Direct Femap Interface to ADINA — the 3D-bolt

In ADINA the 3D-bolt element is available for accurate modeling of bolts. A bolt is modeled by 3D solid elements with the options of bolt-force or bolt-shortening as specified in a table. Contact can also be modeled on the boundaries of the 3D-bolt.

In this Brief, we demonstrate the use of the Direct Femap Interface to ADINA to perform a nonlinear static analysis of a bracket with a bolt, modeled with 3D elements, followed by a restart to a frequency analysis.

Figure 1 shows the geometry of the bracket assemblage.  The upper and lower brackets are held together by a bolt and nut.

Figure 1  Bracket assemblage analyzed

In the finite element model, we use tetrahedral solid elements with an elastic material model for the whole bracket assemblage. Initially, the two parts of the bracket are bolted together by a 2000 N bolt tension force. A pressure load of 1 MPa is then applied to the top of the upper bracket as shown in Figure 2. Figure 3 shows the connections (contact surfaces) defined between the bolt, the lower bracket and the upper bracket. 

Figure 2  Finite element model of bracket assemblage

Figure 3  Connections in bracket assemblage

Using the ADINA 3D-bolt element, users can specify various modeling options as shown in Figure 4. In Figure 5, we show how the 3D-bolt plane and bolt loading sequence is defined.

Figure 4  Defining the 3D-bolt element in TRANSOR for Femap

(a)	(b)
Figure 5  Defining (a) the 3D-bolt plane and (b) bolt loading sequence in TRANSOR for Femap

Figure 6 shows the effect of the bolt pre-tension and applied pressure with a band plot of the von Mises stress.

Figure 6  Deformation of bracket assemblage showing von Mises stress

Subsequent to the above static analysis, a frequency analysis is performed in the deformed configuration corresponding to the bolt load, applied pressure and contact conditions. The first mode shape with a band plot of the total displacement is depicted in the movie above.

The entire analysis, from pre-processing to post-processing, is performed within the Femap environment using the direct Femap interface to ADINA. Thus, users already familiar with Femap can use the advanced capabilities of ADINA easily and effectively.

Keywords:
Femap, Nastran, pre-processor, post-processor, bolt, contact, frequency analysis, CAD, CAE