Piston Ring Carriers Close to the Top-Stress Analysis of the Alfin Bonding Layer

Due to emission requirements there is a general trend to move the first ring towards the piston top. In this paper, the changes in mechanical, thermal and residual stresses at the ALFIN layer due to the raising of the ring carrier are examined, for a single and a double carrier, through an axissymetric finite element model.

The proposed failure mechanism is fatigue propagation of pre-existing unbonded areas under the action of fluctuating tensile stresses normal to the interface.

It is concluded that the proposed mechanism gives results according to preliminary field testing results, i.e., considering a piston with a diameter of 114 mm: (i) no failure is expected for a 14 mm top land height (single carrier); (ii) failure is expected along the top interface for a 6.5 mm top land height (single carrier); (iii) accelerated failure is expected along the back interface for a 6.5 mm top land height (double carrier).