Flexible Beams in Adams using FE Parts

Published 2019-11-01

 

Did you know about FE Parts in Adams? They are neither MNF based flex bodies nor Adams Flex bodies, but are instead a completely different flexible body type intended for beam or rod applications.

FE Parts have been in Adams since the Adams 2014 release. MSC describes it as: “a wholly Adams-native modelling object that has mass and is accurate for very large deformation cases (that is, geometric non-linearity) of beam like structures”. The difference between the FE Part and the linear flexible body option in Adams/Flex is that the FE Part is better suited to large deformations than a flex body that uses the linear modes approach and the FE Part does not require you to generate an MNF file.

The FE Part comes in two basic flavours, a 3D formulation and a 2D formulation. The 2D formulation defines a two-dimensional representation of the beam that can move, stretch and bend parallel to the plane that you specify. The 3D formulation, as you can guess, is a fully non-linear representation of the beam that you specify in all three dimensions. For the 3D formulation the FE part can account for not only stretching and bending, as with the 2D formulation, but also shear and torsion.

So how do you create an FE part?

The steps below, on how to create a flexible beam in Adams, are illustrated in this short video tutorial:

The FE Part icon can be found under the Bodies tab in ADAMS View in the Flexible Bodies section.

Once you click on what appears to be a three-dimensional S icon, the FE Part GUI opens up. This GUI will guide you through three steps in order to generate your FE Part.

First up is the Formulation step. Here you can define your part’s name, material, damping ratios and whether you want the 2D or 3D formulation.

The next step is the Centerline step. As the name suggests, in this step you will define the centerline of your FE-Part. Adams presents you with two options on how to define the centerline. You can either use an existing curve, or you can generate a line by selecting the start and end points.

The third and final step is the Nodes step. During this step you will define your beam section and orientation.

If you right-click in a section cell, you can select an existing section, or generate a new one. If you generate a new section a window will open up where you can choose what type of beam section you want to define. There are various options to choose from, ranging from solid round through to an I-beam section. However if these section are not suitable for you there is the Properties section type and the Generic section type. When you choose the Properties section type you are required to enter the cross sectional area of your beam section, as well as its moments of inertia. The Generic section type gives you the opportunity to define your section profile in Adams using coordinates that you can either enter manually or import from a text file. Adams will then use this profile to calculate the required properties.

In order to load the FE Part you can make use of the FE Load. This load was added to Adams specifically for the FE Part and allows you to apply a distributed load, force or moment, along the FE Part’s centerline.

 

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