Rolling Conditions Research Articles

Numerical analysis of high temperature potassium heat pipe under marine condition

A heat pipe (HP) is a two-phase heat transmission device with very high effective thermal conductivity, extensively employed in multiple industrial fields. In the nuclear engineering area, numerous experimental and numerical studies are widely produced for its thermal behavior performance in high temperatures. In this paper, a HP that potassium as the working fluid with a capillary wick structure was taken into consideration under marine conditions through numerical simulations. The physical properties of potassium and the additional force method of rolling motion are utilized with user-defined functions (UDFs). This CFD model verified with available experimental results, is employed to investigate the influence of HP surface wall temperature distribution and thermal resistance by several parameters including inclination angle, filling ratio (FR), and rolling period. Besides, the charts of phase change and wall temperature distributions are visible with the help of CFD simulation under static and rolling condition. Therefore, the high temperature HP application of design and evaluation is provided as a reference in present work under marine condition.

Effect of Shot Peening Process on Rolling Contact Fatigue Performance of EN 31 Alloy Steel

This paper aims to study the effect of shot peening on the Rolling Contact Fatigue (RCF) life of EN 31 Steel subjected to a pure rolling condition. Tests were carried out under lubricated contact conditions using a two-disc on-cylinder test rig. The orthogonal stress distributions and depth of deformation zones under static loading conditions were calculated using an elastic model by Finite Element Analysis (FEA) method. Shot peening increased the surface hardness by 20 % and imparted residual stress, which resulted in a 2-fold improvement of life. The depth of origin of the crack from the sub-surface was found to be in good agreement with the depth of maximum shear region obtained from the finite element model.

Parking-Specific Parameterization Method for FTire

ABSTRACT Virtual steering system layout in the early development phase requires adequate tire models to predict realistic steering rack forces. An accurate representation of parking is particularly important, as the largest steering rack forces occur during this maneuver. Physical tire models are mainly parameterized for rolling conditions. Since the tire exhibits different mechanical behavior under nonrolling conditions, this article introduces a new parameterization procedure for the physical tire model FTire that characterizes the conditions during parking maneuvers. To this end, an additional full vehicle measurement setup is used to understand the tire motions, forces, and torques during parking. It is also shown that a tire model based on a standard parameterization procedure results in steering speed-dependent parking torque deviations of up to 17.5% when compared with component measurements. Thus, new measurement methods are developed to help parameterize the tire model for this maneuver. A linear friction tester is used to determine the friction interaction between tire and road at the relevant relative velocities. In addition, measurements are performed on a tire stiffness test rig, in which translatory and rotatory movements are overlaid. Furthermore, the contact patch shape, ground pressure distribution, and tire outer contour are digitalized and added into the model. A tire model based on the new parking optimized parameterization is then compared with the standard tire modeling approach and component measurements as well as the full vehicle measurements. In conclusion, improvements of up to 12% for drilling torque, up to 15% for longitudinal force, a more realistic lateral stiffness, a more realistic pressure distribution, and improvements of up to 8% when simulating the steering rack force can be stated. After the results are evaluated and interpreted, recommendations for future developments of this parameterization procedure and an extension of the virtual tire model are discussed.

Experimental study of steam condensation heat transfer characteristics in a horizontal tube under rolling motion

As an efficient heat transfer method, in-tube condensation heat transfer is widely used in various fields, including passive residual heat removal systems (PRHRS) of floating power plants under ocean conditions. The experimental investigation aimed to study the condensation heat transfer characteristics of steam in a 25 mm inner diameter horizontal tube with a heat transfer length of 1050 mm under rolling motion. The study used a mass flux of 30 kg/(m2·s) and investigated average vapor qualities, rolling amplitude, and rolling period ranging from 0.32 to 0.79, 0 °–20°, and 10 s–20 s, respectively. The experimental results show that the condensation flow patterns under rolling conditions are more complex than those under non-rolling motion due to the influence of the rolling period and rolling amplitude. The instantaneous heat transfer coefficient (IHTC) changes periodically due to the rolling motion and has the same change period. The pulsation amplitude of the IHTC increases with increasing rolling amplitude but weakens as the vapor quality increases. The effect of the rolling period on the IHTC is much less than that of the rolling amplitude. At low vapor quality, the time-averaged heat transfer coefficient (THTC) under the rolling motion condition increases with the rolling amplitude and period, and the maximum enhancement of THTC is 44%. As the vapor quality increases, the THTC under rolling conditions is the same as that under non-rolling conditions. These findings provide important insights into the condensation heat transfer characteristics of vapor in a horizontal tube under rolling motion, which can help improve the design and operation of in-tube condensation heat transfer systems in various fields.

Improvement of the cold rolling mill diagnostic system based on the data base of its electromechanical processes

Purpose. To improve the diagnostic system of the cold rolling mill based on the database of its electromechanical processes, by developing a fuzzy decision-making system as to the condition of the rolling mill electrical drives, which will increase the efficiency of the existing diagnostic system. Methodology. Mathematical and computer modeling. Findings.A fuzzy decision-making system about the state of two interconnected electric drives of the unwinding mechanism and the rolling mill has been developed to investigate and prevent the pre-emergency state associated with the break of the rolling metal strip. The specified decision-making system is built on the basis of a database of electromechanical processes of electric drives of the skin-threat single-celled state of cold rolling of the cold rolling shop No. 1 of PJSC "Zaporizhstal". At the input of this system, the voltage of the armature circuit of the unwinding mechanism motor, the armature circuit current of the unwinding mechanism motor, the tension of the rolled metal strip in the area between the unwinder and the rolling cage are set. At the output, the general state of the system is obtained, which depends on the values of the input data. Information on the value of the tensile strength of the rolled metal strip can be obtained on the basis of the pressure data and voltage sensors, which are installed on industrial equipment. Information about the value of the tension force of the rolled metal strip can be obtained both by installing additional measuring devices and indirectly, using mathematical models of the roll current radius and the linear speed of the rolled metal strip. Originality. The system for diagnosing the condition of cold rolling has been improved by introducing a fuzzy decision-making system into its composition based on a database of electromechanical processes of the electric drives of the unwinding mechanism and the cage, which will allow to prevent an emergency condition caused by a break in the rolled metal strip. Practical value. Prevention of breaking of the rolled metal strip on the basis of an improved system for diagnosing the state of cold rolling, which uses information from the database of its electromechanical processes in order to improve the efficiency of the product quality management process. Using complete organized information and experience of operating a cold rolling mill, you can form technical and technological solutions for the modernization of existing and development of new technological equipment and systems for automatic control of electric drives of rolling mills.

Thermo-mechanical behavior of solid rubber tire under high-speed free rolling conditions

Thermo-mechanical behavior of solid rubber tire under high-speed free rolling conditions

Analysis of the tribological and dynamic performance of textured bearings under contaminated conditions

Wear resulting from particle intrusion is one of the principal causes of failure in rolling bearings. Furthermore, studies have demonstrated that surface texturing can improve the frictional properties of such bearings. To evaluate the damage resistance of textured surfaces, four typical contaminants with varying physical properties were added to the textured bearings. The tribological and dynamic properties of the textured bearings under lubricant-contaminated conditions were investigated, and the mechanism of wear reduction on textured surfaces under rolling conditions was discussed. Test results indicate that textured surfaces have a significant impact on wear reduction for brittle and plastic materials that are not magnetic. However, the reduction effect is not significant for bearings contaminated with magnetic materials.

Incremental proportion integration differentiation control of all-terrain vehicle magnetorheological suspension system under low-frequency disturbances

In intelligent control systems of magnetorheological (MR) suspension of all-terrain vehicle (ATV), low-frequency disturbance (LFD) in the measured feedback signal (acceleration) makes the controller unable to calculate the theoretical control force accurately. In particular, when the frequency of the LFD signal is close to that of the actual acceleration signal, the LFD cannot be filtered by designing a traditional filter. Based on the above questions, this paper proposes an incremental proportion integration differentiation (IPID) strategy to address the issue of LFD in the measured feedback acceleration signal of the MR suspension system of ATV. First of all, the model of 1/4 vehicle suspension in consideration of LFD is established, the source of LFD is analyzed which is due to the transformation of Coriolis acceleration under the condition of vehicle body pitch and roll. Next, a semi-active IPID controller is designed by utilizing differential derivation of discrete PID and semi-active principle to eliminate the LFD component mixed in the acceleration signal by making a difference. The particle swarm optimization (PSO) algorithm is utilized to optimize the parameters of the controller, which is then verified through numerical simulation. Subsequently, a real vehicle control experiment is carried out based on a 4 × 4 ATV equipped with the MR suspension system and implemented by DSP controller with the designed IPID algorithm. The effectiveness of the proposed method is evaluated under the speed 10 km h−1 and E road, and the designed method is compared with the traditional proportion integration differentiation (PID) control algorithm through simulation and experimentation to demonstrate the superiority and rationality of ‘filtering out’ LFD signal and improving control effectiveness.

Rolling-Sliding Performance of Radial and Offset Roller Followers in Hydraulic Drivetrains for Large Scale Applications: A Comparative Study

Generally speaking, excessive side thrust and roller slippage are two different aspects affecting cam-roller mechanisms. In novel large-scale hydraulic drivetrains for offshore wind turbines, the highly dynamic nature of these mechanisms combined with the interplay of cyclic loads, frictional torques and inertia promote slippage at the cam-roller interface. At larger scales, the effects of roller inertia become much more pronounced, as the inertia escalates exponentially with the roller’s radius. This study presents a comparative analysis between radial and offset roller followers in novel large-scale hydraulic drivetrains, where offset followers are incorporated to minimize the side thrust. The framework encompasses a comprehensive kinematic and force analysis, to provide the inputs for two lubrication models integrated into the torque-balance equation, where the possibility of slippage is allowed. The findings reveal that the equivalent side thrust can be reduced by 51% with offset followers. Both configurations experience slippage during the low-load phase, but it rapidly diminishes during the high-load phase. This sudden transition in rolling conditions results in a sharp increase in surface temperature and traction force, emphasizing the importance of minimizing sliding at the interface. However, besides the substantial side thrust reduction, offset followers showed superior tribological performance, mitigating undesirable thermal and frictional effects.

Oblique impact of a buckling table-tennis ball on a rigid surface.

We report on the rebound of a table-tennis ball impinging without any initial spin in oblique incidence on a rigid surface. We show that, below a critical incidence angle, the ball rolls without sliding when bouncing back from the surface. In that case, the reflected angular velocity acquired by the ball can be predicted without any knowledge of the properties of the contact between the ball and the solid surface. Beyond the critical incidence angle, the condition of rolling without sliding is not reached within the time of contact with the surface. In this second case, one can predict the reflected angular and linear velocities, as well as the rebound angle, provided the supplementary knowledge of the friction coefficient associated with the ball-substrate contact.

Influences of Cold Rolling and Aging on Microstructure and Property of CuCrSn Alloy.

The CuCrSn alloy is promising as a high-strength and high-conductivity Cu alloy due to its relatively low smelting requirement. However, thus far investigations into the CuCrSn alloy are still quite lacking. In this study, the microstructure and properties of Cu-0.20Cr-0.25Sn (wt%) alloy specimens prepared under different rolling and aging combinations were comprehensively characterized, in order to reveal the effects of cold rolling and aging on properties of the CuCrSn. The results show that increasing the aging temperature from 400 °C to 450 °C can noticeably accelerate precipitation, and cold rolling before aging significantly increases its microhardness and promotes precipitation However, the deformation hardening is eliminated during the aging process, making the microhardness decrease monotonically when the aging temperature and the cold rolling ratio before aging are high. Performing cold rolling after aging can maximize precipitation strengthening and deformation strengthening, and the adverse impact on its conductivity is not serious. A tensile strength of 506.5 MPa and a conductivity of 70.33% IACS were obtained by such a treatment, whereas only the elongation decreases a little. Different strength-conductivity combinations of the CuCrSn alloy can be achieved through appropriate design of the aging and post-aging cold rolling conditions.

Experimental investigation on flow boiling characteristics in zigzag channels under different sloshing conditions

In order to reveal the effects of sloshing condition on the performance of the printed circuit heat exchangers (PCHEs), the flow boiling heat transfer characteristics in PCHEs with zigzag channels were investigated experimentally under different sloshing conditions adjusted by 6-DOF (six degrees of freedom) moving platform. The results show that, among the six sloshing types, rolling and heaving movements have significant effects. Rolling conditions always deteriorate the flow boiling heat transfer in PCHEs, with a maximal deterioration of 14.0%; the deterioration appears mainly in annular flows and worsens with the increase of the vapor quality, due to the non-uniform gas-liquid distribution in the lateral direction of the channel inlets. Heaving conditions always enhance the flow boiling heat transfer in PCHEs, with a maximal enhancement of 22.8% corresponding to the critical point of flow pattern transformation from slug to annular flow. Correlations for predicting the effects from rolling and heaving conditions are proposed with deviations within ±10%. The results will provide new data and correlations for optimizing the heat exchangers to avoid performance deterioration in FLNG platforms.

Electrical Contact During a Rolling Vibratory Motion Considering Mixed Lubrication

Abstract In many devices and applications, electrical contacts are exposed to vibrations, sliding, or rolling conditions and are prone to fretting-based degradation. Thus, lubricants are often employed in such contacts to reduce sliding wear and fretting corrosion. However, due to the non-conductive behavior of the lubricants with fluorocarbons and hydrocarbons, lubricants lead to a few adverse problems. Also, the fluid dynamics upon excitation, vibration, or sliding causes extended breaks or gaps in between the conducting surfaces. In reality, this can be noticed during vibrations occurring as a result of earthquakes or technical personnel maintenance. This could also have applications to electrified rolling element bearings. Factors such as surface roughness and fluid viscosity will determine the time taken for the two surfaces of the connectors to separate from a solid conductive contact. In this work, a coupled structural–fluid theoretical model is developed for evaluating such intermittent contact breaks/gaps when two metallic rough surfaces in contact are under vibrations. The model is capable of predicting the increase in the fluid film as well as the contact resistance change with time due to the possible connector vibration. The experimentally observed rocking vibration mode seen in connectors and the time-dependent squeeze film lubrication effect are also considered.

Numerical study on fluctuation characteristics of free surface in steam generator under rolling conditions

Numerical study on fluctuation characteristics of free surface in steam generator under rolling conditions

Experimental study on condensation heat transfer characteristics in C-shaped tube under rolling conditions

C-shaped tube heat exchanger has the advantages of good performance in heat transfer, space-saving, and reliability, and thus it has great potential to be used as passive residual heat removal heat exchanger in offshore nuclear power plants. In the present study, the condensation heat transfer characteristics in a C-shaped tube, which is the basic unit of C-shaped tube heat exchanger, were investigated experimentally, and the experiment was carried out under steady state and rolling conditions respectively. The effect of heat flux and rolling conditions on the condensation heat transfer characteristics were studied. The heat flux varies from 73.3 kW/m2 to 446.7 kW/m2; the rolling amplitude varies from 5° to 15°; and the rolling period ranges from 5 s to 20 s. The experimental results show that the condensation in the C-shaped tube is gravity-dominated. Based on the experiment data, a new correlation used to calculate the heat transfer coefficient of a C-shaped tube under steady state has been obtained. The rolling motion has significant effect on the condensation heat transfer of the C-shaped tube. With the increase of rolling angle from 0° to 15°, the condensation heat transfer performance of the C-shaped tube gradually increases and the increase rate of the condensation heat transfer coefficient is up to 18%. On the other hand, with the increase of rolling period from 5 s to 20 s, the condensation heat transfer performance of the C-shaped tube decreases. Further investigation revealed that, as the heat flux increases, the effect of rolling motion on the condensation heat transfer decreases.

Study on flow and heat transfer characteristics of supercritical CO2 inside horizontal tube under ocean rolling condition

The flow and heat transfer characteristics of supercritical CO2 in a horizontal tube are studied numerically under the condition of ocean rolling. It is found that the rolling motion is beneficial to alleviate the deterioration of heat transfer at the top of the tube. However, the heat transfer deterioration is performed periodically with the rolling motion, which can cause periodic fluctuations in temperature and thermal stress of tube wall. This will affect the service-life. At a relatively small mass flow rate or large heat flux, the effect of rolling motion on the heat transfer performance increases since the density difference and buoyancy is relatively large. With the increase of inlet temperature and the decrease of buoyancy effect, the influence of rocking motion on heat transfer gradually decreases. The influence of rolling motion on the heat transfer for the floating nuclear power plant should be taken into consideration in the design.

Analytical investigation of multi-layered rollable displays considering nonlinear elastic adhesive interfaces

To design the multilayered structures of reliable rollable displays, finite element method (FEM) investigations are conducted at various rolling conditions. Given that the optically clear adhesive (OCA) is the only flexible component and interfacial layer that plays an important role in allowing flexibility in rollable displays, we investigated its nonlinear elastic properties in detail. Hereto, FEM of rollable displays have been limited and inaccurate because OCA has been assumed to be a linear elastic material. In addition, despite the fact that rolling deformation exhibits complex bending characteristics, unlike folding, the mechanical behaviors over the entire area of rollable displays at all positions have not yet been addressed. In this study, we describe the dynamic and mechanical characteristics of rollable displays at all positions considering the hyperelastic and viscoelastic properties of OCA. The maximum normal strain of the rollable displays was applied about 0.98%, and the maximum shear strain of the OCA was shown to be around 720%. To assess the stability of the rollable displays, normal and yield strains were compared to each layer and investigated. Consequently, mechanical modeling of the rollable displays was conducted and stable rolling behaviors that did not cause permanent deformation were investigated.

Tribomonitoring of the quality of aviation hydraulic oils according to lubricity and rheological indicators

The study proposes a diagnostic control method for assessing the quality of commercial batches of hydraulic oils based on the kinetics of changes in the thickness of lubricating layers, shear stresses of the lubricating material, and effective viscosity in tribotechnical contact. Timely and high-quality tribomonitoring of lubricants provides a perspective on their rational use and reduced wear of equipment parts. The developed methodology simulates the operation of gears in rolling conditions with a slip of 30% using a roller analogy. Samples of AMG-10 oil from two manufacturers were analyzed. For "Bora B" AMG-10 oil (sample 1) with gradients of the sliding speed of the lubricating layer in contact from 5.63·103 to 5.73·105 с-1, the effective viscosity is set at the level of 4249 and 5039 Pa·s at a bulk oil temperature of 20 and 100 oС, respectively, which indicates the resistance of oil components to destruction under conditions of increasing shear rate gradient. For AMG-10 oil (sample 2), the effective contact viscosity decreases by 1.53 times both at an oil temperature of 20 oС and at 100 oС and is 2764 Pa·s (at 20 oС) and 3309 Pa·s (at 100 oС), which indicates the destruction of the components of the lubricant. For "Bora B" AMG-10 oil, effective lubricating properties have been established both during the start-up period and at maximum revolutions in conditions of rolling with slipping. It was shown that at start-up, regardless of the temperature of the lubricant, the mixed lubrication mode dominates. At the maximum revolutions of the tested samples, the hydrodynamic lubrication mode dominates, which indicates the effective lubricating properties of the Bora B AMG-10 oil. According to the kinetics of changes in the rheological parameters of oils, it was established that the resistance of the lubricant's components to mechano-thermal destruction under non-stationary lubrication conditions contributes to the effective formation of a lubricating layer in contact with a high bearing capacity

Prediction Technique of Surface Characteristics of Fatigue Specimens of Austenitic Stainless Steels by Controlling Finish Processing

In order to develop the technique to predict the surface characteristics of fatigue specimens of austenitic stainless steels by controlling finishing processing of lathe turning and shot peening, the applicability of the response surface models formerly created by the present authors using experimental design of experiments approaches to the fatigue specimens with different types and/or rolling conditions of austenitic stainless steels have been investigated. The conclusive remarks could be summarized as follows: (1) The predicted surface residual stress obtained by the response surface model of the lathe turning created for the round bars of SUS304 agreed with the observed surface residual stress of the fatigue specimen of SUS316. (2) The response surface model of the shot peening created for the flat plate of SUS316 was applicable to the prediction of the surface roughness RSm, the surface hardness and the surface residual stress of the fatigue specimen of SUS316 in spite of the different processing of the shot peening and the rolling conditions of the material.

Influence of marine conditions on thermal efficiency of SCO2 Brayton cycle for waste heat recovery

The supercritical CO2 Brayton cycle has great advantages for waste heat recovery in ships. The rolling motion would affect heat transfer as well as the efficiency of Brayton cycle, but few literature have studied the influence on the cycling efficiency. In view of this, the purpose of this paper is to obtain the effect of rolling motion the Brayton cycle and clarify its mechanism. Therefore, the heat transfer characteristics as well as thermal efficiency under rolling motion are calculated by numerical simulation coupled with the inertia force. The results show that rolling conditions lead to the instability of thermal performance in the heat exchanger and likewise the instability of thermal efficiency. Specially, as the rolling cycle decreases or the angle increases, fluctuations of outlet temperature and mass flux of supercritical CO2 are enhanced, which deteriorates the instability of thermal efficiency. The main reason for the instability is the influence of additional forces on the fluid under the rolling motion. In the axial view, the rolling motion has the strong influence on the fluid in the middle section of the heat exchanger, and has the significant effect on the fluid near the wall in the radial direction.