Infinite FEA

Determining the element size during meshing is a crucial step in finite element analysis (FEA) as it directly influences the accuracy and efficiency of the simulation. The appropriate element size depends on several factors, and here are some considerations to help you decide: Geometry and Features: For complex geometries or areas with intricate details, smaller elements may be required to capture the nuances accurately. Simpler geometries may allow for larger elements without sacrificing accuracy. Material Properties: Materials with rapidly changing or localized stress/strain concentrations may necessitate a finer mesh to capture these variations. Homogeneous materials with consistent properties might allow for coarser meshing. Boundary Conditions: The size of the elements should be refined near areas with boundary conditions, such as fixed or applied loads, to accurately capture localized effects. Curvature and Gradients: Regions with high curvature or rapid changes in gradients may ...

In FEA, the term "hourglassing" refers to a phenomenon that occurs in certain types of elements, particularly in meshed structures. Hourglassing is a form of element distortion that can affect the accuracy of simulation results. It is characterized by an hourglass shape that forms within the finite element during analysis. Hourglassing can be problematic because it introduces artificial deformations in the simulation, leading to inaccurate results. It is often associated with elements that have reduced integration, which means they use fewer integration points than standard elements. Several techniques and element formulations have been developed to address or minimize hourglassing effects, such as using specialized hourglass control algorithms, adjusting material properties, or choosing different element types. Engineers and analysts need to be aware of hourglassing issues and take appropriate measures to ensure the reliability of their FEA simulations.

Structural Deformation in Crash Crush Space Measurement Static Crush Space = Free Crush + Crushed Components Dynamic Crush = Static Crush Space + Dynamic Dash Intrusion Load Distribution Philosophy Transition zone bridges offset between load paths in crush zone & safety cage; enables  effective load transfer & provide stability controls.

Before I start to explain you about RBE2 and RBE3, one should know what rigid elements are, and why do you use them? A rigid element is a link from one node to one or more other nodes, where the motion of the node(s) is governed by the "degrees of freedom" you choose to connect. A few examples of rigid elements used in some applications given below: To model the dynamic behavior of the vehicle, sometimes the engine can be modelled as a mass elements connected by an RBE2 rigid element to the engine's multiple mounting locations. The mass is located at the centre of gravity of the engine, and the rigid element links the engine mass to the rubber mounts (eg. springs or bushes). Bolts at pre-load needs to be modelled, but does not need to modelled with any other than as a "bar" or "beam" element. An RBE2 can be used to connect the end node of the "bolt" element to the multiple nodes which represent the washer area over which the bolt load acts. ...

I assume you already know the term "Meshing" in FEA. If you still want to read it then  you can visit below link of my previous article https://feadirect.blogspot.com/2020/05/what-is-meshing-in-fea.html Ok ! lets come to the point.  From the above image, you can imagine the representation of elements used in FEA. Here are the details : 1D Elements : 2 nodes It is also referred as line elements. Often used to represent the members, which are too long compared to the measurement of the cross section (L/r > 20). Useful when bending is the root cause of failure. Fundamental assumption : Changes in material properties along the cross section is negligible. Used to represent rods, beams, trusses, cables, frames etc. 2D Elements : 3, 4 nodes It is also referred as shell elements. Often used when thin sheet structures are under bending deformation. Can consider 2D stress conditions and bending and shear deformations. Fundamental assumptions : Changes i...