Strength Of Rods Research Articles

Optimizing the geometry of the connecting rod in opposite pistons engine

The article presents the results of simulations research carried out, using Finite Element Method. The simulations were made in the Abaqus software. Studies were related to the reduction and improving of stress distribution in the connecting rod of opposite pistons combustion engine. The connecting rod has been developed in a 3D environment in the Catia software, then imported into the simulation tool, in which stress tests were performed. The connecting rod was subjected to a compression and stretching tests. Boundary conditions of forces used in simulation tests have been developed on the basis of the dynamic model created in the MSC Adams software. The study included nine iterations of geometric changes of connecting rod. Shape as well as properties such as parametric dimensions (rod length) were changed. The changes were dictated by the reduction of the maximum values of the stresses and the size of the fields with large stress values. As a result of the simulations, the improvement of the connecting rod strength was obtained by its geometrical change (which was obtained by reducing the stress fields).

Critical Impact Yaw for Long-Rod Penetrators

This paper presents an improved model for the critical impact yaw (or simply the critical yaw) in long-rod penetration with considering the deceleration and rotation of the rod and the crater shape of the target. Two critical yaws, θc1 and θc2, under normal impact were identified, below which there is no contact between the rod and crater sidewall (for θc1) and between the rod and the crater entrance (for θc2) during the entire penetration process. Contact functions and iterative algorithms were proposed in order to obtain these two critical yaws numerically. The influences of four dominant nondimensional numbers (i.e., the ratio of the target resistance to the rod strength λ, Johnson's damage number of the rod ς, square root of the target–projectile density ratio μ, and the diameter–length ratio of the rod ψ) on two critical yaws were studied for three typical rod–target systems (tungsten alloy rods penetrating steel targets, steel rods penetrating aluminum alloy targets, and steel rods penetrating steel targets). The relationship between two critical yaw angles was also discussed. A new empirical formula for the critical yaw θc2 was proposed based on the parametric study results and dominant nondimensional numbers, which extends the valid application range of the existing empirical formula.

Resistance-curves and wood variability: Application of glued-in-rod

The current study investigates the withdrawal strength of glued-in rods as part of linear elastic fracture mechanics. An experimental campaign was performed in order to observe the effect of the specie (spruce and oak) on the axial strength of glued-in rods for given geometrical configurations. Finite elements modelling was presented in order to consider the progressive damage and the crack propagation located at the wood-adhesive interface (failures obtained during experiments). The approach aims at separating the progressive failure due to mode I and mode II. For this, Resistance-Curves, regarded as material properties, were used to characterize the peeling and the shear effects at the ultimate state. The study reveals that the mode I initiates the damage in the glued interface. Using several finite element runs, the predicted pull-out strengths were estimated from the elastic properties of substrates (wood, adhesive and steel) and the fracture properties of wood. Numerical results show the dependence of the strength according to the stiffness of the materials. Moreover, the scattering of the results is also affected by the variability of the fracture energies of the wooden substrates. The investigation leads to propose a robust approach which is able to predict the axial strength of glued-in-rods, considering the variability of each material and combining damage and crack propagation of the wooden substrate. It reveals that the prediction of the ultimate load cannot be performed considering only the failure mode II.

Implant Failure of Titanium Versus Cobalt-Chromium Growing Rods in Early-onset Scoliosis.

Retrospective case series of one institute database. To investigate the differences in the metallic strength of rods used for implant failure in the dual growing rod technique and evaluate clinical outcomes. The dual growing rod technique in which implanted rods extend with the growth of the spine is a useful treatment for early onset scoliosis. However, many complications, particularly those associated with rods, exist. Especially, the implant failure of growing rod focused on metallic strength is unknown. Thirteen patients (42 lengthening surgeries) who underwent surgery by this technique at our hospital from 2007 were divided into a titanium rod plus titanium connector group (T group, n = 4, 26 lengthening surgeries) and cobalt-chromium rod plus titanium connection group (C group, n = 9, 16 lengthening surgeries). The incidence of implant failure and the site of fracture were retrospectively investigated. Implant failure occurred in three patients in the T group, because of rod fracture in two patients and connector fracture in one. In the C group, implant failure occurred in six patients, because of rod fracture in one patient and connector fracture in seven. Fracture occurred twice in two patients. The rod fracture rate decreased with the use of cobalt-chromium rods but the rate of connector fracture increased. We performed a stress distribution analysis using the finite element method to clarify the mechanisms underlying implant failure in both groups. Regardless of the rod type, the greater load was placed on the distal rod. However, differences in the metallic strength caused the rod to fracture when titanium rods were used and connectors (weak metallic strength) to fracture when cobalt-chromium rods were used. Rod fractures occurred more commonly with titanium rods and connector fractures with cobalt-chromium rods.

Creep fracture of plates with variable bending moments in the presence of an aggressive medium

The dissipated fracture of a rectangular plate with bending under conditions of a time-varying plane stress state taking account of the effect of an aggressive medium is investigated. A method for determining the time up to the fracture of such a plate when it is successively bent in different planes is proposed. Using Rabotnov's kinetic theory, the times up to fracture are compared in the case of scalar and vector damage parameters using a power creep model. The deviations of the sum of the partial times from unity are investigated in the case of piece-wise constant relations between the level of the bending moment and time. An analogy with the results of experiments on the creep strength of rods with a piecewise-constant tensile stress is shown.

Manufacturing of high-strength Ni-free Co–Cr–Mo alloy rods via cold swaging

The strengthening of biomedical metallic materials is crucial to increasing component durability in biomedical applications. In this study, we employ cold swaging as a strengthening method for Ni-free Co–Cr–Mo alloy rods and examine its effect on the resultant microstructures and mechanical properties. N is added to the alloy to improve the cold deformability, and a maximum reduction in area (r) of 42.6% is successfully obtained via cold swaging. The rod strength and ductility increase and decrease, respectively, with increasing cold-swaging reduction r. Further, the 0.2% proof stress at r=42.6% eventually reaches 1900MPa, which is superior to that obtained for the other strengthening methods proposed to date. Such significant strengthening resulting from the cold-swaging process may be derived from extremely large work hardening due to a strain-induced γ (fcc)→ε (hcp) martensitic transformation, with the resultant intersecting ε-martensite plates causing local strain accumulation at the interfaces. The lattice defects (dislocations/stacking faults) inside the ε phase also likely contribute to the overall strength. However, excessive application of strain during the cold-swaging process results in a severe loss in ductility. The feasibility of cold swaging for the manufacture of high-strength Co–Cr–Mo alloy rods is discussed.

Prediction of Properties of Metal upon Combined Alloy Processing of the Al–REM System Based on the Stepwise Evaluation of Their Mechanical Properties

The data of experimental studies on determining the mechanical properties of long-length deformed semifinished products in a form of bars and wire made of alloys of aluminum with rare-earth metals, which are fabricated using the combined treatment methods, are presented. The application of the combined technology of casting, rolling, and pressing makes it possible to increase the strength of hot-extruded rod by 15–20 % on average compared with combined rolling–extruding the cast billet formed in an electromagnetic crystallizer. It is also shown that a decrease in the REM content in the alloy leads to the strength reduction and an increase in plastic characteristics. Herewith, it is possible to control the level of physicomechanical characteristics of the final product varying the summary deformation ratio during drawing and applying annealing.

Creep and long-term strength of rods under stretching and bending in aggressive environment

The article describes the features of high-temperature deformation of the rods in aggressive environment. In the first section it is considered the related problem of the long-term strength of a stretched rod in aggressive environment. Unlike the known solutions, it is taken into account the interdependence of the environment concentration level in the material of the rod and the value of accumulated damage. Obtained are the values of the time before failure of the rod with different formulations of the problem. In the second section it is investigated creep of the rod in pure bending under these conditions, taking into account different rod-resistance to tension and compression. The solutions of problems at steady creep of the rod, with additional accounting of accumulated damage of the material and influence of aggressive environment.

A testing procedure for predicting strength in artificially cemented soft soils

It is globally recognized that soft soils will have low strength and high compressibility and that under reduced loads might collapse or suffer large displacements. In order to reduce settlements and increase bearing capacity of structures built on such soils, their stabilization using cementitious materials such as Portland cement and/or quicklime (increasing strength and stiffness) is an efficient technique used worldwide. The focus of this research is to present and check the accuracy of a new testing procedure to evaluate strength gain in very soft soils when using cementation as a means of improvement. This testing procedure was intended to fasten acquiring strength results in artificially cemented soft soils. In short, in the proposed procedure the force applied to embed a flat base rod into a soil mass is measured by using high resolution load rings. The proposed flat base rod embedding test was shown to be adequate for evaluating the gain in strength of cemented soils. Results of embedding flat base rod strength have unique linear relations with both unconfined compressive strength and splitting tensile strength, being independent of type and amount of cementitious material (Portland cement and/or quicklime), as well as of the curing time period. The wrap up of present studies is that the developed testing procedure can be used as a substitute of unconfined compression and splitting tensile tests as a dosage test, being easier to mold specimens (might be molded in the field) and faster in acquiring strength results (can be carried out in a bucket filled with soil and the cementitious material, in which will be attached to the load ring) in artificially cemented soft soils.

Influence of Rod Contouring on Rod Strength and Stiffness in Spine Surgery

For spinal fusion or the correction of spine deformity at multiple levels, intraoperative rod contouring is required to realign the spine. A French bender is the most common contouring tool used. There are several reports on the mechanical properties of various rods with manufactured straight rod; however, few reports describe the changes in a rod's mechanical properties after rod contouring. The authors investigated the influences of rod contouring on rod strength and stiffness. A 3-point bending test was conducted. Each 18-cm rod was loaded at a rate of 10 mm/min with a load applicator. Three different rod diameters (5.5, 6.0, and 6.35 mm) and 2 types of materials (titanium [Ti] alloy and cobalt-chromium [CoCr] alloy) were assessed. Different rod curvatures were evaluated: (1) a no-preparation rod of 0° (control); (2) a 0° rod bent at one point to make tangential angles of 10° and then bent back from the opposite side; (3) a bent rod with tangential angles of 20°; and (4) a 40° bent rod. The yield strength in all types of rod materials and diameter decreased after rod contouring using a French bender. The extent of decrease depended on the degree of bend. The bending stiffness of each rod also decreased. The CoCr rod showed higher bending stiffness than the Ti rod of the same diameter. Rod contouring using a French bender reduced the yield strength and stiffness in all types of rods. Decrease of yield strength correlated to the degree of bend. In the comparison of 20° and 40° contoured rods, the 6.0-mm CoCr rod showed the highest reduction force. This study found that rod contouring procedures reduced rod yield strength and stiffness.

단일 고전단 링앵커의 전단강도 평가

The usage of anchors has increased in joints of new and old concretes for the purposes of seismic retrofits, remodeling, strengthening of existing structures, and so on. In most cases, the shear capacities of the anchors are governed by the steel strength of anchor rods. A lot of anchors should be installed to develop full strength of new structures. In this study, high-shear-capacity ring anchors consisting of steel ring and rod were developed and their shear capacities were examined through shear tests with varying beam width, concrete compressive strength, embedment depth of anchor rod, ring shape, epoxy types, and anchor types. For the specimens with the shallow width that is less than 3.33 times of the ring diameter, splitting failures occurred with the side cover concrete spalling. In splitting failure, the shear capacity increased as the specimen width increased. For the specimens with the wide width, the ring anchors failed due to bearing and the width did not affect the shear capacity. The shear capacities of the ring anchors are at least 1.75 times and up to 4.37 times of the shear capacity of the rod anchor. In addition, the ring anchors had higher stiffness and in most cases the maximum capacities were developed at 2 mm or less displacement. The improved stiffness may enhance the usage of the ring anchors for seismic retrofits. The embedment depth also affects the shear capacities of the ring anchors. With an embedment depth of 125 mm, the ring anchors have shear capacities of at least 3.3 times of the shear capacity of the rod anchor. Therefore, the number of anchors can be significantly reduced.

High strength chitosan rod prepared via LiOH/urea solvent through centrifugation induced orientation processing

High strength chitosan rod prepared via LiOH/urea solvent utilizing the unique centrifugation induced orientation method.

Impact and Penetration of SiC: The Role of Rod Strength in the Transition from Dwell to Penetration

The phenomenon of dwell during projectile impact on ceramics has been an active area of research for several decades. Dwell in confined ceramics has received much attention, particularly the role of cover plates and their influence over the dwell to penetration transition. Dwell during long rod impact on unconfined ceramics has received relatively less attention. The present work will compare and contrast the results of two series of long rod impacts on hot pressed silicon carbide targets. One series utilized gold wire rods. The other series utilized rods fabricated from tungsten carbide with 10% cobalt matrix. A novel ten-flash X-ray system captured spatially resolved images of the penetration events. The experimental results are compared with simulations and predictions from the Alekseevskii-Tate equation to explore the role of shock pressure, the effects of the strength of the rod material in dwell to penetration transition behavior, and the behavior of defects within silicon carbide.

Shear behavior of basalt fiber reinforced polymer (FRP) and hybrid FRP rods as shear resistance members

This paper investigates the shear properties of basalt fiber reinforced polymer (BFRP) and the hybrid FRP rods as shear resistance members. The shear properties of FRP rods and the corresponding resin casting rods were studied separately, including variables representing rod diameters of 4–16mm, resin types of epoxy and vinyl ester resins and fiber types comprising basalt, carbon and their hybridization. The ratio between shear stress and shear deformation was first described according to experimental results, and the shear contribution mechanism was clarified for different stages. An equation for predicting the shear strength of BFRP and hybrid FRP rods was proposed by discussing the influence of different variables. The results show that the shear strength and shear deformation ratio of different FRP rods is maintained almost constantly regardless of the variation in diameters, resin types and fiber types. The major shear resistance in FRP rods is contributed by the internal fibers, whereas the resin contributes only 8% of the overall strength and acts only in the first stage. A three-stage model is proposed to describe the entire stress to deformation ratio. A derived equation based on the shear contribution analysis is also used to predict the shear strength of the BFRP and hybrid FRP rods with high accuracy.

Effect of Process Parameters on Friction Surfaced Coating Dimensions

Friction surfacing is a novel technology to build corrosion and wear resistant coatings and build functionally graded metallic layers. In this work, the coating dimensions as affected by process parameters and high temperature strength of consumable rods have been compared. Friction stir welding equipment, RM-1 model procured from MTI was used. Carbon steel, austenitic stainless steel and Ni-based alloy coatings were deposited. Following process parameter ranges were used: rotational speed: 1000-2000 RPM, feed rate: 50-150 mm/min and axial load: 3-12 kN. Results showed that the coating width and thickness decreased with a) increased magnitude of the process parameters used and b) increased high temperature strength of the consumable rod.

The Effect of Contouring on Fatigue Strength of Spinal Rods: Is it Okay to Re-bend and Which Materials Are Best?

Study DesignSmall-diameter spinal rods were tested in fatigue loading before and after contouring in pedicle screw constructs using dynamic testing machines. ObjectiveTo characterize the change in fatigue performance of spinal rods resulting from contouring. Background SummarySpine surgeons have a variety of rod materials to choose from, and selecting the best rod depends on patient characteristics and rod material properties, including fatigue performance. MethodsFour rod materials were tested, all 4.5 mm in diameter: titanium alloy (Ti), cobalt-chromium alloy (CoCr), and 2 different grades of stainless steel (SS and ultra SS). Three conditions were tested: straight (virgin rods), bent (rods bent to a radius of curvature of 100 mm), and re-bent (rods over-bent to a radius of 50 mm, then partially straightened to a 100-mm radius). Fatigue testing was conducted on unilateral vertebrectomy constructs with polyaxial screws. ResultsIn all conditions, the endurance limit of the CoCr rods was at least 25% higher than the other materials but could not be determined because screw failure precluded rod failure. In the bent condition, the endurance limits of Ti, standard SS and ultra SS were reduced between 20% and 40%. In the re-bent condition, the endurance limit of Ti, standard SS, and ultra SS increased compared with the bent condition. Changes in fatigue performance are best explained by residual rod stresses induced during contouring. ConclusionsIt appears safe to over-bend and then re-bend, for 1 cycle, small-diameter spinal rods made of the materials tested in this study using tube benders, and CoCr rods were clearly superior for all conditions. However, larger rods, multiple cycles of bending and re-bending, and rods bent using other instruments such as French benders were not studied and may result in different performance under the same conditions.

Predicting the penetration of long rods into semi-infinite metallic targets

Analytical equations are presented herein to predict the penetration of semi-infinite metallic targets struck normally by long rods at high velocities for Y p<S where Y p is the rod strength and S is the static target resistance. The equations are derived based on energy balance method. It is assumed that the kinetic energy loss of a long rod is related to the energy dissipated by the plastic deformations in the target, the energy consumed by the long-rod penetrator itself and the energy carried by the eroded rod debris. Secondary penetration is also examined in the present paper due to the fact that the eroded rod debris forms a tube which can penetrate the target further if the density of the rod is greater than that of the target and the impact velocity is high enough. The present analytical equation is found to be in good agreement with the experimental data for a wide range of impact velocities.

Optimization Design of Connecting Rod in Twin-Rotor Cylinder-Embedded Piston Engine

For cylinder-embedded piston in Twin-rotor piston engine, the piston and rod are both the important component of power transmission, and their design directly affects the efficiency of engine. For comparison of the piston, ether from sealing and lubrication or the appearance, it is consistent with that of traditional engine, but the rod is different from the old one. In this paper, the static strength of rod is modeled and analyzed, and based on that the structure of rod is optimized by ANSYS workbench. It can be concluded that: for the rod, the maximum of mass, stress and deformation are determined by the three parameters, which are rod length L, width b and height H. The mass of rod is proportional to them, and the levels of impact of the parameters to the targets, from maximum to minimum, are b, H and L successively. However, a comprehensive consideration is necessary for the parameters selected based on the practical condition.

Functional polyacetylenes: hybrids with carbon nanotubes

Functional polyacetylenes (PAs) have attracted great interest and a series of tutorial reviews dealing with the recent progress in the related fields can be found in the literature. The investigation of the hybrids of functional PAs and inorganic nanostructures is a newly asserted and developing area. In this review, we summarise the related works on the hybrids of functional PAs and carbon nanotubes (CNTs) reported in the last decade. The effects of the structural parameters such as the polymer mainchain, functional pendants and the linker between them on the solvating power towards CNTs are explored step-by-step. Concerning the mechanisms of dispersing CNTs into solvents, a novel factor, or donor–acceptor interaction, has been singled out, thus providing a novel concept to design functional polymers for the fabrication of CNT-based processable hybrids. The strong solvating power of properly designed functional PAs facilitates the non-harmful surface functionalization of CNTs and permits using the hybrids of PAs/CNTs as templates to derive multi-component nanocomposites. Different nanostructures including Ag nanoparticles, ZnO nanocrystallites, CdS nanorods and γ-Fe3O4 nanoparticles are successfully incorporated into the functional PAs/CNTs hybrid systems, which show efficient charge transfer, charge carrier transport, enhanced solvatochromism, and superparamagnetic properties. Rationally functionalized PAs demonstrate good biocompatibility and their hybrids with CNTs can be used as active additives to reinforce the bending strength and modulus of chitosan rods. Finally, a brief outlook of the promising directions in this promising research area is contributed.

Flexural Analysis of Full-Scale RC Beam Strengthened with Steel Rods

This paper presents an analytical method of evaluating the flexural behavior of RC beams externally strengthened with unbonded high-tension steel rod. A simple summation method proposed in this paper basically assumes that the total strength of RC beams strengthened with rod is equal to the sum of the strength of RC beam and the strength of rod. The strengthening steel rods connected to beam with U and V shape profile are considered as a truss system for the analysis. This analytical method also includes the effect of compressive force applied to RC beam due to the tension of rod as well as the effect of effective prestress in steel rod. A comparison of the analytical and experimental results leads to the conclusion that the simple summation method can simulate the flexural behavior of RC beam strengthened with rod with a good level of accuracy.