PSI - Issue 14

G Vamsi Krishna et al. / Procedia Structural Integrity 14 (2019) 820–829 G. Vamsi Krishna / Structural Integrity Procedia 00 (2018) 000–000

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Subsystem 1

Subsytem 2

Honeycomb Bracket

Fig. 1: Honeycomb bracket with electronic packages mounted

The construction details of the honeycomb bracket is shown in Fig. 2 and Fig. 3. Two 2mm thick aluminium alloy sheets are glued to the aluminium alloy honeycomb core on its top and bottom face. 2mm thick aluminium alloy sheet is also glued to the core all around its periphery.

Sleeves

Top face sheet

Mounting holes around periphery

Face sheet around the periphery

Honeycomb core

Bottom face sheet

Fig. 2: Honeycomb bracket configuration

This assembly is provided with number of mounting holes. Different set of holes are used for fastening of bracket to the section and for mounting of the two subsystems on the bracket. Torqueing loads due to fastening are highly localized and are relatively high. To avoid the local buckling of honeycomb bracket, aluminium alloy sleeves are employed in the mounting holes as depicted in Fig. 3. These sleeves are given close running fit (H7g6) with bracket holes and its length is given +0, -0.05 mm tolerances on basic size of bracket thickness. This tolerance on length of sleeves ensures, proper holding of the package to the bracket, at the same time ensuring the maximum amount of transfer of fastening loads through the sleeves. Since the stiffness of sleeves is much higher than the honeycomb bracket, much of load transfer happens through the sleeves.