Ansys Pressure Vessel Pdf
Finite Element Analysis of Ellipsoidal Head. Pressure vessel is the main body of the pneumatic. Finite Element Analysis of Pressure Vessel Using ANSYS i.
This tutorial is an educational tool designed to assist those who wish to learn how to use the ANSYS finite element software package. It is not intended as a guide for determining suitable modelling methods or strategies for any application. The authors of this tutorial have used their best efforts in preparing the tutorial.
These efforts include the development, research and testing of the theories and computational models shown in the tutorial. The authors make no warranty of any kind, expressed or implied, with regard to any text or models contained in this tutorial. The authors shall not be liable in any event for incidental or consequential damages in connection with, or arising out of, the furnishing, performance, or use of the text and models provided in this tutorial. There is no gaurantee that there are no mistakes or errors in the information provided and the authors assume no responsibility for the use of any of the information contained in this tutorial. Overview In this tutorial you will examine the expansion of a pressure vessel due to an internal pressure using ANSYS.
The problem is adapted from case study E on page 327 of the textbook Practical Stress Analysis with Finite Elements (2nd Ed) by Bryan J. You will determine the principal stresses in the pressure vessel due to the applied loading and boundary conditions. An axisymmetric solid element will be used for this analysis.
We will use SI system units for this tutorial: length = m, mass = kg, time = sec, force = N, stress/pressure = Pa. In this case the vessel is made from steel (E = 207 Gpa, v = 0.27) and the internal pressure is 10,000 Pa.
Figure 1: Details of the Pressure Vessel - all dimensions in mm. There are standard theories available for the behaviour of thin and thick walled cylinders subjected to internal pressure. These equations can be found in any text book on mechanics of solids or in any reference book. We can use these theories to predict the expected stresses in the pressure vessel due to the applied loading. The calculations for the various stresses is shown on pages 328 to 329 of Practical Stress Analysis with Finite Elements (2nd Ed) by Bryan J.
Mac Donald and is summarised in the table below. • Click on OK and then click close to close the Element Type dialog box. Step 3: Define the Material Model • In the Main Menu click on Preprocessor >Material Props >Material Models, the Define Material Model Behaviour dialog box will now appear. • Expand the options in the right hand pane of the dialog box: Structural >Linear >Isotropic • In the dialog box that pops up, enter suitable material parameters for steel ( E = 207 x 10 9 Pa, Poissons ratio = 0.27): • Click on Ok to close the dialog box in which you entered the material parameters. • Close the Define Material Model Behaviour dialog box by clicking on the X in the upper right corner. Step 5: Create the Model Geometry • In the Main Menu click on Preprocessor >Modelling >Create >Areas >Rectangle >By 2 Corners • Enter the values shown below to create the bottom rectangle of the pressure vessel. Step 7: Apply the Boundary Conditions • Although the solver already knows that we are performing an axisymmetric analysis due to an axisymmetric element being used, we still need to place a symmetry constraint on the edges of the model that touch the Y-axis.
• Preprocessor >Loads >Define Loads >Apply >Structural >Displacement >Symmetry B.C. >On Lines pick the lines on the axis of symmetry (i.e. The two vertical lines on the left hand edge of the model) then click OK in the picker dialog box. • You should notice small 'S' symbols appear near the lines to indicate that a symmetry boundary condition has been applied. • In order to prevent any unwanted movement of the entire model in the vertical direction (rigid body motion) we must constrain at least one node in the vertical direction: • Preprocessor >Loads >Define Loads >Apply >Structural >Displacement >On Nodes • Click on any node in the centre of the side wall of the vessel and then click on OK • In the dialog box that appears make sure the DOFs to be constrained is set to UY only and then click on OK. • You will probably get a warning saying that ' Both solid model and finite element boundary conditions have been applied to this model. As solid loads are transferred to the nodes or elements, they can overwrite directly applied loads'.
This is OK just click on Close to dismiss this dialog. Step 8: Apply the Internal Pressure Load • In the Main Menu click on Preprocessor >Loads >Define Loads >Apply >Structural >Pressure >On Lines • Click on all the lines representing the internal wall of the pressure vessel and then click on OK in the picker dialog box.
• The 'Apply Pres on a Line' dialog box will now appear. Enter 10000 as the pressure value as shown below. Step 9: Solve the Problem • In the Main Menu select Solution >Analysis Type >New Analysis • Make sure that Static is selected in the dialog box that pops up and then click on OK to dismiss the dialog. • Select Solution >Solve >Current LS to solve the problem • A new window and a dialog box will pop up. Take a quick look at the infromation in the window ( /STATUS Command) before closing it.
• Click on OK in the dialog box to solve the problem. • Once the problem has been solved you will get a message to say that the solution is done, close this window when you are ready.
Step 10: Examine the Results • In the Main Menu select General Postproc >Plot Results >Deformed Shape • Select Def + undef edge in order to show both the deformed and undeformed shapes. Introduction To Nanotechnology Poole Pdf Editor more. • Your screen should look something like this. • It is clear that the side wall of the pressure vessel has slightly 'bowed' out due to the internal pressure. The end caps have significantly deformed in comparison to the side wall.
The maximum displacement is, however, approximately 2 x 10 -6 m which is well below the yield stress for steel - meaning our assumption of a linear elastic material is valid. Torrent Elements Of Programming Interviews. Note that ANSYS, by default, will exaggerate any deformation by scaling it up in order to make it obvious. • Now let's examine the principal stresses: General Postproc >Plot Results >Contour Plot >Nodal Solu >Stress >1st Principal Stress, click on OK to display the plot, which should look like this. • The first principal stress is the Hoop Stress and we are expecting a value of approximately 55,000 Pa based on our analytical calculations.
Clearly something is wrong with this plot. We are seeing very large stress concentrations at the sharp corner where the end caps join the side wall. It is likely that the stress in the side wall itself is quite close to the predicted analytical value. Let's investigate this by only displaying results for the elements at the middle of the vessel side wall: • Utility Menu >Select >Entities • In the 'Select Entities' dialog box that appears make sure that 'Elements' is selected in the top box and then click on OK.
Summary This tutorial has given you the following skills: • The ability to model axisymmetric problems in ANSYS. • The ability to select a subset of a finite element model and only examine the result for that subset. • Experience in comparing the results obtained from your finite element model with other results and validating your results against the other results. Log Files / Input Files The log file for this tutorial may also be used as an input file to automatically run the analysis in ANSYS. In order to use this file as an input file save it to your working directory and then select Utility Menu >File >Read input from. and select the file. You should notice ANSYS automatically building the finite element model and issuing all the commands detailed above. Quitting ANSYS To quit ANSYS select Utility Menu >File >Exit.
In the dialog box that appears click on Save Everything (assuming that you want to) and then click on Ok.