The InKoMar project, funded by the German Federal Ministry of Education and Research (BMBF) under the call numbers FKZ 03SX364, 03SX445B and 03SX415B, aimed to develop cost‑ and emission‑optimised lightweight pistons for marine dual‑fuel large engines. The effort was carried out by a consortium of industry and research partners, with MET Motoren‑und Energietechnik GmbH leading the simulation‑driven design and manufacturing work. SECO GmbH supplied material characterisation and fatigue testing, while WTZ gGmbH provided experimental support for strain‑gauge measurements and validation of the virtual piston model. The project built on earlier research programmes (INKOV, G‑KOM, SimShaker) and ran over a multi‑year period, during which the consortium integrated computational fluid dynamics (CFD) and finite‑element method (FEM) tools into a fully coupled workflow.

Technically, the project demonstrated that a conventional piston cooling scheme—oil supplied through the connecting rod and sliding shoe or through piston bolts—was thermally equivalent to a simpler spray‑oil injection system. This finding allowed the design team to adopt the spray‑oil approach for the friction‑welded lightweight piston, reducing mechanical complexity without compromising cooling performance. The FEM analysis of the piston’s lower side, incorporating forces from secondary piston motion, predicted a maximum tensile stress of 43 N/mm², which matched closely with strain‑gauge data collected over four crankshaft revolutions at 75 % load. The close agreement between simulation and experiment validated the numerical model and opened avenues for further refinement of the calculation procedures.

The hybrid methodology extended beyond design into manufacturing. Casting simulations, friction‑welding process models, and thermal compensation calculations for the post‑weld heat treatment were all performed within the same simulation environment. This integration shortened development time, increased the reliability of novel solutions, and reduced overall costs. The project achieved a 50 % reduction in piston mass and a 30 % decrease in manufacturing effort, directly addressing the economic pressures of the shifting maritime industry and the tightening emission regulations. Fatigue testing of selected piston samples was extended from the standard 10⁶–10⁷ load cycles to over 10⁸ cycles, confirming the long‑term durability required for marine service. Additionally, the virtual piston technology demonstrator enabled non‑experimental assessment of operating behaviour, including predictions of oil‑coking risk and thermal damage, which were subsequently corroborated by experiments on the MET oil‑coking test rig.

Collaboration within the consortium was tightly integrated. MET coordinated the overall project, performed the CFD/FEM analyses, and manufactured the prototype pistons. SECO conducted material‑technical investigations of the friction‑welded cores, providing critical data on microstructure and mechanical properties. WTZ supplied the strain‑gauge instrumentation and carried out the fatigue tests, ensuring that the virtual models reflected real‑world performance. The project’s outcomes—validated simulation tools, a lighter piston design, and a demonstrator platform—offer a scalable pathway for future marine engine development, aligning with the industry’s dual goals of cost efficiency and emission reduction.