Week 7-Long Piston With Cam
Week 7 Challenge: Long Piston with Cam Challenge
Course: Structural Analysis Using Ansys Workbench
Submitted by: Amanpreet Singh Whan
Supervisor: Vineet G
March 18, 2022
List of Figures
Figure 1- Static Structural Analysis workflow for the challenge.
Figure 2- Imported given CAD Model.
Figure 3- Face Sizing used for the highlighted faces.
Figure 4- Meshed given CAD Model.
Figure 5- The fixed joint was created for the barrel face.
Figure 6- Revolute joint was created for the Barrel Cam face.
Figure 7- Revolute joint was created for the Cam follower face.
Figure 8- Joint rotation defined for the highlighted face.
Figure 9- Frictionless contact defined between faces of the given model for case 1.
Figure 10- Frictional contact defined between faces of the given model for case 2.
Figure 11- Frictional contact defined between faces of the given model for case 3.
Figure 12- Modified Structural Analysis Settings.
Figure 13- Procedure to be followed to calculate results.
Table of Contents
3.1 Importing and Meshing of CAD Model
1 Introduction
ANSYS is a general-purpose, finite-element modeling package for numerically solving a wide variety of mechanical problems. These problems include static/dynamic, structural analysis, heat transfer, and fluid problems, as well as acoustic and electromagnetic problems. There are two methods to use ANSYS. One method is to use the graphical user interface (GUI). This method follows the conventions of popular Windows and X-Windows-based programs. Another method is to use command files. The command-file approach has a steeper learning curve for many, but it has the advantage that the entire analysis can be described in a small text file, typically in less than 50 lines of commands. This approach enables easy model modifications and minimal file-space requirements. The ANSYS environment contains two windows: the main window and an output window. A large number of files are created when ANSYS simulation is run.
2 Aims
- Simulate Long Piston with Cam movement using appropriate material for the given Model.
- Apply appropriate Boundary Conditions and Joint Loads.
- Lastly, Determine Total Deformation and Maximum Stress results for the performed simulations and compare the results for the same.
3 Methodology and Results
The section describes the different stages that were performed using an engineering tool Ansys Workbench 2022 for the completion of the Week 7 Challenge. These stages can be further broadly sub-categorized into three key steps, importing the CAD model to apply the boundary conditions and finally performing the simulation to obtain the desired results.
3.1 Importing and Meshing of CAD Model
After opening the Ansys Workbench, the first step is to select the Analysis type and then define appropriate material from the Engineering Data options for the given CAD model. Considering the challenge requirements, Transient Structural was selected for the Analysis type while structural steel was selected for the long piston with a cam model. The following figures highlight the analysis system and material card parameters in detail.
After updating the CAD model in the Ansys Workbench, the next step is to generate a good quality mesh. Meshing is a phase where the CAD geometry is discretized to represent the computational domain in which the solver will discover a solution. A refined mesh helps to achieve better results. The mesh was generated in two steps: the face sizing method with an element size of 3 mm was used to refine the faces in contact; for other areas in contact the mesh was generated using default element size.
3.2 Joints
A joint is a type of connection or junction at which usually two bodies are joined together in a way that restricts some degrees of freedom (DOFS) while leaving others free. For a joint, one reference is considered the stationary reference, while the other is considered the mobile or moving reference. The mobile and stationary references of the joint must be on two different bodies. Joints can also be defined as “grounded”. In this case, the joint connects the mobile reference to a fixed location in space. The stationary references are fixed in space, that is they have all DOFs fixed. Properties of a joint are defined as a joint behavior and can be applied to more than one joint. Joint behavior is characterized by the rotational and translational degrees of freedom of the mobile reference of the joint, as fixed or free concerning the stationary one.
The following figures represent the three-body to ground joints such as fixed joint, translational joint, and revolute joint are created as per the challenge requirements.
3.3 Boundary Constraints
Boundary conditions are constraints necessary for the solution of a boundary value problem. The Fixed support constraint restricts all the translation degrees of freedom over the assigned entities to be zero. The force boundary condition applies a distributed force to the structure. It can be assigned to any number of faces of a structure. This boundary condition works as surface traction on each element of the assigned topological entity and its value is proportional to each element’s area.
A Joint Load constraint is assigned to fulfill the challenge requirements. The process followed to assign the boundary constraint is presented in the following figure.
3.4 Contact
In structural analysis software, the contact is generated by pair. Three different contact behaviors are available. They are named node to node (point to point), node to the surface (point to the surface), and surface to surface. As default in Ansys software, point to surface and surface to surface contact types are used. For the point to surface contact, the “point” is contact, and the “surface” is the target. Several contact types are used. These names might be called with different names according to software. In Ansys software, contact names are titled frictional, frictionless, rough, bonded, and have no separation. The Frictionless and frictional contact with frictional coefficients of 0.1 and 0.2 were defined for the challenge purposes and is represented in the following figures.
3.5 Analysis Settings
The given Buckle Clip model was simulated for a total number of 9 steps to determine appropriate total deformation and other stress-strain results. Therefore, the Large Deflection option was turned on to prevent Penetration and Intersection errors. The following figure represents the modifications performed in the analysis settings.
Simulation Results
To visualize the simulation or results, the desired output cards have to be created. Total Deformation, Equivalent Elastic Strain, and Equivalent Stress (Von Mises Stress) cards were created using the procedure illustrated in the following picture. It must be noted that the results have to be generated by running the solve command.
Case1: Simulation Results
Deformation Results:
Strain Results:
Stress Results:
Contact Tool Results:
Case2: Simulation Results
Deformation Results:
Strain Results:
Stress Results:
Contact Tool Results:
Case3: Simulation Results
Deformation Results:
Strain Results:
Stress Results:
Contact Tool Results:
4 Conclusion
The main aim of the Week 7 challenge was to Simulate Long Pison with Cam movement using structural steel material for the given Model. From the results, it was found that the total deformation resulting in all cases is exactly equal. The elastic strain resulting in case 1 is minimum in comparison to case 2 and case 3. Similarly, the resulted Equivalent Stress in case 1 is lowest in comparison to case 2 and case 3.
In conclusion, considering the above simulation results, it would not be wrong to say that case 1 has yielded the best results in comparison to the other two cases. The jump in stress-strain values for both case 2 and case 3 is essentially due to the addition of the frictional coefficient in the transient analysis of the given Long Piston with Cam model.