The selection of a motor-reducer unit in electrical servo-systems has a profound impact on the dynamic performance of a machine. This choice must be made considering all the limits imposed by each component of the system and all the operational constraints. This article proposes a useful and practical methodology for the correct sizing of a motor-reducer unit. The relationships between motor and transmission are investigated by introducing some easily calculated factors useful for comparing all the available motor-reducer couplings and selecting the best solution. The article suggests an innovative approach for the selection of a motor-reducer unit that involves solving the problem with the use of graphs that would allow showing all the possible alternatives.

Sophisticated computational aero-hydro-elastic tools are being developed for simulating the dynamics of Floating Offshore Wind Turbines (FOWTs). The reliabilty of such prediction tools for designers requires experimental validation. To this end, due to the lack of a large amount of full scale data available, scale tests represent a remarkable tool. Moreover, due to the combined aerodynamic and hydrodynamic contributions to the dynamics of FOWTs, experimental tests should take into account both. This paper presents the design process of a 6-Degrees-of-Freedom robot for simulating the dynamics of FOWTs in wind tunnel scale experiments, as a complementary approach with respect to ocean wind-wave basin scale tests. Extreme events were considered for the definition of the robot requirements and performance. A general overview on the possible design solutions is reported, then the machine architecture as well as the kinematic and dynamic analysis is discussed. Also a motion task related to a 5-MW Floating Offshore Wind Turbine nominal operating condition was considered and then the ability of the robot to reproduce such motions verified in terms of maximum displacements, forces and power, to be within the design boundaries

A new extrusion-based additive manufacturing technique is described in this paper together with the main components of the machine capable of carrying out the process. Innovative characteristics of the machine are the fixed extrusion head and the workpiece moving thanks to a 5-axis parallel kinematics handling system, allowing the capability of inclining the part during the material deposition and consequently avoiding support structures. The extrusion head and nozzle have been designed in order to be able to extrude high viscosity mixtures with low polymeric content. Preliminary tests prove that a good final density can be obtained after de-binding and sintering and that it is possible to achieve a good bonding of extruded and deposited wires in case of AISI 630 stainless steel