Cummins Inc. is an American multinational corporation that designs, manufactures, and distributes engines, filtration, and power generation products. This paper presents an overview of the design, analysis and testing carried out by Cummins to demonstrate the capability of a new structural engine for an agricultural tractor application. In general applications, the powertrain assembly is mounted onto a vehicle chassis via vibration isolators. Due to tight packaging constraints in agricultural tractors, leaving no room for the chassis rails. The engine in conjunction with the transmission and a front axle carrier becomes an integral member of the vehicle chassis. This leads to the engine being directly subjected to the wide range of agricultural tractor application specific loads.
Multiple analysis lead design (ALD) iterations were carried out using cutting edge CAE software such as Ansys, Dassault Systems fe-safe, and PTC Creo to ensure all elements of the complex acceptance criteria were satisfied within the tightly coordinated program schedule. The key technical requirement for the first prototype engine build was to validate its structural integrity in a hydraulic rig test wherein the loading blocks were representative of severe duty end user application including abusive load case scenarios.
The rig test was completed successfully, and the prototype engine underwent comprehensive post-test examination for mechanical fatigue. Magnetic particle inspection confirmed no cracks in any of the structural engine components. Additional data acquisition during the test comprised of strain measurements at key locations. The correlation between test and FEA stresses was assessed for the cylinder block and oil pan under the given load cases. While most of the strain gauge locations demonstrate close agreement within 30% w.r.t FEA results, few thermocouples exhibit certain variations over 50%. Overall, the results indicate a reasonable correlation between test and FEA, with most locations showing that the FEA results are on the conservative side. The observed differences mainly arise from modelling assumptions, and experimental uncertainties. This comparative verification provides high confidence in the FEA model and the engine’s durability.