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The evolution of materials technology has provided in recent decades the replacement of the raw material of many parts made of metal by polymers, carbon fibers, ceramics, and composite materials. This process has been driven by the permanent need to reduce weight and costs, which, even after replacing raw materials, still demand permanent improvement and optimization in the sizing process and in the manufacturing process. In the automotive industry, many components have been replaced by fiber-reinforced polymers, from finishing parts to structural components that are highly mechanically stressed and often also subjected to high temperatures. Although they are lighter and have a lower final cost than conventional metallic parts, components made of fiber-reinforced polymers bring great technological challenges to the development project.

This paper describes an experimental method to correlate experimental and theoretical bending stress found in a rotating fatigue test for ICE valves. Specimens of actual engine valves were instrumented with strain-gages. The ICE valve fillet stress was measured and compared with theoretical values found by analytical method and finite element analysis. The test allows a fast and relative inexpensive way to study influences like surface finish on the valve fatigue limit. A careful design of the test fixture and load mechanism was necessary to assure pure bending and reduce deviations from test to test. With the result of the stress values correlation, it was carried out an analytical verification of pure bending phenomenon which allowed a stress loading test closer to real-world stress values found on the critical region of the ICE valves.

This work shows a case study of a cavitation problem in a heavy duty diesel engine. We propose to solve this cavitation problem by studying the piston secondary motion. The first step was to simulate the piston secondary motion in order to evaluate the piston excitation against the liner that could cause the high frequency vibration. The second step was to optimize the piston secondary motion by changing pin offset. The solution proposed in this work was tested in the engine and the cavitation problem was solved. It was studied also the solution robustness for pin offset manufacturing tolerance. After opmizing the pin offset it was performed also a piston profile optimization.