The frame below consists of 4 points. A point, will always result in a node in the mesh. The number of nodes depends on the chosen mesh size. How to show the point numbers: Opt for a wireframe representation. Go to the mesh configuration. Regards, Alex. Yes thanks Alex, so I figured. Red Flag This Post Please let us know here why this post is inappropriate.
Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. Learn methods and guidelines for using stereolithography SLA 3D printed molds in the injection molding process to lower costs and lead time.
Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now. This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. Close Box. Log In Come Join Us! LANG - Generates a straight line at an angle with a line.
LARC - Defines a circular arc. LATT - Associates element attributes with the selected, unmeshed lines. LCSL - Divides intersecting lines at their point s of intersection.
LDIV - Divides a single line into two or more lines. LFSURF - Generates surface elements overlaid on the edge of existing solid elements and assigns the extra node as the closest fluid element node. LGEN - Generates additional lines from a pattern of lines. LINA - Finds the intersection of a line with an area. LINL - Finds the common intersection of lines.
LINP - Finds the pairwise intersection of lines. LINV - Finds the intersection of a line with a volume. LIST - Lists out the sets in the results file. LPTN - Partitions lines. LSBA - Subtracts areas from lines. LSBL - Subtracts lines from lines. LSBV - Subtracts volumes from lines. LSBW - Subtracts the intersection of the working plane from lines divides lines.
LSEL - Selects a subset of lines. LSLA - Selects those lines contained in the selected areas. LSLK - Selects those lines containing the selected keypoints. LSTR - Defines a straight line irrespective of the active coordinate system. LSUM - Calculates and prints geometry statistics of the selected lines. LTAN - Generates a line at the end of, and tangent to, an existing line. M Commands M - Defines master degrees of freedom for superelement generation analyses. MAP - Maps pressures from source points to target surface elements.
MAT - Sets the element material attribute pointer. MFEM - Add more element types to a previously defined field number. MMF - Calculates the magnetomotive force along a path. MODE - Specifies the harmonic loading term for this load step. MOPT - Specifies meshing options. MOVE - Calculates and moves a node to an intersection. MP - Defines a linear material property as a constant or a function of temperature.
N Commands N - Defines a node. NANG - Rotates a nodal coordinate system by direction cosines. NCNV - Sets the key to terminate an analysis.
NDSURF - Generates surface elements overlaid on the edge of existing elements and assigns the extra node as the closest fluid element node. NGEN - Generates additional nodes from a pattern of nodes.
NKPT - Defines a node at an existing keypoint location. NLOG - Forms the natural log of a variable. NSEL - Selects a subset of nodes. NSLA - Selects those nodes associated with the selected areas. NSLE - Selects those nodes attached to the selected elements.
NSLK - Selects those nodes associated with the selected keypoints. NSLL - Selects those nodes associated with the selected lines. NSLV - Selects those nodes associated with the selected volumes.
NSOL - Specifies nodal data to be stored from the results file. NSVR - Defines the number of variables for user-programmable element options. NSYM - Generates a reflected set of nodes. PATH - Defines a path name and establishes parameters for the path. PDEF - Interpolates an item onto a path. PDOT - Calculates the dot product of two path vectors along the current path. PLAS - Plots a specified acoustic quantity during postprocessing of an acoustic analysis.
PLF2D - Generates a contour line plot of equipotentials. PLLS - Displays element table items as contoured areas along elements. PLMC - Plots the modal coordinates from a mode-superposition solution. PLZZ - Plots the interference diagram from a cyclic modal analysis.
PMAP - Creates mapping of the path geometry by defining path interpolation division points. POLY - Creates a polygonal area based on working plane coordinate pairs. PPATH - Defines a path by picking or defining nodes, or locations on the currently active working plane, or by entering specific coordinate locations. PRAS - Prints a specified acoustic quantity during postprocessing of an acoustic analysis. PRED - Activates a predictor in a nonlinear analysis.
PROD - Multiplies variables. PSEL - Selects a path or paths. PSMAT - Writes an assembled global matrix to a postscript format that graphically displays nonzero matrix values. PTR - Dumps the record of a binary file. PTXY - Defines coordinate pairs for use in polygons and prisms. QUAD - Generates a quadratic line of nodes from three nodes.
QUOT - Divides two variables. R Commands R - Defines the element real constants. RACE - Defines a "racetrack" current source. RATE - Specifies whether the effect of creep strain rate will be used in the solution of a load step. RCYC - Calculates cyclic results for a mode-superposition harmonic solution. RDEC - Defines the decimation parameters used by the radiosity solver method. READ - Reads coordinate and pressure data from a file. REAL - Sets the element real constant set attribute pointer.
RESP - Generates a response spectrum. ROCK - Specifies a rocking response spectrum. Take a look at this drawing:. Sadly, the red springs will expand as well. Of course, drawing all those springs in our CAE environment would be pretty problematic and a bit inaccurate.
This sounds so nice and all, but of course, this is not the end of the story. There is one last thing we are missing: We have far more than a single Element, and they share Nodes!
Simply put, each Node can belong to more than one Element, and each Element will put its own shape functions onto the Node.
When solver finishes this task, you have a LOT of small stifness matrixes one for each element. This connection happens, thanks to the common nodes between elements!
Solver assumes, that deformations in any given Node should be the same, regardless from which Element shape functions you use! What this means is, that firstly, the solver gets the deformations at the nodes. Then knowing what is the deformation between nodes, using Element shape functions it can calculate strain in the Element.
This is pretty simple — if Nodes 6 and 9 got closer to Nodes 5 and 8 this means that the Element D on the drawing above is compressed in the horizontal direction. Knowing strain, we can easily calculate stress, knowing the stress-strain relation we implemented in our FEA model. There is one final twist in this story! Thanks to that, it can calculate stress within this Element boundary. The problem is, that each Element will obtain a different value, based on its own shape functions!
You know, Element A will use relative movement between nodes 1, 2, 4, and 5 to calculate its strain while Element D will do the same thing, but for Nodes 5, 6, 8, and 9. Obviously, this will lead to different answers in Node 5! This effectively means that in the central Node we get 4 different stress values! Which one is correct? Well, all of them and none of them at the same time! This looks more or less like this:. But rather, an average from all the answers each Element sharing that Node is producing!
This is where Element size comes into play! Whatever model you have, on the sufficiently small scale the stress is almost constant in any given place. You just need to zoom close enough! If you have a problem of big differences between nodal values in your model, the best approach then is to get the nodes closer to each other. Also, Element quality is a factor. Shape functions work best if you have a square QUAD4 element.
Above, I used a nifty explanation with the springs connecting Nodes in Finite Elements. To be completely honest, this is not how it works. In fact, it would be a bit more complicated. You see, the Element does not calculate strain based on how much each spring in our simplified model elongated or shortened. That would be too simplistic. Instead, it solves some not too difficult equations.
In the 2D problem, Node can move in 2 directions such movement is often called translation and rotate in the plane of our problem. This is why usually in 3D you have the support option that lists all 6 of those.
However, 3D solid elements lite HEX8 have 3DoF in each node… there is no point for the solid element to carry Rotations in its nodes… so it just carries Translations solid elements deal with rotation as a translation difference between Nodes in a single Element. There is no obvious answer. HEX elements require much more work when you have even not-so-complex geometry. I think it comes down to a question: how many times will you recalculate the model?
If it will be a few times I think that HEX elements will run faster but require time up front for meshing.
On the other hand, TET elements mesh faster but compute longer. I get the feeling that outcomes obtained from HEX mesh would be more trusted on average :. I have an online course that goes really deep into Finite Element Analysis… and you can get a free lesson from it by signing up below this post!
I have over 10 years of practical FEA experience I'm running my own Engineering Consultancy , and I've been an academic teacher for a decade. Here, I gladly share my engineering knowledge through courses, and on the blog!
Great article, I thoroughly enjoyed it. The link leads to a report that only includes an introduction with a "To Be Continued! Sadly I don't know if Angus finished his article - perhaps he is still working on it. I guess he is in a similar situation to mine - it's fun to do those "extra things" but in reality, we have a business to run, and work to do, so developing my blog or his articles is more or less a hobby of ours I run quad4 and quad8 meshing.
I decreased the mesh size in ansys until its error. For Quad 4, a mesh size of 0. Does that mean quad8 is better because it only required 0. Yea, while I cannot be sure about the values you mentioned, in general, QUAD8 elements will converge with bigger elements. The problem is, as I mentioned in the previous reply, that they also compute longer. So it's a tradeoff. What is the difference between quad 4 nodes and 8 nodes? But let's try anyway!
0コメント