Radial Deflection Research Articles

Improvement of bionic surface of thrust rod ball joint and finite element analysis

The thrust rod is an important component of heavy-duty vehicles. It can transmit force and torque during vehicle driving and play the role of flexible connection. This paper mainly applies the bionic friction-increasing principle of locust foot pads to the rubber surface of the thrust rod ball joint of commercial vehicles. A bionic ball crown-shaped flexible protrusion is constructed on the surface of the rubber ball joint to increase the stiffness of the ball joint. The height, radius and spacing of the bionic flexible protrusion are changed, and the finite element analysis is performed using Abaqus software to study the radial stiffness, deflection stiffness and torsional stiffness of the thrust rod ball joint. The results show that the best effect is achieved when the protrusion height is 1 mm, the radius is 4 mm and the spacing is 10 mm. Finally, the optimal solution is comprehensively analyzed, and the feasibility of the solution is verified through simulation and experiment.

Radial Deflection of Ring-Stiffened Cylinders Under Hydrostatic Pressure

Abstract Ring-stiffened cylinders under hydrostatic pressure have been analyzed for more than a century. The contribution of Salerno and Pulos in the fifties of the previous century can be considered as a standard that nowadays still can be found in the rules and guidelines of classification societies. Their work comprises stresses and deformation in a perfectly circular cylindrical shell with ring frames, and solutions are presented midbay between the frames and at frame position. It is remarkable that the formula for the radial deflection midbay is much simpler than the one for frame position. This brief note shows a significant simplification of the latter one.

Frictional Slippage of Annular Elastomeric Disks Compressed Between Rigid Platens

Abstract Compression of compressible, linearly elastic, annular disks by flat rigid platens is analyzed. Coulomb (Amonton) friction is assumed to act at the interfaces between the disk and the platens. Slip may occur in an outer annular region while the inner annular (bonded, stick) region of the disk does not slip. The critical radius (slip boundary) is of major interest. The governing equilibrium equations in terms of the deflections are satisfied exactly. Approximations are made in some of the boundary conditions and the transition (matching) conditions at the critical radius. Numerical results are presented for nearly incompressible disks. The effects of the radius ratio, aspect ratio, and Poisson's ratio of the disk, and of the coefficient of friction at the platens, on the critical radius, effective compression modulus, stresses, and radial deflection are investigated. Applications include structural (especially bridge) bearings, seismic-isolation devices, mounting blocks and bushings, gaskets, and sealing components.

Assessment of dynamic response of armor grade steel plates and FMLs under air-blast loads

This numerical study represents an effort to characterize the dynamic behavior of distinct armor-grade steel plates and fiber metal laminates (FMLs) of the same masses under blast loads. The blast resistance of finite element models of square steel plates and FMLs is evaluated by applying conventional weapon effects program air-blast loading ranging from 1 to 3 kg of trinitrotoluene (TNT) at a fixed stand-off distance (SoD) of 0.1 m. A user-defined subroutine is used to implement a failure criterion to determine realistic failures in the composite. A variation of kinetic energy, radial deflection, and energy absorptions of the steel plates and FMLs are determined to discover their blast mitigation performance. The deformation modes and equivalent plastic strain of both the steel plate and FMLs are also compared. The obtained results show that the armor-grade AISI 4340 steel has up to 50.5% smaller peak deflection than the other armor-grade steels. The use of FML with multi-thin layers of composite laminate and steel sheets instead of equivalent AISI 4340 steel plate significantly reduces the peak deflection up to 23.9% under similar blast loading conditions. The findings of steel plates and FMLs also represent their applicability for making complex protective structures.

Wind-structure interaction mechanism of circular storage shells- a critical review

A critical review on the valuable researches about the aerodynamic load and consequent structural behavior of cylindrical storage shells, has been carried out. The wind-shell interaction mechanism has been explored through literatures to understand aerodynamic pressure characteristics, wind-induced vibration, buckling and design of cylindrical storage shell and stiffener. Important input parameters have been presented in a tabulated manner so as to correlate and compare critical output parameters (graphically) with an emphasis on circumferential wind pressure coefficient and radial deflection per unit thickness under wind-induced buckling. The scopes for future studies in this field of research have also been recommended.

Auxetic honeycomb core layer effect on vibrations of annular plates based on shear deformation theory

Light composite materials such as auxetic honeycomb structures offer a unique combination of strength, lightweight, and durability, making them ideal for a wide range of industrial and structural applications. Consequently, it is crucial to study the effect of these materials on the dynamic behavior of structures. In this study, an analytical solution based on the multiple-scale method has been proposed to solve equations of motion of a multilayer axisymmetric annular plate. The plate includes two top and bottom isotropic layers and one auxetic honeycomb core layer. By considering both radial and transverse deflections, the governing equations are derived based on the first-order shear deformation theory. The radial and transverse frequencies of the plate are determined from the order zero of equations and a correction coefficient for each frequency has been extracted from the order one and solvability conditions. The response of the plate under harmonic transverse excitation has been determined analytically and by conducting a parametric study, the effect of different geometrical and mechanical parameters on the free and forced vibration responses has been studied. It is observed that employing a honeycomb core in the multilayer plate allows us to significantly decrease the plate weight while the dynamic response and the frequencies remain nearly the same or vary slightly. The results are validated by comparing them with the finite element method and some other references.

An axisymmetric characteristic model for enhancing prediction of centrifugal compressor characteristics

Rapid and accurate determination of compressor characteristic maps is essential for the initial design of centrifugal compressors in aircraft power systems. The accuracy of existing methodologies, which rely on combinations of loss models, varies significantly depending on the compressor’s geometry and operational range. This variance necessitates substantial experimental or Computational Fluid Dynamics (CFD) data for coefficient calibration. To address this challenge, this study presents an axisymmetric characteristic model for compressor performance assessment. This model incorporates the factors of blade angle, meridional passage area, and the radial deflection angle of meridional streamlines of the compressor. These factors are derived from fundamental aerodynamic equations encompassing mass, momentum, and energy conservation of the compressor. In contrast to conventional one-dimensional approaches, the proposed method reduces the number of loss coefficients and more effectively accounts for the impact of geometric alterations on centrifugal compressor properties. Furthermore, the model reduces dependence on experimental and CFD data. Efficacy of the model is validated using experimental data from four distinct types of centrifugal compressors. Correlation analysis reveals that the model’s coefficients can be expressed as functions of the ratio of the Reynolds number to the impeller tip speed. This ratio serves as a characteristic parameter for the design and optimization of centrifugal compressors. Consequently, the proposed method offers an efficient and accurate means for the quick computation of centrifugal compressor characteristics. This is of great significance for improving the efficiency of centrifugal compressors and reducing energy consumption.

Termostressed state of a three-layer rectangular plate under non-stationary convective heating conditions

The study considers a rectangular isotropic plate with a layered irregular structure. It is convectively non-stationarily heated by an external environment. The initial relationships of the non-stationary heat conduction and thermoelasticity problem are formulated using a five-mode mathematical model based on the shear deformation theory of thermoelasticity. Using the methods of Fourier and Laplace integral transforms, general solutions have been obtained for the non-stationary heat conduction problem and the quasi-static thermoelasticity problem for a hinge-supported plate along its edges. A numerical analysis of the temperature field, radial deflections, normal forces, bending moments, and normal stresses, depending on geometric parameters and the Bi criterion, has been performed for a three-layer plate. The materials of its layers are made of ceramics and metal. The temperature and mechanical parameters have been analyzed for the layering configuration of the plate: metal-ceramic-metal.

Analytical and numerical buckling of bi-material pipelines reinforced by novel composite polyhedral linings

This study concerns the mechanical stability performances of a composite lining constrained in a cracked pipeline. A polyhedral cross-section is used to improve the load capacity of the tightly constrained lining. The lining deflects inward due to the confinement of the pipeline. The contact surface is frictionless between the lining and the pipeline. A periodic variation is found for both the radius and bending rigidity of the cross-section of the polyhedral lining, which is approximated analytically to simplify the derivation. By adopting the classical shell criteria, and a trigonometric function to express the radial deflection, the potential energy function is expressed, yielding two formulae of equilibrium. Then, the path of equilibrium is illustrated analytically for a composite polyhedral short lining under a point load. The present analytical predictions are compared with the other two results, and good agreements are obtained. A profile factor is introduced by defining the buckling load of the polyhedral lining over the circular one. Finally, parametric evaluations indicate that the profile factor reduces with the rise of thickness, and side numbers, respectively. Therefore, a lining with a thin-walled polyhedral cross-section is recommended in engineering practices.

Effect of different roller end-flange constructions on the fatigue life of the cylindrical roller bearings: A novel flange deformation formula

This paper performs the fatigue life analysis of the radial Cylindrical Roller Bearings (CRBs) with consideration of various roller end-flange shapes such as toroidal-toroidal, spherical-toroidal, and spherical-conical. A novel formula for each flange contact deformation in cylindrical roller bearing with different roller end-flange geometry including toroidal geometry is developed. Inner ring misalignment angle and radial deflection results obtained from the present study are verified with numerical and experimental results from the literature. The results approach to that of literature when the flange is changed from toroidal geometry to conical geometry. Using formulas developed in the present study, the effect of various roller end-flange geometries on the bearing life is investigated for different external loadings. It is observed that the bearing life increases when the roller end and flange are changed to toroidal geometry.

On the efficient simulation of pass-by noise signals from railway wheels

The article presents an approach for calculating pass-by sound pressure radiated from railway wheels in the time domain using moving Green’s functions. The Green’s functions are obtained by using Finite Element (FE) and Boundary Element (BE) methods in the frequency domain, subsequent inverse Fourier transform, followed by convolution with a time series of rolling contact forces to obtain the pass-by time signals. However, traditional BE methods are computationally expensive due to the low structural damping of the wheel, necessitating a high frequency resolution.To overcome this issue, a modal approach is introduced in which the pass-by sound radiated by each wheel mode is calculated separately. This approach incorporates the dynamic response of the wheel in the time-domain processing and thus reduces the cost of the BE solution. A modal source signal is introduced to describe the excitation of each mode at each time step. The sound field radiated by unit modal amplitudes is calculated in BE and subsequently approximated by spherical harmonic (SH) equivalent sources, which allows for efficiently calculating acoustic transfer functions for varying relative positions of the wheel and a stationary receiver. Convolution of the source signal with the moving acoustic transfer function produces the pass-by pressure signal.The article investigates the directivity of the radiation from each mode and finds that most modes, including those with dominant radial deflection, radiate in mostly axial direction at high frequencies. Modes that dominate the pass-by pressure level are identified, both in frequency bands and with respect to the relative positioning of the wheel to the receiver. Finally, it is found that an SH expansion order of approximately 30 is required to satisfy the employed error measures, although lower orders may suffice for an auralisation of the signal.

Investigation on the showerhead film cooling of the turbine vane considering combustor swirling outflow

The mutual interference between the combustor and turbine of modern aero-engines has gradually increased with recent advancements, and turbine cooling design considering the flow characteristics at the combustor exit has not been investigated thoroughly. More importantly, no effective solution has been proposed for the negative impact of swirling inflow on vane cooling. This paper presents a comprehensive study on vane leading edge cooling, where the region is most susceptible to the swirling inflow. The film cooling effectiveness (η) of the showerhead film cooling is measured by PSP (pressure-sensitive-paint) technology, and flow characteristics are obtained by numerical simulation. Based on the in-depth analysis, a new film hole layout is proposed to suppress the negative impact of the swirl intake condition on film cooling. The results show that the swirling inflow changes the vane pressure distribution, leading to a significant radial deflection of the film. This causes the film to concentrate in the partial area of the vane, thereby increasing the film distribution inhomogeneity. The mass flow ratio increase only restrains the negative influence of swirling inflow on the cooling effect to a certain extent under the high swirl intensity intake condition (SN = 0.45). At SN = 0.45, an efficient showerhead cooling scheme is desired, and we propose a new cooling scheme to this end. According to the pressure distribution on the leading edge, the new film hole layout scheme can exhibit excellent inhibitory effect on the radial deflection of the film. Therefore, the new cooling scheme can increase the film coverage area and improve the uniformity of film distribution. The increase in surface-averaged film cooling effectiveness (ηsur-ave) is up to 23.1%. Furthermore, the new cooling scheme reduces the relative standard deviation of film cooling effectiveness by up to 24.1%. Thus, the proposed scheme highlights the influence of the combustor outflow on the showerhead film cooling, which can provide a reference for vane cooling design.

Topology optimization for structural mass reduction of direct drive electric machines

Topology optimization is well suited to computationally achieve highly optimized designs with respect to objective and constraint functions, and when coupled with additive manufacturing, enables the fabrication of complex structures that can offer improved generator performance and increased power density. Here, topology optimization was used for light-weighting high power direct drive generators. The rotor of a 5 MW wind turbine generator was analyzed to determine geometric avenues of mass reduction with varying safety factors. Three designs were created with safety factors between 1 and 2 which resulted in structural mass reductions ranging between 54%–67% compared to a baseline design leading to a 13%–25% increase in power density. These designs represent a ∼50% structural mass reduction compared to a previous structural optimization design using triply periodic minimal surfaces. All deflections were less than their critical limits and the topology optimized rotor designs exhibited 64% lower radial deflection than baseline. Deflections of the topology optimized designs were verified with commercial code and supported through experimental validation using digital image correlation with additively manufactured rotors. Computational resource use was reduced as compared to past parameter optimization approaches, and manufacturability studies demonstrated that topology optimization holds potential for significant mass reduction of direct drive generators.

A Semi-Analytical Method for the Sealing Performance Prediction of Subsea Pipeline Compression Connector

To predict the sealing performance of the subsea pipeline compression connector, a semi-analytical method is proposed and verified. The leakage condition is obtained as a function of the minimum radial deflection. The semi-analytical method consists of three parts: a macroscopic analytical model for the interference process deduced based on the membrane theory, a mesoscopic two-dimensional finite element analysis of the internally turned sealing surface according to scanning electron microscope observation, and a formulation of the leakage ratio according to the Abbott–Firestone curve. The influences of the geometry parameters are analyzed. The prediction and identification of the leakage condition near the minimum preloaded deflection are investigated. Experimental tests are also carried out to verify the proposed method. The results show that, within five times the pipeline threshold of the thin wall thickness, compression connectors designed by the proposed method can create a reliable seal with a rough internally turned surface, saving 57% of the design time while reducing the machining time and costs.

Structural analysis of motorcycle spokes design using finite element analysis with alloy materials

The use of alloy wheels on a motorcycle is very necessary in order to ensure that the motorcycle's weight is distributed evenly. The spokes of an alloy wheel must be shaped and positioned in a specific way to counteract the forces imparted to the bearing surface of the rim and hub. Alloy wheel spokes are subject to a wide range of forces, such as radial, impact, bending, torsion, and maximum deflection. Thus, the wheel's response to such loads must be evaluated. Two separate designs of motorcycle alloy wheel spokes were modelled and designed to meet the requirements and preferences of sports motorcycles. For the purpose of testing the alloy wheel under typical loading conditions and boundary conditions, the aluminium and magnesium alloys were selected as the testing materials. In this study, two separate models of alloy wheel spokes were examined for structural stress and maximum deflection. The alloy wheels were also examined for the factor of safety, which provides evidence that the vehicle can be driven safely.According to the stress analysis, the magnesium alloy produces more deflection and a stress concentration on both design, whereas design I produces less deflection and a stress concentration over the design II.

Surface stress size dependency in nonlinear thermomechanical in-plane stability characteristics of FG laminated curved nanobeams

In the present exploration, the effect of surface stress type of size dependency on the nonlinear in-plane stability characteristics of functionally graded (FG) laminated composite curved nanobeams subjected to uniform radial pressure together with a temperature rise is examined. To accomplish this motivation, the Gurtin-Murdoch continuum elasticity is applied within a higher-order shear flexible curved beam theory in the presence of geometric type of nonlinearity. The effective properties of the employed nanocomposites are approximated via the Halpin-Tsai homogenization scheme corresponding to different lamination patterns and are considered in the principle of virtual work to establish the surface elastic-based nonlinear differential equations of the stability problem. It is found that by taking the surface stress effect into account, the values of the radial load related to the first and second bifurcation points get larger. Also, it causes to increase the curved beam deflection associated with the first bifurcation point, while it leads to decrease the radial deflection at the second bifurcation point. Accordingly, the effect of surface stress type of size dependency resulted in a reduction in the slope of bifurcation path related to the nonlinear radial load–deflection equilibrium curve of a curved nanobeam. It can be also observed that the temperature rise causes to increase the radial loads associated with the upper limit and the first bifurcation points, while it leads to reduce the values of radial load related to the lower limit and the second bifurcation points. In this regard, there is a unique intersection point as all equilibrium curves traced for different temperature rises pass through that.

Clinical Study of Wrist Arthroscopy Combined with Oblique Ulnar Shortening Osteotomy in the Treatment of Ulnar Impaction Syndrome.

To explore the clinical effects of wrist arthroscopy combined with oblique ulnar shortening osteotomy in the treatment of ulnar impaction syndrome. This was a retrospective study of 60 patients with ulnar impaction syndrome who were admitted to our department from January 2016 to December 2019. According to different surgical methods, they were divided into an observation group and a control group, with 30 cases in each group. The control group was treated with oblique ulnar shortening osteotomy, and the observation group used wrist arthroscopy based on the control group. The two groups of patients were compared in terms of wrist function before and 12months after surgery. We compared the Disabilities of the Arm, Shoulder, and Hand Score (DASH Score), Patient-Rated Wrist Evaluation Score (PRWE Score), Visual Analog Score (VAS), and ulnar variation between the two groups at 12months after surgery. The excellent and good rates by Mayo wrist score were compared between the two groups at the last follow-up. All patients were followed up for 12-36months, with an average of 14.5months. Bone union was achieved at the oblique osteotomy of the ulna, with an average healing time of 13.6 weeks. The observation group was examined by wrist arthroscopy, and the triangular fibrocartilage complex (TFCC) Palmer classification was confirmed in three cases of type IIA, seven cases of type IIB, 14 cases of type IIC, and six cases of type IID. Compared with before surgery, the grip strength, flexion-extension, ulnar radial deflection, and forearm rotation of the two groups of patients were significantly improved at 12months after surgery. The DASH score, PRWE score, and VAS score of the observation group were better than those of the control group, and the difference in ulnar shortening length was not statistically significant between the two groups. The excellent and good rates of the observation group (93.3%) were better than those of the control group (87.5%) at the last follow-up, and the difference was statistically significant. Compared with oblique ulnar shortening osteotomy alone, combined wrist arthroscopy can better reduce the pain of patients with ulnar impaction syndrome, restore wrist function, and improve the excellent and good rates. Therefore, it is clinically worthy of promotion.

Observation of a Magnetic Switchback in the Solar Corona

Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks’ formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvénic turbulence, shear-driven Kelvin–Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph on board a Solar Orbiter of a single large propagating S-shaped vortex, interpreted as the first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the east and west. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind.

Simulation of Fluid Flow during Egg Pickling under Different Inlet and Outlet Conditions in a Pulsed Pressure Tank with Liquid Circulation.

Pulsed pressure pickling is an emerging highly efficient osmotic dehydration technique. However, the immobility of the pickling liquid and the material, the formation of layers, and the uneven pickling efficiency in different sections make it difficult to use industrially. This work aims at improving and optimizing the conditions of fluid flow in the pickling tank with a liquid-cycle system to reduce the unevenness in the production process. Fluid flow around the eggs was numerically investigated by solving three-dimensional Reynolds-averaged Navier–Stokes equations within the flow regime, adopting different angles and positions at the inlet and outlet. The simulation results show that the inlet with a radial deflection of 35° and the outlet with axial direction were characterized by the best flow efficiency. Under these conditions, the average flow velocity and the global uniformity index were 0.153 m/s and 0.407, respectively. Furthermore, the experiments were carried out using an equivalent scale model of the pulsed pressure equipment with liquid circulation. The experimental results showed that, under optimal conditions, the salt content in all four layers of the egg white was about 2.8% after 48 h. This study provides a solution to ensure the constant salinity of different layers of pickled eggs and to improve pickling efficiency, especially in industrial-scale production.

Effect of axial slot casing treatment on a counter-rotating axial-flow compressor aerodynamic performance and stability

Counter-rotating axial-flow compressor (CRAC) technology is an important technical way to improve the thrust-to-weight ratio of aero-engines. To explore the stall margin improvement potential of axial slot casing treatment (ASCT) in the CRAC, a two-stage CRAC is selected to investigate the influence of axial position and radial deflection angle of slots on the stabilization capability of ASCT by numerical method. The paper also revealed the stability expansion mechanism of ASCT in the CRAC and the effect of casing treatment on the rotor/rotor interference effect between the front and rear rotors. Results show that the axial position of slots has little effect on stall margin improvement capacity of ASCT but has a great influence on peak efficiency. Increasing the radial deflection angle of slots to further improve the stabilization ability of ASCT is not remarkable, but it is beneficial to decline the efficiency penalty. The suppression of tip leakage flow by slots and the transport of low-energy fluid near the blade tip can delay the occurrence of the stall, and the maximum stall margin is improved by about 10.75%. Besides, the ASCT decreases the unsteady interference effect between the rotors and inhibits the potential flow effect of the downstream blade passage and improves the inlet flow field quality of the rear rotors.