Flexible Parts Research Articles

Investigation on the performance of a torque-driven undulatory swimmer with distributed flexibility

The locomotion of fish provides insight for the design of efficient swimming robotic devices. The current study presents a systematic investigation of the locomotion performance of a fish-like swimmer with a wide range of parameter settings. Two-dimensional simulations with the immersed boundary method in the framework of Navier–Stokes equations are employed for the fluid–structure interaction analysis. Unlike most previous studies where the kinematics of the swimmer is predetermined, the locomotion of the current swimmer is the response of a single periodic torque applied to the anterior part. In addition, current simulations applied a direct correspondence between code units and real-world units, providing more engineering-related guidance for the future design of microrobotic swimmers. The effect of the distribution of body stiffness on swimming performance and propulsion generation is discussed with different pitch frequencies and amplitudes. It was shown that swimmers with a more flexible posterior part have an advantage in undulatory swimming performance when the pitch angle is low or moderate. However, such an advantage disappears when the pitch angle or actuating frequency exceed a certain level. An analysis of the phase-averaged vorticity field and thrust sequence is given to clarify the change in performance due to the variation of flexibility.

Supramolecular Self‐Assembled Nanospheres for Enzyme Encapsulation Based on Cyclodextrin

Based on the cyclodextrin (CD) and guest molecules inclusion, a novel rigid‐flexible polymeric nanosphere was prepared by supramolecular self‐assemble. The rigid part was formed by α‐cyclodextrin (α‐CD) and methoxypolyethylene glycol (mPEG) necklace‐like crystallites while the flexible part was sodium alginate (Alg). The rigid and flexible parts were linked by β‐cyclodextrin (β‐CD) and ferrocene (Fc) inclusion complex. This kind of nanosphere exhibited good glucose oxidase (GOD) encapsulation ability. The encapsulated enzyme, in comparison to the free enzyme, is able to retain its high activities across a rather broader range of pH, temperature, and time. After 20 days, the encapsulated enzyme can retain its almost 86% initial activity which exhibited good storage stability. These studies suggested that CD host‐guest inclusions to form stable polymeric nanospheres may be an effective way for enzyme encapsulation in various biomedical applications.

Workpiece Pose Classification Framework for Flexible Part Feeding Systems Using Machine Learning and Synthetic Datasets

In previous work, a concept for a novel flexible part feeding system based on aerodynamic feeding was presented. In contrast to conventional part feeding systems, such as vibratory bowl feeders, aerodynamic part feeding systems use controlled pressurized air jets to reorient the workpieces. The proposed concept aims to increase flexibility and eliminate retooling times to meet the challenges of modern automated production with regard to increasing uncertainties, shorter product life cycles and higher cost pressure. Regarding these objectives, the determination of the workpiece poses in the feeding system requires flexible image processing, which will be enabled using machine learning and synthetic datasets.This work presents a framework which enables the classification of workpiece poses using a standard industrial camera and convolutional neural networks (CNN). The training of CNNs usually requires large datasets. However, in order to eliminate the need to create and label datasets of real images, which would cause machine downtimes and increase the retooling effort, the CNNs will be trained with synthetic datasets. Based on the CAD-data of the workpieces, artificial images of each pose are rendered using the open source engine Blender. Several CNN architectures are selected, trained with the artificial datasets and evaluated using real images of the workpieces. The results show that high classification accuracies of over 99 % can be achieved. It is concluded that the presented approach enables the classification of workpiece poses with high accuracy, while eliminating the need for the cumbersome creation of real image datasets. The approach is not limited to the use in the aerodynamic part feeding system but can be transferred to other applications in which the orientation of a workpiece has to be classified.

A flexible, modular and versatile functional part assembly toolkit for gene cluster engineering in Streptomyces

Streptomyces has enormous potential to produce novel natural products (NPs) as it harbors a huge reservoir of uncharacterized and silent natural product biosynthetic gene clusters (BGCs). However, the lack of efficient gene cluster engineering strategies has hampered the pace of new drug discovery. Here, we developed an easy-to-use, highly flexible DNA assembly toolkit for gene cluster engineering. The DNA assembly toolkit is compatible with various DNA assembling approaches including Biobrick, Golden Gate, CATCH, yeast homologous recombination-based DNA assembly and homing endonuclease-mediated assembly. This compatibility offers great flexibility in handling multiple genetic parts or refactoring large gene clusters. To demonstrate the utility of this toolkit, we quantified a library of modular regulatory parts, and engineered a gene cluster (act) using characterized promoters that led to increased production. Overall, this work provides a powerful part assembly toolkit that can be used for natural product discovery and optimization in Streptomyces.

BF2-Functionalized Benzothiazole Amyloid Markers: Effect of Donor Substituents on One- and Two-Photon Properties.

Investigation of amyloids with the aid of fluorescence microscopy provides crucial insights into the development of numerous diseases associated with the formation of aggregates. Here, we present a series of BF2-functionalized benzothiazoles with electron-donating methoxy group(s), which are tested as amyloid fluorescent markers. We evaluate how the position of donor functional group(s) influences optical properties (fluorescence lifetime (τ) and fluorescence quantum yield (FQY)) in a solution and upon binding to amyloids. We elucidate the importance of surrounding environmental factors (hydrogen-bonding network, polarity, and viscosity) on the observed changes in FQY and evaluate how the localization of a donor influences radiative and nonradiative decay pathways. We conclude that a donor attached to the benzothiazole ring contributes to the increment of radiative decay pathways upon binding to amyloids (kr), while the donor attached to the flexible part of a molecule (with rotational freedom) contributes to a decrease in nonradiative decay pathways (knr). We find that the donor-acceptor-donor architecture allows us to obtain 58 times higher FQY of the dye upon binding to bovine insulin amyloids. Finally, we measure two-photon absorption (2PA) cross sections (σ2) of the dyes and their change upon binding by the two-photon excited fluorescence (2PEF) technique. Measurements reveal that dyes that exhibit the increase/decrease of σ2 values when transferred from highly polar solvents to CHCl3 present a similar behavior upon amyloid binding. Our 2PA experimental values are supported by quantum mechanics/molecular mechanics (QM/MM) simulations. Despite this trend, the values of σ2 are not the same, which points out the importance of two-photon absorption measurements of amyloid-dye complexes in order to understand the performance of 2P probes upon binding.

Preparation of polylactic acid (PLA) films plasticized with a renewable and natural Liquidambar Orientalis oil

Polylactic acid (PLA) is a brittle biodegradable thermoplastic due to its relatively high glass transition temperature (Tg ∼ 60 °C). This Tg limits the using of PLA in flexible applications, for example packaging films. In this study, it has been shown for the first time that the Liquidambar Orientalis (LO) oil as a nontoxic, environmentally friendly, and green additive can be successfully used as a natural, renewable, and sustainable plasticizer to produce flexible PLA parts and improve its thermal and physical properties and application potential. Natural oil obtained from Liquidambar Orientalis tree was introduced into PLA (as 10, 20, and 30 phr) by melt compounding (MC) and solution mixing (SM) methods. Effect of LO oil amount on the glass transition temperature, melt and cold crystallization behaviors, and degree of crystallinity values of samples were determined with differential scanning calorimetry (DSC). In addition, solid state viscoelastic properties of PLA films were also characterized with dynamic mechanical analysis (DMA) tests. Results showed that LO oil significantly reduced the Tg and storage modulus (E') value of PLA and LO oil showed an excellent plasticizing effect for PLA due to reducing strong hydrogen bonds and secondary interactions between PLA chains.

Research on the Accuracy of Clothing Simulation Development: The Influence of Human Body Part Characteristics on Virtual Indicators

Currently, many virtual simulation design studies of compression pants do not consider pressure distribution and human body characteristics. Therefore, this study aimed to optimize the simulation design accuracy of compression pants by investigating female body characteristics to improve the pressure distribution and enhance comfort. Firstly, we divided the body part features into flexible and rigid parts, performed compression relationship analysis between the material and the body, and collected qualitative and quantitative data related to the potential influencing factors. Subsequently, by conducting correlation analysis of the data, a pressure prediction model was established to address the pressure value errors in the simulation data. The research results showed that there was a significant difference between the real and virtual pressures in the flexible parts of the female body, and that the real pressure was closely related to the elasticity and thickness properties of the material. By optimizing virtual pressure values, the consistency between the virtual pressure and real test results can be significantly improved. The accurate prediction and optimization of pressure values can lead to the reduction of material waste and energy consumption during the manufacturing process.

Investigation on using graphite filler for 3D printing of flexible electrically conductive polymer by extrusion‐based additive manufacturing

AbstractThe rapid use of additive manufacturing (AM) in electronic industry identifies the need of flexible electrically conductive materials suitable for 3D printing. Challenges like buckling of flexible filament and complexity in addition of conductive fillers makes pellet‐based extrusion the most suitable alternative for part printing. In the present work, graphite powder is combined with ethylene vinyl acetate (EVA) to print flexible electrically conductive parts. EVA graphite composite with filler loading up to 30% has been investigated for its electrical conductivity and part printability. The composite made was found electrically conductive and suitable for part printing. The parts were printed on a CNC milling machine by using a retrofitted material extrusion tool with nozzle of 0.4 mm diameter and temperature range of 130–140°C. Parts were printed on a detchable heating bed placed on the milling machine setup. Samples of EVA with graphite filler by weight of 5%, 10%, 20%, and 30% were printed and were checked for electrical conductivity. When the filler content was increased from 10% to 20%, the electrical resistance of the composite was reduced by 62.6%. The presence and uniform dispersion of graphite flakes in the polymer matrix of EVA were guaranteed by the rheological and morphological characterization of the composite. Applications of 3D printable flexible electrically conductive parts lies in numerous domains including biosensors, wearable health monitoring devices, capacitors, field effective transistors, light emitting diodes, solar cells, and electronic displays.Highlights CNC milling machine‐assisted 3D printing is used for part printing. Graphite powder is combined with EVA pellets. Pellet‐based extrusion is used to print flexible parts. 3D printability of parts with resistivity 32.64 Ω‐cm was achieved.

Analysis of the performance of robotic assembly systems considering the usage of tools or jigs for the task-board task in the WRS 2018

ABSTRACT A task-board task is a task in which robots perform a set of fundamental assembly operations related to the assembly of a specific product such as inserting a part into another part, tightening bolts and nuts, attaching flexible parts, etc. In the task-board task competition in the industrial robotics category of the World Robot Summit (WRS) 2018, 15 teams from around the world performed the task. In our previous work, we observed recorded videos of the competition frame by frame and manually investigated the performance of robotic systems of the top four teams, focusing only on whether robots contact target parts. In this paper, we introduce frame sets to represent mainly contact states between robots, tools, or jigs and target parts to be handled for such a frame-by-frame analysis of the recorded videos, and based on the frame sets, we analyze the performance of robotic assembly systems of other teams as well as the top four teams in the task-board task competition in the WRS 2018, considering the usage of tools or jigs.

Flexible interconnected ceramic parts 3D printed by two-component material extrusion with water-soluble support structures

Flexible interconnected ceramic parts 3D printed by two-component material extrusion with water-soluble support structures

Influence of proton irradiation on the magnetic properties of two-dimensional Ni(II) molecular magnet

The influence of 1.9 MeV proton irradiation on structural and magnetic properties has been explored in the two-dimensional (2D) NiSO4(1,3-phenylenediamine)2 coordination ferrimagnet. The X-ray powder diffraction and IR spectroscopy revealed that the octahedrons with Ni ion in the center remain unchanged regardless of the fluence a sample received. In contrast, proton irradiation greatly influences the hydrogen bonds in the flexible parts in which the 1,3-phenylenediamine is involved. Dc magnetic measurements revealed that several magnetic properties were modified with proton irradiation. The isothermal magnetization measured at T = 2.0 K varied with the proton dose, achieving a 50% increase in magnetization in the highest measured field µ0Hdc = 7 T or a 25% decrease in remanence. The most significant change was observed for the coercive field, which was reduced by 90% compared to the non-irradiated sample. The observed results are accounted for the increased freedom of magnetic moments rotation and the modification of intralayer exchange couplings.

Design and Implementation of a Compliant Gripper for Form Closure of Diverse Objects

This research presents a comprehensive study on the design and implementation of a flexible robotic gripper. Conventional grippers utilized in articulated robotic arms are often limited in their capabilities, being restricted to specific tasks or fixed object sizes. While soft grippers are a viable option, they have limitations in terms of grasping objects across a wide range and providing complete coverage. In this study, a novel compressible gripper is developed to enable safe and secure grasping of objects with varying sizes and shapes within a wide range. The gripper features a grasping area measuring 14 cm × 6 cm, allowing complete coverage of objects within this surface area. The current prototype with 7 cm of compressibility demonstrates the ability to grasp objects with a width difference of 7 cm with a maximum thickness of 15 cm, enabling manipulation of objects with varying widths, as defined by user-programmable parameters. The functionality of the gripper is based on the compressibility of the 3D-printed thermoplastic polyurethane (TPU) material. The flexible part of the gripper can be easily interchanged, offering versatility by accommodating different thicknesses without the need to replace the entire gripper mechanism. The gripper system operates using an open-loop control system, enhancing user-friendliness. Experimental evaluation of the gripper involved the creation and analysis of a CAD model followed by the fabrication of a prototype. The prototype exhibited exceptional performance in grasping objects of diverse sizes, shapes, and textures, demonstrating the effectiveness of the developed soft gripper system. The scalability of the soft gripper enables seamless integration with various types of articulated robotic arms, while the maximum weight limit for objects will be defined based on the robotic arms’ limitations. The research findings highlight the promising capabilities of the compressible gripper in enhancing the versatility and efficiency of robotic grasping systems, offering a significant contribution to the field of robotics.

Toward an interoperable, intraoperative situation recognition system via process modeling, execution, and control using the standards BPMN and CMMN

PurposeFor the modeling, execution, and control of complex, non-standardized intraoperative processes, a modeling language is needed that reflects the variability of interventions. As the established Business Process Model and Notation (BPMN) reaches its limits in terms of flexibility, the Case Management Model and Notation (CMMN) was considered as it addresses weakly structured processes.MethodsTo analyze the suitability of the modeling languages, BPMN and CMMN models of a Robot-Assisted Minimally Invasive Esophagectomy and Cochlea Implantation were derived and integrated into a situation recognition workflow. Test cases were used to contrast the differences and compare the advantages and disadvantages of the models concerning modeling, execution, and control. Furthermore, the impact on transferability was investigated.ResultsCompared to BPMN, CMMN allows flexibility for modeling intraoperative processes while remaining understandable. Although more effort and process knowledge are needed for execution and control within a situation recognition system, CMMN enables better transferability of the models and therefore the system. Concluding, CMMN should be chosen as a supplement to BPMN for flexible process parts that can only be covered insufficiently by BPMN, or otherwise as a replacement for the entire process.ConclusionCMMN offers the flexibility for variable, weakly structured process parts, and is thus suitable for surgical interventions. A combination of both notations could allow optimal use of their advantages and support the transferability of the situation recognition system.

Investigation on the properties of chemically treated flexible parts fabricated through material extrusion based additive manufacturing technology

AbstractThe poor strength and surface texture of the additively manufactured components has restricted its usage as a functional part. The post processing methods can overcome this limitation and open new opportunities in different application areas. In the present study, chemical finishing process has been employed for the flexible components build through material extrusion based additive manufacturing technology. Thermoplastic polyurethane (TPU) has been chosen as the material for printing flexible parts. Taguchi orthogonal array‐based design of experiments has been employed. Three process parameters that is, solvent type, infill density and immersion time have been selected for the study. The percentage improvement in the surface roughness as physical property and compressive strength as mechanical property has been chosen as the response parameters. The dimensional deviation was investigated by measuring the change in the dimensions of the manufactured components. It has been observed from ANOVA analysis that the improvement in surface roughness and compressive strength depends significantly on the immersion time. The Dimethyl sulfoxide (DMSO) solvent and immersion time of 125 s has been found significant for different properties of the chemically treated TPU parts.

Suture Tie-down Forces and Cyclic Contractile Forces after Undersized Tricuspid Annuloplasty Using a Tri-Ad Adams Tricuspid Annuloplasty Ring in an Ovine Model.

This study evaluated suture tie-down forces and cyclic contractile forces after undersized tricuspid annuloplasty using a hybrid band. Downsized tricuspid annuloplasty was planned in adult male sheep using eight force transducers attached from the septal to the anterior annular areas of the ring (segments 1 and 2, flexible septal; segments 3 and 4, semi-rigid posterior; segments 5 and 6, semi-rigid anterior; segments 7 and 8, flexible anterior). Cyclic contractile forces were analyzed at three different levels of peak right ventricular pressure: 30, 50, and 70 mmHg. Eight 5-year-old male Corriedale sheep (average body weight = 66.8 kg) were used. The average suture tie-down force was 4.42 (standard deviation: 2.32) N. When the forces were compared, it was lowest in the flexible anterior area and highest in the flexible septal area (p < 0.001). With right ventricular pressure of 30 mmHg, the average cyclic contractile forces was lowest at segment 3 (0.07 [standard deviation: 0.07] N) and highest at segment 7 (0.15 [standard deviation: 0.08] N). The cyclic contractile forces were 0.12 (standard deviation: 0.1) N, 0.09 (standard deviation: 0.12) N, 0.14 (standard deviation: 0.1) N, and 0.13 (standard deviation: 0.09) N in the flexible septal, semi-rigid posterior, semi-rigid anterior, and flexible anterior parts, respectively (p = 0.208). As the peak right ventricular pressure increased to 50 and 70 mmHg, the cyclic contractile forces of each area increased significantly (p < 0.001). Despite this increase, the cyclic contractile forces remained low (0.1 and 0.3 N), and differences in cyclic contractile forces between segments and between annular areas showed similar patterns. The flexible end of the hybrid band reduces the cyclic contractile forces and might prevent annular tears after ring tricuspid annuloplasty, and the risk of tear would be low even in the septal area.

Structural analysis of the water channel AQP2 by single-particle cryo-EM

Water channels, which are small membrane proteins almost entirely buried in lipid membranes, are challenging research targets for single-particle cryo-electron microscopy (cryo-EM), a powerful technique routinely used to determine the structures of membrane proteins. Because the single-particle method enables structural analysis of a whole protein with flexible parts that interfere with crystallization, we have focused our efforts on analyzing water channel structures. Here, utilizing this system, we analyzed the structure of full-length aquaporin-2 (AQP2), a primary regulator of vasopressin-dependent reabsorption of water at the renal collecting ducts. The 2.9 Å resolution map revealed a cytoplasmic extension of the cryo-EM density that was presumed to be the highly flexible C-terminus at which the localization of AQP2 is regulated in the renal collecting duct cells. We also observed a continuous density along the common water pathway inside the channel pore and lipid-like molecules at the membrane interface. Observations of these constructions in the AQP2 structure analyzed without any fiducial markers (e.g., a rigidly bound antibody) indicate that single-particle cryo-EM will be useful for investigating water channels in native states as well as in complexes with chemical compounds.

Stability and Bifurcation Analysis in Turning of Flexible Parts with Spindle Speed Variation Using FEM Simulation Data

This study investigates the effect of variable spindle speed with sinusoidal modulation on chatter vibrations generated in turning of flexible parts. The Euler–Bernoulli beam theory is assumed for mathematical modeling of the slender workpiece that is clamped at the chuck and pinned at the tailstock. The induced force as interaction between tool and workpiece (A2024-T351) during chip formation is calculated using finite element simulation. Numerical-based semi-discretization approach is utilized to seek stability regions and chatter frequencies regarding coupled dynamic model of tool and workpiece, in the form of delay differential equations with time varying delay term. The simulated data are validated and compared with those for a rigid part. The results indicate the efficiency of periodic modulation in improvement of machining stability especially for low spindle speeds. The stability charts for different interaction location and also time history response are studied, extensively. Finally, detection of period-one, flip and secondary Hopf bifurcations for different spindle speeds at instability borders are analyzed and discussed by solving corresponding eigenvalue problem.

Experimental and simulated study of 3D-printed couplings’ suitability for industrial application

This paper explores the possibility of applying reverse engineering to flexible coupling spare parts through additive manufacturing. Although couplings’ simplicity makes them go unnoticed, they connect elements that transmit power between two shafts, thus being an essential component for most of the machinery currently used in the industry. In this study, flexible couplings with different infill density (60% and 80%) were 3D printed by the fused filament fabrication technique. The original and the additive manufactured couplings were modelled to compare their compressive response and energy-absorbing characteristics, and experimental tests were performed to validate finite element analysis. To derive an optimal material distribution within coupling structure, a generative design approach was conducted through nTopology software. With this novel simulation-driven design, it is possible to reduce the weight of the redesigned part up to 15.8% by defining the wall thickness of the internal structure based on the results of finite element simulation, while maintaining its functionality. Moreover, an economic-environmental study was carried out. Results ensure that the 3D printed prototypes are suitable for replacing the original one under its current operating conditions. Additionally, the economic study shows that the redesigned couplings allow companies to save more than €2700 per coupling in relation to CO2 emission payments.

Chemical Interaction Regulates the Folding and Topology of the G-Quadruplex Exclusively Induced by a Crowder.

The folding and stability of G-quadruplexes (Gq) are correlated with cancer and depend significantly on the chemical environment. Crowders are an important constituent of living cells. However, an understanding of the folding and topology of Gq induced exclusively by a crowder is lacking. Hence, folding and stabilization of the human telomere (htel) induced by polyethylene glycol and its derivative crowders have been studied using different biophysical techniques without the addition of salt. The data suggest that the crowder can alone induce the folding of the htel sequence into Gq and the topology of the folded structure depends on the composition of the crowder. Interestingly, a small chain size crowder favors the folding of the htel duplex to Gq, whereas a larger crowder prefers to stabilize the duplex form. Thermochemical data suggest that the nonlinear trend of the stability of folded Gq is modulated mainly by hydrogen bonding between the flexible part of the crowder and nucleobases, and the role of the excluded volume is not prominent. These findings might play an important role in improving our understanding of the folding and stabilization of htel in complex bimolecular environments.

Deformation error compensation in 5-Axis milling operations of turbine blades

The precision and performance of machined flexible parts are under influence of deformation errors during end milling operations. Thus, prediction and compensation of deformation errors during milling operations of flexible parts can provide a key tool in accuracy enhancement of part production. In this study, an improved virtual machining system is proposed in order to assess and compensate deformation errors caused by cutting temperature and forces in 5-axis milling operations of flexible parts. The improved Johnson–Cook model is utilized to investigate the cumulative impact of strain rate and deformation temperatures on flow stress during milling operations of turbine blade. To estimate deformation errors caused by cutting forces and temperature on the workpiece and cutting tool, the finite element analysis is then applied. As a result, volumetric vectors of deformation error at each cutting location along the machining pathways are then generated in order to be compensated within new compensated machining tool paths. Thus, the deformation error created by cutting forces and temperature on the workpiece and cutting tool are compensated in order to enhance accuracy during 5-axis milling operation of flexible turbine blades. Experiments are carried out using a 5-axis CNC machine tool and errors are quantified using a CMM to verify the developed strategy in the study. As a consequence, precision of machining operations on flexible turbine blades can be enhanced by employing the developed virtual machining system in the study.