Force Of Rod Research Articles

7A25 Effect of screw placement configurations to the corrective forces in rods during scoliosis surgery

7A25 Effect of screw placement configurations to the corrective forces in rods during scoliosis surgery

Study on the Pretightening Assembly Moving Beam of Open-Die Forging Hydraulic Press

The FE model of the pretightening assembly moving beam of open-die forging hydraulic press is built with FE simulation software ABAQUS in the study. With the FE model, the force status of pretightening assembly moving beam is studied. Then the pretightening force of assembly moving beam is further studied and the computing method of pretightening force is given. The main achievements of the study include: Under pretightening, the stress of main moving beam is very low and that of guild sleeves is also lower than the allowable stress. Under center loading, the stress of the center field of main moving beam is higher and that of guild sleeves is almost same to that of pretightening. Under eccentric loading, the stress of same deviation field of main moving beam is higher and the effect of pretightening force on the stress of main moving beam is very small. The stress distribution of guild sleeves with different pretightening force is same and the effect of pretightening force on its strength is very low. The pretightening force of tension rod can be computed with the force of press, the allowable eccentric value of the workpiece, the distance between up guild section and down guild section of guild sleeve and the quantity of tension rods. The results of the study are very useful to design and install the pretightening assembly moving beam of open-die forging hydraulic press.

Symmetrical Beauty: Pneumatic Press Based on Quadratic Orthogonal Force Amplifier Driven by Double-Face Rack-Gear Mechanism

Pneumatic Presses are marked by features of high-motion speed, high productivity, energy conservation and environmental protection. The drawback is its low air system pressure, generally only 0.4-0.7 MPa, which unsuited to occasion require large output force. A new pneumatic press, based on quadratic orthogonal toggle force amplifier, is introduced in this paper. The output force of pneumatic piston is amplified for two times and force amplifying ratio can up to 20, thus to increase the output force substantially, although with constant piston diameter and system pressure. Moreover, with the application of symmetrical double-face rack-gear mechanism, radial force on piston rod and lateral force on pressure head are perfectly balanced. The entire mechanical system boasts features of low friction loss, low vibration and noise and high transmission efficiency.

Predictive position and force control for shape memory alloy cylinders

In this paper, a linear lightweight electric cylinder constructed using shape memory alloy (SMA) is proposed. Spring SMA is used as the actuator to control the position and force of the cylinder rod. The model predictive control algorithm is investigated to compensate SMA hysteresis phenomenon and control the cylinder. In the predictive algorithm, the future output of the cylinder is computed based on the cylinder model, and the control signal is computed to minimize the error and power criterion. The cylinder model parameters are estimated by an online identification algorithm. Experimental results show that the SMA cylinder is able to precisely control position and force by using the predictive control strategy though the hysteresis effect existing in the actuator. The performance of the proposed controller is compared with that of a conventional PID controller.

Advanced Signal Processing Tools for the Vibratory Surveillance of Assembly Faults in Diesel Engine Cold Tests

This paper addresses the use of several signal processing tools for monitoring and diagnosis of assembly faults in diesel engines through the cold test technology. One specific fault is considered here as an example: connecting rod with incorrectly tightened screws. First, the experimental apparatus concerning the vibration tests is introduced. Subsequently, the dynamic analysis of the engine has been carried out in order to calculate the connecting rod forces against the crankpin for predicting the position where mechanical impacts are expected. Then, a vibration signal model for this type of faults is introduced. It deals with the cyclostationary model in which the signal is subdivided into two main parts: deterministic and nondeterministic. Finally, the acceleration signals acquired from the engine block during a cold test cycle at the end of the assembly line are analyzed. For quality control purposes in order to obtain reliable thresholds for the pass/fail decision, a method based on the image correlation of symmetrized dot patterns is proposed. This method visualizes vibration signals in a diagrammatic representation in order to quickly detect the faulty engines in cold tests. Moreover, the fault identification is discussed on the basis of the cyclostationary model of the signals. The first-order cyclostationarity is exploited by the analysis of the time synchronous average (TSA). In addition, the residual signal is evaluated by subtracting the TSA from the raw synchronized signal, and thus, the second-order cyclostationarity analysis is developed by means of the Wigner–Ville distribution (WVD), Wigner–Ville spectrum (WVS), and mean instantaneous power. Moreover, continuous wavelet transform is presented and compared with the WVD and WVS.

112 2次元壁面間移動機械

This technology obliquely presses multiple elastic rod in respect of parallel wall surfaces. And, the falling of the movement machine is prevented by contact friction force. In addition, the tip of elastic rod moves pressurization and unloading to wall surface on this machine by the elastic force of elastic rod, and it repeatedly moves in shell two dimensions. Generally, the vertical movement of the machine which moves wall surface is done using rope and chain by the roll-up style of the motor. However, the movement machine itself moves, though this method is pulled, though the machine does do not move it, and though the main body is retained by the self-help. Moreover, it moves by the control of the computer.

Inner Force Analysis of Two Typical Frames with Vertical Displacement

Finite element method is often used to obtain exact solution in the course of internal force calculation of some complex frames which contain nodal vertical displacement such as frames with transferring layer and mega-frames with sub-structure. In the phase of scheme comparison and schematic design, methods which can quickly produce calculation results of the above said frameworks are necessary. Based on the basic principle of displacement method, this paper proposes a simple analytical method for frameworks that contain nodal vertical displacement. According to the proposal, the basic structure for calculation is the framework in which is added vertical chain-pole at relevant node; the basic unknown quantities are the nodal vertical displacement of the basic structure; the basic equation is fixed according to the equilibrium of node forces; unit vertical displacement as well as bending moment and shear diagram of the basic structure under external load are respectively obtained by using moment redistribution method; nodal vertical displacement is determined through substitution of shear force of relevant rod into the equilibrium equation of the chain-pole node; the actual internal force is determined through superposition of actual vertical displacement and internal force diagram algebra of the basic structure under vertical external load. An engineering example is introduced, which is intended to provide reference for the simple calculation for the above said complex frameworks.

Shape Transition and Propulsive Force of an Elastic Rod Rotating in a Viscous Fluid

The deformation of an elastic rod rotating in a viscous fluid is considered, with applications related to flagellar motility. The rod is tilted relative to the rotation axis, and experiments and theory are used to study the shape transition when driven either at constant torque or at constant speed. At low applied torque, the rod bends gently and generates small propulsive force. At a critical torque, the rotation speed increases abruptly, and the rod forms a helical shape with increased propulsive force. We find good agreement between theory and experiment. A simple physical model is presented to capture and explain the essential behavior.

Principle of Asymmetric Crank Mechanism of New-type Rolling Shear

Based on rolling-cut simulation,a 3 000 mm single-shaft,double-eccentricity and cut-to-length rolling shear of a certain large-scale iron steel company that adopts asymmetric new-type structure is used as the calculation model by establishing motion path equation of spatial shear mechanism.After comparing and analyzing the shear force on steel plates with asymmetric front and rear,connecting rod force,and horizontal force component of connecting rod,the asymmetric formula is deduced.The asymmetric crank structure can decrease the horizontal force component of connecting rod during rolling-cut process,increase the effective drive force of connecting rod at the period of the maximum shear force,and decrease the extrusion of blade arc on steel plate edge as well. Theoretical analysis results and on-spot steel plate shear quality show that the asymmetric structure is an important means to improve shear capability,decrease blade wear,prolong blade life and improve shear quality.

Buoyant force and sinking conditions of a hydrophobic thin rod floating on water

Owing to the superhydrophobicity of their legs, such creatures as water striders and fisher spiders can stand effortlessly, walk and jump quickly on water. Directed toward understanding their superior repellency ability, we consider hydrophobic thin rods of several representative cross sections pressing a water surface. First, the shape function of the meniscus surrounding a circular rod is solved analytically, and thereby the maximal buoyant force is derived as a function of the Young's contact angle and the rod radius. Then we discuss the critical conditions for a rod to sink into water, including the maximal volume condition and the meniscus-contact condition. Furthermore, we study the sinking conditions and the maximal buoyant forces of hydrophobic long rods with elliptical, triangular, or hexagonal cross-section shapes. The theoretical solutions are quantitatively consistent with existing experimental and numerical results. Finally, the optimized structures of water strider legs are analyzed to elucidate why they can achieve a very big buoyant force on water.

CROSS-PLY BENDING EQUATION AND APPLICATION FOR COMPRESSED ROD WITH CRACK

The aim of this paper is the analysis of rod cross‐ply bending and stability of rod systems in the presence of cracks. The power concept (its theoretical base is Maxwell's theorem about the reciprocity of displacements) and linear fracture mechanics methods for research of mechanical properties of rod systems in the presence of cracks nave been used. The main equation of the rod cross‐ply bending and the common solution of this equation were obtained. The expression of the relationship between rod deflection and the disturbing cross‐force was obtained. Some transcendental equation allows defining the inferior boundary of critical force of rod with a crack.

The “FAD” (Floating Alveolar Device): A bidirectional distraction system for distraction osteogenesis of the alveolar process

The following study illustrates preoperative and perioperative vector management in alveolar distraction using a new distraction system--the "Floating Alveolar Device" (FAD). The FAD is a bidirectional alveolar distractor that allows augmentation of an atrophic alveolar process in several planes, assures easy intraoperative positioning of the planned vector of distraction, and provides correction of the horizontal position of the transported segment during and after vertical distraction. The FAD is composed entirely of stainless steel and has the following basic components: an upper member, a distraction rod, a lower base plate supporting the vertical force of the distraction rod, a jointed hinge that connects the upper and the lower members, and a tightening rod that provides blocking of the hinge. The clinician can manipulate and adjust the tightening rods, allowing a change in the angle of the hinge, thereby altering the transverse dimension of the vector of distraction. A total of 4 patients aged to 19 to 40 years underwent bidirectional alveolar distraction. All procedures were performed in the mandible. In all treated patients, planned distraction height and direction were achieved. In all cases it was possible to place implants at the planned time. The most common complication, axial displacement, is easily eliminated by moving the bone with the "floating" rod of the FAD during or immediately after the distraction period, according to the principles of the floating bone concept.

Development of circumferential through-wall crack K-solutions for control rod drive mechanism nozzles

The US Nuclear Regulatory Commission (USNRC) has undertaken a program to assess the integrity of control rod drive mechanism nozzles in existing plants that are not immediately replacing their reactor pressure vessel heads. This paper summarizes some of the efforts undertaken on behalf of the USNRC for the development of circumferential crack-driving force solutions to be used in probabilistic determinations of the time from detectable leakage to failure. Detailed three-dimensional elastic–plastic finite element analyses of these nozzles were conducted to determine the effects of operating conditions, tube-to-head interference fit, tube yield strength, and nozzle-to-head angle on the crack-driving force. Three major observations to date are: • Conducting simple tube-only analyses can severely overpredict the actual crack-driving force in the control rod drive mechanism nozzles. • The crack-driving force is a strong function of the nozzle yield strength, nozzle-to-head angle, interference fit, and weld residual stress; and • In many cases, when the crack is made to be perpendicular to the wall of the nozzle, the operating conditions and residual stresses appear to create some crack closure along the crack faces, suggesting that cracks in service will grow at an angle through the thickness.

Abnormal transient phenomena in the continuous casting process: Part 1

This paper is the first of a series of two describing online monitoring of the continuous casting machine and the abnormal transient phenomena observed. The present paper, Part 1, pays attention to assessment of the friction between the billet and mould based upon the cam rod force and the electric current intensity of the mould oscillation motor. Information relating to casting parameters before 58 breakouts has been obtained with a monitoring computing program. Almost 40% of the breakouts could have been forecast through assessment of the billet-mould friction force before the breakouts. Transient phenomena in the withdrawal machine have been detected. The jerking of the strand is related to high billet-mould friction; however, other parameters such as the billet cutoff unit and roller bed design also have some effects on this transient phenomenon. Some mechanisms influencing the jerking of the strand are proposed.

Tissue response during monofocal and bifocal leg lengthening in patients

The purpose of this investigation was to compare the tissue response during mono- and bifocal limb lengthening. The study includes four patients undergoing leg lengthening. All patients started out bifocally with a total diurnal distraction of 1.75 mm, but proceeded monofocally with a rate of 1 mm a day when the distal distraction was terminated due to contractures or pain. The tissue response was monitored by registration of axial force in the distraction rods. The force increased linearly during bifocal lengthening, but culminated or decreased in the period of monofocal lengthening. Average tissue stiffness, defined as the immediate force increase due to each 0.25 mm distraction increment, was significantly higher in the bifocal lengthening phase. The force decay between each distraction was significantly lower during bifocal lengthening, thus indicating decreased tissue accommodation. Details in the force registrations indicated that the soft tissue, not the regenerate, was the main contributor to the tensile force. Conclusively, the tissues at the two osteotomy sites do not lengthen independently. Bifocal lengthening exposes the entire soft tissue to large loads, resulting in increased tissue stiffness and reduced ability to adapt to the increased length. Accordingly, bifocal leg lengthening requires special attention to soft tissue adaptation.

The design of overlapped crankshafts Part 1: Crankpin fillets

The finite element (FE) technique, with two-dimensional (plane strain) and three- dimensional meshes, has been used to determine the surface stress distributions in 19 shapes of undercut crankpin fillets under radial bending due to the connecting rod force and under pure torsion. In radial bending, two-dimensional analyses are as valid as three-dimensional ones. The stress concentration factors (SCFs) are compared with symmetrically notched and shouldered bars in pure bending. The information in this paper helps the designer to obtain low stress concentration factors in multi-circular arc or spiral fillets of chosen axial and radial extents.

Limit States and Factor of Safety in Design of an Anchored Sheet Pile Wall

Factors of safety in the traditional design of anchored sheet pile walls have been introduced in a variety of ways. Furthermore, empirical and semiempirical factors are used to modify the calculated depth of embedment, anchor rod force, and maximum bending moment in sheet piling. This leads to a range of designs within the traditional allowable stress design (ASD) approach. Even in the new ultimate limit states design (LSD) method, two approaches are available. One approach is to use load and resistance factor design (LRFD), and the other is to use partial safety factors on the material properties in combination with load factors. In view of the number of design alternatives available, a calibration study of LSD with ASD for an anchored bulkhead was performed. The practical problem of a steel sheet pile wall in a layered cohesionless soil and cohesionless soil overlying cohesive soil was analyzed. The depth of embedment, the anchor rod force, and the maximum bending moment in sheet piling were determined for a range of soil parameters by using LSD and ASD methods. The factors recommended in various codes, manuals, and handbooks were used to perform calibration studies. The results of the parametric study indicate that the load and resistance factors recommended in the LRFD approach must be reevaluated.

A study on an estimation method for applied force on the rod

A Kalman filter method is used to estimate a timewise variation rod force source on the rod end with free boundaries in this study. The one-dimensional wave propagation equation with force source at known location is expressed in the continuous-time state equations. By virtue of the Kalman filter adaptor with the input estimation technique, the residual innovation sequence is generated to estimate the strength of a time-varying force. In order to examine the accuracy of the proposed method, the rod is subjected to three types forces, sinusoidal, triangular and random forces. The estimated results have a good agreement with the exact values in all cases tested.

A Dynamic Study of Valve Jump Mechanism(1st Report, Observation of Jump Phenomena).

Overhead valve mechanism (OHV) is a widespread mechanism for internal combustion engine, but in this type of valve train, a serious problem known as valve jump is likely to occur at high speed. A rig test is arranged in such a way as to enable the measurement of the push rod force representing the vibration state of valve mechanism under different engine speed. By means of FFT analysis, the engine speed at which the first jump occurs can accurateiy be determined. Accurate detection of the part responsible for the jump can be achieved by isolating electrically all the parts constituting the valve train and measuring the different forces under different rpm's. It is clarified that valve jump is the phenomenon which separates between can and tappet, those which constitute valve mechanism.

Presurgical finite element analysis from routine computed tomography studies for craniofacial distraction: II. An engineering prediction model for gradual correction of asymmetric skull deformities.

Finite element analysis from routine computed tomography studies (CT/FEA) allows clinicians to predict the mechanical and anatomic consequences of specific distraction systems before human application. A realistic three-dimensional CT/FEA engineering model of an actual plagiocephalic infant with unicoronal synostosis was developed using 4215 parabolic triangular shell elements and intracranial pressure conditions ranging from 10 to 20 mmHg. The completed finite element analysis model was used to predict the anatomic outcome of multiaxial distraction delivered by hypothetical patterns of rod and node distraction units. The predictions for the various patterns of distraction units were also compared quantitatively with respect to force, stress, strain, and intracranial volume. Best anatomic corrections were achieved with bilateral patterns of distraction units that simultaneously elongated the ipsilateral cranium and shortened the contralateral cranium. Greatest strain levels were experienced within the osteotomy callus, greatest stress levels at the appliance anchorage sites, and the greatest rod force at the ipsilateral lower coronal position.