Additive manufacturing (or three-dimensional (3D) printing) is constantly growing as an innovative process for the production of complex-shape components. Among the seven recognized 3D printing technologies, fused deposition modeling (FDM) covers a very important role, not only for producing representative 3D models, but, mainly due to the development of innovative material like Peek and Ultem, also for realizing structurally functional components. However, being FDM a production process involving high thermal gradients, non-negligible deformations and residual stresses may affect the 3D printed component. In this work we focus on meso/macroscopic simulations of the FDM process using abaqus software. After describing in detail the methodological process, we investigate the impact of several parameters and modeling choices (e.g., mesh size, material model, time-step size) on simulation outcomes and we validate the obtained results with experimental measurements.

Nitinol stents continuously experience loadings due to pulsatile pressure, thus a given stent design should possess an adequate fatigue strength and, at the same time, it should guarantee a sufficient vessel scaffolding. The present study proposes an optimization framework aiming at increasing the fatigue life reducing the maximum strut strain along the structure through a local modification of the strut profile.The adopted computational framework relies on nonlinear structural finite element analysis combined with a Multi Objective Genetic Algorithm, based on Kriging response surfaces. In particular, such an approach is used to investigate the design optimization of planar stent cell.The results of the strut profile optimization confirm the key role of a tapered strut design to enhance the stent fatigue strength, suggesting that it is possible to achieve a marked improvement of both the fatigue safety factor and the scaffolding capability simultaneously. The present study underlines the value of advanced engineering tools to optimize the design of medical devices.

This article presents different physical arrangements of filters using conical posts as the basic element of design. The proposed resonator is similar to that of the classical combline filter, however, in this case, a conical post (truncated cone) is exploited. A hollowed enclosure is positioned on top of a rectangular metallic cavity for housing the upper part of the conical resonating post. Considering that the post upper radius is smaller than the post lower radius, an enclosure having the same dimensions as the resonating post can be taken. This results in a housing that can also work as an additional resonator for another cavity. As a result, cavities can be piled in a vertical arrangement and the conical post of each cavity is also used for housing the post of the cavity below it. Mixed vertically and/or horizontally arrangements are also feasible. More compact structures can be achieved with the possibility to obtain different footprints while maintaining similar unloaded Q-factors than conventional combline filters. The structure also has the advantage of having a wider spurious-free range than the classical combline filter configuration (cylindrical post inside a rectangular cavity). Enhanced responses with higher rejections are also possible thanks to the introduction of transmission zeros. Several different filter configurations are presented in this article: 3-order filter and 4-order filter. The design procedure is explained for both of them. A 4-order filter has been manufactured using additive manufacturing techniques and measured in order to validate the proposed structure.