Spring Tube Research Articles

Defining the segmental tension generated in a vertebral body tethering system for scoliosis.

Vertebral body tethering (VBT) uses a flexible tether affixed across the curve convexity with tension applied at each segment to treat scoliosis. Intraoperative tether tension may be achieved directly with a counter-tensioner or with an extension spring tube. The purpose of this study was to quantify the force generated with and without the extension spring tube using current FDA-approved VBT instrumentation, to understand the variation between surgeons using the same instrumentation, and to define the force range that is generated intra-operatively. Using a benchtop mechanical testing setup to simulate a spinal segment, we affixed the tether and applied tension using a tensioner and counter-tensioner alone (method T1) or by adding an extension spring tube (method T2). Eight orthopedic surgeons used T1 and T2 at six tensioner settings, and one surgeon completed three trials. A two-way ANOVA with a Tukey's HSD post hoc test (p < 0.05) compared the tensioner methods and testing levels. Inter- and intra-rater reliabilities were calculated using intraclass correlation coefficients (ICCs). Methods T1 and T2 exhibited linear tension-setting relationships, with high determination coefficients (R2 > 0.93). T2 consistently produced higher forces (increase of 62.1 N/setting), compared to T1 (increase of 50.6 N/setting, p < 0.05). Inter-rater reliability exhibited excellent agreement (ICC = 0.951 and 0.943 for T1 and T2, respectively), as did intra-rater reliability (ICC = 0.971).

Temperature drift mechanism of deflector jet servo valve under temperature shock

To study the mechanism of the deflector jet servo valve under temperature shock, a complete temperature theoretical model is proposed in this article. The temperature change affects the performance change of the torque motor by affecting the drift of the air gaps’ thickness, the permanent magnets’ reluctance, and the magnetomotive polarization force. Moreover, the temperature variation will act on the flow coefficient of the pilot stage, the size of the deflector, and jet pan, which influences the performance of the pilot stage hydraulic amplifier. Furthermore, the armature components, including the stiffness of the spring tube, the stiffness of the feedback rod, and the armature’s arm of force, are also related to the temperature variation. Comprehensively, considering the interaction influence of these factors, by analyzing the electromagnetic characteristics of the torque motor, the fluid mechanics’ characteristics of the pilot stage hydraulic amplifier, and the temperature performance of the armature assembly, the temperature drift model of deflector jet servo valve is constructed, which is represented as a ninth-order nonlinear equation. Based on the equation, the influence of temperature on the control precision of the servo valve is analyzed. The calculation results show that in the range of 20°C–250°C, the impact of temperature on the control accuracy will exceed 30%, the flow coefficient is the most significant affecting on the control accuracy, followed by the structural deformation of the pilot stage is the second factor affecting the temperature drift, and other factors have little effect. Comparison with the experimental results, the temperature drift model of the deflector jet servo valve can predict the control accuracy caused by temperature and provide a theoretical foundation for the optimization of the deflector jet servo valve.

Paralel Akışlı Çift Borulu Isı Eşanjöründe Yeni Pervaneli Türbülatör Tasarımının Teorik Analizi

In this study, the usage purposes of turbulators are mentioned. The advantages and disadvantages of two different turbulator models are examined. In addition, the working principle of the turbulator was examined to create the analysis conditions. Parts used in turbulators and their alternatives are introduced. The necessary engineering calculations for the analysis were made, the flow analysis to be applied to the turbulator was made and the results were interpreted. Flow simulation, one of the simulation plug-ins containing the SolidWorks commercial program, was used in the analysis. Also turbulator analysis; it was made to determine fluid pressure, fluid velocity, fluid temperature, turbulent energy, turbulent viscosity. The heat exchanger is approximately 1000 mm long. For the turbulators, copper material was chosen as its thermal conductivity is better than aluminum. In the study conducted with two types of turbulators; numerical simulation results were calculated as 4,771 Mpa, 20,15 0C, 211,168 J/kg, 14,81 Pa.s for the spring turbulator, while these values were calculated as 7,811 Mpa, 20,32 0C, 165,518 J/kg, 18,62 Pa.s for the propeller turbulator. In addition, it has been observed that the fluid velocities are 61.5 m/s for the spring turbulator and about 75 m/s for the propeller turbulator. Due to the continuous increase in turbulent energy and turbulent viscosity over time, it has been recommended to use a finned turbulator instead of a spring tube. When all these results are examined, it will open new ideas and fields of study to further improve the overall thermal-aerodynamic performance of turbulators. In this study, a design that will be an alternative to turbulator designs has been realized.

Affordable Earthquake Building

Abstract: Nowadays springs are the main component in the structures. A new low-cost seismic isolation system which is related on spring tube bracings has been proposed and studied, and according to that study when springs are performed their designated jobs there is very little reason to spare them much thought. One area that you might not have considered the worth of springs within is the science of architecture, but actually springs are being used in buildings all around the world. As per the study, multiple compression-type springs are positioned in a special cylindrical tube to obtain a symmetrical response in tension and compression-type axial loading. An isolation floor, which consists of pin-ended steel columns and spring tube bracings, is constructed at the foundation level or any intermediate level of the building. An experimental campaign with three stages was completed to evaluate the capability of the system. First, the behavior of the spring tubes subjected to axial displacement reversals with varying frequencies was determined. In the second phase, the isolation floor was assessed in the quasi-static tests. Finally, a ¼ scaled 3D steel frame was tested on the shake table using actual acceleration records. The transmitted acceleration to the floor levels is greatly diminished because of the isolation story, which effects longer period and higher damping. There are no stability and self-centering problems in the isolation floor.

Numerical simulation of heat transfer performance of different heat exchange tubes in heat recovery steam generator

For the purpose of reducing the cost of hydrogen production in process engineering and practice and enhancing the heat exchange efficiency of heat recovery steam generator, a new spring-blade mixed heat exchange tube was creatively put forward, and the performance evaluation criterion (PEC) was used as evaluation index of comprehensive heat transfer performance. To explore the heat transfer performance, the velocity distribution, temperature distribution, pressure distribution and comprehensive heat transfer performance were analyzed, and heat transfer coefficient and the value of PEC were obtained. The addition of spring and blade in the mixed heat exchange tube has obvious positive impacts on the velocity, temperature and pressure drop. In the Reynolds number range of 20000–40000, the heat exchange coefficient increment of the mixed heat exchange tube is increased by 35% and 45% than that of the spring and blade heat exchange tube respectively. The pressure drop is positively correlated with the heat exchange coefficient, and its increase leads to the decrease of PEC value.

Modeling and Analysis of the Geometry‐Dependent Mechanical and Thermal Properties of Coiled Carbon Nanotubes

Coiled carbon nanotubes (CNTs) have attracted much attention thanks to their unique geometrical structure along with outstanding mechanical and thermal properties. However, the relationship between the geometrical parameters and mechanical and thermal properties of coiled CNTs remains largely unexplored. Herein, coiled CNTs are constructed with various geometries by phase‐field crystal (PFC) modeling and their mechanical and thermal properties are investigated by molecular dynamics (MD) simulations. It is found that the effect of geometrical parameters of coiled CNTs on the Young's modulus can be well captured by analytical formulas derived from the mechanical spring tube model. These extensive MD simulations show that the Young's modulus of coiled CNTs increases with an increase in coil pitch l and CNT radius r, but decreases with an increase in coil radius R. Furthermore, using the nonequilibrium MD (NEMD) method, it is found that the thermal conductivity of coiled CNTs decreases with an increase in coil radius R, but increases slightly with an increase of coil pitch l and CNT radius r. Valuable insights into the mechanical and thermal properties of coiled CNTs are provided and the findings here may serve as useful guidelines for the design of coiled CNTs for device applications.

Mechanism of temperature-induced zero drift on electro-hydraulic servo valve

An electro-hydraulic servo valve is objectively asymmetrical in the process of fabrication and assembly, and the zero position is the result of comprehensive adjustment. During the use of the electro-hydraulic servo valve, the rapid rise of temperature will lead to the zero drift phenomenon and the change in the flow state of the servo valve. With the change in temperature, the thicknesses of air gaps, the size of the orifice, the flow coefficient, the armature’s arm of force, the permanent magnets’ reluctances, and the polarization magnetomotive force, the stiffness of the spring tube and feedback rod will act on the property of the torque motor and the pilot stage. Considering the factors of temperature and processing assembly on the zero drift of the electro-hydraulic servo valve, a mathematical theory model describing the temperature zero drift characteristics is constructed. When the temperature range is 20–270 °C, the analysis demonstrated that the control error of the servo valve will exceed the expected 15%. The temperature has the most significant effect on the servo valve through the flow coefficient. The initial installation angle deflection is the domain route on the temperature zero drift, and other factors have less effect. Compared with the experimental results, the temperature-induced zero drift model correctly calculates the control error trend of the servo valve caused by an increase in temperature, and it will contribute to improving the control precision of the servo valve.

Measurement and Evaluation of the Stiffness Characteristics of Precision Spring Tubes in Hydraulic Servovalves

Abstract The spring tube is the core component of the hydraulic servovalve, and its stiffness characteristics determine the sensitivity of the servovalve. For the difficulty in measuring and ensuring the stiffness of spring tube in complex structures, based on the principle of structural characteristics and stiffness measurement, an effective method for measuring and evaluating the stiffness of spring tube was proposed. First, by the force analysis of the spring tube in the valve structure, using improved stiffness measurement theory, an equivalent measurement model of single-arm is established. Second, the stiffness measurement system of the spring tube is constructed based on this model. Furthermore, using the deformation and the spatial position recurrence method, the accuracy of the measurement system is further improved. Thirdly, using the orthogonal test method and linear optimization method of the neural network model, the stiffness characteristics of the spring tube under the influence of different factors are studied further. Finally, the validity of the models is verified by using the software comsol and the experimental platform. The stability of the effective stiffness for the spring tube is further analyzed by the measurement data. The contribution and novelty of this paper are that based on the force analysis of the spring tube in the servovalve internal structure, an effective and systematic stiffness measurement and evaluation method are proposed. On this basis, experiments and stiffness characteristics analysis are carried out. Furthermore, several structural factors affecting the stiffness characteristics of spring tube are considered, and the stiffness characteristics of spring tube are systematically studied and analyzed. Based on this research and analysis, the systematic study of measurement and characteristics of precision components is very important for practical complex systems in this field. This makes it possible to further study the measurement of precision components which are difficult to measure in the actual structure. It is instructive to study the characteristics of precision components in complex structures.

Mathematical modeling of an armature assembly in pilot stage of a hydraulic servo valve based on distributed parameters

The dynamic performance of a nozzle-flapper servo valve can be affected by several factors such as the disturbance of the input signal, the motion of the armature assembly and the oscillation of the jet force. As the part of vibrating at high frequency, the armature assembly plays a vital role during the operation of the servo valve. In order to accurately predict the transient response of the armature assembly during the vibration, a mathematical model of armature assembly is established based on the distributed parameters method (DPM) and Hamilton principle. The new mathematical model is composed of three main parts, the modal eigenfunction, modal mechanical response expressions of the spring tube and the motion equation of the other armature assembly. After programing, the purpose of using the DPM to predict the dynamic response of different positions located on the armature assembly is achieved. For verifying the validity of the mathematical model, the finite element method (FEM) and classic model (CM) of armature assembly are applicated by commercial software under the same condition. The comparison results prove that the DPM can effectively predict the axial and tangential deflection of the armature assembly different positions which the CM can’t duing to its over-simplification. A certain error is generated when predicting the axial deformation at different heights by DPM, which is caused by an approximate method to simulate the torsion of the spring tube. The comparison results of the spring tube deflection at different vibration frequencies shows that the adaptability of DPM is significantly higher than the classic model, which verify the model is more adaptable for predicting the dynamic response of the armature assembly.

Distributed parameters modeling for the dynamic stiffness of aspring tube in servo valves

The stability and dynamic performance of a flapper-nozzle servo valve depend on several factors, such as the motion of the armature component and the deformation of the spring tube. As the only connection between the armature component and the fixed end, the spring tube plays a decisive role in the dynamic response of the entire system. Aiming at predicting the vibration characteristics of the servo valves to combine them with the control algorithm, an innovative dynamic stiffness based on a distributed parameter model (DPM) is proposed that can reflect the dynamic deformation of the spring tube and a suitable discrete method is applied according to the working condition of the spring tube. With the motion equation derived by DPM, which includes the impact of inertia, damping, and stiffness force, the mathematical model of the spring tube dynamic stiffness is established. Subsequently, a suitable program for this model is confirmed that guarantees the simulation accuracy while controlling the time consumption. Ultimately, the transient response of the spring tube is also evaluated by a finite element method (FEM). The agreement between the simulation results of the two methods shows that dynamic stiffness based on DPM is suitable for predicting the transient response of the spring tube.

Analysis of The Properties and Quick of Wave Creation on A Simple Ripple Tank Using Frequency Sensors

Practicum is one of the effective methods for students in learning Natural Sciences (IPA), especially Physics subjects. The purpose of the practicum is to make it easier for students to understand concepts and help explain physics concepts that cannot be observed directly by the eye. The 2013 curriculum demands physics learning to integrate various concepts, so that students have a thorough understanding of a phenomenon. This study aims to determine the effect of spring strain and tube length on the speed of propagation and wavelength. Ripple tank experiments that currently exist, only calculate variations in fluid height, gap size, vibrator frequency, and so on. The method used in this research is experimental, for the components used consist of a set of simple ripple tank tools and frequency sensors. The analytical technique used in this research is descriptive quantitative. The highest and lowest frequencies produced from the small tube were 20 Hz (l=70 cm; = 0.04 cm) and 1 Hz (l=5 cm; = 4.30 cm). The highest and lowest frequencies obtained from the large tube were 52 Hz (l=70 cm; = 0.05 cm) and 3 Hz (l=5 cm; = 4.95 cm). The highest and lowest wave propagation velocities produced by the small tube are 4.3 cm/s (l=5 cm) and 0.89 cm/s (l=70 cm). The highest and lowest wave propagation velocities produced by the large tube are 9.87 cm/s (l=5 cm) and 2.69 (l=70 cm). Based on the results of the study, it was shown that the greater the spring strain, the higher the frequency, the wavelength and the speed of wave propagation.©2019 JNSMR UIN Walisongo. All rights reserved.

Study on the endoscopic inspection of ITER thermal shield cooling pipes

A novel endoscope is developed for the inspection of long and complex-shaped cooling pipe of ITER Thermal Shield (TS). The mechanical design of the endoscope is improved for its easier insertion into long pipe routing. Main break-through is to reduce the cable friction against metal pipe surface as well as to maintain the elastic rigidity of the cable for the insertion. Spacers are attached on both the camera head and the cable to reduce the friction. Plate spring tube is used to protect signal wire and to maintain elastic rigidity of the cable. The conceived endoscope was tested to the pipe routing mock-up, which is similar to the longest and most complex TS pipe routing. Special device is also presented for making the endoscope insertion be easier. The insertion test result is compared with that of a conventional endoscope. Several endoscopic images are also discussed for typical pipe samples and for the curved region of pipe routing.

Mechanism of Temperature’s Acting on Electro-Hydraulic Servo Valve

To understand temperature's influence on the electro hydraulic servo valve, a theoretical model of describing the detailed mechanism is necessary. For a servo valve experiencing actual working conditions, the temperature variation acts on the performance of the torque motor, which results from drifts of the air gaps' thicknesses, the permanent magnets' reluctances, and the polarization magnetomotive force. And with the temperature variation, the nozzle orifice's size and its flow coefficient also change, which will act on the performance of the valve's pilot hydraulic amplifier. Furthermore, the mechanical characteristics, including the stiffness of the spring tube, the stiffness of the feedback rod and the armature's arm of force, are also related to temperature. Then, considering all these factors, a comprehensive temperature influencing model, referred to as the temperature-induced angular drift model (TAD), is constructed. With fluid, structure and electromagnetic field integrated, this theoretical model reflects complexity of the system and can be characterized by a ninth-order equation with nonlinear time-variant coefficients. On this basis, the routes by which temperature affects the servo valve's control accuracy are investigated. Calculations show that when the temperature ranges from 20°C to 270°C, the valve's control error will exceed 15% of the expected output. Among the temperature's acting routes, the flow coefficient is dominant, the nozzle orifice's diameter and the magnetomotive force are secondary, and others are insignificant. An experiment shows that the TAD model correctly predicts the tendency of the control error caused by temperature's rise, and it will aid in optimizing the servo valve's temperature performance.

Uni-axial shaking table tests and validations of a seismic isolation system made of spring tube braces

A new seismic isolation system based on spring tube braces was studied. An isolation story, which consisted of pin ended steel columns and spring tube braces, is arranged at the foundation level and/or any intermediate storey of the building. A series of experimental and analytical studies were carried out to evaluate the capability of the proposed seismic isolation system. Three storey ¼ scale 3D steel frames, with the proposed seismic isolation storey, were tested on the shake table using the real earthquake records. The transmitted accelerations from ground to floor levels were largely diminished by means of the isolation system, contrary to the fixed based specimen. Results showed no stability or self-centring problems for the proposed isolation system. The energy balance equations and dynamic force-displacement relations indicated that the equivalent damping arising from the seismic isolation storey was roughly 20%. This relatively high damping property, which can be attributed to the friction on the pinned connections of beam to columns as well as the period elongation, is effective for diminishing seismic response.

Sulfur Dioxide Desorption Characteristics of Basic Alkali Aluminum Sulfate Desulfurization Rich Liquid by Falling Film Evaporation with a Spring Tube

This paper presented a novel technology for the desorption of SO2 in the basic aluminum sulfate solution (BASS) by falling film evaporator with spring tube. The liquid film falling along the internal surface of the evaporation tube was heated by the steam outside. The desorption performances of the vertical single falling film evaporators with spring tube and smooth tube were comparatively investigated. The film distribution on the inner surface of the two tubes were also analyzed through visualization experiments. Compared with the smooth tube, the spring tube was found to be much better in heat transfer and mass transfer. Thus, analysis on the operating parameters for the desorption of SO2 was performed only in the spring tube. The results showed that the flow rate of BASS rich in SO2, heating steam temperature, vacuum of the system, and initial concentration of SO32– played important roles in the desorption performance.

Numerical and Experimental Analysis of Spinning Process for Gas Spring Tube

In this study a methodology was developed for performing 3D finite element (FE) simulation of metal tube spinning process for automotive application. Modelling of the process was related to the experimental setup. The latter provides input parameter as well as geometrical data of the specimen used for a validation of the simulation results. Solid works was used for modelling the spinning setup, hyper mesh was used for creating finite element modelling. Explicit FE model was used for spinning simulation using LS-DYNA. Numerical results were compared with experimentally obtained tube dimensions to validate the spinning simulation Parametric study was done to improve the spinning process without any failure.

Heat transfer enhancement and fuel consumption reduction in heaters of CGS gas stations

In this study, the effect of turbulators (coiled wire tube insert) as a passive method for heat transfer enhancement on heater performance of Mokhtar city gate station of Yasuj city has been evaluated. To analyze the performance and the effect of geometrical parameters of turbulators and physical parameters of the flow, steady state and incompressible flow were simulated through ANSYS CFX 14.5. Shear stress transport (SST) turbulence model for modeling turbulated flow regime besides the wall has been used. Using simulation results, important performance parameters such as friction factor, Nusselt number, and thermal performance factor were calculated and deeply studied. In this study the effect of coiled wire tube insert as a turbulator on the performance of heater in two states of circular and elliptical tubes with similar cross sections has been surveyed. The result show that the spring tube insert with diameter ratio of 10 for the elliptical tube heater, and diameter ratio of 0.95, have the best performance.

Spring tube braces for seismic isolation of buildings

A new low-cost seismic isolation system based on spring tube bracings has been proposed and studied at the Structural and Earthquake Engineering Laboratory of Istanbul Technical University. Multiple compression-type springs are positioned in a special cylindrical tube to obtain a symmetrical response in tension and compression-type axial loading. An isolation floor, which consists of pin-ended steel columns and spring tube bracings, is constructed at the foundation level or any intermediate level of the building. An experimental campaign with three stages was completed to evaluate the capability of the system. First, the behavior of the spring tubes subjected to axial displacement reversals with varying frequencies was determined. In the second phase, the isolation floor was assessed in the quasi-static tests. Finally, a ¼ scaled 3D steel frame was tested on the shake table using actual acceleration records. The transmitted acceleration to the floor levels is greatly diminished because of the isolation story, which effects longer period and higher damping. There are no stability and self-centering problems in the isolation floor.

Investigation into recurring military helicopter landing gear failure

Abstract The skid landing gear of a military helicopter failed while the helicopter was moored on the ground at the airport. The rear cross tube of the landing gear assembly was found fractured into two separated pieces. The fracture occurred in the right flange of the rear cross tube, where a connection with the spring tube is established using a clamp. The initial visual inspection of the fracture zone revealed a presence of heavy corrosion and significant damage of the anti-corrosion protective layer on the outer surface of the flange of the rear cross tube. Fractographic analysis highlighted corrosion as the main cause of the failure. Evidence was found to show that the fracture was initiated from corrosion pits located on the exterior, underside of the cylindrical part of the flange. Metallographic examination discovered corrosion pits with micro cracks and multiple branched secondary cracks in the crack origin area, indicating the occurrence of stress corrosion cracking. Chemical analysis of the corrosion deposits showed the presence of sodium, chlorine, calcium and sulfur. The stress analysis of the helicopter landing gear assembly, carried out by means of finite element method, confirmed that the crack origin was located at the area with the maximum tensile stress in the flange.

Design and Development of Soft Gripper System for Handling Non Rigid Materials

Automation and flexible system development are an imperative need of current Industrial applications. End effectors are mainly used to achieve many tasks in material handling. There are varieties of grippers/end effectors developed and used for multiple purposes in automation fields. The conventional end effectors mainly used for pick and place the products like hard, soft, variable shape and very thin materials using various principles. But there is a need in fluid transfer through flexible end effectors. We proposed a pliable end effector which has been developed under Bernoulli's principle. The focus of studies in fluid handling course is on the methods, mechanical equipment, systems and related controls used to achieve the functions like movement, quantity, time, space, and control of the end effector. To design and develop a novel dupe for fluid transfer by means of toothed quadrant sector, windup coil spring and bourdon tube. This operates with mechanical linkage mechanisms and attractive-suction forces are applied to the fluid surface. Then the end effector suck and release fluids automatically under the mechatronics control systems. This experiment has been carried out with different viscous fluids and the results compared with analytical results.