{"id":26168,"date":"2013-12-06T15:28:44","date_gmt":"2013-12-06T15:28:44","guid":{"rendered":"https:\/\/www.padtinc.com\/2013\/12\/06\/the-10-coolest-new-features-in-r15-of-ansys-mechanical-apdl\/"},"modified":"2022-03-29T19:03:39","modified_gmt":"2022-03-29T19:03:39","slug":"the-10-coolest-new-features-in-r15-of-ansys-mechanical-apdl","status":"publish","type":"post","link":"https:\/\/www.padtinc.com\/2013\/12\/06\/the-10-coolest-new-features-in-r15-of-ansys-mechanical-apdl\/","title":{"rendered":"The 10 Coolest New Features in R15 of ANSYS Mechanical APDL"},"content":{"rendered":"

On Tuesday we posted on what I thought were the 10 coolest features in ANSYS Mechanical for R15<\/a>. Now it is time to take a good look at ANSYS Mechanical APDL, or MAPDL (classic ANSYS, black window ANSYS, or my favorite: ANSYS).\u00a0 The developers have been very busy and added a lot of useful features, and there are a large number of \u201cOh Yes!\u201d capabilities in this release that different groups of users will be very excited about.\u00a0 For this posting though, we are going to stay focused on the things that impact larger groups of users and\/or expand capability in the code.\u00a0 As always, you can learn more by attending one of the many upcoming ANSYS webinars<\/a> or reading the release notes in the help.<\/p>\n

\"image\"1: Rezoning Enhancements and Additions<\/h2>\n

This is my favorite change in R15, a mix of some improvements and some new capabilities. The whole idea of rezoning is that when you have a part that sees a large amount deformation, the mesh often gets very distorted. It often gets so distorted that the elements are no longer accurate and crazy strains are calculated and the element literally blows up.\u00a0 Or it turns inside out and generates an error in the solver.<\/p>\n

Rezoning has been around for a while but at this release some holes are plugged and some big advances are made.\u00a0 The first change was a hole plug, you can now rezone areas that contain surface effect\u00a0 (SURF153\/154) elements.\u00a0 It is very common to have that type of load on highly distorted geometry, so this is welcomed.<\/p>\n

The next change was adding mesh splitting for 3D\u00a0 tetrahedral elements. This is used for manual rezoning with the REMESH command. It was available before with 2D elements.\u00a0 The 2D example from the manual shows it best:<\/p>\n

\"image\"<\/p>\n

The advantage of this approach is that the subsequent stress field that is placed upon the new mesh is already accurate at the nodes that existed for the original mesh, and are fairly accurately interpolated for the new nodes.\u00a0 When you read in a completely new mesh, you have to interpolate the stress field and then iterate till the stresses are accurate.\u00a0 This approach can be much faster.<\/p>\n

The third and best addition is Automatic Rezoning or Mesh Nonlinear Adaptivity.\u00a0 This process is completely automatic and does not require the user interaction that rezoning does.\u00a0 Both splitting and remeshing are used. You can turn remeshing on based upon position, energy levels, or contact conditions.<\/p>\n

Here is an example from the user manual:<\/p>\n

\n
R15_Example_5p8p1_Mesh_adaptivity.mac<\/div>\n<\/div>\n

\"seal2\" <\/picture><\/p>\n

And here is an example that ANSYS, Inc. is showing on the new :<\/p>\n

\"Seal_Squish1\" <\/picture><\/p>\n

\"image\"2: Bolt Thread Modeling<\/h2>\n

Modeling bolt threads.\u00a0 Classic newby mistake right?\u00a0 They model threads on 37 bolts and then try and set up contact on all of them.\u00a0 Never goes well does it. ANSYS MAPDL has had a bolt modeling capability for some time that allows you to simulate a bolt as a cylinder with preload and everything. But what that approximation missed was the fact that the contact is at an angle that is not normal to the cylinder surface.<\/p>\n

At R15 you can now specify your thread geometry and the contact algorithm will calculate the proper normal and contact pattern for the contact forces. Much more efficient. There is a great example in the Technology Demonstration Guide, Section 39, showing all three approaches: model the threads in the mesh, use the new contact threads, or just bond the threaded area.<\/p>\n

\"image\"<\/p>\n

Needless to say we will be doing an in-depth posting on this one in the future.<\/p>\n

\"image\"3: Mode-Superposition for Harmonic Analysis of Cyclic Structures<\/h2>\n

I started my career in turbomachinary and from day one, one of the holy grails was to be able to do a harmonic analysis using blade pressure loads from a CFD run: getting the actual stresses in the blades caused by the varying aerodynamic load as they spun around and dealt with variations caused by passing frequencies and resonance in the flow itself.\u00a0 It was always doable as a full 360 model on both the CFD and structural side. And you could have done it using the full method for a few releases.\u00a0 But now we can use cyclic symmetry and mode-superposition.<\/p>\n

The ANSYS MAPDL side of things is released in R15.\u00a0 You can take your complex loading info from CFD and apply that as a load on your blades using the new \/MAP pre-processor (see below), a bit of a pain to do in the past.\u00a0 The other big change was making it all work with modal-superposition.\u00a0 The grail is almost complete.<\/p>\n

\"image\"4: Arc Length<\/h2>\n

This is one of those things buried in the code that the user really doesn\u2019t have to do anything to benefit from. If you are not familiar with the method, it is an approach used on non-linear problems using the Newton-Raphson method. Most solves use other methods,\u00a0 but for things like non-linear buckling it is a better method. Check out 14.12 in the Theory Reference for the math and all that.<\/p>\n

The bottom line at R15 is that they changed the algorithm to use the Crisfield Method and to avoid Driftback.\u00a0 What it means to you the user is those nasty non-linear buckling problems that always seem to have a hard time converging, or that require really small steps to converge, should converge now or converge faster.<\/p>\n

\"image\"5: Mode Selection<\/h2>\n

This is another one of those advanced options that users of other solvers have been asking for in the past. When you do a modal analysis that produces a ton of modes, you often want to ignore the majority of them and focus on the few modes that are strong or that get excited.\u00a0 In the past you could specify a range only, and only one range. At R15 you can now select which modes to use in modal-superposition analysis.\u00a0 You can decide which modes to use based on the modal effective mass, the mode coefficient, or the DDAM Procedure. Or, if you have your own criteria, you can use APDL to create a table that specifies a 1 for keep, and a 0 for toss. Very handy.<\/p>\n

\"image\"6: Acoustics Enhancements<\/h2>\n

This is really not one new feature, but an overall continuation of adding functionality to the acoustics capability in ANSYS MAPDL. For decades, this capability was not really focused on advanced acoustic modeling. But over the last couple of releases we have seen added functionality that put the functionality on a par with specialty acoustics codes.<\/p>\n

The key enhancements at R15 are:<\/p>\n