Smart Guide

 FEA - Finite element Analysis in General has the following four phases . Problem Understanding. Pre processing Processing Post processing In Problem Understanding phase one should define the problem statement and requirement clealry that inturn helps to select the components that are needed to be meshed. Pre processing involves Geometry prepartion, geometry cleanup and meshing of required components, applying load cases and other restraints. Processing is nothing but feeding the mesh model into a FEA solver and requests the solver to run the Model and solve the calculation. Nastran,  Hyperworks optistruct are some of the familiar FEA solvers in the market. Post processing involves interpretation of the results using a post processing application and generating reports to check whether the component meets the required target criteria like stress, amplitude, modal frequency etc.

 Free Free Run in FEM analysis is a common method to check in Ansys and other FEM solvers whether the FEM is mesh modelled correctly without any free edges or missing connections. Free free Run solves the model without fixing constraints, so that the whole model will be floated in space . If the model is meshed correctly, then if you run the free free run, then the complete mesh model will move in X, Y, Z respectively for first three mode. Incase if the mesh is not done properly, some connections are missed, then some parts will be hanging seperately when you animate the free free run mode shapes. Based on this observation , you can fix the model.

Present day CAE tools like Hyperworks, NX Advanced simulation tool  give you access to powerful geometry construction and editing capabilities, extensive capabilities for building models, and a wide selection of solutions to simulate real world conditions. Information on design performance is fed back to you in graphical form so that it's easier to understand and communicate through the design process. The Simulation tools are tightly coupled into a team engineering environment. These powerful capabilities are easy to use and provide intelligent guidance through the simulation process. Important features of the Simulation package will include: Geometry tools Modeling tools Integrated solvers Post processing tools Intelligent tools The Geometry tool will assist you to prepare the CAD model of the components and Pre-processing tasks like meshing, defining boundary conditions can be carried out using Advanced simulation tools. The mesh model can be solved using

To meet the quality criteria like threshold angles, Jacobian ratio, aspect ratio, warp, distortion etc, we can manually drag the nodes of the elements. Therefore, Dragging a Node can interactively re-position nodes associated with 2D type elements, such as thin shell, plane strain, plane stress, axis symmetric solid, plate, and membrane. When you drag a node, it maintains associativity with the surrounding elements and the underlying geometry. As you drag the node, the software previews how the elements associated with the node will be affected. In general, we can only drag one node at a time. However, any mid-nodes adjacent to the selected node will also move. If you drag a node in a mesh that contains higher order elements, such as parabolic or cubic elements, the pre processor software (Hypermesh, Ansys, Solidworks) translates the mid-nodes to preserve their initial characteristics. Requirements for Dragging a Node on Geometry If a node is constrained to: an ed

When we use Element Collapse to remove triangular elements from your model, we should be very careful in selecting the elements to collapse. In many cases, we won't want to collapse all elements that don't meet the specified quality criteria like, included angle threshold. For example, depending on your geometry, when you use Element Collapse, the resulting mesh may not have nodes at the vertex of two edges. For illustration, just assume a simple model of a block with a shallow groove cut through the top. and an FE models created and defined a mesh of linear triangle elements on all surfaces. Now, assume We used the Tri-Inc Angles option on the Element Quality Checks form to check the model for triangular elements with included angles smaller than 15°. Now the software will show a group of the elements that failed the check. show the same group of elements displayed within the context of the model's surfaces. As case 1, we can make Element Collaps

To solve Element Interference Interference Check tools are used to check the mesh model for element interference, the Element Interference Result/Fix form allows us to view, manipulate, and try to solve the areas where interference occurs. The tools on the Element Interference Result/Fix form should only be used to repair regions where the amount of interference is relatively small, relative to the elements' size and thickness. Usually, the Element Interference Result/Fix form does not allow we to fix areas of self-intersection within a single component. The Element Interference Result/Fix form divides the model into separate "problem areas" that represent the regions where interference occurs. Generally the pre-processor software designates these regions by finding each interfering element and then clustering an interconnected set of elements that interfere with each other. Because resolving interference on a large model can be a difficult and iterative process

Checking Shell Element Normals in thin shell meshing All shell elements have a normal (perpendicular) that defines the top and bottom of the mid surface meshing. If we create,copy or move elements, shell normals may have a chance to change their different directions. During Post Processing and Optimization, it is necessary that the elements should have consistent tops and bottoms . All perpendiculars must point the same direction . Shell normals and material orientation are independent of one another.Usually the pre-processing softwares have two tools for controlling shell element normals. Shell Element Normals (Meshing task) lets you change shell element normals on a model that doesn't contain underlying geometry. Material Side (Modeling task) lets you specify shell element normals on a model that contains underlying geometry. Using Shell Element Normals To use Shell Element Normals, select a " base element " with the desired orientation. Star

Intelligent Tools Finite element modeling requires some necessary decisions like selecting Element type, Mesh density Applying Constrains, Restrains and loads  Current generation Pre processing tools has several capabilities that intelligently guide us through the simulation process, and help us to get accurate / correct results. Adaptive Analysis One of such major intelligent tool is Adaptive analysis capability . Adaptive analysis includes some primary decision parameters like number of elements required to accurately capture the desired performance measure. To capture displacements or Eigen values (resonant frequencies), generally a relatively coarse mesh will suffice. To study the stress results generally requires more elements and more attention to having elements in high stress regions. Finite element mathematical formulations generally assume limited variation of stress across any one element. Adaptive analysis allows proper element density to be s

Quality of the element is very important criteria , in FEA pre-processing. Higher the qulaity of the mesh, we can get reliable results given that you have given perfect boundary conditions. At the same time, we should also consider the memory limitation of the computers available with us. So , we should optimize the FE model equally considering the cost of the solving and accuracy that is needed. Understanding Element Quality Checks Quality checks measure different aspects of an element's deviation from an ideal size and shape. That ideal shape depends upon the element type.You can choose one or more checks and set threshold values, or limits for deviation, for each. You can perform these checks on shell and solid elements. There are several ways to check your mesh. You can use: Auto Mesh Checking to have the software automatically evaluate aspects of element quality while it generates a mesh Element Quality Checks to set quality thresh

Handling Free Element Edges When we combine elements within a mesh, it may result in the creation of free edges in the interior of the mesh. It is mandatory to cross check and ensure that there are no free edges at the interior of the mesh , before sending the model to Solver. For example, let us assume we combined four linear elements to create a single linear element (A). And now, the mid-nodes on the new element aren't connected to this element; they're connected to surrounding elements (B). (The new element isn't a 6-noded quadrilateral hybrid element.) Therefore, free edges occur in the interior of the mesh where the new element is adjacent to existing elements (C). You can eliminate free element edges in one of two ways: Use Combine Elements  option to propagate the combined elements throughout the mesh. This eliminates all free element edges. Here: A = mesh containing combined elements B = combined groups of four elements C = Fre

In general , the basic platform and tools for Meshing task is common in all FEA pre-processing softwares like NX Nastran, Hypermesh,Cosmol, Abaqus, Ansys etc. This article will give a brief overview of the basic of mesh generation technique in FEA. Defining and Generating a Mesh The Meshing task will provide tools to help us to define and generate a FE mesh. We can use the geometry checking tools to verify that your geometry is ready for meshing define parameters for the mesh preview the mesh before you generate nodes and elements generate the mesh based on the mesh parameters check the quality of the mesh update the mesh after solution modify individual nodes and elements as necessary Defining a Mesh When we define a mesh, we should specify parameters such as: mesh type. Mesh generation can produce either regularly-spaced finite elements (mapped mesh) or less restrictive free elements (free mesh). element type and length elements' physical