Twisting Forces Research Articles

Carbon nanotube-doped Ag[formula omitted]O ink: A cost-effective method for strengthening inkjet-printed flexible circuits

Silver ink demonstrates significant potential in the field of printed electronics due to its excellent electrical conductivity and stability. However, traditional silver electrodes still face issues such as microscopic fractures under mechanical stresses like bending, twisting, and stretching, which are common in conformal circuits and flexible electronic devices. This study introduces a cost-effective, one-step method for synthesizing high stability carbon nanotube (CNT)-doped Ag2O ink. The feasibility of using CNTs as a scaffold with silver as the conductive network is validated. The study investigated the microscopic structural characteristics and composition of the printed films. It also analyzed their electrical conductivity and mechanical properties before and after annealing. A special surfactant ratio was employed to ensure the ink remains stable for an extended period of time. In testing, CNT-doped silver films exhibit exceptional electrical conductivity, and the printed lines achieve extremely low resistance after low-temperature (200 °C) annealing. The ink with a 5.45% mass fraction of CNTs achieved a minimum resistivity of approximately 1.4×10−7Ωm. Under external twisting forces, CNTs enhance the yield strength of the conductors by transferring and absorbing stress, refining the grain structure within the conductive network, and increasing the dislocation density. The printed circuits maintained nearly the initial resistivity even after multiple twists. The CNT-doped Ag2O ink demonstrates outstanding mechanical strength and flexibility, showcasing its potential for practical applications.

Analysis of fabric movement and dust removal performance due to twist motion in a clothing care system

This study aims to explore effective dust removal methods for the improvement of clothing care systems by analyzing the fabric movement caused by the twist motion and examining its influence on dust removal performance. The finite element method simulation was used to model the tension at different vertical and horizontal positions of the fabric as a spring array, to calculate the fabric movements at each position over time when a twisting force was applied and enable comparison with experiments. When observing the fabric movement due to the twist motion with actual fabrics, silk showed the greatest movement, followed by cotton and linen. Cotton experienced decreasing force from the top to the bottom, with increased amplitude at the bottom due to fluttering caused by the bottom not being fixed. When examining the fabric movement according to the velocity, slower velocity did not effectively transmit twist force to the bottom, while faster velocity resulted in more small movements. The analysis revealed that greater force at faster velocity led to better dust removal performance. Therefore, for efficient dust removal, the force transmitted to the fabric should be increased. Most dust is removed within the first 10 min, so exerting a strong force for a short duration is important.

Helical motors and formins synergize to compact chiral filopodial bundles: A theoretical perspective

Chiral actin bundles have been shown to play an important role in cell dynamics, but our understanding of the molecular mechanisms which combine to generate chirality remains incomplete. To address this, we numerically simulate a crosslinked filopodial bundle under the actions of helical myosin motors and/or formins and examine the collective buckling and twisting of the actin bundle. We first show that a number of proposed mechanisms to buckle polymerizing actin bundles without motor activity fail under biologically-realistic parameters. We then demonstrate that a simplified model of myosin spinning action at the bundle base effectively “braids” the bundle, but cannot control compaction at the fiber tips. Finally, we show that formin-mediated polymerization and motor activity can act synergitically to compact filopodium bundles, as motor activity bends filaments into shapes that activate twist forces induced by formins. Stochastic fluctuations of actin polymerization rates and slower cross linking dynamics both increase buckling and decrease compaction. We discuss implications of our findings for mechanisms of cytoskeletal chirality.

Bending and twisting behavior of multilayer graphene

In this work, multilayer graphene was chosen and modeled in ANSYS software. In the software, it was subjected to bending forces through various bend angles. In order to test for bending, the model is subjected to rigid support on the base side. Then a force is applied on the side on which the angle is provided to simulate Bending. Stress–strain plots were analyzed for various bending angles. The graphene sheet was also subjected to twist forces within the software. In order to test for torsion, the model is subjected to rigid support on both sides. Then a couple is applied on the opposite sides to simulate torsion. Torsional stress and strain measurements were analyzed. The trends were studied and correlations with the material properties of graphene were established. The quest is to identify a magic angle for bend and twist.

Cardiac cycle timing and contractility following acute sport-related concussion

ABSTRACT Cardiac sequelae following sport-related concussion are not well understood. This study describes changes in the cardiac cycle timing intervals and contractility parameters during the acute phase of concussion. Twelve athletes (21 ± 2 years, height = 182 ± 9 cm, mass = 86 ± 15 kg, BMI = 26 ± 3 kg/m2) were assessed within 5 days of sustaining a diagnosed concussion against their own pre-season baseline. A non-invasive cardiac sensor (LLA RecordisTM) was used to record the cardiac cycle parameters of the heart for 1 minute during supine rest. Cardiac cycle timing intervals (Isovolumic relaxation and contraction time, Mitral valve open to E wave, Rapid ejection period, Atrial systole to mitral valve closure, Systole, and Diastole) and contractile forces (Twist force and Atrial systole: AS) were compared. Systolic time significantly decreased during acute concussion (p = 0.034). Magnitude of AS significantly increased during acute concussion (p = 0.013). These results imply that concussion can result in altered systolic function.

Chiral Liquid Crystalline Elastomer for Twisting Motion without Preset Alignment of Mesogens.

A chiral liquid crystalline elastomer (CLCE) actuator is demonstrated. The solution-cast polydomain film of CLCE can twist upon order-disorder phase transition without any preset alignment of mesogens. The handedness of twisting is specific to the molecular chirality of the chiral dopant in the CLCE structure, while the degree of twisting, in terms of helical pitch and diameter, is sensitive to the aspect ratio and the thickness of the CLCE strip as well as the chiral dopant content. This phenomenon appears to stem from the local twisting forces and deformations of randomly oriented helical domains, which cannot cancel each other out due to the chirality and thus result in a macroscopic "chiral" force acting on the CLCE actuator. This finding reveals a materials design for preparing twisting LCE actuators.

Turbulent flow and heat transfer of helical coils with twisted section

An innovative heat transfer enhancement method that integrates helical coil and twisted channel to augment swirl intensity is newly proposed. The characteristics of turbulent flow and heat transfer of five twisted helical coils with identical helical geometries but different twist pitches are numerically explored using ANSYS-Fluent code. Acting by the twist forces along the twisted helical coils, the swirl number, Sw, and turbulent kinetic energy of the flows are enhanced from those in the untwisted helical coils. Swirl enhancements in the twisted helical coils are derived as the function of channel twist ratio. The correlative flow and heat transfer analysis confirms the enhanced swirl intensity is the dominant flow physic for heat transfer enhancement due to the channel twist. The ratios of Nusselt number and friction factor between the twisted and untwisted helical coils at different Reynolds numbers and twist ratios are converged into the Sw functions. With all the thermal performance factors above than unity for the present twisted helical coils, the twisted coil with the twist ratio of three channel hydraulic diameters offers the maximum 19% of heat transfer elevation and 69.8% of friction augmentation from the untwisted-coil references. Based on the numerical heat-transfer and pressure-drop results, two sets of correlations that permit the evaluations of averaged Nusselt number at developed flow regime and the Fanning friction factor of the twisted helical coils are developed for relevant applications.

Investigation of the Causes and Determination of Critical Mechanical Actions on Pins in Metal-Glass Articles Resulting in Loss-of-Tightness

The results of an experimental study of the influence of twisting and bending forces on pins resulting in loss-of-tightness in sealed metal-glass articles (MGA) are reported. The critical values of the angles of rotation and bending of the pins at which glass begins to break are indicated. The technological features of MGA fabrication that increase the strength of a metal-ceramic seal are shown. The results are of interest for the manufacture of different hermetic relays and devices and explain the possible causes of the loss-of-tightness in devices.

Helical twist direction in the macrofibrils of keratin fibres is left handed

Macrofibrils, the main structural features within the cortical cells of mammalian hair shafts, are long composite bundles of keratin intermediate filaments (KIFs) embedded in a matrix of keratin-associated proteins. The KIFs can be helically arranged around the macrofibril central axis, making a cylinder within which KIF helical angle relative to macrofibril axis increases approximately linearly from macrofibril centre to edge. Mesophase-based self-assembly has been implicated in the early formation of macrofibrils, which first appear as liquid-crystal tactoids in the bulb of hair follicles. Formation appears to be driven initially by interactions between pre-keratinized KIFs. Differences in the nature of these KIF-KIF interactions could result in all macrofibrils being internally twisted in a single handedness, or a 50:50 mixture of handedness within each cortical cell. We data-mined 41 electron tomograms containing three-dimensional macrofibril data from previously published studies of hair and wool. In all 644 macrofibrils examined we found that within each tomogram all macrofibrils had the same handedness. We concluded that earlier reports of left- and right-handed macrofibrils were due to artefacts of imaging or data processing. A handedness marker was used to confirm (using re-imaged sections from earlier studies) that, in both human and sheep, all macrofibrils are left-handed around the macrofibril axis. We conclude that this state is universal within mammalian hair. This also supports the conclusion that the origin of macrofibril twist is the expression of chiral twisting forces between adjacent KIFs, rather than mesophase splay and bending forces relaxing to twisting forces acting within a confined space.

Investigation of Stress, Deformation, and Cracks in the Brakes of Car Using Finite Element Method

Twisting forces in disc brakes and friction forces between disc brakes and bearings produce heat on the disc brakes. The compression force produced by the brake piston pushes the brake pads to produce heat and deformation in the disc brakes. For the development of vehicle braking systems, wrought iron is used to make disks. However, a failure still occurs during a crack testing. The results of the analysis using the finite element method showed that the highest total deformation was 4,411 x 105 mm. The highest maximum equivalent stress (represented by the red area) is 715.48 MPa. The maximum value of SIFS (K1) around the disc brake hole is -0.9030 MPa.mm0.5, while at the edge of the disc is 5.385 MPa.mm0.5.

EDGE STATE METHOD IN MECHANICS PROBLEMS CONCERNING ANISOTROPIC THIN PLATES

ObjectivesThe aims of the study are to expand the edge state method for solving bending and torsion problems concerning anisotropic thin plates, develop the theory of construction of the bases of spaces of interior and edge states based on a general approximate solution to the plate bending problem, formulate the relationships determining the desired elastic state and implement the developed theory in solving specific problems.MethodsThe fulfilment of the tasks is assumed to be based on the edge state method. The state spaces comprising the methodological basis are formed according to the fundamental system of Weierstrass polynomials.ResultsAn isomorphism of interior and edge state spaces is demonstrated, allowing a correspondence between the elements of these spaces to be unambiguously established. The isomorphism of spaces allows the process of finding the internal state to be reduced to the study of the edge state isomorphic to it. The mechanical characteristics are represented in the form of a Fourier series. In the case of the first and second fundamental mechanics problems, the Fourier coefficients are represented by scalar products having an energy implication: in the space of edge states, this consists in the work of external forces; in the space of internal states, it is the internal energy of elastic deformation. In the case of mixed mechanical problems, the search for an elastic state in the terms of the edge state method is reduced to solving an infinite system of algebraic equations. ConclusionThe solution of the first-tested basic problem of bending with torsion for a rectangular fibreglass plate with corresponding conclusions is given, as well as the problems of torsion for a plate of nontrivial form. Commentaryis provided concerning the unreasonableness of the solution of the second fundamental problem, as well as the problem with mixed boundary conditions for a rectangular plate where twisting and bending forces are defined simultaneously on the one face, while the opposite face is squeezed. Both explicit and indirect signs of the convergence of the solution to the problem are presented along with a graphical visualisation of the results.

Controlling polar-toroidal multi-order states in twisted ferroelectric nanowires

The toroidal order of electric dipoles in ferroelectric materials has attracted attention in the past decade due to fascinating properties and great potential for enabling novel memory devices, and functional devices in general. However, facile manipulation of toroidal order in ferroelectrics remains challenging. Here, using first-principles derived simulations, we demonstrate an efficient scheme to control the polar-toroidal multi-order (PTMO) states in ferroelectric nanowires. Two feasible strategies of controlling PTMO states by a combination of homogeneous electric field and torque are carried out in ferroelectric/paraelectric composite nanowires. This is possible based on trilinear coupling between polarization, toroidization and the twist force. As a result, switching of the toroidization of the nanowire can be readily achieved by reversal of the axial polarization. The torque threshold needed to control PTMO states is also calculated and found to be relatively small, indicating the feasibility of this method. Our study demonstrates facile control of PTMO states, including ferroelectric skyrmions, in ferroelectrics and is a step towards designing ferroelectric devices based on multi-order states.

Clockwise and Counter-Clockwise Twisting Strength in Different Operational Angles on Crown Plane

Hand tools can be seen as the extent of human hands. The evolution of hand tools was positively correlated with human development. The hand tools design affects the convenience and safety of human use. The wrenches are the most frequently used hand tools in Taiwan. However, it is lack literatures focus on the twisting force for operating hand tools. To provide reference for the hand tools design, this study surveyed the two twisting forces in five operational angles in crown plane when use wrenches. Eighty volunteer adults (half male and half female) were recruited as subjects. The maximum twisting forces of dominant hand were measured. Palm facing to ground is defined as 0 degree. Hand in supine positions are defined as positive angle and in prone positions are defined as negative angle. The five angles are: 0, 15, 22.5, 30, and 45 degrees. The two twisting forces are: clockwise and counter clockwise in vertical plane. A digital twisting force wrench was used as the measurement apparatus. The twisting forces model was constructed. In the vertical plane, the down force is greater than the up force. The forces in positive angles were greater than that in the negative angles. The force of male is greater than that of female. The results of the study can be reference for research and other hand tools design.

Playground slide-related injuries in preschool children: increased risk of lower extremity injuries when riding on laps

BackgroundThe purpose of this study was to better understand the factors associated with playground slide-related injuries in preschool children and to test the hypothesis that riding on laps increases the likelihood of lower extremity injuries.MethodsPlayground slide-related injuries (product code 1242) in children ≤5 years of age treated in emergency departments from 2002 to 2015 were identified (N = 12,686) using the U.S. Consumer Product Safety Commission’s National Electronic Injury Surveillance System (NEISS). Descriptive and comparative analyses, including chi-square testing and binary logistic regression, were performed.ResultsBased on NEISS stratified national sampling estimates, over 350,000 children ≤5 years of age were injured on slides from 2002 to 2015. Overall, 59% of the children were male, and 65% were white. Almost 60% of injuries occurred in parks or other public areas. The most frequent diagnosis was a fracture (36%); lacerations were 19% of the injuries. A higher proportion of musculoskeletal injuries were seen in toddlers < 3 years old as compared to those 3–5 years of age (p < 0.001). Injuries to the lower extremities increased in frequency as age decreased, whereas injuries to the upper extremities and head/neck/face were more common in older preschoolers. Children < 3 years of age were 12 times more likely to be identified from narratives as being on another person’s lap at the time of injury. Children identified as being on a lap had an increased odds of injury to the lower extremity than to other body parts (OR 43.0, 95% confidence interval (CI) 32.0–58.0), and of lower leg/ankle fracture than fractures elsewhere (OR 49.5, 95% CI 31.7–77.4).ConclusionsDecreasing age was associated with a higher likelihood of being identified as sliding down on another person’s lap and a higher likelihood of lower extremity injuries. Healthcare providers should be mindful of the potential for these slide-related injuries as they can result in a toddler’s fracture of the tibia, which may be occult. Parents should also be made aware of this increased risk and counseled that a child’s foot can catch on the slide’s surfaces when going down on a person’s lap with subsequent twisting forces that can result in a fracture.

Twisted spectral geometry for the standard model

In noncommutative geometry, the spectral triple of a manifold does not generate bosonic fields, for fluctuations of the Dirac operator vanish. A Connes-Moscovici twist forces the commutative algebra to be multiplied by matrices. Keeping the space of spinors untouched, twisted-fluctuations then yield perturbations of the spin connection. Applied to the spectral triple of the Standard Model, a similar twist yields the scalar field needed to stabilize the vacuum and to make the computation of the Higgs mass compatible with its experimental value.

Development of Coiled Springs with High Rectangular Ratio in Cross-section

Some robots often have to be made compact as they work in limited spaces, for example, in disaster rescue sites and operation theatres for surgery. One of the problems in downsizing the robots is how to fabricate the joints which are complicated and tend to be large. Coiled springs with high rectangular ratio recently have started to be used as the joint mechanism, because they are compact, easy to be bent, and able to convey strong twist force. However, these springs are now made by machining, resulting in low productivity and high cost. In this study, a new and inexpensive forming method is proposed, where a stainless wire is wound around into the shape of coiled spring, and subjected to upset in the spring axis direction. The finite element analysis was conducted for estimation of the work-hardening. The high work-hardening will realize the high yield stress, which is one of important features required for robot joints, as they must be used without plastic deformation. Based on the analysis, a series of experiments were carried out, and the formed springs were evaluated in terms of tension, torsion and bending characteristics.

손목회전운동 재활로봇을 위한 6축 힘/모멘트센서 설계

Most serious stroke patients have the paralysis on their wrists, and can`t use their hands freely. But their wrists can be recovered by rehabilitation exercises. Recently, professional rehabilitation therapeutists help stroke patients exercise their wrists in hospital. But it is difficult for them to rehabilitate their wrists, because the therapeutists are much less than stroke patients in number. Therefore, the wrist twist-exercise rehabilitation robot that can measure the twist force of the patients` wrists is needed and developed. In this paper, the six-axis force/moment sensor was designed appropriately for the robot. As a test result, the interference error of the six-axis force/moment sensor was less than 0.85%. It is thought that the sensor can be used to measure the wrist twist force of the patient.

P‐159: Slit Pattern for Dynamic Stability of TN‐VA LCD

AbstractWe investigated the dynamic stability of disclination lines (DLs) generated near the boundary of adjacent domain with different Liquid crystal orientation in the conventional multi‐domain twist nematic‐vertical alignment (TN‐VA) LCDs. The Liquid crystal molecules collide with each other at the reverse twist boundaries due to the strong reverse twist force competitions at a high voltage, and pushes DLs deeply penetrate into the active region, resulting in a decreased transmittance in the panel. To ameliorate these drawbacks, the slit pattern was induced at the location of reverse‐twist boundary with the function to suppress the reverse twist force and eliminates the distortion, thus make DLs remain very slim near boundary areas. As a result, the transmittance dynamic stability is greatly improved.

Microelectromechanical Systems Resonator Utilizing Torsional-to-Transverse Vibration Conversion

A silicon microelectromechanical systems (MEMS) resonator utilizing the torsional-to-transverse vibration conversion is designed, fabricated and evaluated. The resonant frequency for the torsional modes mostly depends on only beam length, providing a large tolerance in the fabrication process. It has been, however, a critical issue to investigate the mechanism for generating the torsional vibration and the reduction of motional resistance. We propose a new beam structure, in which four torsion beams are vibrated by twist force generated by a transverse beam. The novel process for fabricating resonators provides a narrow gap surrounded by flat surfaces, which can reduce the motional resistance. The fabricated resonators are measured with a laser-Doppler (LD) vibrometer. The scanning function of the LD vibrometer confirms the torsional-to-transverse vibration conversion has been successfully achieved. The measured resonant frequency, 10.96 MHz, is in good agreement with the simulated one. The Q-factor has been also measured to be as high as 2.2 ×104 in vacuum. The electrical characteristic is evaluated with an impedance analyzer. At the resonant frequency, the extracted motional resistance for the 0.5-µm-gap resonator is 2.0 MΩ, which is greatly reduced, owing to the narrow gap effect, from that of the 1-µm-gap resonator. The temperature coefficient of the resonant frequency between -40 and 85 °C, has been measured to be -24.4 ppm/deg. The resonant frequency linearly decreases as the temperature rises.

Current in Periodic Lorentz Gases with Twists

We study electrical current in two-dimensional periodic Lorentz gas in the presence of a twist force on the scatterers. In this deterministic system, billiard orbits are still geodesics between collisions, but do not reflect elastically when reaching the boundary. When the horizon is finite, i.e. the free flights between collisions are bounded, the resulting current J is proportional to the strength of the twist force measured by e. We also prove the existence of a unique SRB measure, for which the Pesin entropy formula and Young’s expression for the fractal dimension are valid.