Rod Material Research Articles

Comparison of Boron Carbide, Gadolinium Oxide, and Hafnium as Qualified Molten Salt Reactor’s Control Rods Material

The development and research of the Molten Salt Reactor (MSR) has recently seize the attention. Lots of MSR designs have been modeled based on its materials, neutronic behaviour, thermal-hydraulic behaviour, and particularly its safety systems. A reactor’s core has been modeled based on the design of ThorCon Reactor using Monte Carlo N-Particle 6 computational code with BeF2-NaF-UF4-ThF4 mixture as the fuelsalt. The core contains 84 hexagonal fuel logs and a hexagonal control rod log. This research compared three different materials of control rods, i.e. B4C, Gd2O3 and Hf. The comparison between those materials are seen according to reactor’s criticality. The keff at fully withdrawn position is 1.01887 that indicates a critical condition. When the control rods are fully entered the keff are (0.98293 ± 0.00012); (0.97386 ± 0.00011); (0.99203 ± 0.00012) for control rods’ materials in sequence B4C, Gd2O3 and Hf. The decretion of the criticality shows the materials’ ability to absorb the neutron. The lower the criticality, the better material’s absorption ability.

Effects of long-term operation on mechanical and physical characteristics of structural materials

Mechanical and physical properties of bainitic steel 15Cr2MnMoV used as a material of oil pump rods were studied in three states: as received, after operation in hydrogen sulfide-containing environment, and after hydrogen charging in H2S-containing media for 1 week. In addition, the austenitic corrosion-resistant steel 12Cr18Ni10Ti has been studied in two states: as received and after operation for 6 years. No degradation of the standard mechanical properties of the investigated steels after operation was revealed, although a decrease in the fatigue properties of the austenitic steel 12Cr18Ni10Ti was observed. Mechanical properties were most affected by hydrogen charging of bainitic steel, after which a decrease in ductility, fracture energy, and fatigue life is observed. Four stages of fracture development of the investigated steels under tension are distinguished. It is shown that acoustic emission is the most sensitive method for assessing the degree of structural degradation after operation or hydrogen charging. It is established that the magnetic methods of nondestructive testing show the greatest sensitivity at the elastic stage and at the stage of deformation localization before fracture.

Cutting brittle rods using elastic wave propagation

For the sake of intended industrial applications, the stress wave propagation in thin rods of brittle material is measured and explored. Based on the known theory of a non-dispersive wave propagation in rods, a numerically efficient method for the calculation of wave propagation and reflection is presented. The effects of an impact applied to a thin rod are tested and measured on a test bench. The results of these measurements carried out on glass capillary tubes are successfully compared with theoretical results and they confirm the possibility of brittle rod cutting by means of elastic waves with the required fracture surface quality.

Analysis of surface finish and residual stresses with shot peening on cylindrical specimens

Abstract Machining of cylindrical metal pieces effects the surface parameters due totool and type of contact. Due to the surface contact of the tool with the work material, the surface texture may deteriorate depending on the machining parameters applied. In order obtain good surface finish, the tool and machining parameter are the major considerations. In this paper shot peening was considered to determine good surface finishing. Cylindrical rods of different materials were considered for obtaining good surface finishing using the shot peening process. The nozzle was turned to an angle of 10 degrees from the principal axis. The blast pressure was controlled to obtain required surface finish. The surface hardness obtained after shot peening was measured. The residual stresses induced from the depth of the surface are determined and compared for various peening pressures.

Longitudinal vibrations of a cylindrical bar from the action of harmonic forces

The longitudinal vibration of a cylindrical rod has been studied in an elastic medium from the action of axial harmonic forces in a state of compression tension. The consideration took into account the damping of vibration of the rod according to the theory of E.S. Sorokin. Taking into account, internal friction made it possible to approach the real state of the rod as a source of wave radiation. The amplitude-frequency characteristic of the structure is built, taking into account changes in the parameters of the environment and the rod. The possibilities of the emergence of the resonance state of the rod are established. At the same time, cases were considered with and without inelastic properties of the rod material. The analysis of the influence of the properties of the environment and the rod on the amplitude of the displacement of the latter is carried out.

Limiting sulfur and mastering the diffusion of lithium ions with cerium oxide-based porous carbon rods.

Cerium dioxide nanocrystals embedded in porous carbon rod materials were used for sulfur storage and embedding. Polar cerium dioxide effectively adsorbed polysulfide and inhibited the shuttle effect. By calculating the diffusion coefficient of the lithium-ions, it was concluded that the porous carbon rod material with cerium oxide was beneficial for the rapid binding of lithium ions and sulfur.

On the correspondence of theoretical models of longitudinal vibrations of a rod with experimental data

A number of theoretical models are known for describing longitudinal vibrations of a rod. The simplest and most common is based on the wave equation. Next comes a model that takes into account lateral displacement (Rayleigh correction). The Bishop model is considered to be more perfect, taking into account both transverse displacement and shear deformation. It would seem that the more perfect the theoretical model, the better it should be consistent with experimental data. Nevertheless, when comparing with a really defined experimental spectrum of longitudinal vibrations of a rod on a large base of natural frequencies, it turns out that this is not quite so. Moreover, in the relative loss is the most complex Bishop model. Comparisons were made for a smooth long cylindrical rod. The questions of refinement with the help of experimentally found frequencies of the velocity of longitudinal waves and the Poisson’s ratio of the rod material are also touched.

Ageing Tests of Samples of Glass-Epoxy Core Rods in Composite Insulators Subjected to High Direct Current (DC) Voltage in a Thermal Chamber

In this article, we presented the results of the tests performed on three sets of samples of glass-reinforced epoxy (GRE) core rods used in alternating current (AC) composite insulators with silicone rubber housing. The objective of this examination was to test the aging resistance of the rod material when exposed to direct current (DC) high voltage. We hypothesized that the long-term effects of the electrostatic field on the GRE core rod material would lead to a gradual degradation of its mechanical properties caused by ionic current flow. Further, we hypothesized that reducing the mechanical strength of the GRE core rod would lead to the breakage of the insulator. The first group of samples was used for reference. The samples from the second group were subjected to a temperature of about 50 °C for 6000 h. The third group of samples were aged by temperature and DC high voltage for the same time. The samples were examined using the 3-point bending test, micro-hardness measurement and microscopic analysis. No recordable degradation effects were found. Long-term temperature impact and, above all, the combined action of temperature and DC high voltage did not reduce the mechanical parameters or change the microstructure of the GRE material.

Study of cooling process of plasma jet flowing around a thin ablating graphite rod

We present results of spectroscopic measurement of electron temperature in submerged nitrogen and argon mixture plasma jet for cases of free flow and introduction of thin graphite rod into the jet. The observed cooling of plasma caused by rod introduction agrees with the calculated enthalpy decrease from graphite rod heating and ablation. In this experiment, a marker was used to create artificial optical inhomogeneities in the flow, which allowed us to determine flow velocity from the analysis of their movement. In this case, we aim to determine the degree of influence of rod introduction into the plasma on its parameters. Upon introduction into the plasma, the rod was heated and partially destroyed by the plasma flow, reducing its temperature by 8-20% depending on the flow rate of the plasma-forming gas. The observed plasma cooling was compared with the calculated decrease in enthalpy caused by the cost of heating and ablation of the rod material.

Vibration response and band gap characteristics of functionally graded frame structure

Vibration response and band gap characteristics of the functionally graded frame structures are investigated based on the first-order shear deformation theory. The material properties of functionally graded material rods vary continuously in thickness direction according to a power law. Spectral stiffness matrix of the periodic functionally graded material frame structure in the global coordinate system is derived in detail. Consequently, the vibration band gap properties of the functionally graded material frame structure can be calculated and analyzed by using the spectral element method. The calculation accuracy for dynamic responses of the functionally graded material frame structure is validated by the finite element method. The results demonstrate that the wider band gaps in the low and medium frequency ranges can be achieved for the functionally graded frame structures comparing with the homogeneous ones. Moreover, the frequency windows and ranges for the band gaps of the functionally graded material frame structure can be effectively adjusted through designing the gradient indexes for the functionally graded material rods, which provide a novel idea for vibration suppression of frame structures.

Carbon Nano Tubes: Synthesis and Characterization for Microwave Applications

Attenuators are used to suppress the reflections in the helix traveling wave tubes and these attenuators are normally fabricated with the coating of some lossy material on the helix support rods. Carbon is the most commonly used attenuator material for the microwave applications and is usually deposited by pyrolytic or sputtering methods. However, other materials like iron and nickel are also used sometime for the attenuation applications. Helix is usually supported by the rods of some ceramic material like APBN (Anisotropic Pyrolytically Deposited Boron Nitride) or Alumina etc. Attenuator materials are deposited on these support rods to absorb the reflections. In order to look forward to new methods of deposition as well new attenuator materials, Carbon nanotubes have been proposed as another alternative attenuator material. Multi-Wall Cabon Nano-Tubes have been grown on the rectangular alumina substrate using the chemical vapour deposition method. Microwave attenuation/loss has been measured on these samples with X-band microwave frequencies. Specific experimental set-up has been designed for the measurement. The work is centered toward making good quality novel attenuators for the microwave applications and particularly the TWT.

Pengaruh Beban Tersebar dan Terpusat Terhadap Lendutan (Cantilever) Batang Besi

In development planning in the mechanical industry or civil engineering construction, it is very common to use the properties of the iron rod material which can deflect or what is known as a cantilever. The factors that affect the size of the force exerted on the stem are directly proportional to the amount of deflection that occurs. In other words, the greater the load experienced by the rod, the greater the deflection. Deflection of rods plays an important role, especially in building construction, wherein certain parts such as the shaft, deflection is very undesirable. Because of deflection, the work of the shaft or construction will be abnormal so that it can cause damage to the construction or other parts. This study aims to find out how much deflection of cantilevered rods using metal plate material when given a distributed and concentrated load. Based on the data obtained from the research process, the results in this study indicate that there is an effect of slackening distance on the iron plate with 3 variations in loading. The results showed that the loading rate affected changes in the angle of deflection of the iron plate in every variation of the number of plates used. The greatest effect occurred in the plate variation size of 0.8 mm with a loading level of 3 kg, namely 3.64 x 10-5 and the smallest effect on plate variations was 1.8 mm with a loading rate of 3 kg, which was 0. The results showed that the loading rate was spread across 3 plate variations. with a load of 3 kg spread over 3 points with a distance of 15 cm from point 1 to point 3. The biggest deflection effect occurs in plate variations of 0.8 mm which is 3.64x10-5 and the smallest effect on plate variations is 1.8 mm with the same load of 0.

Influence of the mushroomed projectile's head geometry on long-rod penetration

Self-sharpening has been observed in experiments and simulations of long-rod penetration. Penetration performances are influenced by different nose shapes occurred in the penetration of long rods made by different materials. In this paper, to model this nose shape effect, the resistance of the target in the standard Alekseevskii-Tate model is replaced by the resistance determined by the spherical cavity expansion approximation for general nose shapes. The function of nose shape is constructed to establish a modified model of long-rod penetration, in which the nose geometry during the long rod penetration is represented by two main parameters, i.e., the diameter ratio of rod nose and shank η and the nose shape factor N*. The influences of η and N* on long-rod penetration and their mechanisms are analyzed. The penetration performance decreases with an increasing diameter ratio η, whose physical basis is the increased radial flow of rod material around the nose, which in turn, leads to the loss of kinetic energy due to larger cavity formed in the targets. The nose shape factor N* reflects the sharpness of nose shapes, and a smaller value of N* corresponds to a sharper nose. N* obviously affects the ballistic performance of long-rod penetration, however, depending on the initial impact velocity. In general, the influence of N* is relatively smaller than that of η.

Study on Microstructures of Complex Plant Polysaccharides Aerogels and Their Effects on Porosity

The microstructure of polysaccharide aerogels is a key factor affecting porosity, and directly determines the efficiency of its application as filter rod material. Scanning electron microscopy was used to observe the effects of different amounts of starch on the microstructure of the complex plant polysaccharide aerogels. The experimental results showed that the aerogel samples showed a complete and homogeneous three-dimensional network structure. With the increase of starch content, the pore size became smaller and the pore structure on the hole wall became smaller. After adding starch, the concentration of the system increased, that is, the solute in the unit volume increased, the moisture content decreased, and the air replaced the water in the gel after freeze drying, resulting in the increase of the density of the aerogel and the decrease of porosity. All aerogels showed a trend of increasing filtration efficiency with increasing particle size. The filtration performance of aerogels with different starch content was tested by using the comprehensive performance test bed of filter media. The test results showed that the capture of filter material was mainly through inertial collision. When the particle size was bigger, the greater the inertia, the greater the possibility of particle contamination being captured, so the higher the filtration efficiency.

Mechanical Properties and Structure of Titanium-Alloy Overlays Alloyed With Oxygen from the Oxide Layer of Filler Rods

Prospects of oxygen alloying of alloys in the process of deposition of rods on parts from titanium alloys aimed at raising their hardness are considered. Experiments on fabrication of samples of titanium alloys with remelting of filler rods with oxide coating formed by plasma electrolytic oxidation are performed. The main mechanical characteristics of the overlay rod material modified by introduction of oxygen from the oxide layer are determined and the structural features of the material are analyzed.

Optimizing the centrally compressed step-variable stiffness rods

The article deals with the optimization parameters of centrally compressed step-variable stiffness rods, with the material that is able to work both within and out of proportionality. The following algorithms are developed: the maximization algorithm of loading critical parameter at the given volume of the rod material, and the minimization algorithm of the rod material volume observing the restrictions on durability and stability, taking into account the own weight of the rod. The analysis of the optimization results is carried out and the recommendations on calculation and rod design are offered.

Weakly nonlinear wave propagation in nanorods embedded in an elastic medium using nonlocal elasticity theory

In the present research, the nonlocal elasticity theory is utilized with the aim of examining nonlinear wave propagation in nanorods, which are embedded in an elastic medium. Constitutive equations on the basis of Eringen’s nonlocal elasticity theory are used in the formulations. Equations of motion are written in terms of material coordinates, and nonlinear equations of nanorods are obtained according to nonlocal elasticity theory. In the study, the rod material is treated as a single-walled carbon nanotube. With the solution of the field equation by the reductive perturbation method, the Korteweg–de Vries (KdV) equation is acquired as the evolution equation, which is governed by the nanorod in an elastic medium. The solitary wave solution of the KdV equation characterizing the motion of carbon nanorods in the elastic medium is given depending on the nonlocal parameter and the parameter of the stiffness of the elastic medium, and it is demonstrated how the nonlocal parameter and the stiffness parameter affect the wave profile.

Comprehensive In Silico Evaluation of Accessory Rod Position, Rod Material and Diameter, Use of Cross-connectors, and Anterior Column Support in a Pedicle Subtraction Osteotomy Model: Part II: Effects on Lumbosacral Rod and Screw Strain.

In silico finite element study. The aim of this study was to evaluate effects of six construct factors on rod and screw strain at the lumbosacral junction in an in silico pedicle subtraction osteotomy (PSO) model: traditional inline and alternative Ames-Deviren-Gupta (ADG) multi-rod techniques, number of accessory rods (three-rod vs. four-rod), rod material (cobalt-chrome [CoCr] or stainless steel [SS] vs. titanium [Ti]), rod diameter (5.5 vs. 6.35 mm), and use of cross-connectors (CC), or anterior column support (ACS). Implant failure and pseudoarthrosis at the lumbosacral junction following PSO are frequently reported. Clinicians may modulate reconstructs with multiple rods, rod position, rod material, and diameter, and with CC or ACS to reduce mechanical demand. An evaluation of these features' effects on rod and screw strains is lacking. A finite element model (T12-S1) with intervertebral discs and ligaments was created and validated with cadaveric motion data. Lumbosacral rod and screw strain data were collected for 96 constructs across all six construct factors and normalized to the Ti 2-Rod control. The inline technique resulted in 12.5% to 51.3% more rod strain and decreased screw strain (88.3% to 95%) compared to ADG at the lumbosacral junction. An asymmetrical strain distribution was observed in the three-rod inline technique in comparison to four-rod, which was more evenly distributed. Regardless of construct features, rod strain was significantly decreased by rod material (CoCr > SS > Ti), and increasing rod diameter from 5.5 mm to 6.35 mm reduced strain by 9.9% to 22.1%. ACS resulted in significant reduction of rod (37.8%-59.8%) and screw strains (23.2%-65.8%). Increasing rod diameter, using CoCr rods, and ACS were the most effective methods in reducing rod strain at the lumbosacral junction. The inline technique decreased screw strain and increased rod strain compared to ADG. N/A.

Comprehensive Evaluation of Accessory Rod Position, Rod Material and Diameter, Use of Cross-connectors, and Anterior Column Support in a Pedicle Subtraction Osteotomy Model: Part I: Effects on Apical Rod Strain: An In Vitro and In Silico Biomechanical Study.

In silico finite element study. The aim of this study was to evaluate the effect of six construct factors on apical rod strain in an in silico pedicle subtraction osteotomy (PSO) model: traditional inline and alternative Ames-Deviren-Gupta (ADG) multi-rod techniques, number of accessory rods (three- vs. four-rod), rod material (cobalt-chrome [CoCr] or stainless steel [SS] vs. titanium [Ti]), rod diameter (5.5 vs. 6.35 mm), and use of cross-connectors (CC), or anterior column support (ACS). Rod fracture following lumbar PSO is frequently reported. Clinicians may modulate reconstructs with multiple rods, rod position, rod material and diameter, and with CC or ACS to reduce mechanical demand or rod contouring. A comprehensive evaluation of these features on rod strain is lacking. A finite element model (T12-S1) with intervertebral discs and ligaments was created and validated with cadaveric motion data. Apical rod strain of primary and accessory rods was collected for 96 constructs across all six construct factors, and normalized to the Ti two-rod control. Regardless of construct features, CoCr and SS material reduced strain across all rods by 49.1% and 38.1%, respectively; increasing rod diameter from 5.5 mm to 6.35 mm rods reduced strain by 32.0%. Use of CC or lumbosacral ACS minimally affected apical rod strain (<2% difference from constructs without CC or ACS). Compared to the ADG technique, traditional inline reconstruction reduced primary rod strain by 32.2%; however, ADG primary rod required 14.2° less rod contouring. The inline technique produced asymmetrical loading between left and right rods, only when three rods were used. The number of rods and position of accessory rods affected strain distribution on posterior fixation. Increasing rod diameter and using CoCr rods was most effective in reducing rod strain. Neither CC nor lumbosacral ACS affected apical rod strain. N/A.

Generalized Thermoelastic Waves Propagation in Non-uniform Rational B-spline Rods Under Quadratic Thermal Shock Loading Using Isogeometric Approach

Generalized thermoelasticity based on Lord–Shulman theory that admits the second sound effect is developed for continuum-based modeling of the thermoelastic wave propagation in functionally graded material (FGM) rods with a variable cross-sectional area under quadratic thermal shock loading. The geometry of the problem, as well as the distribution of material properties, is defined continuously with Non-uniform rational B-spline. To assure the exact modeling of geometry, the problem is analyzed using the isogeometric approach. The effects of geometry and material distribution on thermoelastic waves are discussed in detail. Also, propagation, reflections, and propagation speed along the rod axis are investigated. It is shown that the amplitudes and speed of thermoelastic waves can be desirably controlled by the cross-sectional area and the material distribution of the rod, respectively.