1. Set up and validate an efficient and accurate FE model of a complex engineering component, assembly or structure under non-linear and/or dynamic loading.
2. Critically evaluate the output from non-linear and general dynamics FE analysis.
Answer:
Finite Element Modelling
A finite element modelling is consisting of three stages: Pre-processing (initial step), Processing (intermediate step) and post processing (final step)
Pre-processing
Pre-processing, also known as model preparation, is typically the most labour-intensive step in FEA. For the observer of the component surface, this usually means the disassembly of the component into small parts, the finite (i.e. small but finite) elements
First of all, we designed the required part in Solidworks with given geometric dimensions.
After creating the model in Solidworks, save it as IGES format so that we can export in to Abaqus.
Now, open Abaqus CAE from program list and import the above file.
The stiffened plate will be visible in the modelling area of abaqus.
The next step is the assignment of the material, because the ability to bear external loads depends heavily on the material. To create a material with required properties, click the Module tab and choose property from drop down menu.
To create a new material chose the first option ‘Create Material’ in the left taskbar and a window will pop up
Name the material as steel and apply following properties
- Young’s Modulus, E=200GPa
- Poisson’s Ratio, ν=0.3
- Density, ρ=7800kg/m3
All the calculation done here is in millimetre, Newton, second and Ton (mm, N, s, Ton).
Create a solid homogeneous section and apply it to the plate, you will see a color change in plate which confirms that the section has been successfully applied.
Next Step is meshing, choose meshing from the Module drop down menu.
Since, our geometry has curves, we will use tetrahedral meshing option with element size as 35 mm
To apply boundary conditions, we have to make several sets of nodes and surfaces. To create a set click on Tools
Select all the nodes on the circumference on the plate and create a set names circumference.
Same as above procedure, create a surface using tools option and the surface to be selected is the non-stiffened side of the plate.
Now, to apply loads choose loads from the Module.
Create a pressure load of 5000N/m2 on the non-stiffened side.
Fix the circumference of the plate so there is no motion in any direction
Now, the most important part is to create a step
Case 1
As per the documentation the first analysis is General Static Analysis. Create a step choosing Static General as step mode
The solver is a huge system of equations behind an FEM model. The first result of a solving process always includes the shifts of the individual nodes. In subsequent steps, distortions, stresses and nodal forces can then be calculated. In addition to mechanical parameters, thermal, electrical or magnetic parameters can also be calculated if a thermal or electromagnetic solver is used accordingly. At the end of a sol run, the results are passed to the post processor of the FE program.
Create a job to solve the step and name the job as static_analysis. It will take few minutes to complete and you can see the results click on Results in job tab.
Post-processing
After successful computation, the postprocessor displays the computation results graphically, so here the data evaluation takes place. By clicking on the result tab, visualisation tab will open. These include not only the displacements but also the tensions and nodal forces. The displacements provide the deformation information of the model. The comparison stresses allow a statement about the mechanical durability of the component
Case 2
As per the case 2, we have to do frequency analysis to find out the natural frequency of the plate. Copy the model of Static General Analysis and replace the replace the step with Frequency.
Choose the require number of mode shapes as 5, in details of Frequency step.
Create a new job as Frequency and submit it for solution
After getting the results, you can see the different modes in Visualization window.
