{"id":10056,"date":"2021-03-22T08:30:47","date_gmt":"2021-03-22T12:30:47","guid":{"rendered":"https:\/\/blogs.mathworks.com\/simulink\/?p=10056"},"modified":"2021-03-22T08:30:47","modified_gmt":"2021-03-22T12:30:47","slug":"modeling-flexible-bodies-using-the-reduced-order-flexible-solid-block","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/simulink\/2021\/03\/22\/modeling-flexible-bodies-using-the-reduced-order-flexible-solid-block\/","title":{"rendered":"Modeling flexible bodies using the Reduced Order Flexible Solid block"},"content":{"rendered":"

Today I am happy to welcome guest blogger David Balbuena<\/a>. If you are getting started using the Reduced Order Flexible Solid<\/a> block from Simscape Multibody<\/a>, I strongly recommend that you go through David's MATLAB Central contribution. Whether you are importing your reduced-order model from the Partial Differential Equation Toolbox<\/a> or any other third-party finite-element analysis software, this should help you avoid common mistakes and get you running quickly.
---Guy<\/em><\/p>\r\n\r\n\r\n\r\n\r\n

In this post, I am introducing a MATLAB Central submission<\/a> to help you validate your workflow for generating the data required by the Reduced Order Flexible Solid<\/a> block. <\/p>\r\n\r\n

Before diving in, let\u2019s review the evolution of flexible bodies in Simscape Multibody. <\/p>\r\n\r\n

Evolution of Flexible Bodies in Simscape Multibody<\/strong><\/p>\r\n\r\n

Prior to R2018b, Simscape Multibody did not include built-in blocks to model flexible bodies. In those days, you had to use a series of rigid bodies connected by springs and dampers, as Guy demonstrated in a previous post<\/a>. Since then, we've added lots of new capabilities for modeling flexible bodies! Here's a quick summary:<\/p>\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Release<\/th>\r\nBlock<\/th>\r\nDescription<\/th>\r\nImage<\/th>\r\n<\/tr>\r\n
R2018b<\/td>\r\nGeneral Flexible Beam<\/a><\/td>\r\nFlexible beams with a constant cross-section<\/td>\r\n\"General<\/td>\r\n<\/tr>\r\n
R2019b<\/td>\r\nReduced Order Flexible Solid<\/a><\/td>\r\nYou can start with the CAD geometry of your component, generate a finite-element mesh, apply the Craig-Bampton FEA substructuring method, and generate a reduced-order model<\/td>\r\n\"Cylinder<\/td>\r\n<\/tr>\r\n
R2020a<\/td>\r\nFlexible Beams with standard cross sections<\/a><\/td>\r\nStandard flexible beams added to the library<\/td>\r\n\"Flexible<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

<\/p>\r\n

Now you can easily build and simulate cool stuff like this flexible four bar mechanism:<\/p>\r\n\r\n

\"Flexible<\/p>\r\n\r\n

Reduced Order Flexible Body<\/strong><\/p>\r\n\r\n

\r\nThe Reduced Order Flexible Solid<\/a> block is different from the other flexible beams because it can use data generated from FEA software. It requires a reduced-order model (ROM), which you can get by taking the CAD geometry of your component, generating a finite-element mesh, applying the Craig-Bampton FEA substructuring method<\/a>, and then generating a reduced-order model.<\/p>\r\n\r\n

The nature of this block comes with a challenge: since it uses data from a third-party software, it is impossible for us (MathWorks) to check that the data you provide actually represents what you intend.<\/p>\r\n\r\n

Once you have the ROM, you can enter the data generated in the Simscape Multibody block along with the CAD part:<\/p>\r\n\r\n

\"ROM<\/p>\r\n\r\n

The ROM data primarily consists of 3 matrices\r\n