3D-printed programmable tensegrity for soft robotics

2020 ◽  
Vol 5 (45) ◽  
pp. eaay9024
Author(s):  
Hajun Lee ◽  
Yeonwoo Jang ◽  
Jun Kyu Choe ◽  
Suwoo Lee ◽  
Hyeonseo Song ◽  
...  
Keyword(s):  
Smart Materials ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Structural Complexity ◽  
System Level ◽  
Design Parameters ◽  
Tensegrity Structures ◽  
Tensegrity Systems ◽  
3D Printed ◽  
3D Shapes

Tensegrity structures provide both structural integrity and flexibility through the combination of stiff struts and a network of flexible tendons. These structures exhibit useful properties: high stiffness-to-mass ratio, controllability, reliability, structural flexibility, and large deployment. The integration of smart materials into tensegrity structures would provide additional functionality and may improve existing properties. However, manufacturing approaches that generate multimaterial parts with intricate three-dimensional (3D) shapes suitable for such tensegrities are rare. Furthermore, the structural complexity of tensegrity systems fabricated through conventional means is generally limited because these systems often require manual assembly. Here, we report a simple approach to fabricate tensegrity structures made of smart materials using 3D printing combined with sacrificial molding. Tensegrity structures consisting of monolithic tendon networks based on smart materials supported by struts could be realized without an additional post-assembly process using our approach. By printing tensegrity with coordinated soft and stiff elements, we could use design parameters (such as geometry, topology, density, coordination number, and complexity) to program system-level mechanics in a soft structure. Last, we demonstrated a tensegrity robot capable of walking in any direction and several tensegrity actuators by leveraging smart tendons with magnetic functionality and the programmed mechanics of tensegrity structures. The physical realization of complex tensegrity metamaterials with programmable mechanical components can pave the way toward more algorithmic designs of 3D soft machines.

Direct Coupling of a Two-Dimensional Fan Model in a Turbofan Engine Performance Simulation

2016 ◽  
Author(s):  
Ioannis Templalexis ◽  
Alexios Alexiou ◽  
Vassilios Pachidis ◽  
Ioannis Roumeliotis ◽  
Nikolaos Aretakis
Keyword(s):  
Three Dimensional ◽  
Engine Performance ◽  
System Level ◽  
Design Parameters ◽  
High Fidelity ◽  
Two Dimensional ◽  
Performance Simulation ◽  
Cfd Models ◽  
Component Design ◽  
Complex Phenomena

Coupling of high fidelity component calculations with overall engine performance simulations (zooming) can provide more accurate physics and geometry based estimates of component performance. Such a simulation strategy offers the ability to study complex phenomena and their effects on engine performance and enables component design changes to be studied at engine system level. Additionally, component interaction effects can be better captured. Overall, this approach can reduce the need for testing and the engine development time and cost. Different coupling methods and tools have been proposed and developed over the years ranging from integrating the results of the high fidelity code through conventional performance component maps to fully-integrated three-dimensional CFD models. The present paper deals with the direct integration of an in-house two-dimensional (through flow) streamline curvature code (SOCRATES) in a commercial engine performance simulation environment (PROOSIS) with the aim to establish the necessary coupling methodology that will allow future advanced studies to be performed (e.g. engine condition diagnosis, design optimization, mission analysis, distorted flow). A notional two-shaft turbofan model typical for light business jets and trainer aircraft is initially created using components with conventional map-defined performance. Next, a derivative model is produced where the fan component is replaced with one that integrates the high fidelity code. For both cases, an operating line is simulated at sea-level static take-off conditions and their performances are compared. Finally, the versatility of the approach is further demonstrated through a parametric study of various fan design parameters for a better thermodynamic matching with the driving turbine at design point operation.

Split Vibration Modes in Acoustically-Coupled Disk Stacks

1995 ◽  
Author(s):  
Jung-Ge Tseng ◽  
Jonathan Wickert
Keyword(s):  
Natural Frequencies ◽  
Three Dimensional ◽  
System Level ◽  
Thin Plates ◽  
Mode Shapes ◽  
Design Parameters ◽  
Phase System ◽  
Acoustic Coupling ◽  
Annular Plates ◽  
Vibration Model

Abstract Vibration of an array of stacked annular plates, in which adjacent plates couple weakly through an acoustic layer, is investigated through experimental and theoretical methods. Such acoustic coupling manifests itself through split natural frequencies, beating in the time responses of adjacent or separated plates, and system-level modes in which plates in the array vibrate in- or out-of-phase at closely-spaced frequencies. Laboratory measurements, including a technique in which the frequency response function of all in-phase modes but no out-of-phase modes, or visa versa, is measured, demonstrate the contribution of coupling to the natural frequency spectrum, and identify the combinations of design parameters for which it is important. For the lower modes of primary interest here, the natural frequencies of the out-of-phase system modes decrease as the air layer becomes thinner, while those of the in-phase mode remain sensibly constant at the in vacuo values. A vibration model comprising N classical thin plates that couple through the three-dimensional acoustic fields established in the annular cavities between plates is developed, and its results are compared with measurements of the natural frequencies and mode shapes.

Geometric Accuracy Prediction for Additive Manufacturing Through Machine Learning of Triangular Mesh Data

2019 ◽  
Author(s):  
Nathan Decker ◽  
Qiang Huang
Keyword(s):  
Machine Learning ◽  
Additive Manufacturing ◽  
Three Dimensional ◽  
Triangular Mesh ◽  
Geometric Accuracy ◽  
New Approach ◽  
Machine Learning Model ◽  
3D Printed ◽  
3D Shapes ◽  
Complex Parts

Abstract While additive manufacturing has seen tremendous growth in recent years, a number of challenges remain, including the presence of substantial geometric differences between a three dimensional (3D) printed part, and the shape that was intended. There are a number of approaches for addressing this issue, including statistical models that seek to account for errors caused by the geometry of the object being printed. Currently, these models are largely unable to account for errors generated in freeform 3D shapes. This paper proposes a new approach using machine learning with a set of predictors based on the geometric properties of the triangular mesh file used for printing. A direct advantage of this method is the simplicity with which it can describe important properties of a 3D shape and allow for predictive modeling of dimensional inaccuracies for complex parts. To evaluate the efficacy of this approach, a sample dataset of 3D printed objects and their corresponding deviations was generated. This dataset was used to train a random forest machine learning model and generate predictions of deviation for a new object. These predicted deviations were found to compare favorably to the actual deviations, demonstrating the potential of this approach for applications in error prediction and compensation.

scholarly journals Biomechanical Assessment of Design Parameters on a Self-Developed 3D-Printed Titanium-Alloy Reconstruction/Prosthetic Implant for Mandibular Segmental Osteotomy Defect

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 597
Author(s):  
Sheng-Ni Huang ◽  
Ming-You Shie ◽  
Yen-Wen Shen ◽  
Jui-Ting Hsu ◽  
Heng-Li Huang ◽  
...  
Keyword(s):  
Oral Cancer ◽  
Cortical Bone ◽  
Three Dimensional ◽  
Design Parameters ◽  
Mandibular Bone ◽  
Biomechanical Assessment ◽  
Metal Printing ◽  
Facial Area ◽  
3D Metal Printing ◽  
3D Printed

Patients with oral cancer often have to undergo the surgery for mandibular excision. Once the bone in the cancerous area is removed, not only the facial area but also chewing function of the patient is needed to be repaired by clinicians. In recent years, the rapid growth of three-dimensional (3D) metal printing technology has meant that higher-quality facial reconstructions are now possible, which could even restore chewing function. This study developed 3D-printed titanium (Ti)-alloy reconstruction implant for a prosthesis designed for mandibular segmental osteotomy defects, and 3D finite element (FE) analysis was conducted to evaluate its biomechanical performance. The analyzed parameters in the FE models were as follows: (1) two prosthesis designs, namely a prosthesis retaining the residual mandibular bone (for patients with mild oral cancer) and a prosthesis with complete mandibular resection (for patients with severe oral cancer); (2) two lengths of prosthesis, namely 20 and 25 mm; and (3) three thicknesses of prosthesis, namely 0.8, 1, and 1.5 mm. A 45° lateral bite force (100 N) was applied to the top of the prosthesis as the loading condition. The results revealed that for the two prosthesis designs, the prosthesis retaining the residual mandibular bone showed higher stress on the prosthesis and cortical bone compared with the prosthesis with complete mandibular resection. Regarding the two prosthesis lengths, no fixed trend of prosthesis stress was found, but stress in the cortical bone was relatively high for a prosthesis length of 20 mm compared with that of 25 mm. For the three prosthesis thicknesses, as the thickness of the prosthesis decreased, the stress in the prosthesis decreased but the stress in the cortical bone increased. These findings require confirmation in future clinical investigations.

Design and Analysis of a Novel Lightweight, Energy Economic Powered Knee Orthotic Device

2019 ◽  
Vol 13 (3) ◽  
Author(s):  
Saikat Sahoo ◽  
Aditya Jain ◽  
Dilip Kumar Pratihar
Keyword(s):  
Knee Joint ◽  
Power Consumption ◽  
Three Dimensional ◽  
Fast Response ◽  
Design Parameters ◽  
Angular Deviation ◽  
Natural Behavior ◽  
Orthotic Device ◽  
3D Printed ◽  
Novel Design

The task of a powered knee orthotic device (PKOD) is to assist the knee joint so that its natural behavior can be restored. The key features of a PKOD that may help to regain such characteristics are low power consumption, fast response, compactness, and lightweight. This study proposes a novel design of PKOD, where we have focused on the betterment of the mentioned features with the help of a new mechanism, namely a four-bar controlled compliance actuator (FCCA). In FCCA, instead of using the widely used screw transmission mechanism, a four-bar mechanism is used to modify the joint's angular deviation and stiffness. The main advantages of using FCCA over other existing mechanisms are to reduce the power consumption by amplification of input motor torque and to achieve a faster response at the same time, and these are achieved by utilizing a simple four-bar mechanism. In the proposed design, FCCA controls both the stiffness of the artificial knee joint using a compliance mechanism as well as knee flexion with the help of a pulley arrangement. A three-dimensional (3D)-printed prototype of the proposed design has been developed, after optimizing the inherent design parameters. Simulation and experimental analysis are carried out in order to justify the performance of the proposed PKOD. The results have shown strong agreement with that obtained using analytical study and optimization. Moreover, the torque amplification is achieved, as desired.

scholarly journals 3D-Printed Oral Dosage Forms: Mechanical Properties, Computational Approaches and Applications

Pharmaceutics ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1401
Author(s):  
Danae Karalia ◽  
Angeliki Siamidi ◽  
Vangelis Karalis ◽  
Marilena Vlachou
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Computational Methods ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Drug Distribution ◽  
Dosage Forms ◽  
Oral Dosage ◽  
3D Printed ◽  
Oral Dosage Forms

The aim of this review is to present the factors influencing the mechanical properties of 3D-printed oral dosage forms. It also explores how it is possible to use specific excipients and printing parameters to maintain the structural integrity of printed drug products while meeting the needs of patients. Three-dimensional (3D) printing is an emerging manufacturing technology that is gaining acceptance in the pharmaceutical industry to overcome traditional mass production and move toward personalized pharmacotherapy. After continuous research over the last thirty years, 3D printing now offers numerous opportunities to personalize oral dosage forms in terms of size, shape, release profile, or dose modification. However, there is still a long way to go before 3D printing is integrated into clinical practice. 3D printing techniques follow a different process than traditional oral dosage from manufacturing methods. Currently, there are no specific guidelines for the hardness and friability of 3D printed solid oral dosage forms. Therefore, new regulatory frameworks for 3D-printed oral dosage forms should be established to ensure that they meet all appropriate quality standards. The evaluation of mechanical properties of solid dosage forms is an integral part of quality control, as tablets must withstand mechanical stresses during manufacturing processes, transportation, and drug distribution as well as rough handling by the end user. Until now, this has been achieved through extensive pre- and post-processing testing, which is often time-consuming. However, computational methods combined with 3D printing technology can open up a new avenue for the design and construction of 3D tablets, enabling the fabrication of structures with complex microstructures and desired mechanical properties. In this context, the emerging role of computational methods and artificial intelligence techniques is highlighted.

scholarly journals Light activation of 3D-printed structures: from millimeter to sub-micrometer scale

Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Hoon Yeub Jeong ◽  
Soo-Chan An ◽  
Young Chul Jun
Keyword(s):  
Smart Materials ◽  
Structural Changes ◽  
Three Dimensional ◽  
Light Activation ◽  
4D Printing ◽  
Comprehensive Review ◽  
Functional Changes ◽  
Active Devices ◽  
3D Printed ◽  
Micrometer Scale

Abstract Three-dimensional (3D) printing enables the fabrication of complex, highly customizable structures, which are difficult to fabricate using conventional fabrication methods. Recently, the concept of four-dimensional (4D) printing has emerged, which adds active and responsive functions to 3D-printed structures. Deployable or adaptive structures with desired structural and functional changes can be fabricated using 4D printing; thus, 4D printing can be applied to actuators, soft robots, sensors, medical devices, and active and reconfigurable photonic devices. The shape of 3D-printed structures can be transformed in response to external stimuli, such as heat, light, electric and magnetic fields, and humidity. Light has unique advantages as a stimulus for active devices because it can remotely and selectively induce structural changes. There have been studies on the light activation of nanomaterial composites, but they were limited to rather simple planar structures. Recently, the light activation of 3D-printed complex structures has attracted increasing attention. However, there has been no comprehensive review of this emerging topic yet. In this paper, we present a comprehensive review of the light activation of 3D-printed structures. First, we introduce representative smart materials and general shape-changing mechanisms in 4D printing. Then, we focus on the design and recent demonstration of remote light activation, particularly detailing photothermal activations based on nanomaterial composites. We explain the light activation of 3D-printed structures from the millimeter to sub-micrometer scale.

scholarly journals 3D and 4D Printing of Multistable Structures

2020 ◽  
Vol 10 (20) ◽  
pp. 7254
Author(s):  
Hoon Yeub Jeong ◽  
Soo-Chan An ◽  
Yeonsoo Lim ◽  
Min Ji Jeong ◽  
Namhun Kim ◽  
...  
Keyword(s):  
3D Printing ◽  
Smart Materials ◽  
Compliant Mechanisms ◽  
Three Dimensional ◽  
4D Printing ◽  
New Paradigm ◽  
Strained Layers ◽  
Three Dimensional Printing ◽  
Mechanical Metamaterials ◽  
3D Printed

Three-dimensional (3D) printing is a new paradigm in customized manufacturing and allows the fabrication of complex structures that are difficult to realize with other conventional methods. Four-dimensional (4D) printing adds active, responsive functions to 3D-printed components, which can respond to various environmental stimuli. This review introduces recent ideas in 3D and 4D printing of mechanical multistable structures. Three-dimensional printing of multistable structures can enable highly reconfigurable components, which can bring many new breakthroughs to 3D printing. By adopting smart materials in multistable structures, more advanced functionalities and enhanced controllability can also be obtained in 4D printing. This could be useful for various smart and programmable actuators. In this review, we first introduce three representative approaches for 3D printing of multistable structures: strained layers, compliant mechanisms, and mechanical metamaterials. Then, we discuss 4D printing of multistable structures that can help overcome the limitation of conventional 4D printing research. Lastly, we conclude with future prospects.

scholarly journals Electrically assisted 3D printing of nacre-inspired structures with self-sensing capability

2019 ◽  
Vol 5 (4) ◽  
pp. eaau9490 ◽  
Author(s):  
Yang Yang ◽  
Xiangjia Li ◽  
Ming Chu ◽  
Haofan Sun ◽  
Jie Jin ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Hierarchical Structures ◽  
High Strength ◽  
Mechanical Reinforcement ◽  
Resistance Change ◽  
Electrically Assisted ◽  
Brick And Mortar ◽  
3D Printed ◽  
3D Shapes

Lightweight and strong structural materials attract much attention due to their strategic applications in sports, transportation, aerospace, and biomedical industries. Nacre exhibits high strength and toughness from the brick-and-mortar–like structure. Here, we present a route to build nacre-inspired hierarchical structures with complex three-dimensional (3D) shapes by electrically assisted 3D printing. Graphene nanoplatelets (GNs) are aligned by the electric field (433 V/cm) during 3D printing and act as bricks with the polymer matrix in between as mortar. The 3D-printed nacre with aligned GNs (2 weight %) shows lightweight property (1.06 g/cm3) while exhibiting comparable specific toughness and strength to the natural nacre. In addition, the 3D-printed lightweight smart armor with aligned GNs can sense its damage with a hesitated resistance change. This study highlights interesting possibilities for bioinspired structures, with integrated mechanical reinforcement and electrical self-sensing capabilities for biomedical applications, aerospace engineering, as well as military and sports armors.

Free-Form Design of Electrical Machine Rotor Cores for Production Using Additive Manufacturing

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Michele Garibaldi ◽  
Christopher Gerada ◽  
Ian Ashcroft ◽  
Richard Hague
Keyword(s):  
Structural Integrity ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Free Form ◽  
Electrical Machine ◽  
Element Analysis ◽  
Torque Density ◽  
Magnetostatic Problem ◽  
Form Design ◽  
3D Printed

This work presents a finite element analysis-based, topology optimization (TO) methodology for the combined magnetostatic and structural design of electrical machine cores. Our methodology uses the Bi-directional Evolutionary Structural Optimization (BESO) heuristics to remove inefficient elements from a meshed model based on elemental energies. The algorithm improves the average torque density while maintaining structural integrity. To the best of our knowledge, this work represents the first effort to address the structural-magnetostatic problem of electrical machine design using a free-form approach. Using a surface-mounted permanent magnet motor (PMM) as a case study, the methodology is first tested on linear and nonlinear two-dimensional problems whereby it is shown that the rapid convergence achieved makes the algorithm suitable for real-world applications. The proposed optimization scheme can be easily extended to three dimensions, and we propose that the resulting designs are suitable for manufacturing using selective laser melting, a 3D printing technology capable of producing fully dense high-silicon steel components with good soft magnetic properties. Three-dimensional TO results show that the weight of a PMM rotor can be slashed by 50% without affecting its rated torque profile when the actual magnetic permeability of the 3D-printed material is considered.

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