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A novel self-balanced internal combustion engine is presented. The new engine has a modular structure composed of two cylinders arranged in opposite way. It is characterized by an innovative system of linking between the pistons and the shaft, which has three toggles. One of these is on the middle of the shaft, whereas the others two are placed symmetrically. Thanks to this particular shape of the shaft, the pistons can rotate with the same timing and so the new engine comes back to be perfectly auto-balanced. Moreover, the fatigue life prediction of the shaft has been studied through numerical methods. In particular, two different approaches have been compared to estimate the maximum number of working cycles: the first is based on a “static” resistance criterion, the second consider the multiaxial nature of the stress and is based on the maximum shear stress (critical) plane criterion. The stress distribution on the shaft during the usual working conditions, has been evaluated by a FEM package. Results highlight that the critical plane approach is more conservative than “static” one.

The topology optimization of a structure is a process that allows to establish if in a point of an assigned domain there should be some material. No assumption is made with regard to the number and the distribution of the contours and the final topology, that can be very different compared to that one initially hypothesized. In this paper a study related to the topology optimization of a connecting rod for an internal combustion engine is presented. The used technique for the optimization is the density (or distribution of material) method. The developed application, besides giving an innovative solution of the topology of the connecting rod with a lower mass in comparison with the initial one, has provided, thanks to the analysis of the results coming from different optimization analyses, useful information about the influence of the constraints on the obtained solution, and which solving method is more suitable for a given optimization problem with a certain number of design and state variables.

Nondestructive evaluation (NDE) represents an important phase in the life cycle of a product to detect defects both in service and in production. NDE techniques most commonly used to detect surface defects are visual inspection and methods based on eddy current and ultrasound. Laser and non-contact sensors have been recently used to inspect ultrasonically without contact. Components with complex geometry are usually inspected combining several NDE techniques, or simply visually where analysis and evaluation of results are performed by an operator based on specific parameters of acceptance. This last method is currently used to inspect the clutch plates since their complex geometry, for the presence of grooves, limits the use of other methods. This work shows the possibility of using a non-contact ultrasonic technique and guided waves (Lamb) to detect surface defects in clutch plates. An appropriate source/receiver configuration allows to overcome the limitations due to the complexity of the geometry. This technique allows, compared to the visual inspection, to detect smaller and internal defects, and to obtain objective results, not depending on the evaluation of the operator. The inspection method can be very fast and applicable in the production line by using a fully automated control system.