Torsion Spring

The torsion rod characteristics of the Sulzer loom can be adjusted in the zero position by means of the adjusting lever and the adjusting actuator of the torsion rod of loom. In the "Sulzer" projectile loom, the movement of the intermediate member results in the axial movement of the adjusting lever to change the position of the zero according the material and characteristics of rod. The intermediate member transmits a force exerted by the adjusting lever to a fixed sliding surface. However, the described device in some countries has a serious drawback, because the tuning drive acts on the torsion rod adjusting lever so that when the projectile is fired into the “Sulzer” loom, the picking mechanism reacts through the sudden, harmful pressure of the tuning drive. A solid wedge-shaped idler that can be moved by the adjusting motor is placed between the sliding surface of the adjusting lever and a fixed sliding surface. In the "Sulzer" projectile loom, known torsion...

Carbon nanotubes 1,2 can be distinctly metallic or semiconducting depending on their diameter and chirality 3 . Here we show that continuously varying the chirality by mechanical torsion 4 can induce conductance oscillations, which can be attributed to metal -semiconductor periodic transitions. The phenomenon is observed in multiwalled carbon nanotubes, where both the torque 5 and the current are shown to be carried predominantly by the outermost wall . The oscillation period with torsion is consistent with the theoretical shifting 8 of the corners of the first Brillouin zone of graphene across different subbands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Carbon nanotubes could be ideal torsional springs for nanoscopic pendulums 4,9,10 , because electromechanical detection of motion could replace the microscopic detection techniques used at present. Our experiments indicate that carbon nanotubes could be used as electronic sensors of torsional motion in nanoelectro-mechanical systems . Owing to the promise of carbon nanotubes for application in nanoelectromechanical systems (NEMS) , the effects of mechanical deformations on their electronic properties have attracted great interest 14 . Linear electromechanical responses have been observed for axial , radial 17 and flexural 18 strain. Torsional electromechanical effects have been predicted by several groups , but not yet observed. Conductance oscillations have been observed with magnetic fields 6 and gating , but not with strain. To measure the conductance of carbon nanotubes under varying torsional strain, we built torsional nanotube-based NEMS as shown in Fig. , where a suspended multiwalled carbon nanotube is mechanically and electrically connected to a pair of electrodes and a small pedal in the middle. The nanotube is twisted by pressing against the pedal with an atomic force microscope (AFM) tip, and the electrodes allow us to simultaneously measure the twoterminal conductance across the nanotube. The devices were fabricated in an electron-beam lithography lift-off process, followed by wet etching and critical-point drying. Similar devices have been built with multiwalled 5,9,23 and single-wall 10 carbon nanotubes, and used as torsional pendulums 9,10 and nanorotors , but no torsion-dependent electrical measurements were reported.

In the article, the authors present an advanced model of hyperbolic torsion spring based on the Finite Element Method (FEM). This model takes into account the contact forces between the spring arms, which allows you to simulate its operation even in the case of a large twisting angle. On the basis of this FEM model, the spring stiffness characteristics were constructed. Based on this characteristics, the existing 2S1 track platform model has been rebuilt. In this model, a much higher mass of the body is allowed than in the original model. On the basis of the elastic spring model, parameters such as the static deflection of the suspension have also been determined, as well as its range of mobility compared to the original suspension based on torsion bars. In addition, spring deflection phases have been presented in terms of internal stresses, which are important for the strength analysis of the spring. The originality of the described solution lies in the unique design of the so-called a hyperbolic spring. This design has not been previously described in the literature.

In specific energy saving measures, special attention is paid to driving technologies, as electric drives account for two thirds of industrial energy consumption. Paper deals with appropriate selection of electric motor with higher efficiency for shuttleless weaving grapple machine in order to retrofitting the electric drive. Such machines are not single pieces, but are always a certain se t of a given production company. Once electricity consumption is reduced by investing in energy-saving engines, this can be the basis for intelligent and efficient energy management, accurate predictions of electricity consumption for future periods, which ultimately leads to increased energy efficiency of manufacturing enterprises.and systems.

A general scheme as been presented for deriving the equations of motion for classical particles in the presence of given external fields. In this paper we illustrate the method for the case of a massive chargeless particle whose spin interacts with the curvature and torsion of a gravitational field. We solve these equations for the case of a constant vector torsion.

Hospital beds are mainly designed to carry static load of patients and to provide more comfort to them by means of their ergonomic design. As a result, in the case of bed ridden patients bystanders will have to put in a lot of effort to move the patients to various positions, which are essential for their quick recovery. Patients will also have to be moved to various positions in order to prevent further complications in their existing medical conditions. Hence an affordable bed having various movements to bring the patients into suitable comfort positions becomes a necessity. The authors aim to solve these problems by the development of a conceptual bed here onwards known as care bed. Care bed is a novel concept which, by providing an additional side wise movement to the bed in addition to the bed to wheel chair transformation movements. As a surplus benefit of this added movement, easy transformation of patients from bed to stretcher became much simpler and easier to accomplish. T...

The resultant response of the rotating torsion bar antenna for gravitational waves discussed in [M. Ando et al., Phys. Rev. Lett. 105 (2010), 161101.] is re-investigate from a general-relativistic point of view. To do this, the equation of motion of a free falling particle in the proper reference frame of a rotating observer is used. As a result, the resultant response derived in the above paper is also valid even when ωg ∼ Ω, where ωg and Ω are the angular frequencies of gravitational waves and the rotation of the antenna, respectively.

One of the promising capabilities of magnetic microswimmers is towing a cargo, which can be used for targeted drug delivery or performing tissue biopsy. A key question is what should be the optimal size ratio between the cargo and the swimmer's exible tail. This question is addressed here for the simplest theoretical model of a magnetic microswimmer undergoing planar undulations a spherical load connected by a torsion spring to a rigid slender link. The swimmer's dynamic is formulated and leading-order expressions for its motion are obtained explicitly under small-amplitude approximation. Optimal combinations of magnetic actuation frequency, torsion stiness, and tail length for maximizing displacement, average speed or energetic eciency are obtained. The theoretical results are compared with reported experiments in several types of cargotowing magnetic microswimmers. Recent technological progress has enabled manufacturing and operation of micro-and nanorobotic swimmers, which are commonly actuated by a time-varying external magnetic eld whose direction is either rotating or oscillating in plane. 13 The design of such microswimmers is greatly inspired by swimming microorganisms 4 , whose motion is governed by low Reynolds number hydrodynamics, where viscous eects dominate while inertial eects are negligible. 1 Three dierent types of magnetic microswimmers currently exist, listed as follows. The rst type is made of a rigid helix which is possibly connected to a spherical head or cargo. The swimmer is propelled in a corkscrew-like motion under application of a rotating magnetic eld, cf. 3 The second type 57 consists of a rigid magnetic head attached to a exible thin lament, under a magnetic eld with a constant component superposed with a rotating component in a perpendicular plane. Under the combined magnetic eld, the exible wire deforms into a constant helical shape and the microswimmer again moves in steady corkscrew motion. The third type of a magnetic microswimmer is actuated by a magnetic eld whose direction undergoes periodic oscillations within a plane, which induce planar undulations of the swimmer's shape that result in net propulsion. A pioneering example of this type of microswimmer has been demonstrated by Dreyfus et al, 1 which consisted of a chain of magnetized beads connected by DNA links and composing a exible magnetic tail which was attached to a red blood cell. Other recent versions of planar microswimmers of this type are the bio-inspired magnetopserm swimmer of Khalil et al, 8 as well as the microswimmers of Jang et al, 9 which are composed of discrete chains of two or three rigid links connected by exible hinges, whose dynamics has been analyzed theoretically in. 10 These three types of microswimmers dier fundamentally in their direction of net motion: for the rst swimmer type, the direction is determined only by the handedness of the rigid helix, so that reversing the sense of the rotating magnetic eld results in reversing the swimming direction. On the other hand, the second and third types of swimmers with a exible tail swim towards the direction of the constant component of the magnetic eld and orient themselves with the magnetic part at the front. Therefore, the microswimmers in 6,8 and 9 move towards their magnetic head while in Dreyfus' microswimmer 1 the non- magnetic red blood cell is pulled towards the magnetic tail. Another key dierence between the three types of magnetic microswimmers is the dependence on actuation frequency ω of the magnetic eld: for the rst type of rigid helical swimmer, the forward speed V increases linearly with ω until reaching an ultimate upper bound at a critical value of ω called step-out

Torsion-balance measurements became well known in the early 1900s, with Eötvös' famous high-precision verification of the equivalence of gravitational and inertial mass. This equivalence later became the basis of general relativity. A new golden age of these measurements began in 1985, when Fischbach and his colleagues discovered regularities in the small deviations detected by Eötvös, which had previously been considered random. This led to the shortrange 5th force hypothesis, whose existence and source still have not yet been proven. Our research team started to work on the modernization of the Eötvös torsion-balance, the repetition of the EPF equivalence principle measurement and the investigation of the source of the 5th force in connection with the Eötvös Year 2019. During the experiment, particular emphasis was put on the analysis of environmental (e.g. microseismic) disturbances and the detection and filtering of the resulting, sometimes systematic, errors. These perturba...

In the 20 th century, a large amount of torsion balance measurements have been carried out around the world. The measurements still provide a good opportunity to detect the lateral underground mass inhomogeneities and the geological fault structures using the so called edge effects in gravity gradients. Hitherto almost 60000 torsion balance measurements were made in Hungary mainly for geophysical purposes. Only the horizontal gradients were used for geophysical prospecting, the curvature gradients measured by torsion balance remained unused. However, curvature gradients are very useful data in geodesy, using these gradients precise deflections of the vertical can be calculated by interpolation and using astrogeodetic determination of the geoid the fine structure of the geoid can be derived. In our test area a geoid with few centimeters accuracy was determined based on the curvature data. Based on the horizontal and the curvature gradients of gravity the full Eötvös tensor (including the vertical gradients) can be derived by the 3D inversion method. In our earlier research works additional new torsion balance measurements were necessary. Applying the new technical opportunities we reconstructed and modernized our older instruments, and additional torsion balance measurements have been made to study the linearity of gravity gradients.

The main problem of torsion balance measurements is the long damping time however it is possible to significantly reduce it by modern technology. The damping curve can be precisely determined by CCD sensors as well as computerized data collection and evaluation. The first part of this curve makes it possible at least theoretically to estimate the final position of the arm at rest. A finite element solution of a fluid dynamics model based on Navier-Stokes equations is presented here to solve the problem.

This paper makes an attempt to replace the existing spring damper suspension system of a vehicle by compliant mechanism. Suspension details of TATA Sumo vehicle were obtained and analysis of spring was made for static and total deflection. Initial topology of compliant mechanism was obtained through topology optimization in ANSYS. Final topology along with the shape and size of members of compliant mechanism were obtained through trial and error method. Modal and harmonic analysis of obtained compliant mechanism was done to get frequency response curve which subsequently used for calculation of equivalent damping coefficient of compliant mechanism. Using the equation of force transmissibility, force transmitted at various frequency ratios was calculated with the help of equivalent damping coefficient obtained for compliant mechanism. These obtained values of force transmission were then compared with the corresponding values of spring damper suspension system. the force transmission...

Analysis of human running has revealed that the motion of the human leg can be modeled by a compression spring because the joints of the leg behave like a torsion spring in the stance phase. In this paper, we describe the development of a joint mechanism that mimics the elastic characteristics of the joints of the stance leg. The knee was equipped with a mechanism comprising two laminated leaf springs made of carbon fiber-reinforced plastic for adjusting the joint stiffness and a worm gear in order to achieve active movement. Using this mechanism, we were able to achieve joint stiffness mimicking that of a human knee joint that can be adjusted by varying the effective length of one of the laminated leaf springs. The equation proposed for calculating the joint stiffness considers the difference between the position of the fixed point of the leaf spring and the position of the rotational center of the joint. We evaluated the performance of the laminated leaf spring and the effectiveness of the proposed equation for joint stiffness. We were able to make a bipedal robot run with one leg using pelvic oscillation for storing energy produced by the resonance related to leg elasticity.

Curved envelope structural building envelopes have been quite popular in architecture in the past decades, and pose many challenges in their design, manufacturing and planning. In gridshells, a popular structural morphology for curved structure, designers will often strive to orient beams such that their top face is parallel to the envelope surface. However, this tends to induce geometrical torsion along the beam centerline, which complexifies significantly the manufacturing of the connection nodes or of the beams themselves. It is well known that such issue can be avoided by aligning beams with principal curvature directions of the envelope surface, thus yielding a quadrangular paneling. In this article, we study how other types of patterns (non-quadrangular) can be used to design torsion-free gridshells. Based on asymptotic considerations, we derive a set of geometrical rules which, if fulfilled by a pattern, insure that a surface can be covered by this pattern with negligible torsion and limited deviation of beams from surface normals. A wide variety of patterns fulfill these rules, offering interesting possibilities for the design of curved architectural envelopes (Figure ) is shown. As these rules are based on first order asymptotic analysis, we perform global validation on case studies. One main application is for structures in which face planarity is not necessary, for example ones cladded with ETFE cushions.

Curved envelope structural building envelopes have been quite popular in architecture in the past decades, and pose many challenges in their design, manufacturing and planning. In gridshells, a popular structural morphology for curved structure, designers will often strive to orient beams such that their top face is parallel to the envelope surface. However, this tends to induce geometrical torsion along the beam centerline, which complexifies significantly the manufacturing of the connection nodes or of the beams themselves. It is well known that such issue can be avoided by aligning beams with principal curvature directions of the envelope surface, thus yielding a quadrangular paneling. In this article, we study how other types of patterns (non-quadrangular) can be used to design torsion-free grid-shells. Based on asymptotic considerations, we derive a set of geometrical rules which, if fulfilled by a pattern, insure that a surface can be covered by this pattern with negligible to...

In this paper, an attempt is made to replace the existing spring-damper suspension system of a two-wheeler by the compliant mechanism. Suspension details of Hero Igniter bike were obtained and analysis of spring was made for static and total deflection. The initial topology of compliant mechanism was obtained through topology optimization in ANSYS. Final topology along with the shape and size of members of compliant mechanism were obtained through trial and error method. Modal and harmonic analysis of obtained compliant mechanism was done to get frequency response curve which subsequently used for calculation of equivalent damping coefficient of the compliant mechanism. Using the equation of force transmissibility, the force transmitted at various frequency ratios was calculated with the help of equivalent damping coefficient obtained for the compliant mechanism. These values of force transmission were then compared with the corresponding values of the spring-damper suspension syste...

Robot dynamics is necessary not just for simulation and control, but also for the analysis of robot motion planners and controllers. There are a number of dynamic modelling investigations of robots with the different approaches and these investigations mostly focus on the link flexibility, joint friction or actuator dynamics. In addition to that these studies present dynamic model without any attached linear or torsion springs. In this study, the dynamic modelling of a two-link rigid manipulator with attached torsion springs is presented using the Lagrangian approach. The Lagrangian approach is a variational method that relies on the kinetic and potential energy of the mechanism, making it well-suited for the analysis of the two-link planar manipulator considered in this study. Initially, the equations of motion for the two-link rigid mechanism is derived without any attached torsion springs. Subsequently, two torsion springs are attached to the joints of the mechanism, and the existing equations of motion are modified accordingly. The study also presents the kinetic, potential and total energies of the two link-manipulator, angular positions of the links and their velocities. By considering the dynamic modelling of the torsion spring attached two-link rigid manipulator, this study contributes to understanding and analysis of the two-link manipulators and the dynamic effects of the attached springs.

Human-like motion is often considered a key feature for intuitive human-robot interactions. In fact, this feature allows human peers to easily predict the robot's intention, which is perfectly aligned with the paradigm of collaborative industries, contributing to more human-centric and resilient industries. The one-sixth power law (1/6-PL) is well known in human motor control. In this work, the Human-like Upper-limb Motion Planner is used to generate three-dimensional (3D) movements of an anthropomorphic robotic arm. By applying direct kinematics, the position and orientation of the hand of the robot is determined. Subsequently, the respective curvature, torsion and velocity are computed. From a total of 600 movements, divided in six sessions, non-linear regression models are fitted and validated, in order to obtain the slope in the log-space of these movements. A statistical analysis of the parameters of the 1/6-PL is performed, and parametric and non-parametric tests are used to compare the results in each of the six sessions.

The torsion balance is one of the key pieces of apparatus used in experimental searches for weak forces. In the search for an understanding of a Unified Theory, physicists have suggested a number of signatures that are detectable in laboratory measurements. This thesis describes the development of a new torsion balance facility, relocated from the BIPM (Bureau International des Poids et Mesures) [1], which has excellent environmental stability and benefits from a new compact interferometric readout for measuring angular motion which has been characterised and installed onto the torsion balance. The interferometer has sensitivities of 5 × 10 −11 radians/ √ Hz between 10 −1 Hz and 10 Hz, an angular range of over ±1 • and significantly reduces sensitivity to ground tilt. With the new facility the first experiment searching for temporal variations in the Newtonian gravitational constant has been undertaken with a null result for δG/G 0 for both sidereal and half sidereal signals at magnitudes greater than 5×10 −6. These results have been used to set an upper limit on some of the parameters within the Standard Model Extension framework [2]. The thesis also reports on the design and manufacture of prototype test masses with a high electron-spin density of approximately 10 24 and negligible external magnetic field ≤ 10 −4 T. These test masses can be used within the facility to potentially make it sensitive enough to conduct future spin-coupling experiments. In the name of God the Beneficial the Merciful. Firstly I would like to thank Professor Clive. C. Speake for giving me the opportunity to undertake this work. His support throughout the project but specifically near the end when things were particularly difficult was much appreciated. I thank him for always giving me his time even when I randomly turned up outside his office. Secondly my thanks to Dr. Ludovico Carbone who I had the pleasure of working with for a couple of years. His knowledge of the apparatus and practicality when undertaking experimental measurements was an inspiration for me. I can't thank Ludovico enough for his continued support and guidance even after his time with this experiment, it will always be remembered. A big thanks also to Dr. Fabian Peña-Arellano who was greatly supportive during the time of the interferometer development. I thoroughly enjoyed working with him and hope our communication will continue into the future. It has also been a pleasure to work with some of the other colleagues within the group, Dr.

The torsion balance is one of the key pieces of apparatus used in experimental searches for weak forces. In the search for an understanding of a Unified Theory, physicists have suggested a number of signatures that are detectable in laboratory measurements. This thesis describes the development of a new torsion balance facility, relocated from the BIPM (Bureau International des Poids et Mesures) [1], which has excellent environmental stability and benefits from a new compact interferometric readout for measuring angular motion which has been characterised and installed onto the torsion balance. The interferometer has sensitivities of 5 × 10 −11 radians/ √ Hz between 10 −1 Hz and 10 Hz, an angular range of over ±1 • and significantly reduces sensitivity to ground tilt. With the new facility the first experiment searching for temporal variations in the Newtonian gravitational constant has been undertaken with a null result for δG/G 0 for both sidereal and half sidereal signals at magnitudes greater than 5×10 −6. These results have been used to set an upper limit on some of the parameters within the Standard Model Extension framework [2]. The thesis also reports on the design and manufacture of prototype test masses with a high electron-spin density of approximately 10 24 and negligible external magnetic field ≤ 10 −4 T. These test masses can be used within the facility to potentially make it sensitive enough to conduct future spin-coupling experiments. In the name of God the Beneficial the Merciful. Firstly I would like to thank Professor Clive. C. Speake for giving me the opportunity to undertake this work. His support throughout the project but specifically near the end when things were particularly difficult was much appreciated. I thank him for always giving me his time even when I randomly turned up outside his office. Secondly my thanks to Dr. Ludovico Carbone who I had the pleasure of working with for a couple of years. His knowledge of the apparatus and practicality when undertaking experimental measurements was an inspiration for me. I can't thank Ludovico enough for his continued support and guidance even after his time with this experiment, it will always be remembered. A big thanks also to Dr. Fabian Peña-Arellano who was greatly supportive during the time of the interferometer development. I thoroughly enjoyed working with him and hope our communication will continue into the future. It has also been a pleasure to work with some of the other colleagues within the group, Dr.

This paper deals with an approximate solution of Saint-Venant torsion problem of orthotropic bar with solid cross section. The boundary collocation is used to get the approximate analytical solution of the torsion problem. Examples illustrate the applications of the presented numerical solution.

The suspension system of track vehicles is often equipped with torsion bars. The torsion bar is a key element of the vehicle's suspension system. The service life of torsion bars depends primarily on the quality of the material used, the diameter of the torsion bars and the method of attachment and placement. In order to obtain the characteristics of the torsion bar, an experimental test stand was created on which accelerated tests were performed. Furthermore, a virtual model of torsion bar operation was created. The torsion bar was modelled using finite elements (FE part). Dynamic simulation was performed using MSC Adams software. Finally, the values measured in the accelerated tests and the results of simulations were compared. Comparing the values found, it was proved that this difference is not significant. This virtual model can be used to investigate the service life of torsion bars and to predict their service life.

The laminated torsion bar is used for many mechanical purposes where a large angle with decreasing or increasing torque is necessary. The design of laminated torsion bar relates to dissipation of energy by friction between laminae, number of laminae and clamp conditions at the end of bar. The paper presents theoretical, experimental and numerical analysis of a laminated torsion bar with different numbers of laminae. Results show that in the design of a laminated torsion bar it is necessary to consider correction coefficients with respect to the geometry of laminae and the clamping conditions on both sides of the laminated torsion bar. In this paper the correction coefficients are experimentally determined. We present the procedure for determination of correction parameters for the calculation of the laminated torsion spring characteristics with a relatively large ratio of width and thickness, (h/b > 7) for low rigidity of the individual lamella.

A main component of the car suspension is the stabiliser bar, that has the role to reduce the roll oscillations, and it is constructively materializes, within the conventional suspension, via a transversal torsion bar connected direct and indirect between the wheels of the axle. There are constructive solutions of suspensions with torsion bar as elastic element, longitudinal disposed, and that replaces the conventional stabiliser bar with a flexible lamella connected between the ends of the longitudinal torsion bars. So, the flexible lamella has two functions: reduces the roll oscillations and works as an additional elastic element of the suspension. Via this second function it is improved the elastic characteristic aspect of the suspension with positive consequences on the comfort and safety. The paper aims to highlight this influence by the experimental determination of the elastic characteristic of the suspension with and without lamella and the comparing of the two elastic characteristics. It is carried out and a complex theoretical model of the suspension with longitudinal torsion bars and flexible lamella, validated via the experimental research, that allows the optimization of such a suspension.

We have newly interpreted the Newtonian gravitational constant G as the gravitational inertia of vacuum G0. The source mass inserted into vacuum decreases this value G0 to GZ on the dependence of the atomic number Z of atoms in the source mass. This is the mechanism for the attraction of test masses through vacuum – the test mass follows the decrease of the gravitational inertia of vacuum towards the source mass. We have extracted the relationship GZ = G0 (1 – k Z) where k is the experimental constant from ten actual precise experimental determinations of GZ. This model was tested on two precise experimental values of GZ determined for GEARTH, and GBRASS. This model enables to predict values GZ for atoms, molecules and compositions of the studied source masses and to realize experimental verification with the existing experimental technology. The experimental GZ values are thus arranged into a system and the spread in these data is explained as the influence of atoms of the source m...

To investigate the mechanical behavior of bidirectional spring units used as isolators in a kind of isolated floor system, three types of characterization tests were conducted-from spring components alone to the complete spring unit in its implemented configuration. The test results show that the behavior of the springs and spring units is stable when subjected to cyclic repeated motions, and is not sensitive to the velocity of motion. The hysteretic behavior of the spring units was found to be unconventional, with bilinear and different ascending ͑loading͒ and descending ͑unloading͒ branches. Based on the experimental behavior, a physical model was developed to replicate the unique behavior of such bidirectional spring units. Good agreement was found from the comparison between the results from the physical model and the corresponding tests. Finally, a sensitivity study, with respect to the model's four primary defining parameters, shows that this physical model is more sensitive to the sliding friction coefficient between the spring cable and the bushing in the spring unit than to the other three parameters.

To investigate the mechanical behavior of bidirectional spring units used as isolators in a kind of isolated floor system, three types of characterization tests were conducted-from spring components alone to the complete spring unit in its implemented configuration. The test results show that the behavior of the springs and spring units is stable when subjected to cyclic repeated motions, and is not sensitive to the velocity of motion. The hysteretic behavior of the spring units was found to be unconventional, with bilinear and different ascending ͑loading͒ and descending ͑unloading͒ branches. Based on the experimental behavior, a physical model was developed to replicate the unique behavior of such bidirectional spring units. Good agreement was found from the comparison between the results from the physical model and the corresponding tests. Finally, a sensitivity study, with respect to the model's four primary defining parameters, shows that this physical model is more sensitive to the sliding friction coefficient between the spring cable and the bushing in the spring unit than to the other three parameters.

We analyze the initial motion of an elastic bar that is suddenly released after being hung from one end. The analytical solutions uncover some unexpected properties, which can be checked with a digital camera or camcorder in an alternative setup in which a spring is substituted for the bar. The model and the experiments are useful for understanding the similarities and differences between the elastic properties of bars and springs. Students can use the simple experiments to improve their understanding of elastic waves.

Tracked vehicles fitted with torsion bar suspensions are limited in their ability to achieve high mobility. This limitation is due to the linear characteristics and the consequent poorer ride performance. Hydro-gas suspensions due to their inherent non-linear behavior can provide higher mobility and better ride comfort performance. The hydro-gas suspension model has usually been developed from experimental force-displacement characteristics, which requires availability of suspension hardware. In this paper, a hydro-gas suspension system is modeled using polytropic gas compression model to represent the spring characteristics, while the damper orifices are modeled using hydraulic conductance. The analytical model is then validated with experiments individually for spring and damper flow characteristics and then as a suspension-wheel assembly in a test rig. The validated suspension model is incorporated in an in-plane model. Using this model, simulation is carried out for sinusoidal inputs of different wavelengths, amplitudes and vehicle speeds. The simulation model is validated with data measured on a vehicle traversing an APG course. The proposed model agrees very well with the measured data. Based on the validated model, studies on the influence of suspension parameters on the ride comfort of a tracked vehicle are carried out.

The design of torsional springs for Series Elastic Actuators (SEAs) is challenging, especially when it comes to balancing good stiffness characteristics and efficient torque robustness. This study focuses on the design of a lightweight, low-cost, and compact torsional spring for use in rotary series elastic actuator (ES-RSEA) of lumbar support exoskeleton. The exoskeleton is used as an assistive device to prevent lower back injuries. The torsion spring was designed following design for manufacturability (DFM) principles, focusing on minimal space and weight. The design process consisted of determining the potential topology and optimizing the selected topology parameters through finite element method (FEM) to reduce equivalent stress. The prototype was made using a waterjet cutting process with low-cost material (AISI-4140-alloy) and tested using a custom-made test rig. The results showed that the torsion spring had a linear torque-displacement relationship with 99% linearity, and t...

The torsion presetting of a spring-bar is a common technique for extending the elastic twist-angle and increasing torque, but it reduces fatigue lifetime. Spring-bars are used as shock absorbers in caterpillar machines. Spring-bars, made from high strength fine-grain steel, grade VCN, provide a high level of absorbed energy. Any slight change in the presetting procedure has a strong influence on fatigue-lifetime. Within the same loading range, springs can exhibit low-cyclic or high-cyclic fatigue behavior regarding different presetting levels. A model for fatigue-lifetime and shear-stress levels is proposed on the basis of performed tests. Considering prescribed fatigue tests, it is possible to optimize a spring bar's geometry, in order to survive the required number of cycles.

This paper presents a matrix method for stiffness estimation of a general rotational serpentine spring and numerical simulation of electrostatically actuated torsional micromirrors with two symmetrically attached rotational serpentine springs having two serpentine cycles (N=2). Modelling of this kind of micromirrors is carried out for the purpose of designing very soft planar springs for torsional micromirrors that are fabricated by the sophisticated surface micromachining technology. Torsional and bending spring constants of a rotational serpentine spring with 2 serpentine cycles are deduced by matrix method. Thus the static and dynamic performance of an electrostatica actuated torsional micromirror composed of these springs (N=2) are analyzed, and also simulated by the FEA tool (ANSYS), wherein both SOLID45 and TRANS126 elements are selected for structural meshing and electrostatic elements. The difference between analytical and simulated results is clearly shown and analyzed. Electrostatic effects of varied parameters of the springs are also analyzed.

The aim of this investigation is to study the motion of an elastically restrained beam used in tapping mode atomic force microscopy (TM-AFM), which is to be utilized in manufacturing at nano-scale. TM-AFM uses high frequency oscillations to remove material or shape nano structures. Euler-Bernoulli theory and Eringen's theory of non-local continuum are used to model the nano machining structure composed of a nanobeam and a single degree of freedom, spring-mass system. The system is modelled as a beam with a torsional spring boundary condition that is rigidly restrained in the transverse direction at one end; and at the free end is a transverse linear spring attached to the tip. The other end of the spring is attached to a mass, resulting in a single degree of freedom spring-mass system. When the linear spring constant is infinite, the free end behaves as a beam with a concentrated tip mass. When the mass is infinite, the boundary condition is that of a linear spring. When the tip mass is zero, the configuration is that of a torsionally restrained-free beam. The motion of the tip of the beam and tip mass can be investigated to observe the tip frequency response, displacement and force. The tip displacement frequency contains information about the maximum displacement amplitude and therefore the sample penetration depth.

This paper presents the design and construction of an unprecedented, controllable stiffness, elastic series actuator, using two flat spiral torsion springs. This actuator has some advantages compared to elastic series actuators with fixedspring rigidity, which either have little rigidity, and end up deforming undesirably, or have a lot of rigidity and end up damaging themselves and the environment around them. The proposed solution aims to maintain the functionality of protecting the robot and its surroundings, absorbing any unexpected impact that may happen during this interaction. Compliance, combined with intelligent control systems capable of dealing with dynamic environments, has the potential of allowing the development of more versatile robots, as compliant actuators can be under-actuated and embedded computer systems tend to increase in capacity and reduce in cost. The research goes from computer-aided mechanical design, mathematical modeling of a spring and design of compon...

An analytical solution of Saint-Venant's torsion for circular bar with a slit extending in radial direction from the boundary to the axis of bar is presented. The material of the bar is non-homogeneous, isotropic linearly elastic. The shear modulus of the bar is a smooth function of the radial coordinate. This type of the material inhomogeneity is called functionally graded material. The shear modulus as a function of radial coordinate is assumed to be described by a power law function. For arbitrary value of power law index the solution in closed form is obtained for the Prandtl's stress function, shearing stresses, torsion function and torsional rigidity. Results of the presented analytical method are compared with FEM solution.

Torsional bar is used in driver seat for off road vehicle is important for driver comfort. Generally, Torsional bar is designed to absorb both shock and impact load. The proposed work is a special kind of torsion bar for absorbing vibration on the driver seat. A stepped bar with control arm used a mechanism and that bar could be made by two different stiffness to absorb loads transmitted to driver seat. We have analyses the shearing stress distribution, deflection, stiffness and dimensions for proposed stepped bar by using ANSYS and compared the results with numerical result.

The method of approach used in the present study 3 1 Tension-torsion experimental set up 3 2 Schematic diagram of the machine (front view) 3 3 Schematic diagram of the machine (side view) 3 4 The schematic diagram of a moog brushless drive system 3 5 Schematic diagram of a moog brushless servomotor 3 6 The characteristic curve of motor-1 3 7 The characteristic curve of motor-2 3 8 The flow chart of the operation principle of the controllers 3 9 Various connections of the controller and the power supply unit 3 10 Circuit diagram among the controllers and the motors 3 11 The output characteristic curve of the angle measuring transducer 3 12 The RDP Module 600 amplifier 48 3 13 The front panel for constant load test 3 14 The block diagram for constant load test 3 15 The front panel for constant axial displacement test 3 16 The block diagram for constant axial displacement test 3 17 The front panel for constant angular twist test 3 18 The block diagram for constant angular twist test 3 19 The front panel for constant torque test 3 20 The block diagram for constant torque test 3 21 Block diagram of device 1 AT-AO-6 3 22 AT-AO-6 DAQ device 1 3 23 Block diagram of device2 AT-MIO-I6E-IO 3 24 At-MIO-16E DAQ device2 3 25 Axial load calibration curve 3 26 Torque load cell calibration curve 3 27 LVDT calibration curve 3 28 Angle of twist calibration curve 3 29 Geometry of the specimen 3 30 The assembly drawing of the thin-walled tube 331 Specially designed head to fit with the thin-walled tube 3 32 Different types of strain gauges used 4 1 Axial stress versus axial strain 4 2 Uniaxial tensile load versus axial strain 4 3 Torque versus shear strain curve 4 4 Normalised axial load versus normalised torque curves (constant axial displacement) 86 4 5 Normalised shear strain versus normalised axial load and torque curves (F=YL) 88 4 6 Normalised shear strain versus normalised axial load and torque curves (F=75%YL)

The method of approach used in the present study 3 1 Tension-torsion experimental set up 3 2 Schematic diagram of the machine (front view) 3 3 Schematic diagram of the machine (side view) 3 4 The schematic diagram of a moog brushless drive system 3 5 Schematic diagram of a moog brushless servomotor 3 6 The characteristic curve of motor-1 3 7 The characteristic curve of motor-2 3 8 The flow chart of the operation principle of the controllers 3 9 Various connections of the controller and the power supply unit 3 10 Circuit diagram among the controllers and the motors 3 11 The output characteristic curve of the angle measuring transducer 3 12 The RDP Module 600 amplifier 48 3 13 The front panel for constant load test 3 14 The block diagram for constant load test 3 15 The front panel for constant axial displacement test 3 16 The block diagram for constant axial displacement test 3 17 The front panel for constant angular twist test 3 18 The block diagram for constant angular twist test 3 19 The front panel for constant torque test 3 20 The block diagram for constant torque test 3 21 Block diagram of device 1 AT-AO-6 3 22 AT-AO-6 DAQ device 1 3 23 Block diagram of device2 AT-MIO-I6E-IO 3 24 At-MIO-16E DAQ device2 3 25 Axial load calibration curve 3 26 Torque load cell calibration curve 3 27 LVDT calibration curve 3 28 Angle of twist calibration curve 3 29 Geometry of the specimen 3 30 The assembly drawing of the thin-walled tube 331 Specially designed head to fit with the thin-walled tube 3 32 Different types of strain gauges used 4 1 Axial stress versus axial strain 4 2 Uniaxial tensile load versus axial strain 4 3 Torque versus shear strain curve 4 4 Normalised axial load versus normalised torque curves (constant axial displacement) 86 4 5 Normalised shear strain versus normalised axial load and torque curves (F=YL) 88 4 6 Normalised shear strain versus normalised axial load and torque curves (F=75%YL)

This paper presents the failure analysis of an automobile tension spring which failed during assembly. The fractured surfaces as well as the surface of the tension spring material close to the fractured surface were examined in a scanning electron microscope at suitable magnification. Optical microscopy was performed to evaluate the basic microstructure of the as received material. Detailed electron microscopic studies have indicated that the failure was due to presence of surface cracks near the surface of the spring material.

To determine the elastic/plastic deformation value of the part, we used Ansys R19.0 software(CAE), to simulate a torque moment applied to the functional area part, which provided the information set about the part behavior. The mold of the part has 4 cavities, and the part material is a polyamide. Having a requirement imposed by the customer on the drawing, we considered this finite element analysis it is necessary before start manufacturing the molding and starting injection the parts to demonstrate that the customer requirement is achievable. The results obtained from the analysis with finite elements in ANSYS R19 showed that the constructional part could not fulfill the design requirement, namely to withstand a torque of 4500Nmm the part being fixed in the hole with a diameter of 2.5 mm. After analyzing the results, the client will have to modify the current drawing based on the results obtained by us, namely to reduce the torque value from 4500Nmm to 4000.3 Nmm.

The deformation of an aluminum plate, called in this paper, a support plate, which is part of a bending plastic deformation device, is studied in this paper using the Finite Elements Method, respectively design points of the design by optimization using features such as Design of Experiments and Response Surfaces. The start of the analysis was determined by a functional requirement in the design and construction of a sophisticated bending device controlled by steel plates for the production of exhausts for cars. To optimize the project, it was necessary to analyze the behavior of the active material and components of the device. The analysis of material and piece behavior, in working conditions, has been developed by addressing the facilities offered by Ansys software. Following FEA analysis, optimizing the active components of the device has provided proven results in practice through the execution and operation of the device, according to the technology required by the product des...

In this paper we aim to experimentally determine the bearing capacity (the momentum) of the elastic bracelet assemblies. The moment of torsion transmitted by the assembly depends on the clamping force of the assembly and on the friction coefficient between the bushing mounted on the shaft and the hub of the assembly. An experimental stand is used which comprises a hub shaft assembly with a segmented elastic bracelet. The load bearing capacity of the elastic bracelet is determined depending on the strength of the screws. Experimental determination is made on three types of materials. For this purpose, on the shaft is assembled a bush made of different materials: aluminum, bronze, steel. In order to determine the capable assembly moment, strain gauge transducers are used to measure the elastic strains. The recording of the deformations is done by means of an efficient data acquisition system. The assembly characteristic is plotted, namely the dependence between the torque transmitted according to the tightening of the bolts, for three couples of materials.

The thermodynamic dislocation theory developed for non-uniform plastic deformations is used here in an analysis of a bar subjected to torsion. Employing a small set of physics-based parameters, which we expect to be approximately independent of strain rate and temperature, we are able to simulate the torque-twist curve for a bar made of single crystal copper that agrees with the experimental one.

Tracked vehicles fitted with torsion bar suspensions are limited in their ability to achieve high mobility. This limitation is due to the linear characteristics and the consequent poorer ride performance. Hydro-gas suspensions due to their inherent non-linear behavior can provide higher mobility and better ride comfort performance. The hydro-gas suspension model has usually been developed from experimental force-displacement characteristics, which requires availability of suspension hardware. In this paper, a hydro-gas suspension system is modeled using polytropic gas compression model to represent the spring characteristics, while the damper orifices are modeled using hydraulic conductance. The analytical model is then validated with experiments individually for spring and damper flow characteristics and then as a suspension-wheel assembly in a test rig. The validated suspension model is incorporated in an in-plane model. Using this model, simulation is carried out for sinusoidal inputs of different wavelengths, amplitudes and vehicle speeds. The simulation model is validated with data measured on a vehicle traversing an APG course. The proposed model agrees very well with the measured data. Based on the validated model, studies on the influence of suspension parameters on the ride comfort of a tracked vehicle are carried out.

Variable stiffness joints are essential for robots or biomechanical applications to generate torque with sufficient compliance to ensure safety simultaneously. This paper presents the dimensioning of the elastic element for an actuator with Variable Torsion Stiffness (VTS). Analytical and finite element calculations are compared to experimental evaluation of a splined shaft profile realized in a prototype implementation. Based on simplifications and effects in the real test-rig the results show similar behaviour. Furthermore, an analytical and finite element investigation of four cross-sections with torsional load illustrate optimal utilization of cylindrical geometries considering the torsional stress. In contrast, the low stressed edges of uncylindrical cross-sections are adequate areas to bear additional stresses.

Hydro-gas suspension systems cushion shocks and damp oscillations of vehicle hull when it moves on uneven terrain. The hydro-gas suspension provides the vehicle with proper ride comfort due to non-linear characteristics of hydro-gas units. The hydro-gas suspension system can store a large amount of potential energy; accordingly, it can withstand higher shocks than the torsion bar suspension. Consequently, it is preferred to be used in the design of vehicle suspension. In this paper, a mathematical model for hydro-gas unit used in BMR wheeled vehicle is established to evaluate its characteristics using Matlab /Simulink program. The mathematical model is validated experimentally using the data measured for the unit in laboratory using MTS (793) damper test system. The unit is tested using an input sine wave excitation by a frequency and amplitude corresponding to real road conditions.