Search Results (43)

Background: Auricular keloids and ear helix deformities are undesirable and aesthetically unpleasing deformities that can cause significant patient psychologic and self-esteem problems. Pressure therapy for keloids is well documented to be an effective non-invasive treatment modality. However, current devices lack comfort and aesthetic appeal to deliver the pressure forces required effectively and uniformly. This work aims to highlight some different pressure therapy approaches for the management of keloids and irregularities in the ear helix morphology. Methods: A case series of four patients presenting with auricle keloids of various sizes and at different locations secondary to ear piercing and one case of congenital helix deformity were treated successfully with pressure therapy devices. The device designs varied based on the keloids’ characteristics and patients’ preferences and involved wire-based spring-activated appliances resembling ear rings for moderate keloid lesions, modified double-spring systems for large or elongated lesions, and magnet-based devices. A pair of inert magnetic discs of different diameters was positioned on the anterior and posterior aspects of the keloid lesion. The magnets were then encapsulated in acrylic resin to improve retention and adaptation, and the external surface was masked with gold glitter to enhance aesthetics and patient acceptance. The helix-deformity case was treated following a complete digital workflow integration where the sound contralateral ear was digitally scanned, mirror-imaged and then 3D-printed in resin to produce an ear model based on which an anatomically symmetrical pressure device was constructed. Results: All devices were successfully fitted and well tolerated, with no reported discomfort or adverse reactions. The wire spring devices were effective in reducing a large keloids volume; however, frequent reactivation every two weeks was required to ensure continuous pressure application. Incorporating magnets in the customised design allowed controlled and uniform pressure application to small keloid-lesion morphology, with enhanced aesthetics and improved patient acceptance and compliance. The digitally assisted case achieved near-perfect anatomical symmetry with the contralateral ear, reducing operator dependency and fabrication guesswork. Conclusions: Customised pressure therapy devices, of magnetic and spring-based systems, alongside utilising digital technologies, offer effective, non-invasive management for auricular keloids and irregular ear helices as long as the patient is committed to wearing the device. Full article

This paper introduces a compact pneumatic artificial muscle (CPAM) that integrates a coaxial rod and an internal helical compression spring (stiffness 9750 N/m) into a McKibben-type outer muscle and compares it to a commercial DMSP-20-200N from FESTO Budapest, Hungary, with identical outer geometry and materials. Both actuators were mounted in a force-controlled test rig, pre-tensioned, and then cycled quasi-statically between their stretched and maximally contracted states at 13 internal pressures. For each pressure, median loading and unloading force–contraction curves were obtained from five repeats measuring both the cylinder excitation force and a load cell, and hysteresis was quantified by a normalized loop area based on peak force and common contraction range. Under the rated load of 2000 N at 0.6 MPa, the CPAM elongates less (−1.5% vs. −3%) and generates higher forces over most of the contraction range. The normalized hysteresis index of the CPAM is markedly lower at low pressures (≈0.05–0.25 MPa, reductions of about 10–25%), similar near 0.30 MPa, and slightly higher at 0.35–0.60 MPa (≈6–14%). Full article

This work proposes an Enhanced Chimp Optimization Algorithm (EChOA) for solving continuous and constrained data science and engineering optimization problems. The EChOA integrates a self-adaptive DE/current-to-pbest/1 (with jDE-style parameter control) variation stage with the canonical four-leader ChOA guidance and augments the search with three lightweight modules: (i) L’evy flight refinement around the incumbent best, (ii) periodic elite opposition-based learning, and (iii) stagnation-aware partial restarts. The EChOA is compared with more than 35 optimizers on the CEC2022 single-objective suite (12 functions). The results shows that the EChOA attains state-of-the-art results at both $D=10$ and $D=20$. At $D=10$, it ranks first on all functions (average rank $1.00$; $12/12$ wins) with the lowest mean objective and the smallest dispersion relative to the strongest competitor (OMA). At $D=20$, the EChOA retains the best overall rank and achieves top scores on most functions, indicating stable scalability with problem dimension. Pairwise Wilcoxon signed-rank tests ($\alpha =0.05$) against the full competitor set corroborate statistical superiority on the majority of functions at both dimensions, aligning with the aggregate rank outcomes. Population size studies indicate that larger populations primarily enhance reliability and time to improvement while yielding similar terminal accuracy under a fixed iteration budget. Four constrained engineering case studies (including welded beam, helical spring, pressure vessel, and cantilever stepped beam) further confirm practical effectiveness, with consistently low cost/weight/volume and tight dispersion. Full article

The standard EN 13906-2 forms the essential basis for the design and calculation of helical tension springs. It is used not only nationally, but throughout Europe and internationally in the spring industry and by spring users. With regard to cyclic design, the standard only refers to fatigue tests to be carried out. There are no formulas for the analytical calculation of the existing stresses in the loops and no methods or diagrams for determining the permissible stresses for tension springs. Even in the technical literature, there are no reliable analytical formulas for calculating the existing stresses for extension springs with different loop shapes. This article presents solutions for determining existing stresses using numerical calculations, which are necessary for performing fatigue strength analysis for tension springs. Full article

In this investigation, Ni_50.9Ti_49.1 wires cold rolled to 40% and straight annealed at 480 °C, 510 °C, and 550 °C, respectively, were heat treated to shape set these wires as helical springs and enhance their SME for use as electro-mechanical actuators. These spring actuators were heat treated at 350 °C, 400 °C, and 450 °C for 30, 60, and 90 min. The wires’ performance as actuators was assessed on a custom-built testing rig, which measured both the stroke and actuation time for each wire. Additionally, the wires were characterised experimentally by DSC, XRD, and nanoindentation. The final resulting properties of the R-phase transformation helical spring actuator are controlled by the competing mechanisms of dislocation annihilation, and precipitation of Ni₄Ti₃, as well as the prior thermomechanical treatment. The optimum conditions for actuator response in Ni_50.9Ti_49.1 40% cold-worked wires were a straight annealing temperature of 480 °C and shape-setting aging conditions of 450 °C for 60 min. These parameters result in the optimum combination of defect annihilation and density of precipitates, resulting in a high-stroke (56 mm), low-hysteresis (2.68 °C) actuator with an actuation time of 6 s. Full article

This study presents an exact analytical investigation into the static response of helical single-walled carbon nanotube (SWCNT) beams based on Eringen’s differential nonlocal elasticity theory, which captures nanoscale effects arising from interatomic interactions. A key contribution of this work is the derivation of the governing equations for helical SWCNT beams, based on the nonlocal Euler–Bernoulli theory, followed by their exact analytical solution using the initial value method. To the best of the authors’ knowledge, this represents the first closed-form formulation for such complex nanostructures using this theoretical framework of nonlocal elasticity theory. The analysis considers both cantilevered and clamped–clamped boundary conditions, under various concentrated force and moment loadings applied at the ends and midpoint of the helical beam. Displacements and rotational components are expressed in the Frenet frame, enabling direction-specific evaluation of the deformation behaviour. Parametric studies are conducted to investigate the influence of geometric parameters—such as the winding angle ($\alpha$) and aspect ratio ($R/d$) and the nonlocal parameter ($R/\gamma$). Results show that nonlocal elasticity theory consistently predicts higher displacements and rotations than the classical local theory, revealing its importance for accurate modelling of nanoscale structures. The proposed analytical framework serves as a benchmark reference for the modelling and design of nanoscale helical structures such as nano-springs, actuators, and flexible nanodevices. Full article

Tomato brown rugose fruit virus (ToBRFV) has been causing severe agricultural damage worldwide since its recent discovery. While related to tobacco mosaic virus, its properties and infection mechanisms are poorly understood. To uncover their structure and nanomechanics, we carried out atomic force microscopy (AFM) measurements on individual ToBRFV particles. The virions are rod-shaped with a height and width of 9 and 30 nm, respectively. Length is widely distributed (5–1000 nm), with a mode at 30 nm. ToBRFV rods displayed a 22.4 nm axial periodicity related to structural units. Force spectroscopy revealed a Young’s modulus of 8.7 MPa, a spring constant of 0.25 N/m, and a rupture force of 1.7 nN. In the force curves a step was seen at a height of 3.3 nm, which is related to virion wall thickness. Wall thickness was also estimated by predicting coat protein structure with AlphaFold, yielding a protein with a length of 7.3 nm. Accordingly, the structural element of ToBRFv is a right circular cylinder with an equal height and diameter of ~22 nm and a wall thickness between 3.3 and 7.3 nm. Thus, at least four to nine serially linked units are required to encapsidate a single, helically organized RNA genome. Fragmentation of ToBRFV into these cylindrical structural units may result in a facilitated release of the genome and thus efficient infection. Full article

The paper presents aspects of the elastic behavior of a springboard in school gyms after contact with a basketball (0.500 kg) falling from a height of 1 m or a volunteer student jumping from 30 or 60 cm in three different areas at the end of the springboard. The results recorded obtained from three accelerometers mounted under the main plate of the springboard are presented, primarily focusing on the accelerations and vertical displacements after contact. The springboard has a special construction, the upper plate and the curved support plates being provided with two pairs of conical and cylindrical truncated helical springs, respectively. The accelerometers were placed at different points, centrally on the upper plate and on the support plates. It was found that in the dynamic process of a body falling on the springboard, the coefficient of elasticity/rigidity of the elastic system changes, presenting values of 22.14–71.12 kN/m. Normally, both accelerations and displacements are greater on the upper plate, but its vibratory motion also induces additional movements and vibrations on the two lower plates. The results may be useful both for manufacturers of such equipment and for coaches to give appropriate instructions to athletes. Full article

Springs are widely used in industries such as aerospace and automotive. As the demand for emission reduction grows, the research on lightweight spring performance is becoming increasingly important. This study analyses the mechanical performance of triple-layer braided composite helical springs (TCHS) under various loads and compression angles. Firstly, the optimal high-temperature curing condition of the epoxy resin was determined through tensile and three-point bending analysis. Then, TCHS were fabricated based on optimal epoxy curing conditions, and multi-angle compression tests under different loads were carried out. Simultaneously, strain gauges were installed at various positions and orientations on the inner and outer sides of the spring wire to reveal strain patterns during the compression. The test results indicate that stiffness decreases with increasing compression angle. Additionally, the strain in the inner and outer positions in different directions of the same region increased with the rise in compression force and angle, and strains in the helical direction were the largest. Subsequently, strain in the helical direction across different regions further showed that maximum strain occurred in the centre coil (region 2), with inner and outer helical direction strains reaching −5116.89 με and 5700.15 με, respectively, which are 71.3% and 90.4% higher than those in region 1 and 73.2% and 92.9% higher than those in region 3. As the compression load increased, cracks appeared on the outer side of the centre coil. In addition, the crack was perpendicular to the helical direction, further confirming that the highest strain occurred in the helical direction. This study provides an in-depth analysis of the impact of angle-specific loads on TCHS, offering valuable insights for the design and optimisation of composite helical springs and laying a theoretical foundation for their future development. Full article

This study investigates the mechanisms driving current generation, power output, and charge storage in carbon nanotube springs under mechanical strain, addressing the gap between experimental observations and theoretical modeling, particularly in asymmetric electrical responses. Leveraging the Dirac equation in curved spacetime, we analyze how curvature-induced scalar and pseudo-gauge potentials shape two-dimensional electron gases confined to carbon nanotube springs. We incorporate applied mechanical strain by introducing time-dependent variations in the Lamé coefficient and curvature parameters, enabling the analysis of mechanical deformation’s influence on electrical properties. Our model clarifies asymmetric electrical responses during stretching and compression cycles and explains how strain-dependent power outputs arise from the interplay between mechanical deformation and curvature effects. Additionally, we demonstrate mechanisms by which strain influences charge redistribution within the helically coiled structure. We develop a new equivalent circuit model linking mechanical deformation directly to electronic behavior, bridging theoretical physics with practical electromechanical applications. The analysis reveals asymmetric time-dependent currents, enhanced power output during stretching, and strain-dependent charge redistribution. Fourier analysis uncovers dominant frequency components (primary at $\Omega$, harmonic at $2\Omega$) explaining these asymmetries. Theoretical investigations explain the mechanisms behind the curvature-driven time-dependent current source, the frequency-dependent peak power, the characteristics of open-circuit voltage with strain, and the asymmetric electrical property response under applied strain as the generated current and the charge distribution within the carbon nanotube springs. These findings highlight carbon nanotube springs applied to energy harvesting, wearable electronics, and sensing technologies. Full article

Biological bone screws play an important role in fixing fractures and bone defects. The machining of helical grooves on xenogenic materials is a key part of fabricating biological bone screws. The fabrication of helical grooves on bovine bone using micro-abrasive air jets was investigated in this paper. The helical groove shapes were classified and their formation mechanisms were studied. Analyses of the material removal mechanism and the effect of process parameters on the groove shapes were carried out. The results show that the helical grooves could be effectively machined using micro-abrasive air jets with a spring mask. The shapes of the helical grooves could be classified as U-, V-, and W-shaped. Cracks that propagated along the cement line may have led to the formation of a slot. Meanwhile, cracks that propagated in the interstitial lamella may have led to the formation of ridges. The slots and ridges resulted in the appearance of stripes on the groove bottom. The cracks propagated along the axial direction of the osteon at the same time as it propagated into the osteon, leading to the formation of dimples on the groove sidewall. The experimental method proposed in this study can be regarded as a suitable method to fabricate helical grooves on bones. Full article

The continental United States is a global hotspot of severe thunderstorms and therefore is particularly vulnerable to social and economic damages from high-impact severe convective weather (SCW), such as tornadoes, thunderstorm winds, and large hail. However, our knowledge of the spatiotemporal climatology and variability of SCW occurrence is still lacking, and the potential change in SCW frequency and intensity in response to anthropogenic climate warming is highly uncertain due to deficient and sparse historical records and the global and regional climate model’s inability to resolve thunderstorms. This study investigates SCW in the Central and Eastern United States in spring and early summer for the current and future warmed climate using two multi-year continental-scale convection-permitting Weather Research and Forecasting (WRF) model simulations. The pair of simulations consist of a retrospective simulation, which downscales the ERA-Interim reanalysis during October 2000–September 2013, and a future climate sensitivity simulation based on the perturbed reanalysis-derived boundary conditions with the CMIP5 ensemble-mean high-end emission scenario climate change. A proxy based on composite reflectivity and updraft helicity threshold is applied to infer the simulated SCW occurrence. Results indicate that the retrospective simulation captures reasonably well the spatial distributions and seasonal variations of the observed SCW events, with an exception of an overestimate along the Atlantic and Gulf coast. In a warmer-moister future, most regions experience intensified SCW activity, most notably in the early-middle spring, with the largest percentage increase in the foothills and higher latitudes. In addition, a shift of simulated radar reflectivity toward higher values, in association with the significant thermodynamic environmental response to climatic warming, potentially increases the SCW severity and resultant damage. Full article

An H-bond involves the sharing of a hydrogen atom between an electronegative atom to which it is covalently bound (the donor) and another electronegative atom serving as an acceptor. Such bonds represent a critically important geometrical force in biological macromolecules and, as such, have been characterized extensively. H-bond formation invariably leads to a weakening within the acceptor moiety due to the pulling exerted by the donor hydrogen. This phenomenon can be compared to a spring connecting two masses; pulling one mass stretches the spring, similarly affecting the bond between the two masses. Herein, we describe the opposite phenomenon when investigating the energetics of the C–H···O=C bond. This bond underpins the most prevalent protein transmembrane dimerization motif (GxxxG) in which a glycine Cα-H on one helix forms a hydrogen bond with a carbonyl in a nearby helix. We use isotope-edited FT-IR spectroscopy and corroborating computational approaches to demonstrate a surprising strengthening of the acceptor C=O bond upon binding with the glycine Cα-H. We show that electronic factors associated with the Cα-H bond strengthen the C=O oscillator by increasing the s-character of the σ-bond, lowering the hyperconjugative disruption of the π-bond. In addition, a reduction of the acceptor C=O bond’s polarity is observed upon the formation of the C–H···O=C bond. Our findings challenge the conventional understanding of H-bond dynamics and provide new insights into the structural stability of inter-helical protein interactions. Full article

This research focuses on cylindrical helical springs with circular cross-sections made from carbon steel (SH 0.82% C) and stainless steel (AISI 302). The transformation from a linear bar to a circular spiral involves numerous factors such as material mechanical behavior, stress–strain relationships and residual stresses. This research investigates the spring-back phenomenon, which affects the final diameter of helical springs post-manufacture, using analytical, experimental and numerical methods. An analytical model, derived from the mechanical bending process, was proposed to predict spring-back, and its accuracy was validated against experimental data. This study also employed finite element simulations to analyze elastic recovery, confirming the analytical predictions. Results indicated that the spring-back ratio k could be expressed as an exponential function of the spring index C (the ratio between the final diameter of the spring D₂ and the diameter of the wire D_W), with a maximum error of 4.80% for stainless steel and 3.62% for carbon steel. This study’s findings provide valuable insights into optimizing the spring manufacturing process, enhancing the precision of spring diameter predictions, and potentially reducing production errors and material waste. Full article

Even though the design of vibration isolators is well-established for many engineering applications, their efficiency in wide and multiple frequency ranges is still a challenge. In these cases, the use of Phononic-Based Vibration Isolators (PBVIs) may be advantageous as they present different Attenuation Regions (ARs) in which the elastic waves are strongly attenuated. Therefore, the present paper is devoted to the experimental evaluation, in terms of force transmissibility, of different types of supporting devices tested on a load mass and a motor of a Hermetic Compressor (HC). Those devices are the original Helical Coil Spring (HS) that equips the HC, the PBVI, and the Combined Structure (CS) which is composed of a PBVI combined in series with the HS. Results evidentiate the capability of the CSs to isolate vibrations, where the PBVI contributes with its ARs, thus operating as a “filter” in specific frequency ranges, while the HSs maintain the flexibility of the CSs, which is advantageous for impact-loads and/or transient-case scenarios. Hence, the capability, relevance and impact that these PBVIs present for force transmissibility reduction applications is highlighted here, which should capture the attention of and motivate the industry, e.g., producers of isolation systems, since it has wide-ranging engineering applications. Full article