Design of an Additive Manufactured Steel Piston for a High Performance Engine: Developing of a Numerical Methodology Based on Topology Optimization Techniques

Modern high performance engines are usually characterized by high power densities, which lead to high mechanical and thermal loadings acting on engine components. In this scenario, aluminium may not represent the best choice for piston manufacturing and steel may be considered as a valid alternative. In this paper, a methodology involving optimization techniques is presented for the design of an internal combustion engine piston. In particular, a design strategy is preliminary investigated aiming at replacing the standard aluminium piston, usually manufactured by forging or casting, with an alternative one made of steel and manufactured via an Additive Manufacturing process. Three different loading conditions are employed for the topology optimizations set up. Optimization results are then interpreted and the various structural features of the steel piston are designed starting from the density distribution contour plots. Different Finite Element thermo-mechanical models are finally prepared in order to correct and validate the designed geometry

A MATLAB script and a methodology for the powertrain design of a fuel cells-battery hybrid electric supercar

The urgency to decarbonize the transportation sector covers all kinds of vehicles, here included highperformance competition vehicles. Among the technologies able to guarantee zero emissions during the use phase, fuel cells (FCs) and energy storage systems (ESS), e.g. batteries, offer a great and still largely underexplored potential for complementary and synergic use in hybrid powertrains. Vehicles based on such technologies are cells-battery hybrid electric vehicles (FCHEV), and a niche of these are electric supercars (FCHES). In this context, the degrees of freedom of hybrid powertrains design and the different requirements of FCs and batteries frame the highly complex task of defining a clear and objective methodology to identify an optimal ratio among FC-battery power sources, whose lack jeopardizes a rigorous decision process as well as a general consensus and leads to the acceptance of sub-optimal solutions. In this study an energy/power-based methodology is developed in MATLAB environment considering the longitudinal vehicle dynamics of a typical high-performance parallel FCHES, using telemetry data from a real racetrack as common target for all the evaluated powertrain candidates and using realistic mass values. Under the constraint of equal performance (i.e., equal lap time), several FC-battery parallel hybrid powertrains are numerically evaluated with varying relative energy, power, weight, and under different regenerative braking levels. The set of obtained results allows to draw an objective rightsizing on the FC-battery power share and on the required energy capacity for a parallel FCHEV, as well as mass, hydrogen consumption, etc. The presented methodology offers a general use workflow applicable to any category of vehicles, supporting the engineering of hybrid FC-battery high-performance propulsion systems. The developed code will be made available upon request under the FAIR (Findable, Accessible, Interoperable, Reusable) guidelines

VIRTUAL DIVING IN THE UNDERWATER ARCHAEOLOGICAL SITE OF CALA MINNOLA

The paper presents the application of the technologies and methods defined in the VISAS project for the case study of the underwater archaeological site of Cala Minnola located in the island of Levanzo, in the archipelago of the Aegadian Islands (Sicily, Italy). The VISAS project (http://visas-project.eu) aims to improve the responsible and sustainable exploitation of the Underwater Cultural Heritage by means the development of new methods and technologies including an innovative virtual tour of the submerged archaeological sites. In particular, the paper describes the 3D reconstruction of the underwater archaeological site of Cala Minnola and focus on the development of the virtual scene for its visualization and exploitation. The virtual dive of the underwater archaeological site allows users to live a recreational and educational experience by receiving historical, archaeological and biological information about the submerged exhibits, the flora and fauna of the place

Investigation on the Dynamic Behaviour of a Torque Transmission Chain for an Innovative Hybrid Power Unit Architecture

In this contribution, the mechanical torque transmission between the Electric Motor (EM) and the Internal Combustion Engine (ICE) of a P0 architecture hybrid power unit is analysed. In particular, the system is made up of a brand new, single-cylinder 480cc engine developed on the basis of the Ducati 959 Panigale V90 2-cylinders engine. The thermal engine is assisted by a custom electric motor (30 kW), powered by a Li-Ion battery pack. The Ducati 959 Panigale engine is chosen because of its high power-to-weight ratio, and for taking advantage of its V90 2-cylinders layout. In fact, the proposed hybridization process considers to remove the vertical engine head and to replace it by the electric motor directly engaged to the crankshaft using the original valvetrain transmission chain, thus achieving a very compact package. This solution could be suitable for many V-type engines and it aims to obtain a small hybrid power unit for possible motorcycle/small vehicle applications. The original timing chain object of this study is a silent chain, which is commonly employed as a transmission component in hybrid power units because it can operate at high speeds transmitting high loads and ensuring noise reduction. For this reason, the aim of this study is to assess the possibility of using the original chain to couple the EM and the ICE. This investigation allows the replacing of the minimum number of components during the hybridization process leading to a real plug&go solution. Therefore, the mechanical behaviour of the chain is investigated performing a dynamic analysis of the whole crank mechanism. In particular, the original twin cylinders model considering the original valvetrain system is compared with the single cylinder model engaged with the EM. The dynamic analysis provides the maximum load on the single chain link in both configurations, allowing the evaluation of a relative fatigue safety factor

A finite element numerical methodology for the fatigue analysis of cylinder liners of a high performance internal combustion engine

In this paper a numerical methodology is proposed, which aims at predicting the fatigue behaviour of engine cylinder liners in an eight-cylinder V-type four-stroke turbocharged engine. A preliminary kinematic and dynamic study of the crank mechanism is fulfilled in order to properly identify the load cycle that involves the cylinder liner. Finite Element analyses, both thermal and thermo-mechanical, are performed to evaluate the stress and the strain of the component. In particular, non-linear models are developed to mimic the piston-liner interaction when subjected to different loading conditions. A simplified approach is proposed in order to reduce the computational effort of the simulations. FEM results are then processed employing the multiaxial Dang Van fatigue criterion

Structural Analysis of the Forming Process for Hairpin Windings for Electric Motor Applications: Torsional-Flexural Instability Issues

Electric motor manufacturing technology is evolving due to automotive transport development. Besides, environmental issues and the need of CO2 emission reduction have led to an increasing demand for electric drives efficiency. Permanent magnet synchronous machines are widely employed for traction systems and distributed windings produced by using insert techniques are growing in popularity. These methods require preformed wires such as the well-known hairpin shape. The advantages of hairpins are discussed in the pertinent literature. In the present paper, the manufacturing process of a hairpin is investigated by analysing its mechanical behaviour via Finite Element simulations. In fact, many problems might occur during the forming of a hairpin, depending on the shape required. In particular, this study aims at describing the influence of the geometry of the wire cross-section on the resulting final shape of the formed hairpin. Suitable ranges of geometrical and manufacturing parameters are identified to avoid torsionalflexural instabilities

Influence of the thermal deformation on the lubricating performance of the piston-gudgeon pin interface in an internal combustion engine

This contribution describes a methodology to evaluate the influence of bellmouth profiles on the elastohydrodynamic behaviour of the contact interface between the gudgeon pin and the piston of a high-performance internal combustion engine. First, a thermo-mechanical simulation is performed to evaluate the piston bosses thermal strains. Consequently, a Multibody elastohydrodynamic model is set up to evaluate the tribological behaviour of this lubricated interface considering a perfectly cylindrical shape of the piston bosses and their thermal deformation. Then, a preliminary bellmouth profile is adopted and a second Multibody model is performed. Nevertheless, the results, together with issues encountered analysing some tested pistons, suggest that modifications of piston bosses have to be introduced. Finally, an optimised bellmouth geometry is proposed and analysed