Having in mind con-rods for motorbike and car engines, and spurred by the disagreements evidenced in the pertinent literature, the maximum circumferential stresses within the small end are investigated analytically, photoelastically, and numerically. The analytical models are based upon a plane assumption, and they adopt both beam and theory of elasticity idealizations. The plane photoelastic study concentrates on small ends with outer to inner radii ratios ranging from 1.2 to 1.5. A plane numerical model aimed at thoroughly mimicking the pin ovalization is developed, and a design chart of the peak hoop stress within the small end is provided for a wide spectrum of small end and pin geometries, for zero initial clearance. Such diagrams allow a prompt preliminary dimensioning of the small end to be carried out, which may be refined by effecting a three-dimensional finite element study of the specific con-rod geometry. The consequences of an initial clearance between small end bore and gudgeon pin are examined for selected geometries, and three-dimensional aspects are explored for specific con-rod shapes.

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Electrostatic actuated microbeams are frequently encountered in micro electro-mechanical systems (MEMS). The behaviour of these devices is characterized by electromechanical coupling, due to the mutual interaction between the electrostatic field and the deflection of the structure. Besides the non-linearity due to the coupling, geometrical non-linearities due to the microstructure's large deflections can sometimes arise. In this work, a new FEM method based on a sequential field-coupling (SFC) approach is proposed, in which electrostatic loads are gradually applied to the deformed shape of the structure. The solutions are compared with those obtained by means of the best-known numerical methods available in the literature. In the case of voltage values that generate large displacements, the proposed method appears more suitable to describe the microbeam behaviour; in particular, the voltage at which instability occurs can be evaluated and post-instability solutions can also be predicted.