Our renewable products can be downloaded by students across the globe. In the case of matrix algorithms, a pivot entry is usually required to be at least distinct from zero, and often distant from it. It develops and markets multiphysics engineering simulation software for product design, testing and operation. Hey all, i am trying to run ansys apdl through matlab. Is steady linear elasticity inherently illconditioned. Determine whether matrix is ill conditioned matlab.
Fas recommended in the manual i did not succeed to recompile the ansys. Magnetostatic analysis massachusetts institute of technology. This also might result in numerically illconditioned stiffness matrices. Ansys workbench platform software simulation software. Professor jargon has kindly volunteered his services a publication for ansys users. This is usually a result of an ill conditioned matrix possibly due to unreasonable material properties, an under constrained model or contact related issues. I want to test how, badly conditioning of a matrix a, will affect calculation of ax b where a is my increasingly badly conditioned matrix and x is a vector of ones, so we know the exact solution. Finite element analysis fea software from ansys provides engineers the ability to automate and customize simulations and even parameterize them for many design scenarios. Matrix pictures by cspy, a matlab function in the csparse package. Advancing analysis capabilities in ansys through solver technology. Illconditioning is an entire spectrum, going from good to bad to worse. I found that in the project tree that under geometry, the part was imported as a part 1 and part 2, and not as one part.
Ansys offers a comprehensive software suite that spans the entire range of physics, providing access to virtually any field of engineering simulation that a design process requires. Thus, only direct solvers can be used with this option due to the illconditioned matrix. Ansys software is a family of engineering analysis tools including designspace. The student community is a public forum for authorized ansys academic product users to share ideas and ask questions. This can be done by using simple command snippets within ansys mechanical. Basically it is an engineering simulation software. Once the software had been released, users were informed when they had a model with an ill conditioned sti ness matrix. Obtaining a listing of the stiffness matrix load vector from ansys, version 8. Sources of error when using structural analysis software. This is being done by going to menu item prepocessor couplingceqn coincident nodes and in the. Ansys, by default, uses a technique where it creates an equivalent symmetric stiffness matrix to represent the unsymmetric matrix.
Feb 28, 2018 in this video, we will see how to export the ansys stiffness and mass matrix to a text file. Let me clarify my question, i can use ansys to extract the stiffness matrix for a structure using this procedure i want to find stiffness and mass matrix from ansys classic. May 27, 2017 there are plenty of simulation software solutions that compete with them. This is usually a result of an ill conditioned matrix possibly due to unreasonable material properties, an under constrained model, or contact related issues. Forming simulation using rigidplastic material model in marc. I would like to mention that the mathematics you should be using would be partial differential. The test used depends on the type of decomposition. I am modeling a simple rc beam in ansys with perfect bond between steel rebar and concrete. The workbench platform is the backbone for an integrated, comprehensive simulation system that provides access to systemslevel and multiphysics insights that were unattainable before. In magnetostatic analysis the stiffness matrix can be very illconditioned. Perhaps i shouldve written it to begin with, but the singular nature of my matrix comes as no surprise, as since one of the eigenvalues is very close to zero perhaps numerically it is, is the reason for the illconditioned nature of the matrix. Because the pressure terms are kept in the assembled stiffness matrix, the stiffness matrix is unsymmetric. Advancing analysis capabilities in ansys through solver. Obtaining a listing of the stiffness matrix load vector.
Hi all you expert ansys users, i was hoping to get some feedback on one of my models that i am running. It is well known that such a system is illconditioned, which causes difficulty to directly or iteratively solve the whole large system simultaneously. If the model is unconstrained, ansys will attempt to write two equations. Ill conditioning is an entire spectrum, going from good to bad to worse. Once the software had been released, users were informed when they had a model with an illconditioned sti ness matrix.
Nov 09, 20 i want to test how, badly conditioning of a matrix a, will affect calculation of ax b where a is my increasingly badly conditioned matrix and x is a vector of ones, so we know the exact solution. Ansys software is a family of engineering analysis tools including designspace, ansysprofessional and ansysmultiphysics. When using fe software, the solution obtained is an approximate for many reasons. There are plenty of simulation software solutions that compete with them.
Exporting ansys fem models into matlab mass and stiffness. Jargon, professor ebrius from the jargon technical school jts. The second method is to use the mesh200 command and reinforcement commands. I have a working model, and i am confident in the result. A matrix does not suddenly become ill conditioned, falling off the edge of the world.
Matlab and ansys integration matlab answers matlab central. This is usually a result of an ill conditioned matrix possibly due to unreasonable matertial properties, an under constrained model, or contact related issues. Workbench platform software gain higher productivity from integrated applications that leverage common and compatible data models with ansys workbench. Hello everybody, i tried to implement some userdefined model into ansys using usermat subroutine but i found the following. Ill conditioning in structural sti ness matrices let the element sti ness matrix contributed by each element ein the domain be ke. The method is outlined in the following instructions. A matrix does not suddenly become illconditioned, falling off the edge of the world. The illconditioned matrix can occur due multiple reasons such rigid body motion, highly distorted elements, high frictional contacts, units that may results in numbers too bigsmall, or even unstable material models. Follow 102 views last 30 days hassan on 1 apr 2014. Total number of matrices in uf sparse matrix collection.
Then, a modal analysis must be launched if mass matrix is needed otherwise, a simple static analysis is enough for getting the stiffness matrix. To answer this question we rst need to look at the possible causes of ill conditioning. Ansys fea software finite element analysis software. Solver pivot warnings have been encountered during the solution. There are differences in the features provided and hence the industries they are suitable for.
Export the ansys stiffness and mass matrix to text files. The condition number tells you how much solving a linear system will magnify any noise in your data. Jul 28, 2016 let me clarify my question, i can use ansys to extract the stiffness matrix for a structure using this procedure i want to find stiffness and mass matrix from ansys classic. The important thing is to have your expectations clear. Jan 01, 2003 advancing analysis capabilities in ansys through solver technology. This warning message means stiffness matrix of the model is illconditioned. Aug, 2009 matrix factorization, along with ill conditioned matrices that arise from lagrange multipliers or coupledfield elements, need doubleprecision to maintain sufficient accuracy. Organizations around the world trust ansys to deliver the best value for their engineering simulation software investment.
Perhaps i shouldve written it to begin with, but the singular nature of my matrix comes as no surprise, as since one of the eigenvalues is very close to zero perhaps numerically it is, is the reason for the ill conditioned nature of the matrix. The pivot or pivot element is the element of a matrix, or an array, which is selected first by an algorithm e. Ansys analysis system is a brilliant software used for very complex and crucial analysis which are playing vital roles in todays engineering. Stack overflow for teams is a private, secure spot for you and your coworkers to find and share information. Abaqus uses a special iterative solution technique to prevent the illconditioned matrix from negatively impacting the computed magnetic fields. Jargon, jargon technical school padt is pleased to present f. Apr 06, 2017 when using fe software, the solution obtained is an approximate for many reasons. Ansys student products can be installed on any supported ms windows 64bit machine. Typically, the matrix being solved is the stiffness matrix. Ansys software for structural analysis allows you to solve your most complex structural engineering projects and make superior design decisions more quickly. Sep, 2007 hello everybody, i tried to implement some userdefined model into ansys using usermat subroutine but i found the following. If the cutoff value is too small, we have illconditioned stiffness matrix and.
If the model is unconstrained, ansys will attempt to. Thanks to daniels and bills suggestions, im still able to get satisfactory results. One or more contact regions may not be in initial contact. Solver error during structural analysis cfd online. Ansys provides free student software products perfect for work done outside the classroom, such as homework, capstone projects, student competitions and more.
It is well known that such a system is ill conditioned, which causes difficulty to directly or iteratively solve the whole large system simultaneously. The matrix is clearly ill conditioned, although the correct solution can be found with mathematica. Some elements have severe differences in stiffness from other elements. In this video, we will see how to export the ansys stiffness and mass matrix to a text file. We help the worlds most innovative companies deliver radically better products to their customers. Professor jargons term of the month by professor f. However, these types of members may cause the fe process to become illconditioned and produce erroneous results. Swanson sold his interest in the company to venture capitalists in 1993. This is my code, however it gives me correct results no matter how badly conditioned my matrix is. Ansys software is a family of engineering analysis tools including designspace, ansys professional and ansys multiphysics. Hexahedra erke wang, thomas nelson, rainer rauch cadfem gmbh, munich, germany. Our 22668 members have posted 73104 times in 15478 discussions. I have much problem when modelling my project with ansys, one of problem that i met always like this error cp 296. Read 7 answers by scientists with 6 recommendations from their colleagues to the question asked by shagun gupta on mar 3, 2016.
Ansys is the global leader in engineering simulation. As a result, the developers were subsequently faced with the question. Detecting the causes of illconditioning in structural. Solving a linear system with a badly conditioned matrix. By offering the best and broadest portfolio of engineering simulation software, we help them solve the most complex design challenges and engineer products limited only by imagination. This is not the case that we can solve by reformulating the equation or choosing an efficient matrix solver or improving precision in floating point number. Matrix factorization, along with illconditioned matrices that arise from lagrange multipliers or coupledfield elements, need doubleprecision to maintain sufficient accuracy. Ansys will mesh the concrete body and the line body independently and somehow connect them during the solve. How to solve errors for solver output file of ansys workbench. Consider, for example, a simple 1d element with two nodes, x1 and x2. However, these types of members may cause the fe process to become ill conditioned and produce erroneous results. It is interesting to note that the pcg iterative solver in ansys can use single precision to save some memory via the precision command. Msc software confidential msc software confidential forming simulation using rigidplastic material model in marc 20 america user conference gary huang simufactamericas llc.
This is not the case that we can solve by reformulating the equation or choosing an efficient matrix solver. The matrix is clearly illconditioned, although the correct solution can be found with mathematica. I was wondering if anybody had any possible workarounds for this problem. Ansys developed a contact algorithm in which the contact stiffness is based on the results at the. The command wrfull makes the analysis stop after writing the. In the 2000s, ansys made numerous acquisitions of other. How to extract structural matrices mass,stiffness from.