Wrapping Pattern Research Articles

Switchable Pseudo‐Triaxial Structure Enabled Mechanosensory Textiles with Ultra‐Wide Detection Range for Flexible E‐Wearables

AbstractFlexible sensors hold significant promise for wearable monitoring and rehabilitation training applications. However, current flexible strain sensors struggle to compatible their sensing performance and fabrication with textile substrate and weaving technologies, which limits the practical applications of flexible sensors in commercial markets for electronic wearables. Differing from traditional strategies that rely on sophisticated construction of functional materials, leveraging industrial braiding, and weaving technologies, an all‐textile‐based pseudo‐triaxial mechanosensory textile (PTMT) is designed by engineering the wrapping pattern, yarn twist, and fabric architecture. The switchable hierarchically‐structured morphing of the PTMT enables an ultra‐wide strain detection range (up to 140%) along with desirable sensitivity. Moreover, the PTMT shows outstanding air permeability (1915 mm s−1), moisture permeability (1922 g m−2 h−1), high washability, and electromagnetic interference shielding (20.25 dB). The potential applications of PTMT are also demonstrated, such as in simulating fetal‐movement in pregnant women, proving its effectiveness in fetal‐movement health monitoring. Furthermore, by integrating the PTMT into shoe vamps and combining it with machine learning algorithms (CNN, RF, and PSO‐SVM), it is proved that PSO‐SVM outperformed CNN and RF in accuracy and stability, achieving a combined recognition accuracy of 95.42%.

Origami-Wrapped Structures with Corrugated Unfolded Forms

Stowage schemes based on origami wrapping patterns are useful for the design of various deployable spacecraft structures. These origami patterns allow for the compact stowage of flat sheets of small thickness. Typically, some other structure is needed to stiffen this thin sheet when it is fully deployed and flat. This paper describes a class of thin-shell structures that can be compactly stowed using origami wrapping methods but have a corrugated form when deployed. These structures cannot reach a flat state by design. The persistent corrugations provide stiffness without the need for an external structure, thus leading to overall savings in mass and complexity. The geometrical design of the corrugations is highly tunable. This paper describes a method for generating the form of these folding structures; the method guarantees that the structure can be unstrained both when compactly wrapped and when fully deployed. Test articles are fabricated to demonstrate the concept, and stowage experiments and stiffness experiments are conducted. A structural finite element modeling procedure is described to predict the deployed stiffness of these structures, and the stiffness predictions match the experimental results.

Ultimate strength of hybrid repaired offshore pipelines with various slenderness ratio subjected to through-thickness pitting corrosion under axial compressive loading

Offshore pipelines are susceptible to various types of corrosions where pitting corrosion is generally considered the most severe. This study aims to study the effect of ratio of Carbon Fiber Reinforced Polymer to Glass Fiber Reinforced Polymer and wrapping patterns on the repair performance of composite repair system for offshore pipelines subjected to pitting corrosion. Four sets of samples with different slenderness ratios are subjected to axial compression, where the peak loads are recorded as the performance indicator of different repair schemes. Based on the experimental results, the average repair index, which is the ratio of repaired strength to intact strength, increases from 1.06 to 1.40 as the ratio of CFRP to GFRP increases. However, 1G3C repair schemes experience brittle failure while other repair schemes show different extents of ductility upon failure. Longitudinal wrapping pattern achieves the average repair index of 1.19 while Alternate and Horizontal yields the average repair index of 1.18 and 1.15 respectively. Furthermore, Longitudinal wrapping pattern exhibits the highest rigidity followed by Alternate and Horizontal. A higher slenderness ratio can contribute to a lower repair index where the cross-sectional properties have a more prominent effect compared to sample length. The theoretical results calculated based on equations provided in ASME PCC-2 show good agreement with the experimental results as there is only a percentage difference of 5.5% between them.

Single-step extraction of small-diameter single-walled carbon nanotubes in the presence of riboflavin.

We propose a novel approach to disperse and extract small-diameter single-walled carbon nanotubes (SWCNTs) using an aqueous solution of riboflavin and Sephacryl gel. The extraction of small-diameter semiconducting SWCNTs was observed, regardless of the initial diameter distribution of the SWCNTs. Dispersion of SWCNTs occurs due to the adsorption of π-conjugated isoalloxazine moieties on the surface of small-diameter nanotubes and interactions between hydroxy groups of ribityl chains with water. During the SWCNT extraction, specific adsorption of riboflavin to SWCNTs leads to the minimization of interactions between the SWCNTs and gel media. Our experimental findings are supported by ab initio calculations demonstrating the impact of the riboflavin wrapping pattern around the SWCNTs on their interaction with the allyl dextran gel.

Functionalized biological metal–organic framework with nanosized coronal structure and hierarchical wrapping pattern for enhanced targeting therapy

Inefficient tumor-targeted delivery and uncontrolled drug release are the major obstacles in cancer chemotherapy. Herein, inspired by the targeting advantage of coronavirus from its size and coronal structure, a coronal biological metal–organic framework nanovehicle (named as corona-BioMOF) is constructed for improving its precise cancer targeting ability. The designed corona-BioMOF is constructed as the carriers-encapsulated carrier model by inner coated with abundant protein-nanocaged doxorubicin particles and external decorated with high-affinity apoferritin proteins to form the spiky surface for constructing the specific coronal structure. The corona-BioMOF shows a higher affinity and an enhanced targeting ability towards receptor-positive cancer cells compared to that of MOF-drug composites without spiky surface. It also exhibits the hierarchical wrapping pattern-endowed controlled lysosome-specific drug release and remarkable tumor lethality in vivo. Moreover, water-induced surface defect-based protein handle mechanism is first proposed to shape the coronal-BioMOF. This work will provide a better inspiration for nanovehicle construction and be broadly useful for clinical precision nanomedicine.

Shear behaviour of RC deep beams retrofitted with externally bonded GFRP fabrics: Experimental and numerical study

The structural behaviour of reinforced concrete (RC) deep beams strengthened in shear by externally bonded (EB) glass fibre reinforced polymer (GFRP) fabrics are investigated employing both experiment and finite element (FE) analysis using commercial software. Four RC deep beams of 1000 mm length, 120 mm width and 420 mm depth are prepared. One un-retrofitted and other three beams retrofitted with U-wrapping of GFRP fabrics along the shear spans are tested under two-point loading to obtain the various structural responses. Thereafter, the FE model is validated by comparing its structural responses with those of the experiment. From both investigations, it is found that there is a significant enhancement in structural responses, such as load-carrying capacity, deflection, shear capacity, stiffness and energy absorption capacity due to the retrofitting of beams. Then, a comparison of the shear strengths of the experiment, FE model and existing design models is made to check the efficiency of the present FE model. Finally, a numerical study is conducted to examine the influence of various wrapping patterns of GFRP fabrics on the structural performance of the retrofitted beams. From this study, it is found that the wrapping pattern influences the structural performance of the beam remarkably.

Fully Coupled Vibrations of Cable-Harnessed Beams with a Non-Periodic Wrapping Pattern

Power- and signal- cable attachments have a significant impact on the vibrations of space structures. Recent works show the importance of having an analytical model to gain physical insight into the influence of cabling on the dynamics of host structures. The models in the literature focus mainly on pure bending vibrations and ignore the effect of coupling between different coordinates. Recently, the authors demonstrated the importance of modeling the coupling effects in cable-harnessed (CH) beams with straight and periodic wrapping patterns. In real-life situations, the cable attachment patterns are mostly non-periodic, and the cables are also attached to host structures that consist of a combination of several harness elements of same (homogenous) or different (non-homogenous) material properties. Hence, the fully coupled vibration model developed in this article is the first to analyze the vibrations of homogenous and non-homogenous CH beams with non-periodic wrapping patterns. The Frequency Response Functions (FRFs) of the developed model are compared with experiment FRFs in the case of the homogenous non-periodic wrapping pattern. The study shows that the coupling effects are pronounced in non-periodic wrapped CH beams, and the advantage of developing the coupled model over the decoupled model is shown through experimental validation.

Multidimensional Vibrations of Cable-Harnessed Beam Structures with Periodic Pattern: Modeling and Experiment

The dynamics of space structures is significantly impacted by the presence of power and electronic cables. Robust physical model is essential to investigate how the host structure dynamics is influenced by cable harnessing. All the developed models only considered the decoupled bending motion. Initial studies by authors point out the importance of coordinate coupling in structures with straight longitudinal cable patterns. In this article, an experimentally validated mathematical model is developed to analyze the fully coupled dynamics of beam with a more complex cable wrapping pattern which is periodic in nature. The effects of cable wrapping pattern and geometry on the system dynamics are investigated through the proposed coupled model. Homogenization-based mathematical modeling is developed to obtain an analogous solid beam that represents the cable wrapped system. The energy expressions obtained for fundamental repeating segment are transferred into the global coordinates consisting of several periodic elements. The coupled partial differential equations (PDE) are obtained for an analogous solid structure. The advantage of the proposed analytical model over the existing models to analyze the vibratory motion of beam with complex cable wrapping pattern has been shown through experimental validation.

The PHU-NET: A robust phase unwrapping method for MRI based on deep learning.

This work was aimed at designing a deep-learning-based approach for MR image phase unwrapping to improve the robustness and efficiency of traditional methods. A deep learning network called PHU-NET was designed for MR phase unwrapping. In this network, a novel training data generation method was proposed to simulate the wrapping patterns in MR phase images. The wrapping boundary and wrapping counts were explicitly estimated and used for network training. The proposed method was quantitatively evaluated and compared to other methods using a number of simulated datasets with varying signal-to-noise ratio (SNR) and MR phase images from various parts of the human body. The results showed that our method performed better in the simulated data even under an extremely low SNR. The proposed method had less residual wrapping in the images from various parts of human body and worked well in the presence of severe anatomical discontinuity. Our method was also advantageous in terms of computational efficiency compared to the traditional methods. This work proposed a robust and computationally efficient MR phase unwrapping method based on a deep learning network, which has promising performance in applications using MR phase information.

Structural and cracking behaviour of RC T-beams strengthened with BFRP sheets by experimental and analytical investigation

Shear and flexural failure are commonly known as the highest catastrophic failure mode as it never gives any earlier notice before the collapse. The most common shape in the structure of beams and girders is T-section. Therefore it will be more necessary to investigate the condition of these structures. In this research, the flexural behaviour of RC T-beams is investigated experimentally and analytically strengthened with Basalt Fiber Reinforced Polymer (BFRP). A symmetrical one-point static loading system is applied on RC T-beams superficially bonded with 45° degree, and 90° wrapping up to failure. The effects of both wrapping patterns of BFRP on RC T-beams were investigated for ultimate load carrying capacity, deflection, strain, and failure modes. The experimental results demonstrate that superficially bonded BFRP can enhance the flexural capacity and reduce the deflection of the beam significantly. Further, the results show that the most effective wrapping pattern was a 45° degree than 90°wrapping and without wrapping. Then the RC T- beam was modeled by using ABAQUS to validate the present experimental and analytical results. After a series of comparative studies, the analytical results fairly admit with the experimental results. In the end, this study surmised showing different cracking patterns and yield points of the beam with and without strengthening. It is hoped that the results of this study will be of considerable help for the strengthening of T- beams and structures.

Damping Mechanisms in Cable-Harnessed Structures for Space Applications: Analytical Modeling

Abstract Recent developments in the aerospace industry have driven focus toward accurately modeling the effects of the cables and electronic cords on space structures. In the past, researchers have modeled the mass and stiffness effects of these cables but primarily overlooked their damping effects through careful analytical model developments. The objective of the current work is to present analytical models for cable-harnessed structures that also include the damping effects in their vibration response. Obtaining simple, low-order and high-fidelity models are highly advantageous in designing robust vibration real-time control algorithms for structures. Additionally, the analytical models are useful tools in providing insight into and better understanding of the dynamics of space structures as they are often difficult to be tested prior to launch due to their large size and at best only a few components may be tested. Motivated by the space applications, this work considers beam structures wrapped with cables which are modeled using beam and string theory assumptions. Two different damping models namely Kelvin–Voigt and hysteretic damping are considered. The homogenization approach is used as a starting point for structures of periodic wrapping patterns. Using the variational principle, the governing partial differential equation for the transverse coordinate of vibrations is found for three cable patterns and the results are compared to those from the distributed transfer function method (DTFM). Finally, the effects of several structural parameters are studied on the overall system damping.

External surface cracked offshore steel pipes reinforced with composite repair system subjected to cyclic bending: An experimental investigation

In this paper, we experimentally studied the external surface crack growth in steel pipes reinforced with Composite System Repaired (CRS). CRS reinforced surface cracked API 5L X65 pipes were tested, containing three initial notch sizes and four reinforcement schemes. During the tests, the crack growth results, as well as the strain on the external mid-bottom composite laminate around the cracked area, and the vertical deflection of the specimens were recorded. The results showed that within the surface crack growth stage, the composite laminates were adequately bonded on the steel substrate, which significantly decreased the crack growth rate and prolonged the residual fatigue life. In addition, CRS reinforcement has increased the stiffness of the surface cracked pipes. Through the analysis on applying different reinforcement schemes, we indicated that increasing the amount of composite layers evidently facilitated the reinforcement effectiveness, while increasing the bond length did not; and the inversely diagonal wrapping pattern performance less effective.

Techniques for approximating a spatially varying Euler-Bernoulli model with a constant coefficient model

Developing accurate models to describe the behaviour of a physical system often results in differential equations with spatially varying coefficients. A notable example of this that appears in many applications is the Euler-Bernoulli beam equation for transverse vibrations. This equation with spatially varying coefficients, such as when the bending stiffness or mass per unit length varies along the length of the beam, is of interest in the current research. Methods for approximating the Euler-Bernoulli equation with periodically varying coefficients have been proposed yet there is still a need for methods that approximate the more general, non-periodically varying, cases. The goal of this research is to obtain a constant coefficient Euler-Bernoulli equation that accurately approximates the original spatially varying equation using an inverse problem approach. Obtaining such an approximation has advantages in control applications where a constant coefficient model is strongly preferred for computational efficiency. The motivation for this research stems from previous work by the authors on modelling cable-harnessed structures. The spatially varying equation is solved using the Lindstedt-Poincaré perturbation method and these results are used to determine the approximate model. Multiple inverse problem methods for determining the coefficients in the approximate model are considered including metric minimization, the modal participation factor (MPF), and the proper orthogonal decomposition (POD). Continuous version of POD and MPF methods are obtained. Several wrapping patterns and boundary conditions are considered for comparison and the results are in good agreement with analytical and finite element analysis (FEA) results.

Continuum Modeling of Nonperiodic String-Harnessed Structures: Perturbation Theory and Experiments

The cables-to-payload mass ratio can be about 20% for aerospace structures. To ensure a successful mission, predicting the vibrations response of cable-harnessed structures is critical. It is commonplace in industry to account for the added mass of these cables and ignore the stiffness effects; however this leads to inaccurate models. The presented paper studies string-harnessed structures as a means for modeling the mass and stiffness effects of aerospace cables; damping is neglected. As periodic wrapping patterns have been modeled using a homogenization theory and experimentally validated, a natural progression of research is the study of nonperiodic wrapping patterns, which is the focus throughout this paper. A spatially dependent equation of motion is derived for the transverse vibrations of a string-harnessed structure. The equation of motion is similar in form to a spatially dependent Euler–Bernoulli beam model. The Lindstedt–Poincaré method is used to determine the frequencies and mode shapes of the system, which are then used to calculate the frequency response function. It is observed that the frequency response functions of the perturbation theory are in good agreement with experimental results.

Ultrathin ceramic nanowires for high interface interaction and energy density in PVDF nanocomposites

AbstractDielectric nanocomposites with ceramic fillers have a crucial role in energy storage applications. Therefore, poly(vinylidene fluoride) (PVDF) based nanocomposites filled with 20 nm diameter, surface hydroxylated BaTiO3 nanowires (BTnws) were produced by solution‐casting method in this work, in which BTnws were synthesized via solvothermal method. The dielectric constant of BTnws/PVDF nanocomposites was 24 when the content of fillers was 10vol% at 100 Hz and the breakdown strength could increase up to 417 kV/mm before decreasing. The nanocomposites showed enhanced energy density performance and the maximum energy density could reach to 8.1J/cm3 at 320 kV/mm with 10vol% BTnws, nearly tripled that of pure PVDF at 300 kV/mm. Finite element and molecular dynamic simulation results revealed that thin BTnws could create dielectric homogeneity in the nanocomposites and have strong interface interaction with PVDF molecular. The ultrathin BTnws provided the possibility that single PVDF molecular could wrap on its surface, but this molecular wrapping pattern would not occur when the diameter of BTnws was large. Besides, the wrapping pattern could be reinforced by interactions between surface hydroxyl groups of BTnws and F atoms of PVDF molecular. Such contributions could induce good interface compatibility and lead to the improvement of energy density.

Direct Observation of H3-H4 Octasome by High-Speed AFM.

Despite evidence that histone H3 and H4 proteins may act as the precursor for orientating the DNA sequence to form nucleosome structures, there is no direct evidence of the formed compact structure. Here, it is demonstrated that a histone H3-H4 octasome could be constructed without the involvement of histone H2A-H2B under in vitro reconstitution conditions. Atomic force microscopy was used to obtain the first direct observation of the octasome structure, which exhibited a similar core-protein size as that of a nucleosome but with a shorter core histone-binding DNA region. The octasome also displayed a one-step histone-dissociation pattern under heat treatment, distinct micrococcal nuclease and peplomycin accessibility, which suggests a different wrapping pattern to that in nucleosomes.

The numerical boundary conditions of the wrapping pattern of thin insulation

The wrapping pattern of thin insulation is an important issue in cryogenic installations because it can significantly affect heat transport. The major objective of this study is to develop the numerical boundary conditions (BC) needed to model the wrapping pattern of thin insulation. An example of the practical application of the proposed BC includes the heat transfer of Rutherford NbTi cables immersed in superfluid helium (He II) across thin layers of electrical insulation. The proposed BC and a mathematical model of heat transfer in He II are implemented in the open source CFD toolbox OpenFOAM. The implemented mathematical model and the BC are compared with experiments. The study confirms that the thermal resistance of electrical insulation can be lowered by implementing the proper wrapping pattern. The proposed BC can be useful in the study of new patterns for wrapping schemes. Further possible improvements of the tool are indicated in the paper.

The design and analysis of channel transmission communication system of XCTD profiler.

In this paper, a channel transmission communication system of expendable conductivity-temperature-depth is established in accordance to the operation characteristics of the transmission line to more accurately assess the characteristics of deep-sea abandoned profiler channel. The wrapping inductance is eliminated to maximum extent through the wrapping pattern of the underwater spool and the overwater spool and the calculation of the wrapping diameter. The feasibility of the proposed channel transmission communication system is verified through theoretical analysis and practical measurement of the transmission signal error rate in the amplitude shift keying (ASK) modulation. The proposed design provides a new research method for the channel assessment of complex abandoned measuring instrument and an important experiment evidence for the rapid development of the deep-sea abandoned measuring instrument.

Homogenization Modeling of Periodically Wrapped String-Harnessed Beam Structures: Experimental Validation

High-flexibility, small-mass, and high-bandwidth controllers required for inflatable space missions need quite accurate models to predict higher-order dynamics of these structures. Some major components often ignored in dynamic analysis of space structures that result in model inaccuracies are space flight cables. The cables-to-payload-mass ratio can be about 20% in a traditional space structure; this number can increase significantly for inflatable structures due to their extremely light weights. As such, these cables can have significant impacts on the structural dynamics. The presented paper considers string-harnessed beam structures as a way to study the mass and stiffness effects of these cables. As a preliminary step, damping is ignored in the presented models. A homogenization technique is applied to develop the governing partial differential equation for the transverse bending coordinate of vibration of the string-harnessed beam structures. A periodic wrapping pattern is considered for the string throughout this paper. The frequency response functions for the continuum model are then compared to the experimental results, for which strong agreements are observed.

Effects of Ligand Geometry on the Photophysical Properties of Photoluminescent Eu(III) and Sm(III) 1-Hydroxypyridin-2-one Complexes in Aqueous Solution.

A series of 10 tetradentate 1-hydroxy-pyridin-2-one (1,2-HOPO) ligands and corresponding eight-coordinated photoluminescent Eu(III) and Sm(III) complexes were prepared. Generally, the ligands differ by the linear (nLI) aliphatic linker length, from 2 to 8 methylene units between the bidentate 1,2-HOPO chelator units. The photoluminescent quantum yields (Φtot) were found to vary with the linker length, and the same trend was observed for the Eu(III) and Sm(III) complexes. The 2LI and 5LI bridged complexes are the brightest (Φtotxε). The change in ligand wrapping pattern between 2LI and 5LI complexes observed by X-ray diffraction (XRD) is further supported by density functional theory (DFT) calculations. The bimodal Φtot trends of the Eu(III) and Sm(III) complexes are rationalized by the change in ligand wrapping pattern as the bridge (nLI) is increased in length.