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Targeting the current demands for engines with lower emissions, reduced fuel consumption, downsizing and higher peak combustion pressures, thyssenkrupp has developed a new cranktrain concept comprising an increased radial transition between journal and web that extends itself into the bearing’s load-carrying zone, creating a symmetrical U-shaped profile. The resulting non-straight bearing contour restricts the use of a standard bearing shell and led to the development of an integral bearing solution, where a copper based material was applied directly to the connecting rod big end bore. The so-called U-shape cranktrain was experimentally evaluated on a fired engine through a series of eight test steps with varied loads and speeds, being each step condition defined in a way that increased severity was applied to the connecting rod bearings as the test proceeded. The engine was disassembled after each step for analysis and measurement of the crankshaft and connecting rods.

Automotive internal combustion engines use connecting rods to compose its mechanical set-up based on a piston-rod-crank mechanism. Typically, a connecting rod has an i-shaped beam along its length in order to have better moment of inertia distribution on two axes, one aligned to the engine rotating axis and other, orthogonal to the same. An alternative design was developed by the use of an oval shaped beam in order concentrate the moment of inertia just along the engine rotating axis. The structural simulations based on Finite Element Analysis showed that the fatigue and buckling strength were maintained and finally, experimental fatigue testing had proven that oval beam design kept the fatigue and also buckling strength