Bending Of Rods Research Articles

Design and Production of Portable Bar Bender

During this generation many projects and inventions are invented to reduce the man power, time, and difficulties of the work. But still some small types of works are only based on the man power because of the cost price of invention and difficult of handling of inventions. This designed and fabricated hydraulic bar bending equipment is used for bending rods, strips, angles, and bars. During some period a type of hydraulic rod bending machines only used on large scale and industrial works. In our type we simplified the design suitably for small scale construction based rod bending works.

The Stability of a Flexible Vertical Rod on a Vibrating Support

The classical Kapitsa problem of the inverted flexible pendulum is generalized. We consider a thin homogeneous vertical rod with a free top end and pivoted or rigid attached lower end under the weight of the pendulum’s action and vertical harmonic vibrations of the support. In both cases of attachment, we have stability conditions for the vertical rod position. We take the influence of axial and bending rod vibrations and describe the bending vibrations using the Bernoulli–Euler beam model. The solution is built as a Fourier expansion by eigenfunctions of auxiliary boundary-value problems. As a result, the problem is reduced to the set of ordinary differential equations with periodic coefficients and a small parameter. The asymptotic method of two-scale expansions is used for its solution and to determine the critical level of vibration. The influence of longitudinal waves in the rod essentially decreases the critical load. The single-mode approximation has an acceptable accuracy. With pivoting support at the lower end of the rod, we find the explicit approximate solution. For the rigid attachment, we conduct numerical analysis of the critical level of vibrations depending on the problem parameters.

Extended finite element procedures for analysis of bolt crossing multiple intersecting rock joints

An enriched finite element procedure is proposed for formulating interaction of rock bolts with multiple intersecting/ non-intersecting joints in a rock mass. The numerical method involves analysis of reinforced rock mass having arbitrary joint dip angle, bolt angle and joint-bolt-grout properties in extended finite element (XFEM) platform. Shifted Heaviside and junction enrichment is incorporated for the intersecting jointed element. The paper presents procedures and formulation of stiffness matrices of a bolt crossing multiple joints (BCMJ) which may or may not intersect each other. Hence an element may contain two intersecting joints and a bolt. In that case for a 2D element, each node is enhanced to eleven degrees of freedom, 2 for rock displacements, 2 each for displacements of rock joints, 2 for displacements of the junction of joint intersection and 3 for displacements and rotation of bolt. The procedure also allows traction to be applied to a side of an enhanced element and to be transformed as nodal forces at enhanced degrees of freedom. The paper considers elastoplastic behaviour of joint surface and bolt-grout interface using Mohr-Coulomb criterion. For yielding of bolt rod unified tensile and bending criterion is adopted. The proposed method is implemented using 3-noded triangular elements and can be upgraded for higher order elements. The efficacy of the proposed procedure is evaluated by analyzing behaviour of a bolt reinforced jointed sample under direct shear test. The method is also applied to analyze displacements and stresses around a circular tunnel made in rock mass having multiple intersecting joints at different orientations, reinforced by bolts along the periphery of the tunnel. The results in terms of displacements and stresses are compared with those of unbolted rock mass model. The proposed method shows that effect of an individual joint, bolt and their interaction can be analyzed to understand the stability of excavation under given loading conditions and can be applied in wide variety of applications.

Magnetomechanical properties of composites and fibers made from thermoplastic elastomers (TPE) and carbonyl iron powder (CIP)

Magnetoactive elastomers (MAE) made from composites of five thermoplastic elastomers (TPE) of different stiffness with carbonyl iron powder (CIP) as magnetic component were investigated. The composites were produced by melt blending of the magnetic particles with the TPEs in a twin-screw extruder. The resulting materials were characterized by ac permeability testing, stress–strain measurements with and without external magnetic field and magnetically controlled bending of long cylindrical rods in a homogenous magnetic field. The magnetic field necessary for deflection of the rods decreases with decreasing modulus and increasing iron particle content. This effect can be used e.g. for magnetically controlled actuation. Some highly filled MAE show a magnetic field induced increase of Young’s modulus. Filaments could be spun from some of the composites.

The longitudinal-transverse bending of reinforced concrete rods

The longitudinal transverse bending of multilayer rods made of reinforced concrete of arbitrary cross-section is considered. It is assumed that the coefficients in the connection equation between stresses, strains and temperature are different in each layer. The achievement of maximum deformation of the permissible limit value at stretching or compression is accepted as the criterion of conditional limit state in the i-layer. The case of longitudinal-transverse bending of a hinged rod is considered as an example of this method of solution. The distribution of bending moments and longitudinal forces, displacements and deformations is determined.

Proper Responding Strategies to Neuromonitoring Alerts During Correction Step in Posterior Vertebral Column Resection Patients With Severe Rigid Deformities Can Reduce Postoperative Neurologic Deficits.

Retrospective study. To analyze the intraoperative neuromonitoring (IOM) changes in posterior vertebral column resection (PVCR) for severe rigid deformity patients, and describe our stepwise responding strategies. Obvious neurological deficit risk accompanied with PVCR correction has been emphasized repeatedly. The records of 46 patients who underwent PVCR achieved IOM were reviewed. IOM alerts triggered responding protocols: (1) exchange the convex corrective rod to concave stabilizing rod, (2) appropriate compression for spinal shortening, (3) reversed in situ rod bending, (4) translation technique and unisegmental derotation, (5) adjacent segmental resection. The overall scoliotic correction rate was 65.4% (from 112 ± 28.6 to 39 ± 13.4) and segmental kyphotic correction rate was 64.2% (from 101 ± 37.3 to 36 ± 19.2). During correction step, somatosensory-evoked potential warning (3) and somatosensory-evoked potential/transcranial motor-evoked potential warning (8) were detected in 11 patients (23.9%). Probable cause identification including rule out IOM technical factors, residual impingement, and if there was unstable spinal column (1), spinal cord excessive tension on concave side (3), and the excessive opposite spinal displacement between two aspects of resected area (7). After rod change (1), compression (2), bending (3), derotation (3), and adjacent resection (2), all IOM changes went to under warning criteria. All 11 patients revealed neurologically intact postoperatively. There was no difference of correction rate between IOMs alert or not. However, adult, extremely severe or sharp angular curves tend to be more common in IOM alert patients. As three-dimensional spinal column divided and relinked in PVCR, and the correction maneuvers were restricted on single dimension, inevitably resulted in spinal cord tension changes and spinal column opposite displacement. To timely identify them, prompt interventions should be performed, and even enlarge the resected area to reduce the abrupt turning tendency of the spinal cord. 5.

Correction manoeuvres in the surgical treatment of spinal deformities.

Correction manoeuvres are as important as the other issues such as hardware selection, graft options, fusion and osteotomy techniques in the surgical treatment of spinal deformities.The property of materials demonstrating both viscous and elastic characteristics when undergoing deformation is called visco-elasticity. Purely elastic materials change in shape with a stress, and go back to their initial form when the stress is removed. However, visco-elastic materials, like the spine, may protect their new formation unless a back stress is applied. Time is a very important parameter during manoeuvre application to the spine because of its visco-elastic behavior.The most common correction manoeuvres that can be used for spinal deformities are rod de-rotation, distraction-compression, in situ rod bending, segmental de-rotation, en bloc de-rotation and cantilever.Spontaneous correction of a minor curve is possible after selective fusion of a major curve due to coupling phenomenon.Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.170002. Originally published online at www.efortopenreviews.org

On the simultaneous homogenization and dimension reduction in elasticity and locality of $$\varGamma $$ Γ -closure

We provide a framework for simultaneous homogenization and dimension reduction in the setting of linearized elasticity as well as non-linear elasticity for the derivation of homogenized von Karman plate and bending rod models. The framework encompasses even perforated domains and domains with oscillatory boundary, provided that the corresponding extension operator can be constructed. Locality property of \(\varGamma \)-closure is established, i.e. every energy density obtained by the homogenization process can be in almost every point obtained as the limit of periodic energy densities.

Some features of bending of a rod under a strong longitudinal compression

Considered typical processes of rod bending under strong longitudinal compression. The dynamic equation of bending correspponds to a perturbation of the two- dimensional Laplace equation. It is established that, for these processes, expanding of do- mains of rapid increasing of bending begins in small neighborhoods of singularity points of solutions of the limiting Laplace's equation. The initial stages of these increases are described using the Hardy integral.

On the Bending and Twisting of Rods with Misfit

We derive a one-dimensional variational problem representing the elastic energy of a rod with misfit, starting from a nonlinear, three-dimensional elastic energy with nontrivial preferred strain. Our approach to dimension reduction is to find a Gamma-limit as the thickness of the rod tends to 0. The limiting energy is a quadratic function of the rates at which the rod bends and twists, and we give explicit expressions for the preferred curvature and twist in the special case of isotropic elastic moduli.

Application of step-by-step in situ rod bending in posterior internal fixation of lumbar burst fractures

Objective To evaluate the clinical outcome of the technique of step-by-step in situ rod bending used in posterior internal fixation of lumbar burst fractures. Methods A retrospective case control analysis was conducted on 76 cases of lumbar burst fractures hospitalized between March 2007 and March 2014. There were 48 males and 28 females, with a mean age of 40.4 years (range, 18-57 years). Fractured segments included L1 in 32 cases, L2 in 24, L3 in 14 and L4 in 6. According to the different rod bending methods, the subjects were divided into preliminary rod bending group (34 cases) and in suit rod bending group (42 cases). Operation time, amount of bleeding during and after operation, restoration of anterior vertebral height and Cobb angle, and visual analogue score (VAS) were compared between groups. Results Seventy patients were followed up for 12-36 months (mean, 20.9 months). One patient in preliminary rod bending group presented internal fixation loosening, and had implant removal 9 months after operation. No implant breakage occurred. Comparison of preliminary rod bending group and in situ rod bending group showed significant differences in operation time [(88.1±16.0)min vs. ( 79.9±14.7)min], amount of bleeding during operation [(88.3±21.2)ml vs. (74.0±12.5)ml ], amount of bleeding after operation [(71.5±17.3)ml vs.(62.1±16.0)ml] , restoration of anterior vertebral height [(74.1±7.8)% vs.(79.5±8.5)%], and restoration of Cobb angle [ (10.2±2.7)°vs.(8.8±2.6)°](P 0.05), while there was significant difference 9 months after operation [2.2±0.7)points vs. (1.9±0.7)points] (P<0.01). Conclusion In suit rod bending for lumbar burst fractures has advantages over preliminary rod bending in terms of operation time, blood loss, precise restoration and back pain. Key words: Lumbar vertebrae; Fracture fixation, internal; Kyphosis

Bending and torsional reconfiguration of chiral rods under wind and gravity

We seek to understand the effect of chirality on the reconfiguration and the self-buckling strength of chiral plants subjected to wind and gravity by experimental and theoretical modeling of their large deformation. Chiral rod and ribbon specimens are made of polyurethane foam reinforced with nylon fibers and ABS plastic. Wind tunnel tests are performed to evaluate the effect of chirality on flow-induced reconfiguration. A theoretical model is developed by coupling the Kirchhoff rod theory with a semi-empirical formulation for aerodynamic loading evaluation. A range of geometrical, material and flow parameters are studied in the experimental and theoretical model. It is shown that for rods, chirality decreases the maximum root bending moment. For ribbons, chirality leads to a trade-off with higher self-buckling strength but also higher root bending moment. Moreover, chirality reduces the effect of the loading direction on deformation. Chirality plays an important structural role in the interaction of slender structures with fluid flow and gravity loading.

Functionally graded rod with small concentration of inclusions: Homogenization and optimization

This work is devoted to strain analysis and optimal design of a Functionally Graded (FG) rods and beams with small inclusions. The homogenization procedure plays a key role in our investigations. The method is illustrated using an example of the rod longitudinal deformation and bending of a beam. We consider the cases of FG inclusion sizes and FG steps between inclusions separately. Particular problems of optimal design are discussed in some details. The mathematical model of the bending beam, which adapts to the external load action, is proposed and an illustrative example of the adaptation process is given.

3D rod shape changes in adolescent idiopathic scoliosis instrumentation: how much does it impact correction?

Flattening of rods is known to reduce the correction capability of the instrumentation, but has not been studied in 3D. The aim is to evaluate the rods shape 3D changes during and immediately after instrumentation, and its effect on 3D correction. The 5.5mm CoCr rods of 35 right thoracicadolescent idiopathic scoliosis patients were measured from rod tracings prior to insertion, and reconstructed in 3D from bi-planar radiographs taken intra-operatively after the correction maneuvers and 1week post-operatively. The rod bending curvature, maximal deflection and orientation of the rod's plane of maximum curvature (RPMC) were computed at each stage. The relation between rod contour, kyphosis and apical vertebral rotation (AVR) was assessed. Main thoracic Cobb angle was corrected from 58°±10° to 15°±8°. Prior to insertion, rods were more bent on the concave side (curvature/deflection: 39°±8°/25±6mm) than the convex side (26°±5°/17±3mm). Only the concave rod shape changed after the correction maneuvers execution (flattening of 21°±9°/13±7mm; p<0.001) and stayed unchanged post-operatively. After instrumentation, the RPMC was deviated from the sagittal plane (concave side: 27°±19°/convex side: 15°±12°). There was a significant association between kyphosis change and the relative concave rod to spine contour (rod curvature-pre-operative kyphosis) (R 2=0.58) and between AVR correction and initial differential concave/convex rods deflection (R 2=0.28). Correction maneuvers induce a significant change of the concave rod profile. Both rods end in a plane deviated from the sagittal plane which is representative of the spinal curvature 3D orientation. Differential rod contouring technique has a significant impact on the resulting thoracic kyphosis and transverse plane correction.

INTENSIFICATION OF SEPARATION PROCESS OF BAR MATERIAL ON DIMENSIONAL WORKPIECE OF WEDGE-SHAPED KNIVES

Based on the analysis of known methods of separation of bar mix to length determined that the most effective method of forming an annular groove therein plastic tapered section, with a gradual deformation of the metal disc blades recess which is destroyed in the mix zone. In order to reduce the depth of the groove after its shaping proposed to produce in the same local area flexural bar. Based on experimental data obtained an empirical formula relating the dependence of bending rod axis angle on the depth of the annular groove. It is found that the greatest effect on the angle of local bending rod axis in the annular groove zone occurs when changing its depth from 0.5 to 3.0 mm. And this dependence is exponential in nature. Reducing the local axis of the workpiece bending angle for the specified range of the groove depth will be between 8.83o to 2.23o. A further increase in the depth of the annular groove is not practical, because the angle of bending the rod axis with reduced insignificantly. The dependence is valid for the separation process rods tapered disc blades with a local curvature of its axis is almost independent of the original diameter shared assortment. Therefore, the process can be carried out efficiently when the groove depth is not greater than 3.0 mm.

Drilling Performance of Rock Drill by High-Pressure Water Jet under Different Configuration Modes

In the rock drilling progress, the resistant force results in tools failure and the low drilling efficiency; thus, it is necessary to reduce the tools failure and enhance the drilling efficiency. In this paper, different configuration modes of drilling performance assisted with water jet are explored based on the mechanism and experiment analysis of rock drilling assisted with water jet. Moreover, the rotary sealing device with high pressure is designed to achieve the axial and rotation movement simultaneously as well as good sealing effect under high-pressure water jet. The results indicate that the NDB and NFB have better effects on drilling performance compared with that of NSB. Moreover, the high-pressure water jet is helpful not only to reduce the drill rod deflection, but also to reduce the probability of drill rod bending and improve the drill rod service life.

Response and residual curvature of bent-stretched circular rods with applications to metal forming: Closed-form solutions for elastic-perfectly plastic and hyperbolic hardening materials

Here we develop an analytical expression for the curvature of rods of circular cross-section, when subjected to combined bending and axial force. Small deformations are assumed here so that the deflections are small compared to the cross-sectional dimensions. An enhanced material constitutive law having a linear elastic part followed by smoothly matched hyperbolic hardening is proposed. Analysis for two material models are presented which includes elastic-perfectly plastic material as well as hardening. The effects of the axial force on the response and springback are analytically assessed. The analysis is then applied to the bending of rods of circular cross-section. The analytical results are in excellent agreement with numerical calculations.

The Precise Bending Rod Technique: A Novel Method for Precise Correction of Ankylosing Spondylitis Kyphosis.

To report a new technique. To introduce a new method of precise correction controlling for ankylosing spondylitis kyphosis. The exact angle method is excellent for calculating the pedicle subtraction osteotomy angle but is difficult to perform during surgery. In this study, the precise rod bending technique was proposed as a new method for precise correction controlling for ankylosing spondylitis kyphosis through illustrative cases. A preoperative plan using the exact angle method, with exact osteotomy angle and level determined, was prepared using a whole-spine lateral x-ray film. Then a precise contoured rod imitating the predicted spine correction was obtained using the lateral spine x-ray film that was of the actual size of the trunk. This rod model was disinfected and used for precisely controlling kyphosis correction in ankylosing spondylitis patients with good cervical spine and hip joints. Four ankylosing spondylitis kyphosis patients were successfully corrected using the precise bending rod technique. Their mean age was 31 years, the mean operative time was 247 minutes (160-320 min), the mean volume of bleeding was 1482 mL (727-2700 mL), and the average follow-up period was 13.8 months (9-17 mo). All patients regained their sagittal balance (all C7-SSVL≤2 cm). The predicted ostetomy degree was accurate to within 2 degrees compared with the achieved degree at the osteotomy site. No complications occurred during or after surgery. The precise rod bending technique is a simple, effective method for precise correction of kyphosis caused by ankylosing spondylitis. The surgical result corresponded to the preoperative planning.

Application of rod mechanics fundamentals for analysis of stress-strain state of the tubing

A method for analysis of stress-strain state of the tubing column in the spatially curved well section with an arbitrary intensity of changes as the zenith and azimuth angle is developed in the article.Stresses and strains are calculated using the rod mechanics fundamentals. The system of vector differential equilibrium equations in the projections on the axes of the moving coordinate system is used for the analysis of elastic equilibrium of the tubing axis.The analysis is carried out by solving the direct problem of the rod bending by means of iterative numerical method implemented in software-oriented mathematical environment.A method to account for the limiting effect of the well walls to move of the elastic tubing axis is provided based on the processing of its geometrical parameters, as well as data and directional survey and profilometric research of the well bore.Using the designed calculation schemes, it is found that local bend of the well axis substantially increases the bending stress, which can reach the yield strength of the tubing material. For example that discussed in the article, the bending stress is approximately 300 MPa, while the minimum yield strength of steel, which are made tubing, is equal to 379 MPa.Moreover, the axial force change caused by the reciprocating motion of a rod suspension may initiate the occurrence of cyclic bending moments and stresses in the tubing. So, for the considered operating conditions, we received the following: the minimum stress of the cycle σmin = 303 MPa; the maximum stress of the cycle σmax = 346 MPa; stress amplitude of the cycle σa = 43 MPa; loading cycle asymmetry factor Rσ = 0,88. This load pattern allows to speak about the cyclic fatigue of the tubing.

Manufacturing processes of Atlantic Bronze Age annular gold ornaments—A case study of the Guînes gold hard (Pas-de-Calais, France)

ABSTRACTThe gold work from the Western European Middle and Late Bronze Age (about 1500–700 BC) is characterized by solid ornaments and vessels. This article deals with manufacturing techniques of heavy gold jewelry by presenting a gold hoard found at Guînes, Pas-de-Calais, in Northern France, as a case study. In particular, three ornament types will be taken into consideration: (1) solid penannular neck and arm-rings, plain or with linear or geometric decoration; (2) flange-twisted ornaments that appear in different dimensions, as small as ear rings, as neck rings, up to the large size of a belt; (3) complex, composite ornaments. The technological aspects dealt with in this precious metal working context are manifold, including ingot and lost wax casting, hammering and bending of solid rods, the production of flange-twisted rods, chasing as decoration method, and finally joining techniques such as soldering, riveting and folding, and creasing.