1,720,973 research outputs found
3D Printing of Shape Memory Polymers: Embedding Nichrome-Wires to Enhance Their Performance
No full textAdditive Manufacturing for Soft Electromagnetic Robots: Experimental Study to Reduce Vibration
No full textOne-Shot 3D Printed Soft Device Actuated Using Metal-Filled Channels and Sensed with Embedded Strain Gauge
No full textIn this article, the multimaterial extrusion (M-MEX) technology is used to fabricate, in a single step, a threedimensional printed soft electromagnetic (EM) actuator, based on internal channels, filled with soft liquid metal (Galinstan) and equipped with an embedded strain gauge, for the first time. At the state of the art, M-MEX techniques result underexploited for the manufacture of soft EM actuators: only traditional manufacturing approaches are used, resulting in many assembly steps. The main features of this work are as follows: (1) one shot fabrication, (2) smart structure equipped with sensor unit, and (3) scalability. The actuator was tested in conjunction with a commercial magnet, showing a bending angle of 22.4 degrees (when activated at 4A), a relative error of 0.7%, and a very high sensor sensitivity of 49.7 omega/degrees degree. Two more examples, showing all the potentialities of the proposed approach, are presented: a jumping frog-inspired soft robot and a dual independent two-finger actuator. This article aims to push the role of extrusion-based additive manufacturing for the fabrication of EM soft robots: several advantages such as portability, no cooling systems, fast responses, and noise reduction can be achieved by exploiting the proposed actuation system compared to the traditional and widespread actuation mechanisms (shape memory polymers, shape memory alloys, pneumatic actuation, and cable-driven actuation)
Analytical model to predict the extrusion force as a function of the layer height, in extrusion based 3D printing
No full textFused Filament Fabrication is the most widespread 3D printing process, and issues such as improving accuracy and speed are significant areas of research. To better understand and foresee the process, accurate models would be very useful. Several analytical models have been proposed in the literature; however, while the behavior inside the print core has been investigated, to the best of the authors’ knowledge, no studies are reported on the behavior of the melt filament downstream of the nozzle. This lack of research is very important, since the behavior downstream of the nozzle is influenced by the counterpressure generated by the deposited material. Qualitatively, the lower the layer height, the higher the counterpressure should be, while the higher the printing speed, the lower the counterpressure. No such models are available in the literature that take these phenomena into account, and such a model would help in managing the printing process when low layer height is required for improving the accuracy and roughness of the part. In the present study, a new analytical model was developed to compute the minimum force necessary to push the filament into the extruder according to given values of printing process parameters. The model considers both the contribution of the extrusion force and of the deposition force, allowing the prediction of the variation of the required pushing force when variations of the layer height occur and can be a useful tool in the design of process parameters when very accurate components are needed in the process of additive manufacturing (AM)
Electromagnetic assistance enables 3D printing of silicone-based thin-walled bioinspired soft robots
No full textMaterial Extrusion (MEX) is emerging as the leading manufacturing method for fabricating complex silicone structures and is demanded in different fields such as soft robotics, space exploration, and biomedicine. At the state-of-the-art level, the fabrication of small-scale silicone structures (low value of layer height parameter) remains challenging owing to the high printing forces involved. In this study, an innovative approach to considerably decrease the printing force while extruding at low layer heights is presented, thereby enabling the fabrication of thin-walled silicone structures. The proposed approach is based on leveraging silicone mixed with Fe3O4 magnetic nanopowder, which is extruded using a custom-made syringe equipped with 325 electrically charged (4.5 Ampere) copper coils. The electromagnetic force (FEM) generated by these coils pushes the magnetic ink from the syringe towards the build plate, thereby reducing the overall printing force (FT). Here, a maximum reduction of 21.08% is achieved when the layer height of 0.1 mm is set. Further, all the forces involved in the proposed electromagnetic-assisted manufacturing approach are numerically modeled and experimentally measured after equipping the 3D printing system with piezoresistive sensors: a model accuracy of 95.63% is obtained at low layer heights and flow rate values. Finally, small-scale self-transforming soft robots and bioinspired monolithic structures obtained by jointly extruding magnetic ink and stiff thermoplastic materials in the same manufacturing cycle are presented, thereby proving the potential of the proposed additive manufacturing approach
I-support soft arm for assistance tasks: a new manufacturing approach based on 3D printing and characterization
No full textSoft robotics is an emerging scientific field well known for being widespread employed in several applications where dexterity and safe interaction are of major importance. In particular, a very challenging scenario in which it is involved concerns bio-medical field. In the last few years, several soft robotic devices have been developed to assist elderly people in daily tasks. In this paper, the authors present a new manufacturing approach for the fabrication of I-SUPPORT, a soft arm used to help needful people during shower activities. The proposed I-SUPPORT version, based on pneumatic and cable-driven actuation, is manufactured using Fused Filament Fabrication (FFF), the most common and inexpensive Additive Manufacturing (AM) technology. The advantages offered by FFF technology compared to traditional manufacturing methods regard: (i) the possibility to increase the automation degree of the process by reducing manual tasks, (ii) the decrease of assembly operations and (iii) an improvement in terms of supply chain. Moreover, the constitutive I-SUPPORT elements have been printed separately to save time, reduce materials and optimize the waste in case of failure. Afterwards, the proposed soft robotic arm has been tested to evaluate the performances and of the chambers, module and the whole I-SUPPORT manipulator
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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