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A fault tolerant control method has been proposed based on the steer-by-wire system with dual steering actuator motors as presented in this paper. The paper built a real-time fault diagnosis mechanism based on the motor model and adaptive fading Kalman filter firstly. Then the diagnosis results were used to judge whether the angle feedback control and the torque feedback control need to be amended to realize fault tolerant control. Finally, hardware-in-the-loop test bench of this steer-by-wire system has been built for experiments and the results demonstrated that the fault tolerant control method was feasible and accurate. [ABSTRACT FROM AUTHOR]

In this paper, a new possibility of fabricating a metal lattice structure with a continuous rod is demonstrated. A multi-layer, periodic, and aperiodic lattice structure can be manufactured with a continuous thin rod by bending it with a repetitive pattern. However, joining their nodes are challenging and an important problem to solve. This paper is investigating the joining of nodes in a loose lattice structure by delivering materials through the dipping process. Both liquid state (epoxy) and solid-state (inorganic particles) joining agents are considered for polymer–metal and metal–metal bonding, respectively. Liquid Carrier Systems (LCS) are designed considering their rheological behavior. We found 40% solid loading with the liquid carrier system provides sufficient solid particles transfer at dipping and join the lattice node using transient liquid phase bonding (TLP). 3D metal lattice structures are constructed, and their mechanical properties are investigated. The lattice structure shows comparable strength even with smaller relative density (< 10%). The strength and elastic modulus of all the fabricated samples decreases with the increase in cell size, which is consistent with the traditional wisdom. [ABSTRACT FROM AUTHOR]

This paper treats an exact elastica solution for a clamped-hinged beam, and its applications to a carbon nanotube. Although the elastica has a long history, and the exact post-buckling solution for the Euler buckling problem has been known for at least 150 years, it seems that the elastica solution for a post-buckled clamped-hinged beam has never been obtained. Therefore, the exact solution obtained in this paper constitutes an addition to the existing family of elastica solutions. As an application of the results, a post-buckling analysis of a single wall carbon nanotube is studied. Also, a potential use of the post-buckling analysis of the carbon nanotube for the determination of its Young's modulus has been indicated. [ABSTRACT FROM AUTHOR]

This paper deals with the modelling of a plastic beam experiencing softening. This kind of behaviour is observed in steel or reinforced concrete structural members undergoing large rotation amplitudes, which may occur typically for civil engineering structures in the seismic area. The homogeneous cantilever beam loaded by a concentrated force at its extremity is considered. This simple structural problem with gradient bending moment allows an analytical treatment of the evolution problem. It is shown that a local plastic softening model makes the evolution problem ill-posed. Moreover, if we require the plastic curvature to be a continuous variable of the spatial coordinate, Wood’s paradox is encountered. A non-local gradient plastic model is developed in order to overcome this paradox. However classical gradient plastic models may not eliminate the ill-posedness since the beam response may not be continuous with respect to the loading parameter. The new gradient plastic model, presented in this paper, is similar to previous classical gradient models. The main difference is the yield moment considered as a non-local material parameter. This permits to ensure continuity between the elastic and the plastic regions during the loading process. These solutions are controlled by the ratio between the material length and the geometrical length of the beam. The new evolution problem may remain ill-posed as it possesses a finite number of solutions (which can be unique). Closed-form solutions of the unknown deflection are given. [ABSTRACT FROM AUTHOR]

In 1974 W. S. Hemp constructed a prototype structure to carry a uniformly distributed load between two pinned supports. Although Hemp's structure had a significantly lower volume than a parabolic arch with vertical hangers, it was shown to fail the Michell optimality criteria, and therefore to be non-optimal. In this paper we demonstrate that if limiting compressive and tensile stresses are unequal then Hemp's structure is optimal for the half-plane provided the ratio of limiting tensile to compressive stresses falls below a certain threshold. An analytical proof is presented and the finding is confirmed by results from large scale numerical layout optimization simulations. [ABSTRACT FROM AUTHOR]

This paper presents new finite element methods for the analysis of localized failures in plastic beams and frames in the form of plastic hinges. The hinges are modeled as discontinuities of the generalized displacements of the underlying Timoshenko beam/rod theory. Hinges accounting for a discontinuity in the transversal and longitudinal displacements and the rotation field are developed in this context. A multi-scale framework is considered in the incorporation of the dissipative effects of these discontinuities in the large-scale problem of a beam and a general frame. A localized softening cohesive law relating these generalized displacements with the stress resultants acting at the level of the cross section is effectively introduced in the frame response. The resulting models, referred to as localized models, are then able to capture the localized dissipation observed in the localized failures of these structural members, avoiding altogether the inconsistencies observed for classical models in the stress resultants with strain softening. The constructive approach followed in the development of these models leads naturally to the formulation of enhanced strain finite elements for their numerical approximation. In this context, we develop new finite elements incorporating the singular strains associated to the plastic hinges at the element level. A careful analysis is presented so the resulting finite elements avoid the phenomenon of stress locking, that is, an overstiff response in the softening of the hinge, not allowing for the full release of the stress. The accurate approximation of the kinematics of the hinges requires a strain enhancement linking the jumps in the deflection and the rotation fields, given the coupled definition of the transverse shear strain in these two fields. Different enhanced strain elements, involving different base finite elements and different enhancement strategies, are considered and analyzed in detail. Their performance are then compared in several representative numerical simulations. These analyses identify optimally enhanced finite elements for the accurate modeling the localized failures observed in common framed structures. [ABSTRACT FROM AUTHOR]

New systems of pretwisted bars are suggested, and their stability under a conservative load is investigated. In this paper, closed‐form relationships are obtained for the direct evaluation of critical loads of pretwisted cross bracings with different end connections and an arbitrary ratio of the dimensionless parameters of tension and compression elements. The equation for the critical loads is derived for tension and compression braces with different section properties, lengths, and axial loading. It is found that the critical load of a twisted brace is higher than that of a nontwisted brace. Parametric solutions are graphically displayed to clarify the distinct behavior, including the boundary separating symmetric and antisymmetric modes of buckling. [ABSTRACT FROM AUTHOR]

The present paper provides a collision model for Cosserat rods, able to represent a very general collision response, including frictional effects as well as multiple simultaneous collisions of a large number of rods. The proposed collision model falls into the category of constraint-based collision models. This concept is extended to a general class of objects sharing properties of rigid and deformable bodies, here undertaken for viscoelastic Cosserat rods. The collision constraints are imposed by collision impulses added to the external loads of the equations of motion of the colliding objects. No iterations between the equations of motion and the collision model are required. Both parts are executed in a staggered manner, so that the collision model is well separated from the equations of motion. Hence, existing solvers for Cosserat rods or similar objects can easily be extended, so that the range of application is significantly enlarged to the collisional regime. Extensive validations are presented using various test cases, ranging from a collision of a single rod with a wall to more realistic configurations with multiple simultaneous collisions of numerous rods. [ABSTRACT FROM AUTHOR]

Conventional sensors for debris flow monitoring suffer from several drawbacks including low service life, low reliability in long-distance data transfer, and stability in severe weather conditions. Recently, fiber Bragg grating (FBG)-based sensors have been developed to monitor debris flows. However, they can be easily damaged by the impact forces of boulders within debris flow. This paper presents a new FBG-based device to measure the strain induced by the impact force of debris flow with high reliability and effectiveness. The effects of the impact forces of debris flows have been investigated. Then, the relationship between the strain and the debris flow energy correlating with the damage to building structures has been established. It is shown that this new FBG-based device is capable of monitoring and warning about debris flows. [ABSTRACT FROM AUTHOR]

Copyright of Arabian Journal for Science & Engineering (Springer Science & Business Media B.V. ) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A vision-based inspection system has been investigated in order to improve the quality of products and processes found in various industries. In this paper, we propose a new defect detection algorithm for steel wire rods produced by the hot rolling process. Because the steel wire rods are long cylinder rods with a circular cross section, the brightness at the sides and center is inconsistent. Moreover, the various types of steel wire rods and the presence of scales affect the reflection properties of the rod surface. In order to resolve the abovementioned difficulties, the use of dynamic programming and a discrete wavelet transform are proposed. An adaptive local binarization method is used to further reduce the effects of scale. The effectiveness of the proposed method is shown by means of experiments conducted on images of steel wire rods that were obtained from an actual steel production line. [ABSTRACT FROM AUTHOR]

In deep hole boring process, long and flexible boring bars are often used. Due to the large length-to-diameter ratio, the stiffness of the boring bars is inevitably reduced, where the boring bars’ vibration effects will occur. The influences of vibration will significantly degrade the accuracy and the surface quality, or even lead failure of the production. Therefore, it is of significant importance to develop techniques to reduce vibration in deep hole boring. In this paper, a new boring bar with a variable stiffness dynamic vibration absorber (VSDVA) is presented, where the basic parameters of the proposed boring bar are measured. Based on the proposed dynamic model, the vibration characteristics of the proposed boring bar are analyzed, and the change laws of the vibration reduction performance are obtained under different excitation frequencies. A new vibration reduction method is proposed, where best vibration reduction performance can be achieved by adjusting the stiffness of the VSDVA. Finally, the vibration reduction performance of the proposed boring bar is validated and evaluated by boring experiments. These works could provide guidance for designing new types of boring bars, selecting cutting parameters, and adjusting the vibration reduction performance of the proposed boring bar, and as a result, it provides a new design idea for the design of boring bar. [ABSTRACT FROM AUTHOR]

In this paper, a diagnosis method based on Hilbert and discrete wavelet transform (DWT) for broken rotor bars in induction machine has been proposed. The method is based from using Hilbert transform (HT) to obtain the envelope for the stator current and processed via DWT. The main advantage of HT is the removal of the fundamental component to allow a clearer vision of the fault frequencies. The result by HDWT (HT and DWT) is more suitable for emergency signal analysis. This technique is effective for the stationary signal as well as non-stationary signal processing. The HDWT analysis was introduced to overcome the shortcomings of Fourier analysis. The performance of this approach is evaluated in simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a study on the bond characteristics of glass fiber reinforced polymer (GFRP) bars in engineered cementitious composite (ECC). Ninety beam specimens having variable parameters namely bar diameter, GFRP bar types (standard low modulus 'LM' and high modulus 'HM'), two concrete types (ECC and normal concrete 'NC') and embedded length (5, 7 and 10 times bar diameter) were tested as per RILEM specifications. Bond stress-slip characteristics and failure modes of specimens as well as influence of variable parameters on bond strength are described. The performance of various Codes and other existing equations in predicting bond strength of both low/high modulus GFRP bars embedded in ECC compared to NC is described based on experimental results. The bond strength decreased with the increase of embedment length--maximum bond strength reduction of 36% was observed. For both ECC and NC, bond strength reduced with the increase of bar size and ECC produced maximum 1.6 times higher bond strength compared to NC. Code based and other existing equations were found conservative in predicting bond strength of GFRP bars embedded in ECC. [ABSTRACT FROM AUTHOR]

Toward improving conventional beam elements in order to include distortional effects in their analysis, in this paper, independent parameters have been taken into account. Beam's behavior becomes more complex, especially for eccentric loading, due to the coupling between warping and distortion. Thus, the importance of including higher-order phenomena in the analysis arises in order to derive accurate results. Due to the fact that more degrees of freedom are employed, the computational cost of the problem is significantly increased. Isogeometric tools (B-splines and NURBS), either integrated in the finite element method or in a boundary element-based method called analog equation method, are employed in this contribution for the static analysis of beams of open or closed (box-shaped) cross sections toward improving computational effort. Responses of the stresses, stress resultants and displacements to static loading have been studied. [ABSTRACT FROM AUTHOR]

In precise cropping of the metal bars with different geometrical parameters, it is very important to obtain the reasonable initial external forces required by the bars rapidly and accurately. Stress concentration factor and stress intensity factor are proposed to calculate the initial external force accurately in this paper according to geometrical sizes of metal bars. By means of numerical simulation and linear fitting method, the correctional expressions of stress concentration factor and stress intensity factor of V-shaped notch tip, which include the geometric parameters of the bar, are obtained respectively and the error analyses are also performed. The ratio of the depth of V-shaped notch to the diameter of the bar is presented to be a condition parameter. The numerical analytical results show that the method of stress concentration factor can be used to calculate the initial external force accurately when the ratio of the depth of V-shaped notch to the diameter of the bar is more than 0.05, and the method of the stress intensity factor can be used when the ratio is less than 0.05. The calculating formulas of reasonable initial external forces for the bars with different geometrical parameters are also given. The cropping experimental results have confirmed that it is feasible that the reasonable initial external forces required by the bars with different geometrical parameters are calculated effectively by using the stress concentration factor or the stress intensity factor in precision cropping. [ABSTRACT FROM AUTHOR]

The object of this paper is the uniform torsion of inhomogeneous, isotropic, linearly elastic cylindrical bar. The aim is to give lower and upper bounds for the torsional rigidity of the bar with doubly connected cross section. The outer and inner boundary curves of cross section are similar curves. The level lines of the function which gives the change of the shear rigidity on the cross section are also similar curves to the boundary curves. The application of derived bounding formulae is illustrated by examples. An approximated formula to determine the shear stresses is also presented. [ABSTRACT FROM AUTHOR]

Object of the paper is the simulation of reinforced concrete bars behaviour, accounting for crack opening and concrete-rebar slippage. A macro beam element with a single uniform reinforcement is studied in details in the uniaxial case. Distinct constitutive hypotheses are formulated for the materials. The CEB-FIP Model Code 90 rules the behaviour of the materials interface that is assumed to be fully dissipative. Steel is supposed to behave elastoplastically with hardening. Crack opening in the concrete matrix is introduced by means of a strong discontinuity approach (SDA). All the relevant equations of the problem are variationally derived from a mixed energy functional. Two enhancements of the enriched kinematics, based on polynomial or exponential shape functions, respectively, are compared with the usual SDA enhancement. As an alternative approach, high-order interpolation of the displacement field based on B-splines, both for steel and concrete, is proposed. These functions appear to be adequate in reproducing rapidly varying fields, like the stress gradients occurring in the shear lag problem near the boundaries or where slips and/or cracks occur. Their use allow to use few macro-element instead of the very dense meshing required in those areas by the traditional FE interpolations. [ABSTRACT FROM AUTHOR]

Research on convective heat transfer coefficient around a rod bundle has many diverse applications in industry. So far, many studies have been conducted in correlations related to internal and turbulent fully-developed flow. Comparison shows that Dittus-Boelter, Sieder-Tate and Petukhov have so far been the most practical correlations in fully-developed turbulent fluid flow heat transfer. The present study conducts an experimental examination of the validity of these frequently-applied correlations and introduces a manufactured test facility as well. Due to its generalizibility, the unique geometry of this test facility (hexagonal arranged, 7 vertical rods in a hexagonal tube) can fulfil extensive applications. The paper also studies the major deviation sources in data measurements, calibrations and turbulence of fluid flow in this. Finally, regarding to sufficient number of experiments in a vast fluid mean velocity range (3,800 < Re < 40,000), a new curve and correlation are presented and the results are compared with the above mentioned commonly-applied correlations. [ABSTRACT FROM AUTHOR]

The paper deals with wave propagation in an elastic homogeneous bar that includes a prestressed segment in it. The prestress in that segment may be due to some distortion forces acting upon the bar. The end surfaces of the segment act as discontinuity surfaces inside the medium. They partially reflect and partially transmit any pressure wave impinging on them. It is found that the coefficients of reflection and transmission are functions both of the prestress of the segment and of the frequency of the wave. This produces a prestress-induced dispersion-like phenomenon, which in principle should be capable of revealing the state of internal stress of the body. [ABSTRACT FROM AUTHOR]

This paper describes an experimental study of the hysteretic behavior of prestressed truss concrete composite beams (PTCCBs) under cyclic loading. Five beam models were designed and tested, in which the testing parameters include the global reinforcement index β0, the prestress level λ and the ratio of stirrup ρsv in the potential plastic hinge zones. Based on the test results, the failure mode and hysteretic behavior of the tested models are obtained. In addition, the P-Δ and sectional M-φ hysteretic models for the PTCCBs at the midspan are established. The P-Δ hysteretic model shows good agreement with the test results. [ABSTRACT FROM AUTHOR]

In this paper, we describe the nonlinear models of a rod in three-dimensional space based on the Cosserat theory. Using the pseudo-rigid body method and variational principle, we obtain the motion equations of a Cosserat rod including shear deformations. [ABSTRACT FROM AUTHOR]

This paper presents the development of energy-dissipative momentum-conserving algorithms for the numerical integration of the dynamics of nonlinear Cosserat rods. The proposed numerical schemes exhibit a non-negative energy dissipation, controllable through the appropriate algorithmic parameters including an energy-conserving scheme as a particular case. These conservation/dissipation properties are proven rigorously in the general nonlinear setting, accounting specifically for the finite element implementation of the rotational degrees of freedom associated to the motion of the rod's cross-sections. In particular, we consider a direct parameterization of the director fields defining these sections, hence leading to frame-indifferent approximations of the strain measures defining the rod's mechanical response. The robustness added by these considerations when comparing the proposed numerical schemes with existing conserving schemes is illustrated with several representative numerical simulations. [ABSTRACT FROM AUTHOR]

This paper presents a new damping boring bar with a variable stiffness dynamic vibration absorber (VSDVA) based on dynamic vibration absorber theory. The new designed VSDVA is installed in a cavity which is in the front of the damping boring bar. A new vibration reduction method is proposed by adjusting the stiffness of the VSDVA to adapt the different cutting parameters. The dynamic model of the damping boring bar system is established. The influences of the excitation frequency and the overhang length of the VSDVA on the amplitude ratio are discussed, and the optimal curves are obtained. The damping zone and non-damping zone are obtained as well. These analyses provide a theoretical basis for the design of the damping boring bar and the choice of cutting parameters. The proposed damping boring bar is tested with excitation experiments, impact tests, and boring experiments. The results show that the vibration is reduced, which verifies the feasibility of the proposed method. The accuracy of the dynamic model is substantiated by comparing the experimental data with the theoretical data. [ABSTRACT FROM AUTHOR]

In this paper, the problem of global existence of solutions to the following initial value problem is studied:, which comes from viscoelastic mechanics. By making use of integral estimates method, it is proved that this problem has a global solution if, in addition to certain regularity assumptions on the given functions, the following conditions are satisfied: p′(s) ≥ c1 > 0, |q′(s)| ≤ const, λ(0) < 0, λ′(0) < λ2(0) [ABSTRACT FROM AUTHOR]

This paper presents a combination of normalized least mean square (NLMS) filter and Hilbert envelope analysis method to detect the broken rotor bars of a squirrel-cage induction motor. Broken rotor bars are one of the most common fault types that may be seen in induction motors. Rotor faults are reflected in the stator current of the motor as side-band harmonics. Most of the previous works utilize motor current signature analysis using spectral methods to determine required features for detecting motor faults. It may be difficult to detect the faults from stator current when the motor is lightly loaded under noisy conditions. In this study, Hilbert envelope analysis method is used along with an NLMS filter to process the stator current of an induction motor to detect the broken rotor bars. The proposed method is verified experimentally (under 25, 50, and 100 % loading conditions). The results of the recommended method are compared with the results of Fast Fourier Transform (FFT) analysis performed on the stator current of the same motor under the same conditions. The results show that the recommended method gives a more accurate solution compared with the results of FFT method. [ABSTRACT FROM AUTHOR]

Underwater manipulators are very important for a robot to perform a specific operation in water. Conventional robot arm manipulators have been suggested for various operations but have not been suitable for repeated motion in gathering something. This paper presents a new underwater manipulator design for gathering things such as starfish on the sea floor. The manipulator is composed of a four-bar linkage to achieve repeated motion along a loop and compliant linkages to enhance the efficiency of the gathering work. Kinematic and quasi-static analyses were performed to calculate the loop path and the reaction force at the actuation point. Based on the analysis, optimal design was performed to maximize the working distance with the height difference and the reaction moments considered as constraints. A prototype was assembled to test the performance of the manipulator, and the empirical loop path was compared to simulation results. [ABSTRACT FROM AUTHOR]

Truss optimization based on the ground structure approach often leads to designs that are too complex for practical purposes. In this paper we present an approach for design complexity control in truss optimization. The approach is based on design complexity measures related to the number of bars (similar to Asadpoure et al. Struct Multidisc Optim 51(2):385-396 2015) and a novel complexity measure related to the number of nodes of the structure. Both complexity measures are continuously differentiable and thus can be used together with gradient based optimization algorithms. The numerical examples show that the proposed approach is able to reduce design complexity, leading to solutions that are more fit for engineering practice. Besides, the examples also indicate that in some cases it is possible to significantly reduce design complexity with little impact on structural performance. Since the complexity measures are non convex, a global gradient based optimization algorithm is employed. Finally, a detailed comparison to a classical approach is presented. [ABSTRACT FROM AUTHOR]

The paper addresses the methods and results of approximate analytical and numerical calculation of vibrodiagnostic parameters of the presence of a closing semielliptic surface crack in a circular cantilever bar under super- and subharmonic resonances of the lower natural mode of bending vibrations at force and kinematic excitation. The dependences of vibrodiagnostic parameters on crack location and relative depth and on the point of load application are presented. The amplitude-frequency response under the strong superharmonic resonance is shown to differ from those under the weak superharmonic resonance and subharmonic resonance. The reasons why the results of the analytical solution differ from the numerical one obtained by using a finite-element model of the bar have been clarified. [ABSTRACT FROM AUTHOR]

This paper investigates the torsion analysis of coated bars with a rectangular cross-section. Two opposite faces of a bar are coated by two isotropic layers with different materials of the original substrate that are perfectly bonded to the bar. With the Saint-Venant torsion theory, the governing equation of the problem in terms of the warping function is established and solved using the finite Fourier cosine transform. The state of stress on the cross-section, warping of the cross-section, and torsional rigidity of the bar are evaluated. Effects of thickness of the coating layers and material properties on these quantities are investigated. A set of graphs are provided that can be used to determine the coating thicknesses and material properties so as to keep the maximum von Mises stress on the cross-section below an allowable value for effective use of the coating layer. [ABSTRACT FROM AUTHOR]

The paper presents the viscoelastic analysis of composite and prestressed beams using the slope deflection method. For the fixed-end frame element, considering the viscoelastic behavior of concrete and relaxation of prestressing steel, the integral relation between the generalized element forces and the generalized element displacements, i.e., the element stiffness matrix, is derived and presented using the mathematical operators. From the element and system equilibrium equations, the integral equations of the problem with unknown displacements are formulated. Comparing to the analysis of homogeneous elastic structures, the governing equations of the problem are similar, but with integral equations instead of algebraic equations. In the presented method, the solution to the problem is derived using the linear integral operators without introducing any additional mathematical approximations, apart from the adopted rheological relations for constitute materials. In addition, the obtained expressions are general in a sense that any concrete creep functions can be used and the element can be with a variable cross section. [ABSTRACT FROM AUTHOR]

For enhancing the flexural strength of existing reinforced concrete beams provision of external bars at the soffit of the beam is identified as one of the cost effective and easy to execute method. This paper discusses the finite element modeling and nonlinear analysis of reinforced concrete beams with additional external reinforcing bars at the soffit level using ANSYS 12.0 software. Finite element modeling of reinforced concrete beams is carried out using discrete reinforcement modeling and the results are compared with experimental results of twenty numbers of beam specimens under four-point bending. SOLID65, SOLID45, and LINK8 elements were used finite element modeling of the beam. COMBIN39 spring elements were used for simulating the frictional contact between the soffit and the external bars. Wide range graphical display of the results such as deflected shape of the beam, strain variation along the length and depth of the beam and crack propagation at various loading stages were generated by creating a batch file using ANSYS parametric design language. [ABSTRACT FROM AUTHOR]

Research is being conducted on the use of shape memory alloys, in particular NiTi, in civil engineering, due to the superelastic behavior of NiTi which can be used for damping. In this particular application, NiTi has to be joined to steel, which constitutes a major difficulty due to the considerably different properties of materials involved and the poor weldability of NiTi. Brazing was investigated for this application, since it is an economic and efficient process to joint dissimilar materials. This paper presents a study on the mechanical behavior in the superelastic regime of dissimilar NiTi/steel joints and the feasibility of a nondestructive method based on eddy currents to characterize the weld metal. Brazed joints in lap configuration were produced with a 20 % Ag braze alloy and tested under fatigue conditions in the superelastic regime. Lap joints of steel rods to NiTi ribbons have undergone up to 60 cycles of load/unload without rupture at a maximum load of the superelastic plateau close to the pull-out load of the joint. Measurements of the electrical impedance, with a helicoidal cylindrical coil along the lap joint, allowed the identification of the location of the joint, with a good spatial resolution characterizing the morphology of the brazed joints. [ABSTRACT FROM AUTHOR]

This paper is devoted to describing the asymptotic behavior of a structure made by a thin plate and a thin perpendicular rod in the framework of nonlinear elasticity. The authors scale the applied forces in such a way that the level of the total elastic energy leads to the Von-Kármán's equations (or the linear model for smaller forces) in the plate and to a one-dimensional rod-model at the limit. The junction conditions include in particular the continuity of the bending in the plate and the stretching in the rod at the junction. [ABSTRACT FROM AUTHOR]

This paper considers the use of emulsion explosive compositions to join building bars and replace worn thread in the railway wheel axle. The compositions do not contain individual explosives and greatly increase the safety in explosive working of metals. [ABSTRACT FROM AUTHOR]

This paper proposes a novel measuring method for geometric error identification of the rotary table on five-axis machine tools by using double ballbar (DBB) as the measuring instrument. This measuring method greatly simplifies the measurement setup, for only a DBB system and a height-adjustable fixture are needed to evaluate simultaneously five errors including one axial error, two radial errors, and two tilt errors caused by the rotary table. Two DBB-measuring paths are designed in different horizontal planes so as to decouple the linear and angular errors. The theoretical measuring patterns caused by different errors are simulated on the basis of the error model. Finally, the proposed method is applied to a vertical five-axis machining center for error measurement and compensation. The experimental results show that this measuring method is quite convenient and effective to identify geometric errors caused by the rotary table on five-axis machine tools. [ABSTRACT FROM AUTHOR]

Ram-Quill combination spindle has been applied widely in horizontal boring milling machine. It is a great benefit that the machine can be used for various applications. But as the report of experiment, the ram housing bent when it is moved for more than half of its maximum travel. The straightness of Ram housing is out of the tolerance and the runout of the spindle is way behind the requirement when spindle is at the maximum extension point. This paper proposes an electro-hydraulic monitoring and compensation system which will be able to adjust the pressure to the compensation mechanism in time. The experiments prove that the straightness of horizontal surface can meet the requirement, and a ball bar test at the extremely weak point shows an improvement of the roundness tolerance for 65.8 %. This can improve the tolerance of the machine, becoming a superior device. [ABSTRACT FROM AUTHOR]

There is a strong need for the optimized management of the thermal problem in Nd:YAG laser rod and for a powerful, fast, and accurate modelling tool capable of treating the heat source distribution very close to what it actually is. In this paper, a new optimization algorithm called bacterial foraging optimization algorithm (BFOA) is proposed for simulation of the radial heat distribution. A BFOA discloses a simulation method which delivers the exact temperature distribution in a circularly cylindrical structure with a circularly symmetrical, longitudinally, and transversally non-uniform heat source distribution and circularly symmetrical cooling means. The output power is obtained and compared with previously published experimental measurements for different pump power and a good agreement has been found. [ABSTRACT FROM AUTHOR]

The paper addresses a problem of bending of an isotropic elastic plate, bounded by a regular octagon weakened with a required full-strength hole including the origin of coordinates. Coordinate axes pass the middle points of opposite parallel sides of octagon. Rigid bars are attached to each component of the broken line of the outer boundary of the plate. This plate bends under the action of concentrated moments applied to the middle points of the bars. Unknown part of the boundary is free from external forces. Using the methods of complex analysis, the plate deflection and required full-strength contours are determined. Numerical analysis is performed, and the corresponding graphs are constructed. [ABSTRACT FROM AUTHOR]

This paper considers a rod system for which it is possible to correctly formulate and solve the problem of three-dimensional motion in the physical space of an elastic pipeline area containing inertial incompressible fluid flow. The precession of the axis of an elastic pipeline along which inertial incompressible fluid flows is described, a physical phenomenon which has not been previously studied. With the use of rigid body dynamics, it was theoretically established that a three-dimensional dynamic process is possible in an open (exchanging mass with the environment) elastic-inertial rod system. [ABSTRACT FROM AUTHOR]

This paper examines the quasi-static cyclic behavior, lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy (SMA) link-bars. Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column, including a modified four-spring model prepared for the SMA bars. The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars. A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system, considering the residual stress of the martensitic SMA bars. The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%-12% of critical. When large diameter NiTi superelastic SMA bars are incorporated into the column system, the cyclic response varies substantially. The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column. Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly. [ABSTRACT FROM AUTHOR]

This paper is devoted to describe the deformations and the elastic energy for structures made of straight rods of thickness 2 δ when δ tends to 0. This analysis relies on the decomposition of the large deformation of a single rod introduced in Blanchard and Griso (Anal. Appl. 7(1):21-71, ) and on the extension of this technique to a multi-structure. We characterize the asymptotic behavior of the infimum of the total elastic energy as the minimum of a limit functional for an energy of order δ (2< β≤4). [ABSTRACT FROM AUTHOR]

Copyright of Arabian Journal for Science & Engineering (Springer Science & Business Media B.V. ) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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In this paper, we consider thin rods modeled by the direct approach, in which the rod-like body is regarded as a one-dimensional continuum (i.e., a deformable curve) with a triad of rigidly rotating orthonormal vectors attached to each material point. In this context, we present a model for porous thermoelastic curved rods, having natural twisting and arbitrary shape of cross-section. To describe the porosity, we employ the theory of elastic materials with voids. The basic laws of thermodynamics are applied directly to the one-dimensional continuum, and the nonlinear governing equations are established. We formulate the constitutive equations and determine the structure of constitutive tensors. We prove the uniqueness of solution to the boundary-initial-value problem associated with the deformation of porous thermoelastic rods in the framework of linear theory. Then, we show the decoupling of the bending-shear and extension-torsion problems for straight porous rods. Using a comparison with three-dimensional equations, we identify and give interpretations to the relevant fields introduced in the direct approach. Finally, we consider the case of orthotropic materials and determine the constitutive coefficients for deformable curves in terms of three-dimensional constitutive constants by means of comparison between simple solutions obtained in the two approaches for porous thermoelastic rods. [ABSTRACT FROM AUTHOR]

This paper describes a method for the preparation of I brachytherapy sources. The process consist of surface oxidation of a silver rods [0.5 mm (ϕ) × 3 mm (1)], formation of a thin silver bromide over layer and finally replacement of bromide ions by I ions. The effect of various parameters such as I feed activity, iodide carrier concentration and reaction time were examined and optimized for maximum impregnation of I activity on the substrate. Sources containing 74-111 MBq (2-3 mCi) I on a silver matrix could be prepared and encapsulated in titanium capsules [0.8 mm (ϕ) × 4.75 mm (1)] using Nd: YAG laser. Quality assurance tests to ensure nonleachability, uniform distribution of activity and leak tightness that are necessary before application were evaluated. [ABSTRACT FROM AUTHOR]

The paper discusses the data of four-point bending strength for various rock types. Different nonlocal strength criteria are applied to the tensile strength assessments based on measuring the bending strength. The tensile strength calculated using a bar bending model under plastic deformation turns out to be the closest in value to the experimental strength. [ABSTRACT FROM AUTHOR]

The paper addresses the problem of finding a full-strength contour in the problem of plate bending for a cycle-symmetric doubly connected domain. An isotropic elastic plate, bounded by a regular polygon, is weakened by a required full-strength hole whose symmetry axes are the regular polygon diagonals. Rigid bars are attached to each component of the broken line of the outer boundary of the plate. The plate bends under the action of concentrated moments applied to the middle points of the bars. An unknown part of the boundary is free from external forces. Using the methods of complex analysis, the analytical image of Kolosov-Muskhelishvili's complex potentials (characterising an elastic equilibrium of the body) and of an unknown full-strength contour are determined. A numerical analysis is performed and the corresponding plots are obtained by means of the Mathcad system. [ABSTRACT FROM AUTHOR]

Helical equilibrium of a thin elastic rod has practical backgrounds, such as DNA, fiber, sub-ocean cable, and oil-well drill string. Kirchhoff's kinetic analogy is an effective approach to the stability analysis of equilibrium of a thin elastic rod. The main hypotheses of Kirchhoff's theory without the extension of the centerline and the shear deformation of the cross section are not adoptable to real soft materials of biological fibers. In this paper, the dynamic equations of a rod with a circular cross section are established on the basis of the exact Cosserat model by considering the tension and the shear deformations. Euler's angles are applied as the attitude representation of the cross section. The deviation of the normal axis of the cross section from the tangent of the centerline is considered as the result of the shear deformation. Lyapunov's stability of the helical equilibrium is discussed in static category. Euler's critical values of axial force and torque are obtained. Lyapunov's and Euler's stability conditions in the space domain are the necessary conditions of Lyapunov's stability of the helical rod in the time domain. [ABSTRACT FROM AUTHOR]

new mathematical model has been developed to predict the behaviour of a stranded cable assembly under the influence of interfacial radial contact forces and radial contraction of the core. A single layered cable assembly with six helical wires and a straight cylindrical core, all made with the same material, Steel has been chosen to explain this phenomenon when the assembly is under the influence of core-wire radial contact. An attempt is made in this paper to model the strand with a radial (core-wire) contact and deduce its equations of equilibrium. Numerical analysis of strand force, twisting moment, strand stiffness, contact force and contact stresses is carriedout based on the equilibrium of thin rods, and the results are compared with the earlier research work. The importance of the inclusion of interfacial forces at the contact locations and their associated effects of axial and twist slip of the helical wires on the core, is highlighted. The behaviour of the stranded cable assembly due to the contact force in the radial direction and its associated effects on the axial strain of the core due to Poisson's effect is one more additional feature incorporated in the present work. [ABSTRACT FROM AUTHOR]