Friction conditions in the friction brake system of Mi-2 helicopter

• The FEM model precisely imitates kinematics of a drum brake in the symmetric system.
• On the lining surfaces the asymmetric distribution of contact tractions was obtained when contact elements were used.
• In the glue layer, which connects the friction lining to the brake shoe, there was no excessive stresses, which could be a reason of its damage.

An assessment of friction conditions during braking on durability of structural elements of the drum brake is the goal of the work. The analysed brake in a symmetric system is used in Mi-2 helicopter. In the so far applied solutions a friction lining and brake shoe were fastened up by riveting. The new asbestos-free friction linings crack when using riveting technology. One way to avoid cracking is gluing instead of riveting. This paper presents a numerical analysis of the drum brake with the friction lining fastened by gluing. The numerical model includes a three-dimensional structure composed of seven structural elements and comparison of four material groups. A distribution of contact pressure between the frictional elements, and a stress state in the structural elements of the drum brake were determined for the assumed boundary and initial conditions. It was stated that the calculated distribution of the contact pressures is nonuniform and depends on the sense of rotation of the drum brake. This paper also presents the results of comparative tests of bonding strength for three different glues. The tests were carried out on a specially designed for this purpose test stand.