Design for Additive Manufacture of Fine Medical Instrumentation—DragonFlex Case Study

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Filip Jelínek ◽  
Paul Breedveld
Keyword(s):  
Medical Device ◽  
Ceramic Composite ◽  
Design Stage ◽  
Additive Manufacture ◽  
Digital Light Processing ◽  
Advantages And Disadvantages ◽  
Material Choice ◽  
Superior Mechanical Properties ◽  
High Flexibility ◽  
Printing Processes

The recently popularized domain of additive manufacturing (AM) has much to offer to medical device development, especially to the growing field of minimally invasive surgery (MIS). With the advancements in AM materials, one could soon envision materializing not only the proofs of concept but also the final clinically approved instruments. DragonFlex—the world's first AM steerable MIS instrument prototype—was recently devised with the aim to follow this vision. Apart from the medical device design restrictions, several limitations of AM materials and processes had to be considered. The aim of this paper is to present these insights to those opting for this means of manufacture, serving as a helpful design and material guide. Over the course of its development, DragonFlex has gone through four design generations so far, each differing in the AM material and process used. Due to being a prototype of a MIS instrument of miniature dimensions, the printing processes were limited to stereolithography (SLA), as to achieve the best possible precision and accuracy. Each SLA process and material brought along specific advantages and disadvantages affecting the final printout quality, which needed to be compensated for either at the design stage, during, or after printing itself. The four DragonFlex generations were printed using the following SLA techniques and materials in this order: polymer jetting from Objet VeroBlue™; SLA Digital Light Processing™ (DLP) method from EnvisionTEC® NanoCure RCP30 and R5; conventional SLA from 3D Systems Accura® 60; and DLP based SLA process from a ceramic composite. The material choice and the printing orientation were found to influence the final printout accuracy and integrity of thin features, as well as material's postproduction behavior. The polymeric VeroBlue™ proved structurally sound, although suffering from undermined accuracy and requiring postprocessing, hence recommended for prototyping of upscaled designs of looser manufacturing tolerances or overdimensioned experimental setups. The NanoCure materials are capable of reaching the best accuracy requiring almost no postprocessing, thus ideal for prototyping small intricate features. Yet their mechanical functionality is undermined due to the high brittleness of RCP30 and high flexibility of R5. The transparent Accura® 60 was found to lose its strength and appeal due to high photosensitivity. Finally, the ceramic composite shows the best potential for medical use due to its biocompatibility and superior mechanical properties, yet one has to compensate for the material shrinkage already at the design stage.

scholarly journals Cost-Effectively 3D-Printed Rigid and Versatile Interpenetrating Polymer Networks

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4544
Author(s):  
Osman Konuray ◽  
Arnau Sola ◽  
Jordi Bonada ◽  
Agnieszka Tercjak ◽  
Albert Fabregat-Sanjuan ◽  
...  
Keyword(s):  
3D Printing ◽  
Polymer Networks ◽  
Complex Form ◽  
Interpenetrating Polymer Networks ◽  
Dual Processing ◽  
Digital Light Processing ◽  
Superior Mechanical Properties ◽  
3D Printed ◽  
Acrylate Resin ◽  
Printed Materials

Versatile acrylate–epoxy hybrid formulations are becoming widespread in photo/thermal dual-processing scenarios, especially in 3D printing applications. Usually, parts are printed in a stereolithography or digital light processing (DLP) 3D printer, after which a thermal treatment would bestow the final material with superior mechanical properties. We report the successful formulation of such a hybrid system, consisting of a commercial 3D printing acrylate resin modified by an epoxy–anhydride mixture. In the final polymeric network, we observed segregation of an epoxy-rich phase as nano-domains, similar to what was observed in a previous work. However, in the current work, we show the effectiveness of a coupling agent added to the formulation to mitigate this segregation for when such phase separation is undesired. The hybrid materials showed significant improvement of Young’s modulus over the neat acrylate. Once the flexible, partially-cured material was printed with a minimal number of layers, it could be molded into a complex form and thermally cured. Temporary shapes were readily programmable on this final material, with easy shape recovery under mild temperatures. Inspired by repairable 3D printed materials described recently, we manufactured a large object by printing its two halves, and then joined them covalently at the thermal cure stage with an apparently seamless union.

Whole Life/Life Cycle Costing During the Design Stage of a Construction Project

2020 ◽  
Vol 9 (2) ◽  
pp. 66-87
Author(s):  
Daniel Clarke-Hagan ◽  
Michael Curran ◽  
John Spillane ◽  
Mary-Catherine Greene
Keyword(s):  
Life Cycle ◽  
Qualitative Methodology ◽  
Construction Project ◽  
Life Cycle Costing ◽  
Design Stage ◽  
Life Cycle Costs ◽  
Mind Mapping ◽  
Advantages And Disadvantages ◽  
Mapping Software ◽  
Whole Life Costing

The calculations of life cycle costs (LCC) and whole life costs (WLC) are important tools in the life cycle of a project. The aim of this research is to examine life cycle costing, whole life costing, and the possible advantages and disadvantages to their introduction and use. A qualitative methodology encompassing an in-depth literature review, interviews, and qualitative analysis using mind mapping software, this research is important as it can add to the industry's understanding of the design process. It highlights reasons for the success or failure of a construction project, in terms of sustainability at the design stage. Results indicate that the researched topics had many advantages but also had inherent disadvantages. It is found that the potential advantages outweighed disadvantages, but uptake within industry is still slow and that better promotion and their benefits to sustainability, the environment, society, and the industry are required.

scholarly journals Study on Early Warning Method for Water Inrush in Tunnel Based on Fine Risk Evaluation and Hierarchical Advance Forecast

Geosciences ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 392 ◽  
Author(s):  
Sheng Wang ◽  
Shucai Li ◽  
Liping Li ◽  
Shaoshuai Shi ◽  
Zongqing Zhou ◽  
...  
Keyword(s):  
Early Warning ◽  
Risk Evaluation ◽  
Water Inrush ◽  
Entropy Method ◽  
Design Stage ◽  
Tunnel Construction ◽  
Evaluation Theory ◽  
Strongly Nonlinear ◽  
Advantages And Disadvantages ◽  
And Control

Water inrush is one of the most frequent and harmful geological disasters in tunnel construction. In order to effectively prevent and control the occurrence of water inrush, an early warning method based on fine risk evaluation and hierarchical advanced forecast is proposed. Water inrush is a complex dynamic coupling factors system, the relationship between influencing factors and water inrush is strongly nonlinear. Therefore, the efficacy coefficient model, which has the advantages of standardization, conciseness, and freedom from subjective factors, is improved nonlinearly. The fine risk evaluation theory and method based on the improved efficacy coefficient model consisted of two parts: one is static evaluation used in design stage, and the other is dynamic evaluation applied in the construction stage. The index weights are determined scientifically and reasonably by Analytical Hierarchy Process (AHP) and the entropy method. According to the fine risk evaluation results, combined with the advantages and disadvantages of various forecasting methods, a multistep hierarchical detection method of disaster resources for water inrush is proposed to identify the occurrence characteristics and failure level of disaster sources. The theory has been successfully applied to the #3 inclined well of Yuelongmen Tunnel in Cheng-Lan Railway. The evaluation results had good agreement with the actual excavation data, which indicates that the model is of high credibility and feasibility. The method could improve the prediction accuracy of water inrush and explore geometric characteristics and filling of disaster-causing structures. It is of great significance for avoiding water inrush and guiding the rapid and safe tunnel construction.

scholarly journals A review of 3D printing processes and materials for soft robotics

2020 ◽  
Vol 26 (8) ◽  
pp. 1345-1361 ◽  
Author(s):  
Yee Ling Yap ◽  
Swee Leong Sing ◽  
Wai Yee Yeong
Keyword(s):  
3D Printing ◽  
Soft Robotics ◽  
Soft Robots ◽  
Content Type ◽  
Advantages And Disadvantages ◽  
The Future ◽  
3D Printed ◽  
Multiple Materials ◽  
Printing Processes ◽  
Printing Techniques

Purpose Soft robotics is currently a rapidly growing new field of robotics whereby the robots are fundamentally soft and elastically deformable. Fabrication of soft robots is currently challenging and highly time- and labor-intensive. Recent advancements in three-dimensional (3D) printing of soft materials and multi-materials have become the key to enable direct manufacturing of soft robots with sophisticated designs and functions. Hence, this paper aims to review the current 3D printing processes and materials for soft robotics applications, as well as the potentials of 3D printing technologies on 3D printed soft robotics. Design/methodology/approach The paper reviews the polymer 3D printing techniques and materials that have been used for the development of soft robotics. Current challenges to adopting 3D printing for soft robotics are also discussed. Next, the potentials of 3D printing technologies and the future outlooks of 3D printed soft robotics are presented. Findings This paper reviews five different 3D printing techniques and commonly used materials. The advantages and disadvantages of each technique for the soft robotic application are evaluated. The typical designs and geometries used by each technique are also summarized. There is an increasing trend of printing shape memory polymers, as well as multiple materials simultaneously using direct ink writing and material jetting techniques to produce robotics with varying stiffness values that range from intrinsically soft and highly compliant to rigid polymers. Although the recent work is done is still limited to experimentation and prototyping of 3D printed soft robotics, additive manufacturing could ultimately be used for the end-use and production of soft robotics. Originality/value The paper provides the current trend of how 3D printing techniques and materials are used particularly in the soft robotics application. The potentials of 3D printing technology on the soft robotic applications and the future outlooks of 3D printed soft robotics are also presented.

scholarly journals Application of Machine Learning Algorithms for Solving Problems in the Oil and Gas Sector

2021 ◽  
Vol 19 (3) ◽  
pp. 55-64
Author(s):  
K. N. Maiorov ◽  
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Reinforcement Learning ◽  
Machine Learning Algorithms ◽  
Design Stage ◽  
Learning Methods ◽  
Field Development ◽  
Advantages And Disadvantages ◽  
Machine Learning Methods ◽  
The Neural Network

The paper examines the life cycle of field development, analyzes the processes of the field development design stage for the application of machine learning methods. For each process, relevant problems are highlighted, existing solutions based on machine learning methods, ideas and problems are proposed that could be effectively solved by machine learning methods. For the main part of the processes, examples of solutions are briefly described; the advantages and disadvantages of the approaches are identified. The most common solution method is feed-forward neural networks. Subject to preliminary normalization of the input data, this is the most versatile algorithm for regression and classification problems. However, in the problem of selecting wells for hydraulic fracturing, a whole ensemble of machine learning models was used, where, in addition to a neural network, there was a random forest, gradient boosting and linear regression. For the problem of optimizing the placement of a grid of oil wells, the disadvantages of existing solutions based on a neural network and a simple reinforcement learning approach based on Markov decision-making process are identified. A deep reinforcement learning algorithm called Alpha Zero is proposed, which has previously shown significant results in the role of artificial intelligence for games. This algorithm is a decision tree search that directs the neural network: only those branches that have received the best estimates from the neural network are considered more thoroughly. The paper highlights the similarities between the tasks for which Alpha Zero was previously used, and the task of optimizing the placement of a grid of oil producing wells. Conclusions are made about the possibility of using and modifying the algorithm of the optimization problem being solved. Аn approach is proposed to take into account symmetric states in a Monte Carlo tree to reduce the number of required simulations.

Precursor Derived Ceramic Method to Fabricate SiC Ceramic Composite Coatings on Metallic Substrates

2017 ◽  
Vol 864 ◽  
pp. 59-64 ◽  
Author(s):  
Wei Ling Guo ◽  
En Zhong Li ◽  
Da Xiang Yang
Keyword(s):  
Ceramic Composite ◽  
Composite Coatings ◽  
Ceramic Coatings ◽  
The Other ◽  
Ceramic Method ◽  
Metallic Substrates ◽  
Advantages And Disadvantages ◽  
Sic Ceramic ◽  
Development Direction ◽  
Al Powder

In this paper, the polymer precursor derived ceramic (PDC) method, that was used to fabricate the silicon carbide (SiC) ceramic composite coatings on metallic substrates, was briefly summarized. Two different fabrication mechanism of ceramic coatings by PDC method were mainly introduced. One was that Al powder as the active fillers converted into AlN due to the action with N2. The other was that Al powder as the active fillers converted into Al2O3 due to the action with O2. So fabrication mechanism of ceramic coatings by PDC method would be still the research focus in the future. Compared with the other methods, the advantages and disadvantages of PDC method preparing ceramic coatings were displayed. According to the existent problems and future development direction of PDC method, the key research objectives were presented.

POWER SHELL ELEMENTS: DYNAMIC MATHEMATICAL MODELS, POWER SYSTEMS (OVERVIEW)

2021 ◽  
pp. 31-39
Author(s):  
Pavel P. Chernus ◽  
A. K. Arbiev ◽  
Petr P. Chernus ◽  
P. A. Loshitskiy ◽  
V. T. Sharovatov
Keyword(s):  
Power Systems ◽  
Mathematical Models ◽  
Gas Flow ◽  
Transfer Functions ◽  
Theory And Practice ◽  
Design Stage ◽  
Shell Elements ◽  
Advantages And Disadvantages ◽  
Working Medium ◽  
Compressed Gas

This article is a review devoted to the theory and practice of the application of power shell elements (PSE) in pneumatic drives (PD). She makes acquaint the reader with the main provisions of the theory of PD, performed on the PSE. The review briefly presents materials on the development of dynamic mathematical models (DMM) of power units (PU) of shell PDs (SPD), based on the use of static characteristics of SPD, an assessment of the advantages and disadvantages of PU based on traditional pneumatic cylinders (PC) and PSE is given. The main attention in the review is paid to the solution of the problem of creating PU on PSE with the required quality indicators at the design stage, when it is necessary to take into account the properties of compressed gas. For this, an original methodology for the development of nonlinear DMMs for various typical variants of the midrange is proposed, the basis of which is a number of provisions of the theory of gas dynamics. Without invoking this theory, it is impossible to ta into account the properties of compressed gas (compressibility of the working medium, dependence on temperature and gas flow rate in the shell, the nature of the gas expansion processes), and, therefore, to reliably describe the state of unsteady gas processes inside the shell and develop a DMM of the PU, to a sufficient taking into account the mentioned properties. Since the topic of this review is intended mainly for engineers who develop SPD (theoreticians and practitioners), the review also contains materials on the linearization of the found nonlinear DMMs. As a result of linearization, nonlinear DMMs are transformed into transfer functions for displacement of the output coordinate and effort. The correctness of the linearization carried out is confirmed by the results of experiments. The review briefly discusses several options for pneumatic supply systems for SPD. Here, of particular interest for a specialist is the material on imparting invariance properties to SPDs to air intake from the atmosphere nd discharge of exhaust air into the atmosphere, which significantly expands the scope of SPDs and reduce their cost.

Experimental Identification of the Nonlinear Parameters of an Industrial Translational Guide

2006 ◽  
Author(s):  
Jaspreet Dhupia ◽  
Bartosz Powalka ◽  
A. Galip Ulsoy ◽  
Reuven Katz
Keyword(s):  
Relative Velocity ◽  
Relative Displacement ◽  
Force Function ◽  
Hertzian Contact ◽  
Design Stage ◽  
Restoring Force ◽  
Weakly Nonlinear ◽  
Advantages And Disadvantages ◽  
Nonlinear Restoring Force ◽  
Receptance Coupling

Prediction of machine dynamics at the design stage is a challenge due to lack of adequate methods for identifying and handling the nonlinearities in the machine joints, which appear as the nonlinear restoring force function of relative displacement and relative velocity across the joint. This paper discusses identification of such a nonlinear restoring force function for an industrial translational guide for use with the Nonlinear Receptance Coupling Approach (NLRCA) for evaluating machine dynamic characteristics. Translational guides are among the most commonly used joints in machine tools. Both a parametric and nonparametric technique has been employed to identify the nonlinearities. A novel parametric model based on Hertzian contact mechanics has been derived for the translational guide. This model includes the effect of joint geometry, material properties and preload. A nonparametric method based on two-dimensional Chebyshev polynomials is also used. The models derived from the two techniques, i.e., parametric and nonparametric, are fitted to the experimental data derived from static and dynamic tests to get the restoring force as a function of relative displacement and relative velocity across the joint. The resulting joint model exhibits a weakly nonlinear stiffness term and a viscous damping term. The results from both techniques are compared in the frequency domain. The advantages and disadvantages of parametric and nonparametric techniques are also discussed. The design of experiments for evaluating the nonlinearities in such industrial machine tool joints is a challenge, requiring careful alignment and calibration, because they are typically very stiff. This constrains the dynamic experiments to be carried out at high frequencies (e.g. 2000-7000Hz) where the experimental readings are very sensitive to errors in geometry and calibration.

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