33 research outputs found
Caratterizzazione degli elementi genetici che veicolano il gene erm(B) in Streptococcus pyogenes
No full textPhotogrammetry and Additive Manufacturing Based Methodology for Decentralized Spare Part Production in Automotive Industry
No full textAdditive Manufacturing is becoming a suitable production process for many industries: it is based on the idea of adding material layer by layer, in opposite to traditional manufacturing processes. This technology shows advantages as design flexibility, internal logistics minimization and product customization that make it perfect to produce customized parts and all the applications where low production rates occur. The production of spare parts for classic or luxury cars is a field where Additive Manufacturing can be adopted because of low demand and relevant costs to manage stocks keeping several different parts in the after-sales inventory. The photogrammetry technique has been investigated to obtain the 3D model of the component to be replaced and send it to decentralized production centers equipped with 3D printers. This approach can enhance by far the supply chain management for automotive spare parts
Additive Manufacturing Challenges and Future Developments in the Next Ten Years
No full textA significant growth of Additive Manufacturing technology has been noticed in the last few decades due to its well-established advantages. This production process based on the idea of adding material layer by layer, instead of removing it, has several advantages such as: time reduction in the design-to-manufacturing cycle, capability to produce complex shapes in a single piece thus reducing the connections, and weight saving just to mention the main significant. On the same wave of enthusiasm, the research community is significantly focused on this technology and many contributions that are focused on the whole range of aspects connected to this manufacturing way are already available. However, Additive Manufacturing is in a development phase, and the design tools, the material portfolio and the production methodologies are still far from the optimum typical of mature technologies. This paper critically reviews the Additive Manufacturing advantages and weaknesses which nowadays limits its wider application; a discussion about how these problems could be solved is included, together with an outlook of the challenges the practitioners must face off from nowadays up to a time window of ten years
A Voxel-Based 2.5D Panel Method for Fluid-Dynamics Simulations
No full textThe Panel method is an approach for the estimation of the lift of 3D models which is faster than CFD. This can be useful especially in the conceptual design stage where several configurations should be evaluated in a reduced time with a limited computational cost. However, the meshing of the 3D body surface with rectangular panels can be a time-consuming activity because the designer should define from scratch a cloud of points that matches the external surfaces of the tested object to obtain consistent panelling. Therefore, a voxelization-based methodology has been developed to obtain the panels’ position, speeding up and automating the model preparation process. The obtained discretization has been integrated into a panel method available in the literature. Four case studies, of increasing complexity, have been analyzed to investigate the capability of the innovative voxel-based panel methodology. A parametric study has been carried out to study the effect of the voxel grid dimension on the accuracy of the results. Benchmarking values of lift coefficient obtained from literature or xFoil software have been used to evaluate the precision that can be achieved with this approach. The results show a good agreement between the voxel-based panel method and the literature when the overall pressure distributions and aerodynamic coefficient values are considered. Higher errors are noticed with drag
Advanced Smoothing for Voxel-based Topologically Optimized 3D Models
No full textSmoothing algorithms are used for mesh refinement and to remove undesired surface. This numerical procedure is recommended and applied on triangulated file coming from 3D scanners or Topology optimization designs based on voxel representation before the optimized structure is manufactured by Additive Manufacturing technologies. In literature, there are several available algorithms, but many of them suffer from mesh shrinkage and do not give to the designer easy procedures to select regions which do not need the application of the smoothing procedure as holes or flat surfaces. For this reason, an improved vertex-based algorithm is presented in this work along with a case study to prove its performances compared with existent algorithms. The algorithm confirms to be efficient and useful. However, user’s intervention is required to guide the procedure to get proper results
A systematic review of voxelization method in additive manufacturing
No full textAdditive manufacturing (AM) is becoming an important alternative to traditional processes. AM technology shows several advantages in literature, and its use increases in aerospace, automotive and biomedicine. Time reduction in design-to-manufacturing cycle, customization, capability to generate complex shapes in one piece and ability to imitate low-weight bio-inspired shapes are the strength of designs based on AM. Due to its potentials, major progresses were done in AM, thanks to technology evolution and increased computational power. With regard to AM, voxelization can be defined as part’s discretization in hexahedral elements, as done with pixels in 2D image. Voxels are used to speed-up geometry and algebraic manipulation thanks to their inherent advantages. This paper analyses advantages and criticalities of AM and voxel manipulation through a systematic literature review methodology. The analyses are based upon the filtering of a huge amount of publications available in literature up to obtaining the most significant 25 studies published in the last 5 years. The study’s main result is the technology gap’s identification, i.e. where AM and voxelization still need improvements, thus providing the reader with suggestions about possible further studies. Computer elaboration power and voxel discretization algorithms are suggested being key issues in AM’s further development
Efficient part orientation algorithm for additive manufacturing in industrial applications
No full textOver the past few decades, the scientific community’s and industry’s interest in additive manufacturing technologies has surged. This technology is distinguished by the layer-by-layer deposition of the raw materials and the piece’s growth in a
predetermined build orientation. This factor impacts the process’ overall cost, surface quality, and other crucial parameters. Numerous methods to solve competing aspects have been proposed in the literature, with the more promising that iteratively uses ray-tracing techniques. Existing algorithms iterate for each discrete element of the model’s bounding box projection onto the building platform. However, when optimisation algorithms are used on real-life industrial parts, computational time problems arise due to the high number of faces in the models. A new computational technique to determine the appropriate part orientation to reduce the support volume is proposed to address the problem. The method reduces the computational time, cycling the ray-tracing only on the triangles where the model surface is discretised. This approach has been integrated into an enhanced particle swarm optimisation algorithm to prove its efficiency. The approach is intended for industrial applications where it is necessary to handle complicated geometries quickly and efficiently to find the best orientation. Based on the computer’s resources and the complexity of the faceted model, a set of case studies with an industrial engineering
significance is used to demonstrate the approach’s effectiveness
Additive manufacturing in automotive: advantages and criticalities
No full textAdditive Manufacturing (AM) is becoming an important alternative to traditional manufacturing
processes based on chip removal. In AM “the design drives the shape” concept is valid,
opposed to the strategy “manufacturing drives the shape” which applies with traditional parts
obtained through casting, milling, lathing processing where several design constraints should
be respected. In many industries, aerospace and automotive, the lightweight design plays an
important role on the means of transport performances. Owing to AM potentialities, a widerange
of researches are focused on methodologies to obtain structurally optimized shapes:
structures obtained through topology optimization algorithms can be manufactured only in AM
due to their complex shape. The scope of this work is to analyze advantages and criticalities
of AM in automotive applications: a case study to evaluate pros & cons of AM is included,
together with a fuel reduction analysis which can be obtained thanks to proper lightweight
design of automotive components
A 3D Voxel-based Approach for Fast Aerodynamic Analyses in Conceptual Design Phases
No full textThe panel method is a potential-flow numerical approach that shows valuable performances to solve aerodynamic problems in the preliminary design stages. It shows a lower computational effort compared with Computational Fluid Dynamics, wind tunnel tests or ‘on the field’ experiments. However, the 3D surface discretization in rectangular panels is tedious and must be often carried out
manually from scratch. Moreover, the panel method can’t be used to compute the overall drag force due to strong assumptions. To solve these two challenging aspects, the authors propose a voxel-based fluid dynamic approach integrating its programmed functions within a panel method. Voxelization is used to automatically distribute coherently the panels along the external surface of a 3D model in an
automated way. A parametric study is included to demonstrate how the voxel resolution affects the aerodynamic results and provide guidelines for future research. Overall drag is estimated using corrections for both the skin friction and the form drag sources. The Ahmed body case study is included and demonstrates a good agreement between the voxel-based fluid dynamics approach and the
literature benchmarking values, but with lower computational efforts. Further studies involving more complex shapes should be performed to better understand the performances and limitations of the approach
Towards Large Parts Manufacturing in Additive Technologies for Aerospace and Automotive applications
No full textWell-established advantages as design freedom, acceleration of design-to-manufacturing cycle, decreased internal logistics reflect on the wider application of Additive Manufacturing as the main manufacturing process. However, its application to large-scale components manufacturing is still an open challenge, because of the limited printing volume available in off-the-shelf machines, slow manufacturing process, and low production volume. After a review of the available contributions, this paper proposes a methodology to handle large-scale 3D models, to be applied before the slicing process. The methodology is based upon the large-scale component subdivision into subparts within CAD environments, using an innovative approach tailored to the problem, and exploits the multi-head capability of collaborative large-scale AM machines. A UAV fixed-wing shows the positive effects in terms of speeding up the manufacturing process. The approach can significantly reduce the printing time of large parts, but a new generation of Additive Manufacturing machines is required to exploit the methodology
