A rotary extrusion system with a rectangular-orifice nozzle: toward adaptive resolution in material extrusion additive manufacturing

Material extrusion additive manufacturing (MEAM) has revolutionized the production of complex designs while minimizing the amount of effort required due to its simple production pipeline. However, MEAM naturally comes with a well-known trade-off; higher build resolution often tends to enhance the product quality at the cost of a slower build rate. Nozzles, the standard tool for thermoplastic extrusion in MEAM, have evolved into a crucial component of the process for controlling the product’s build resolution. The purpose of this study is to investigate the details of a novel extrusion system that makes use of a rotating nozzle with an unconventional aperture, in contrast to its typical (i.e., circular-orifice) counterparts. The unique nozzle configuration that lacks axial symmetry allows for precise control over the effective dimension of the extrusion via rotational guiding. By positioning the oblong orifice at intermediate orientations, the presented approach seeks to provide continuously variable intralayer and interlayer resolutions for MEAM processes. This paper explores the distinctive characteristics of this new nozzle design as well as the potential uses of the novel extrusion system. The outcomes of the conducted tests demonstrate the proof-of-concept for creating variable bead width within the layers, in addition to adaptable layer heights throughout the 3D objects. Possible limitations of the new approach and future perspectives are discussed in detail

G-PFEM:an open access numerical tool for the simulation of spudcan penetration in clays

Penetration depth of Spudcan foundations for offshore mobile Jack-up rigs is typically predicted by considering a wished-in-place foundation at different depths and following traditional bearing capacity approaches. However, the large penetration depths involved, stress redistributions and the flow of the material around the spudcan are some example of features which make the wished-in-place assumption quite unrealistic. This paper presents an open access application package developed to simulate and hence predict load penetration curves of spudcan installation in multi-layered clay profiles. The numerical tool adopts the recently developed particle finite element method for geotechnical applications (G-PFEM). The potential of this large strain particle finite element application is demonstrated by simulating field data from the literature. The results show that load-penetration curves obtained using G-PFEM capture more efficiently the field results with respect to other numerical and analytical methods. It is also shown how the G-PFEM automatically captures cavity infill. In the paper the computational cost for the simulation of penetration up to 40m on a standard desktop are shown to be low compared to other commercial software

Smart Manufacturing and Intelligent Manufacturing:A Comparative Review

The application of intelligence to manufacturing has emerged as a compelling topic for researchers and industries around the world. However, different terminologies, namely smart manufacturing (SM) and intelligent manufacturing (IM), have been applied to what may be broadly characterized as a similar paradigm by some researchers and practitioners. While SM and IM are similar, they are not identical. From an evolutionary perspective, there has been little consideration on whether the definition, thought, connotation, and technical development of the concepts of SM or IM are consistent in the literature. To address this gap, the work performs a qualitative and quantitative investigation of research literature to systematically compare inherent differences of SM and IM and clarify the relationship between SM and IM. A bibliometric analysis of publication sources, annual publication numbers, keyword frequency, and top regions of research and development establishes the scope and trends of the currently presented research. Critical topics discussed include origin, definitions, evolutionary path, and key technologies of SM and IM. The implementation architecture, standards, and national focus are also discussed. In this work, a basis to understand SM and IM is provided, which is increasingly important because the trend to merge both terminologies rises in Industry 4.0 as intelligence is being rapidly applied to modern manufacturing and human–cyber–physical systems

Finite element analysis of spudcan penetration on layered clay deposits

LAUREA MAGISTRALELa domanda di energia è cresciuta rapidamente nel corso dell'ultimo secolo e con essa l'industria offshore. Le piattaforme mobili, note come jack-up-rig, sono uno dei principali strumenti nel settore offshore, grazie alla loro flessibilità e capacità di essere operative in diverse condizioni meteorologiche. Prima del posizionamento definitivo di queste piattaforme mobili, una valutazione strutturale e geotecnica in sito relativa alla relazione tra carico e spostamento delle fondazioni, denominate spudcan, è fondamentale per valutare la stabilità della struttura. In particolare, nella fase di installazione si effettua un precarico per consolidare il terreno. Questa fase risulta essere una delle piu’ critiche, per via dei potenziali meccanismi di collasso che possono svilupparsi a seconda del tipo di terreno. Le procedure standard di valutazione del jack-up e del comportamento di penetrazione del carico dello spudcan utilizzate generalmente in ambito offshore sono basate sulla tradizionale analisi semi-analitica della capacità portante. Queste analisi sono di semplice applicazione per stratigrafie omogenee, ma risultano di complessa applicazione in caso di profili stratigrafici eterogenei. Le linee guida inoltre non tengono conto del processo di penetrazione continua dello spudcan. Nonostante in letteratura siano stati proposti diversi approcci numerici in deformazioni finite (es. Arbitrary Lagrangian-Eulerian, Coupled Eulerian-Lagrangian e Material Point Method) per modellare correttamente la penetrazione continua dello spudcan e per valutare la capacità portante dello spudcan nei profili stratificati, tuttavia questi metodi non sono generalmente disponibili per la pratica ingegneristica. Ciò è dovuto all’onere computazionale relativamente elevato e alla difficoltà di implementazione in codici ad elementi finiti standard. Questo studio presenta tre approcci di modellazione numerica basati sia su analisi agli elementi finiti in piccole deformazioni (approccio Wished-In-Place -WIP- e metodo Press-Replace -PRM), sia su analisi agli elementi finiti in grandi deformazioni (Particle Finite Element Method - PFEM). I metodi sono stati applicati per affrontare un caso di studio tratto dalla letteratura in un'area offshore situata nel Golfo del Messico.The offshore industry has been growing by leaps and bounds as the solid demand for energy from oil and gas to wind has grown rapidly over the last century. Mobile jack-up platforms remain one of the major tools in the offshore industry due to its capability of self-installation and to be operational in all weather conditions. Before locating the mobile jack-up platforms to the offshore fields, a site-specific structural and geotechnical assessment is fundamental to evaluate the jack-up leg penetration during installation in order to estimate load-penetration response of spudcan foundations and sudden changes in soil reaction which can induce tilting of the jack-up platforms, particularly in multi-layered soils. The main guidelines in the offshore industry are based on traditional semi-analytical bearing capacity analysis used for onshore application to assess spudcan penetration considering wished-in-place method, which is relatively simple to implement for single layer profiles. However, particular attention should be devoted for the multi-layer profiles since the guidelines do not take the continuous spudcan penetration process into account. Various large deformation numerical analysis such as Arbitrary Lagrangian-Eulerian (ALE), Coupled Eulerian-Lagrangian (CEL) and Material Point Method (MPM) were carried out in order to correctly model the continuous spudcan penetration and to evaluate spudcan bearing capacity in multi-layered profiles. Yet, these advanced methods are in general not available or common for engineering practices due to relatively high computational demand and relatively complex implementation into available standard FE codes. This study presents three numerical modelling approaches based on both small deformation finite element analyses (Wished-In-Place approach and Press-Replace Method) and the large deformation finite element analysis (Particle Finite Element Method). Furthermore, a case study from the literature in an offshore area located in the Gulf of Mexico is conducted using WIP, PRM and PFEM

A comprehensive guide to milling techniques for smoothing the surfaces of 3D-printed thermoplastic parts

Purpose: This study aims to thoroughly examine the milling process applied to fused filament fabrication (FFF) parts. The primary objective is to identify the key variables in creating smooth surfaces on FFF specimens and establish trends about specific parameters. Design/methodology/approach: In this study, PLA and ABS samples fabricated by FFF are subjected to side milling in several experiments. Achievable surface quality is studied in relation to material properties, milling parameters, tooling and macrostructure. The surface finish is quantified using profile measurements of the processed surfaces. The study classifies the created chips into categories that can be used as criteria for the anticipated quality. Spectral analysis is used to examine the various surface formation modes. Thermal monitoring is used to track chip formation and surface temperature changes during the milling process. Findings: This study reveals that effective heat dissipation through proper chip formation is vital for maintaining high surface quality. Recommended methodology demands using a tool with a substantial flute volume, using high positive rake and clearance angles and optimizing the feed-per-tooth and cutting speed. Disregarding these guidelines may cause the surface temperature to surpass the material’s glass transition, resulting in inferior quality characterized by viscous folding. For FFF thermoplastics, optimal milling can bring the average surface roughness down to the micron level. Originality/value: This research contributes to the field by providing valuable guidance for achieving superior results in milling FFF parts. This study includes a concise summary of the theoretically relevant insights, presents verification of the key factors by qualitative analysis and offers optimal milling parameters for 3D-printed thermoplastics based on systematic experiments

The Role of Additive Manufacturing in the Era of Industry 4.0

The latest industrial revolution, Industry 4.0, is encouraging the integration of intelligent production systems and advanced information technologies. Additive manufacturing (AM) is considered to be an essential ingredient in this new movement. In this paper, a comprehensive review on AM technologies is presented together with both its contributions to Industry 4.0. The review focusses on three important aspects of AM: recent advances on material science, process development, and enhancements on design consideration. The main objective of the paper is to classify the current knowledge (and technological trends) on AM and to highlight its potential uses

A New Method for Generating Image Projections in DLP-type 3D Printer Systems

This paper presents a novel method for generating image projections required for Digital Light Processing type 3D printer systems where the entire cross-section of the printed object is directly formed via projecting the image onto a vat of photopolymers. The cross-sections (i.e. slices), which are initially represented as bitmap images, are compressed via a novel lossless compression technique which makes good use of relative data encoding. The coherence between the consecutive slices (or images) are taken into account in this proposed paradigm. The method yields satisfactory performance in terms of data compaction achieved in the test cases considered. (c) 2017 The Authors. Published by Elsevier B.V