Search

Despite the rapid growth in the past decade, the industrial adoption of additive manufacturing has not still been achieved due to certain limitations. A recent trend to alleviate its inherent drawbacks is to integrate additive manufacturing with secondary production techniques. Indeed, hybrid additive manufacturing solutions may help overcome the current barriers to today's production systems by making use of the combined merits of merging technologies. This paper presents a comprehensive review of the current state-of-the-art in the field, covering the following three key aspects of the subject: (i) advances in the hybridization of additive manufacturing processes, (ii) developments in process planning for integrated technologies, and (iii) insights into the hybrid additive manufacturing industry. The main objective of the paper is to classify the latest knowledge for the researchers, along with highlighting challenges and future research directions in this field.

Fused filament fabrication technology provides the opportunity to produce complex objects with sophisticated interior features. Here, extruding variable bead widths for desktop 3D printers is presented in order to improve resolution and to decrease the build time. In the proposed method, the cross-section is continuously varied according to the geometric features associated with the layers. That is, thinner beads can be utilized to print features with higher accuracy such as the outer surfaces, edges/corners, and features with finer details. Larger beads could be employed to cover interior regions where the accuracy is not an important concern. In this paper, a comprehensive review on nozzles with variable bead widths is given. Then, new orientation-controlled extruder designs with rectangular orifice, which focuses on controlling the filament flow inside the nozzle to determine variable bead widths at the output of the nozzle, will be introduced. Numerical- and experimental analysis will be conducted to show comparatively the performance of the presented design. The repeatability of this process is also evaluated for nominal bead widths. The studies show that there is a good agreement between numerical and experimental results. The paper will be concluded with key points on the advantages of these proposed nozzle design.

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.

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. (c) 2017 The Authors. Published by Elsevier B.V.

Nowadays, car following models, as the most popular microscopic traffic flow modeling, are increasingly being used by transportation experts to evaluate new Intelligent Transportation System applications. The control of the car following is essential to its safety and its operational efficiency. For this purpose, this paper builds fuzzy sliding mode control (FSMC) system for car following maneuver. The aim of designing of this FSMC system is to obtain a controller that maintain safe longitudinal distance and minimizes the lateral movement of the vehicle with its leader vehicle. These goals were reached by producing proper composite torque and steering angle in car following maneuver. This control system has both advantages of sliding mode and fuzzy logic methods. Also, a nonlinear dynamics model with three degrees of freedom has been used to define sliding surfaces in sliding mode control method. The FSMC's performance was evaluated based on real observed traffic data. The simulation results show that the FSMC controller has a behavior much safer than that of real drivers, and it can provide a pleasant trip for passengers. The designed control system keeps a safe longitudinal distance from its leader and makes much less lateral displacement than the real driver.