Rising technical standards of customers, legal requirements and the trend to minimize maintenance effort raise the thermal, mechanical and tribological loads on components of combustion engines. In this regard, emphasis is laid on improving the piston ring - cylinder liner tribosystem, one with the highest energy losses. An efficient performance has to be guaranteed during its lifetime. Tribological investigations could be carried out on engine test benches, but they are highly cost-intensive and time-consuming. Therefore, a damage-equivalent test methodology was developed with the analogous tribological model, "ring-on-liner". The research was carried out under two characteristic operating conditions. One with a "standard" operating system, modelled in line with ideal lubrication conditions, and the other "extreme abrasive" operating system, typical to a system running on a lubricant contaminated by abrasive particles. To optimize the tribological loading capacity of the cylinder liner, with focus on these two operating conditions, numerous nitride coatings have been investigated. The key aspects being seizure resistance, running-in characteristics and long term wear behaviour.
An alternative FEM algorithm of fi nding piston ring pressure distribution to a contact simulation is introduced. The method is basing on an analytical determining of required nodal displacement boundary conditions. Its several confi gurations are tested using APDL and compared to a no-separation contact simulation of a simple 2D fi nite element model of a two-stroke piston ring made of Titanium alloy. Each of the methods tested in the paper brings displacement result and Huber-Misses equivalent stresses close to each other. However, only one of those brings resulting contact pressure close to a no-separation contact simulation. Nonetheless, the obtained confi guration occurred to be less computationally effi cient than no- separation contact simulation performed in an ANSYS software.