Fatigue as the model to simulate mode I dominant fatigue crack growth. Under the Mode I Dominant Fatigue section, enter the material constants C and m for the Paris law, the initial and maximum crack lengths, and the number of increments for crack growth simulation. In this example, we use C = 1e-10, m = 3, initial crack length = 0.01 m, maximum crack length = 0.05 m, and number of increments = 10.



  • Right-click on the SMART Crack Growth branch and select Insert > Output Controls. This will create a new branch for defining the output variables and options for crack growth simulation.



  • Select the Output Controls branch and go to the Details view. Under the Output Variables section, select the variables that you want to output for crack growth simulation. In this example, we select Crack Length, Stress Intensity Factor, and Crack Growth Rate. Under the Output Options section, select the options that you want to enable for crack growth simulation. In this example, we enable Write Results For All Increments and Write Fracture Data File.



  • Right-click on the Solution branch in the outline tree and select Insert > Total Deformation. This will create a new branch for defining the result item for total deformation.



  • Select the Total Deformation branch and go to the Details view. Under the Location section, select Crack Tip as the location to evaluate the total deformation at the crack tip.



  • Right-click on the Solution branch in the outline tree and select Insert > Equivalent Stress. This will create a new branch for defining the result item for equivalent stress.



  • Select the Equivalent Stress branch and go to the Details view. Under the Location section, select Crack Tip as the location to evaluate the equivalent stress at the crack tip.



  • Save your project and click on the Solve button to run the crack growth simulation.



Crack growth results and postprocessing




After running the crack growth simulation, you can view and analyze the results using Ansys Workbench tools. You can also validate and verify the results using experimental data or other methods.


In this section, we will demonstrate how to view and analyze the crack growth results using Ansys Workbench tools, as well as how to validate and verify the results using experimental data or other methods. We will use the same example of a center-cracked plate under tensile loading to illustrate the steps and procedures.


The steps for viewing and analyzing the crack growth results using Ansys Workbench tools are as follows:



  • After the crack growth simulation is completed, you can see the status and summary of the solution in the Solution Information branch in the outline tree. You can also see the output variables and options for crack growth simulation in the Output Controls branch in the outline tree.



  • Double-click on the Total Deformation branch in the outline tree to open the result item for total deformation. You can see the total deformation contour plot on the structure, as well as the total deformation value at the crack tip. You can also animate the total deformation plot to see how it changes with crack growth increments. To do this, go to the Details view and under the Animation Controls section, select Animate Over Time Steps as the animation type and click on the Play button.



  • Double-click on the Equivalent Stress branch in the outline tree to open the result item for equivalent stress. You can see the equivalent stress contour plot on the structure, as well as the equivalent stress value at the crack tip. You can also animate the equivalent stress plot to see how it changes with crack growth increments. To do this, go to the Details view and under the Animation Controls section, select Animate Over Time Steps as the animation type and click on the Play button.



  • Right-click on any result item in the outline tree and select Insert > Chart. This will create a new branch for defining a chart for plotting any result variable versus any input variable. In this example, we create a chart for plotting crack length versus number of cycles.



  • Select the Chart branch and go to the Details view. Under the Chart Data section, select Crack Length as the Y-Axis Variable and Number of Cycles as the X-Axis Variable. Under the Chart Options section, select Line as the Chart Type and enter a suitable title and labels for the chart. Click on the Update button to generate the chart.



  • You can see the chart for crack length versus number of cycles in the graphics window, as well as the data table for the chart in the tabular window. You can also export the chart or the data table to a file or a clipboard using the Export button.



  • You can repeat steps 4 to 6 to create other charts for plotting other result variables versus other input variables. For example, you can create a chart for plotting stress intensity factor versus crack length, or crack growth rate versus stress intensity factor range.



The steps for validating and verifying the crack growth results using experimental data or other methods are as follows:



  • Obtain experimental data or other reference data for crack growth under similar conditions as your simulation. For example, you can use published literature, standards, databases, etc. to find experimental data or other reference data for crack growth.



  • Compare your simulation results with the experimental data or other reference data using appropriate methods and metrics. For example, you can use graphical comparison, numerical comparison, statistical analysis, error estimation, etc. to compare your simulation results with the experimental data or other reference data.



  • Evaluate the agreement and discrepancy between your simulation results and the experimental data or other reference data using appropriate criteria and thresholds. For example, you can use absolute error, relative error, percent error, coefficient of determination, etc. to evaluate the agreement and discrepancy between your simulation results and the experimental data or other reference data.



  • Identify and explain the sources and causes of agreement and discrepancy between your simulation results and the experimental data or other reference data using appropriate reasoning and evidence. For example, you can use sensitivity analysis, uncertainty analysis, error analysis, etc. to identify and explain the sources and causes of agreement and discrepancy between your simulation results and the experimental data or other reference data.



  • Recommend and implement improvements and corrections to your simulation model, parameters, assumptions, etc. based on the validation and verification results. For example, you can use calibration, optimization, refinement, etc. to recommend and implement improvements and corrections to your simulation model, parameters, assumptions, etc.



Conclusion




In this article, we have provided a comprehensive tutorial on how to perform crack growth simulation in Ansys Workbench using SMART Crack Growth feature. We have covered the following topics:



  • Crack growth modeling: We have introduced the basic concepts and equations for crack growth modeling, discussed the different types of crack growth models and how to choose them, and highlighted the challenges and limitations of crack growth modeling.



  • Crack growth simulation in Ansys Workbench: We have shown how to set up a crack growth simulation in Ansys Workbench using SMART Crack Growth feature, define the geometry, mesh, loads, boundary conditions, and material properties for crack growth simulation, select the crack growth model, parameters, and criteria for crack growth simulation.



  • Crack growth results and postprocessing: We have demonstrated how to view and analyze the crack growth results using Ansys Workbench tools, as well as how to validate and verify the crack growth results using experimental data or other methods.



By following this tutorial, you should have a clear understanding of how to perform crack growth simulation in Ansys Workbench using SMART Crack Growth feature, as well as the benefits and applications of crack growth simulation in engineering design and analysis.


Crack growth simulation is a powerful tool that can help engineers to understand and predict the behavior of cracks under various loading conditions and environments, and to optimize the safety, performance, and reliability of engineering structures. However, crack growth simulation also requires a good knowledge of crack growth modeling, finite element analysis, material properties, experimental data, etc., as well as a careful validation and verification of the simulation results.


Therefore, we recommend that you further explore and learn more about crack growth simulation in Ansys Workbench using SMART Crack Growth feature, as well as other related topics such as fracture mechanics, fatigue analysis, multiphysics simulation, etc. You can find more resources and information on the Ansys website, the Ansys Help System, the Ansys Learning Hub, the Ansys Community, and other online sources.


FAQs




Here are some frequently asked questions (FAQs) about crack growth simulation in Ansys Workbench using SMART Crack Growth feature:



  • What are the advantages of using XFEM and SMART Crack Growth feature for crack growth simulation?



The advantages of using XFEM and SMART Crack Growth feature for crack growth simulation are:


  • They can model arbitrary cracks without remeshing, which saves time and computational resources.



  • They can calculate accurate stress intensity factors (SIFs) using interaction integrals or J-integrals, which are independent of mesh size and orientation.



  • They can simulate mode I dominant fatigue or static crack growth using Paris law or power law, which are widely used and validated models.



  • They can visualize the crack evolution using contour plots or fracture data files, which can provide useful insights into the crack behavior.



  • What are the limitations of using XFEM and SMART Crack Growth feature for crack growth simulation?



The limitations of using XFEM and SMART Crack Growth feature for crack growth simulation are:


  • They cannot model multiple or interacting cracks, which may be present in some structures.



  • They cannot simulate mixed mode or environmental assisted cracking, which may occur in some loading conditions or environments.



  • They require material parameters and experimental data for crack growth modeling, which may not be readily available or reliable for some materials or situations.



  • They depend on the accuracy and validity of finite element analysis and linear elastic fracture mechanics assumptions, which may not hold for some materials or situations.



  • How to improve the accuracy and reliability of crack growth simulation results?



To improve the accuracy and reliability of crack growth simulation results, you can:


  • Use appropriate meshing methods and controls to ensure a good quality mesh near the crack tip.



  • Use appropriate boundary conditions and convergence criteria to ensure a realistic and stable solution.



  • Use appropriate material properties and experimental data to ensure a valid and calibrated crack growth model.



  • Use appropriate validation and verification methods to ensure a consistent and accurate comparison with experimental data or other reference data.



  • How to troubleshoot common errors or issues in crack growth simulation?



To troubleshoot common errors or issues in crack growth simulation, you can:


  • Check the error messages or warnings in the Solution Information branch or the Output Window to identify the source and cause of the error or issue.



  • Check the geometry, mesh, loads, boundary conditions, material properties, crack definition, crack growth parameters, and output controls to ensure that they are correct and consistent.



  • Check the solution progress and convergence to ensure that the solution is converging and not diverging or oscillating.



  • Check the result plots and charts to ensure that they are reasonable and not distorted or erroneous.



  • Consult the Ansys Help System, the Ansys Learning Hub, the Ansys Community, or other online sources to find solutions or suggestions for the error or issue.



  • Where to find more resources and information on crack growth simulation in Ansys Workbench using SMART Crack Growth feature?



You can find more resources and information on crack growth simulation in Ansys Workbench using SMART Crack Growth feature from the following sources:


  • The Ansys website: https://www.ansys.com/



The


About

Welcome to the group! You can connect with other members, ge...

Art and Sustenance Partners

bottom of page