Rolling Conditions Research Articles

Study on the phase structure of the interface zone of Cu–Al composite plate in cast-rolling state and different heat treatment temperatures based on EBSD

The phase structure in the interface zone of Cu–Al composite plate was studied by EBSD after casting and rolling and different heat treatment temperatures. The grain sizes of the matrix and intermetallic compounds in the interface zone were analyzed statistically. The spatial distribution characteristics of the transverse, rolled, normal and various phases were characterized by inverse pole diagram. The results show that with the increase of heat treatment temperature, the phase of the interfacial area of the composite plate is rearranged, the residual stress can be released, and the zero resolution decreases. The interface zone of cast-rolled Cu–Al composite plate is composed of a layer of intermetallic compound, which is Al2Cu; Two layers of intermetallic compounds, both Al, were formed in the interfacial area after heat treatment at 300 °C and 400 °C Al2Cu and Al4Cu9;After heat treatment at 450 °C, the interface region is composed of three layers of intermetallic compounds, which is Al2Cu, AlCu, Al4Cu9;The grain size of copper matrix is obviously larger than that of aluminum matrix. Matrix aluminum, matrix copper, Al2Cu.The average grains of Cu are mostly large Angle grain boundaries, and the orientation difference of adjacent grains in aluminum layer is much smaller than that in copper layer. After heat treatment at 300 °C for 1 h, the recrystallization degree of the interface zone of Cu–Al composite plate is low. After heat treatment at 400 °C for 1 h, the recrystallization in the interfacial zone of Cu–Al composite plate is not complete; After annealing at 450 °C for 1 h, the subgrain boundaries in the aluminum layer grow up, and LAGB is basically converted to HAGB. The distribution characteristics of the characteristic appearance direction in the crystal space of each phase were characterized under the conditions of casting and rolling and different heat treatment temperatures. At the same time, the research results provide theoretical basis and scientific title for optimizing the preparation process and high-end application of Cu–Al composite plate.

Effect of rolling motion on transient characteristics of condensation induced water hammer in an equal-height-difference passive heat removal system

The investigation of condensation-induced water hammer (CIWH) under ocean conditions is crucial to the system safety of the offshore floating nuclear plants (OFNPs). This paper establishes a CIWH numerical model under rolling conditions based on the computational fluid dynamics (CFD) code combined with user-defined functions (UDF). First, the numerical model is verified by published experimental data. Then, the transient behaviors of CIWH events under various rolling parameters are numerically investigated. The results show that the rolling motion causes a significant steam slug and enhances the steam-subcooled water contact area, which promotes the average condensation rate. The average condensation rate increases with an increase in rolling angle, decreases with an increase in rolling period. Due to the larger average condensation rate and reverse flow caused by rolling motion, the pressure peak generated by the CIWH significantly increases compared to static conditions. Similarly, the pressure peak increases as rolling angle increases, decreases as rolling period increase. Moreover, the pressure peak is proportional to steam inlet velocity, and the location of the pressure peak gradually moves back to the outlet direction as the steam velocity increases. These qualitative conclusions are useful to understand the effects of rolling motion on the CIWH and provide a reference for the CIWH simulations.

Numerical investigation on maldistribution of S-CO2 flow inside PCHE under rolling conditions

Heat exchangers with mini-channels, such as the printed circuit heat exchanger (PCHE), are key components for supercritical carbon dioxide (S-CO2) Brayton cycle due to advantages in compactness and structural rigidity. Flow distribution plays an important role for PCHE performance and it is affected by environment conditions like rolling and heaving motions. The flow distributions and heat transfer characteristics among parallel mini-channels for S-CO2 flow under the steady and rolling conditions would be simulated in this paper. Two plateaus/shoulders were observed on the nonuniformity-Rein curve: one was caused by the flow regime changing from laminar to turbulence regime, and another due to the compromise of “heating up” and “flow rate” effects. The rolling effects on the thermal-hydraulic characteristics of S-CO2 flow inside PCHE would be further investigated. In general, the response of thermal-hydraulic characteristics would be slightly delayed, and the rolling effects increase with the rolling frequency, amplitude and radius. As the rolling period increases, the shapes of heat transfer coefficient and friction factor curves would no longer be sinusoidal. The heat transfer characteristics in each channel were also investigated and it could be found that the heat transfer coefficient increases with the flow flux (Re). The effects of rolling conditions could not be neglected for low flow mass rate and high rolling frequency. Adding baffles at manifolds significantly improves the flow distribution under rolling conditions.

Dynamische Modellierung von Schlupf bei Windturbinen Pendelrollen-Hauptlager

This paper considers the problem of the dynamic modelling of macro slip in spherical roller bearings. By revisiting the fundamental physics which drive these systems, potential issues in existing models have been identified. Furthermore, in pure rolling conditions it was found that governing differential equations become “stiff”, requiring the use of implicit methods of time integration. The problem of individual roller macro slip in a wind turbine main bearing is then investigated using a simplified representation of system dynamics. Model results indicate clear links between slip/friction and the operational strategy of the wind turbine, as well as significantly higher frictional effects in the downwind main bearing row. Due to modelling simplifications, these results should not yet be considered conclusive, with further work required.

Testing the Inclination of an Industrial Diesel Engine Under Static Conditions According to the International Convention for the Safety of Life at Sea (SOLAS) Regulations

many industrial diesel engines are used as the main engine of the ship. Apart from being relatively cheaper, the availability of industrial engine is also very abundant, and the repair process is also not too complicated. However, when viewed from the SOLAS regulations related to the main requirements for a ship propulsion engine, it must also be considered, because it operates at sea, so that ship engines must be tougher than industrial engines, especially related to engine performance when experiencing rolling and trim. The purpose of this research is to test the feasibility of industrial diesel engines being operated on ships. By using a water-cooled single-cylinder diesel engine which is commonly used in small ships. The experimental method was used in this research to obtain optimal results according to the conditions in the field, the engine was made in three variations, namely the normal condition (without inclination angle), the rolling condition of 15 0 , and the trim condition of 5 0 which complies with SOLAS regulations related to the inclination angle. The results of the research obtained torque, Specific Fuel Consumption (SFC), and engine thermal efficiency in various engine variations. The highest torque is in the condition of the 15 0 rolling engine, which is 13.87 N.m. The lowest SFC is in the condition of the 15 0 rolling engine, which is 194 gr/kW.h. and the highest thermal efficiency was also obtained at the condition of the 15 0 rolling engine, namely 44.9%. The higher the engine speed, the higher the engine performance value in rolling 15 0 conditions, and the 5 0 trim conditions experience an increasing trend, but in low rotation conditions (750 Rpm) the performance decreases. Seeing the results obtained, a water-cooled single-cylinder diesel engine can be used as a small boat propulsion engine.

Effects of rare earth elements addition on mechanical properties and corrosion behavior of GCr15 bearing steel under different heat treatment conditions

In this work, effects of rare earth addition on mechanical properties and corrosion behavior of GCr15 bearing steel under hot rolled, annealed, and quenched-tempered conditions were investigated via mechanical tests, electrochemical measurements, and immersion tests. Results show that rare earth elements can refine grains, improve hardness, tensile strength, and impact absorption energy of GCr15 bearing steel under different heat treatment conditions. Besides, it has been found that rare earth elements are beneficial to corrosion resistance of GCr15 bearing steel in 0.1 mol/L NaCl solution by electrochemical and immersion measurements.

The Electric-Thermal Uneven Characteristics Simulation of Wide Mg Alloy Strip and Electroplastic Rolling Experiment

In order to solve the problem of wide magnesium strip uneven deformation in electroplastic rolling, an uneven field measurement device was designed. The device simulates the actual electro-thermal characteristics and provides as even and constant field conditions as possible for high-efficiency wide Mg strip rolling. Firstly, the effect of electrode position and distance on the electric field unevenness of magnesium strip is observed by setting the electric rolling condition, to provide the optimal electrical-thermal field quantity coupling conditions required by electric rolling. Secondly, in order to reveal the changing trend of the transient field in the actual rolling, the three-dimensional electric field of wide magnesium strip are simulated by the finite element method. The results show that the even temperature field and stable stress field required by the EPR of a wide Mg strip can be guaranteed to the greatest extent by setting electric field parameter Online. The case proves that the continuous EPR of Mg strip with a thickness of less than 0.13 mm without heat treatment can be realized by fine control of the EPR process.

Effect of Hot Rolling on Friction and Wear Characteristics of TiC Reinforced Copper-Based Metal Matrix Composites

The current study examines the effect of titanium carbide reinforcement (TiC) on the tribological behavior of copper metal matrix composites. The stir-casting process followed by hot rolling was employed to fabricate the composite parts. Hot rolling was performed at 510°C temperature with a 90% reduction ratio. An optical microscope, scanning electron microscope with energy dispersion spectroscopy, and Brinell hardness tester were used to investigate the microstructure, reinforcement particle distribution, and hardness. The microstructural investigations witness the uniform distribution of titanium carbide reinforcing agents along with the excellent binding with the copper matrix. The hardness was improved with the addition of titanium carbide content in both casting and rolling specimens. Dry sliding friction and wear tests were employed on a pin-on-disk setup with load values ranging from 30 to 120 N and sliding velocity values ranging from 0.628–2.512 m/s. In both casting and rolling conditions, the composites have a less coefficient of friction and wear rate than the matrix element. Wear rates of the unreinforced and reinforced cast and hot rolled alloys were enhanced as load and sliding velocity was raised. The incorporation of titanium carbide lowered the coefficient of friction and wear rate. In comparison to the unreinforced cast and rolled alloys, the coefficient of friction and wear of cast and rolled copper metal matrix composites was significantly reduced. Scanning electron microscopy was employed to investigate the worn surfaces and wear debris to confirm the possible wear mechanisms.

Experimental study on wheel-rail rolling contact fatigue damage starting from surface defects under various operational conditions

Surface defects in different railway lines experience different wheel-rail rolling contact actions owing to various railway line characteristics and vehicle operation parameters. This study focused on the evolution of defective wheel-rail rolling contact fatigue (RCF) behaviour under different operation conditions. Conical defects were created using an indentation apparatus. Wheel-rail RCF tests were performed using a twin-disc testing machine. Various operational conditions were simulated considering different slip ratios and wheel linear velocities on uphill and flat lines, as well as different vehicle axle loads and train configurations. The results indicate that surface damage, crack depths, and wear debris size increased only with decreasing wheel linear velocities, whereas the crack angles increased only with decreasing slip ratio. Meanwhile, both the wear rate and oxidation degree of wear debris were simultaneously affected by the slip ratio and wheel linear velocities. Under rolling conditions on flat lines, vehicle axle loads had a negligible influence on the wheel-rail RCF behaviour.

Study on the Density Wave Instability in Natural Circulation System under Rolling Conditions

In the ocean environment, the thermal fluid system installed on the ship moves with the waves. This unsteady transient motion imposes additional body forces on the liquid. Thereby, the thermohydraulic properties of the thermal fluid system are changed, especially for natural circulation systems with a low driving force. Flow instability related to system security is a common two-phase flow system phenomenon. It is an essential subject in the study of thermal-hydraulic characteristics. In this paper, the density wave instability in a low-pressure natural circulation system with several parallel heating channels in the circumstances of rolling motion is studied by PNCMC (Program for Natural Circulation under Motion Condition). PNCMC is a newly developed program by adding extra body force induced by ship motions in two-phase’s momentum equations. The mechanism of rolling motion and its impact on flow oscillation and unstable boundary power are investigated. The supercooled boiling caused by the higher surface heat flux firstly promotes the occurrence of density wave oscillations between parallel heating channels. When enough steam enters the riser, the system density wave oscillation occurs under the gravity pressure drop-flow rate-vapor fraction feedback. A more complicated compound oscillation is created by superimposing the interchannel oscillation and the system density wave oscillation. If the rolling motion has little change to the natural circulation flow, when density wave instability arises, the flux oscillation rule and the instability boundary power are basically consistent with the vertical conditions. When the rolling angle is large, the fairly large amplitude flow oscillation generated by rolling will prevent density wave instability from occurring and force the flow oscillation to obey the law of rolling effects.

An in-plane flexible ring model for the analysis of the free and forced response of a rolling tyre

The increased demand for vibroacoustic comfort as well as regulations on noise and vibration levels have made the NVH (Noise, Vibration, Harshness) performances of a vehicle to become one of the fundamental design criteria. Therefore, predictive models for the analysis of noise and vibration transmission mechanisms represent interesting tools to support the R&D department of the automotive companies. Focusing the attention on passenger's comfort, the vibrations induced by the tyre/road interaction propagate from the contact area to the hub and finally inside the cockpit through structure-borne transmission paths. This can be regarded as one of the major contributors to the car cabin interior noise at low frequencies (between 20 and 500 Hz). Simplified models able to interpret the waves propagating inside the tyre structure and influenced by the angular speed may support the studies in this research field. To this end, an analytical model based on the theory of the flexible ring on elastic foundation has been developed. It allows analysing the tyre dynamics in both static and rolling conditions. Model parameters have been calibrated based on an Experimental Modal Analysis of the static tyre. The free response of the tyre shows the bifurcation effect at different rolling speeds, while a cleat test simulation has been carried out to investigate the forced response of the tyre.

RENAULT Smart Cocoon Technology CAE

RENAULT was the first OEM to introduce mass production Battery Electric Vehicles in Europe with the ZOE in 2012. With the new Megane ETECH, RENAULT set the NVH comfort to higher level to match the customer expectations on BEV vehicles. One of the components that contributes to the silence of Megane is the "Smart Cocoon Technology". This innovative solution has been developed to transform the battery into an acoustically active element. An insulation foam has been embedded between the body floor and the battery casing in order to use the battery mass to improve the floor transparency and damping, and subsequently the Transmission Loss. To support further developments of this technology RENAULT and its CAE partners are developing a simulation methodology to achieve simultaneously three goals: predict the behavior of the smart cocoon technology on the whole vehicle NVH performance, optimize the performance and weight of the insulation package, and secure the assembly process. This paper presents in detail each step of this process. Non-linear simulations of the battery assembly process are used to capture the preloading effects in foam and body panels. The vehicle high frequencies NVH performance is then simulated for vehicle rolling conditions. In a last part of the paper, CAE results are compared with the test measurements on the Megane prototype.

Critical heat flux correlations for tube and annulus geometries under inclination and rolling conditions

In floating nuclear reactors, critical heat flux (CHF) prediction is crucial because the CHF can be influenced under heaving, rolling, and inclination conditions, unlike in land-based reactors. Hence, the existing land-based empirical correlations of the CHF can be invalid under some conditions in marine reactors. Therefore, empirical correlations of the flow boiling CHF were developed in this study to predict the CHF under inclination and rolling motions in tubes and annuli. Available experimental CHF data (616 points) were collected including our previous experimental data (405 points) and their trends under marine conditions were analyzed. The CHF variation was expressed using two types of modified Froude numbers depending on the CHF regime—departure from nucleate boiling and dryout. These parameters were used in correlations for the CHF under inclination. CHF correlations under rolling conditions were developed. Rolling was found to attenuate the CHF variation through the inclination. This observation was reflected in the newly developed rolling CHF correlation. The proposed correlations adequately described the existing CHF experimental data under inclination and rolling within an uncertainty of 9.5%. The developed CHF correlations can be used for the safety analysis and reactor core thermal–hydraulic design of marine reactors.

Revealing Precipitate Development During Hot Rolling and Cooling of a Ti–Nb Micro‐Alloyed High Strength Low‐Alloy Steel through X‐Ray Scattering

High‐energy synchrotron X‐ray small‐angle scattering (SAXS) is used to study the precipitate development during hot rolling and cooling of a commercial Ti–Nb micro‐alloyed, high‐strength, low‐alloy (HSLA) steel. To study precipitation during hot rolling conditions, Gleeble and dilatometer trials are made. Samples are then studied at room temperature using SAXS in conjunction with transmission electron microscopy (TEM). TEM is used to determine the morphology and composition of the precipitates, whilst both TEM and SAXS are used to study the particle sizes. One major advantage with high‐energy SAXS is the ability to make measurements after a minimum of sample preparation and in transmission geometry, as opposed to just at prepared surfaces, plus the possibility to determine volume fractions of the precipitates. The measurements show that after deformation at high temperature, particle coarsening occurs and the volume fraction of precipitates increases after holding for 20 s at 900 °C which confirms strain‐induced precipitation at finishing rolling conditions. The measurements show that holding at 600 or 650 °C for one hour gives a larger volume fraction of nanosized particles. Coiling simulations with slow cooling from 600 to 470 °C show coarsening of particles and an increase in the volume fraction of the smaller particles compared to holding at a constant temperature.

Determination of the wear of the surfaces of barrels of work rolls in a continuous finishing group of stands of a wide-strip hot rolling mill

Compensate for elastic and thermal deformations of the work rolls, as well as to ensure the possibility of rolling a flat strip, the surface of the barrel of the work rolls is profiled. During the production of steel strips on a continuous mill, the initial grinding profiles of the barrel surfaces change due to their wear. According to a number of studies, the shape of the worn surface will be determined by a number of factors: by sliding the rolled metal along the roll in the deformation zone, which depends, among other things, on the length of the produced strip; temperature conditions in the deformation zone; the presence of a movable intermediate layer between the roll and the strip, for example, mill scale during hot rolling or cutting fluid during cold rolling; chemical composition of the rolled steel; quality of rolling rolls; applied steel strip reduction modes in the mill stands; uneven heating of the rolled metal over the section, as well as some other parameters. A study was carried out on the basis of experimental data on evaluating the profile of the barrel of work rolls after they were dumped and cooled from the rolling stands. It was found that the main parameter affecting the wear of the surface is the length of the strip rolled in a given stand. It has been confirmed that wear along the length of the roll barrel is uneven. A method for calculating the wear of the surfaces of the barrels of the work rolls of a wide-strip mill along their length, based on the operating mode, is proposed. The results of the study can be used to improve the shape of the grinding profiling curve of the work roll barrels and it can be used in models for controlling the shape of a strip, and calculate technological rolling conditions

Increase of durability of railway wheels at JSC “Aktyubinsk ferroalloys plant”

Compensate for elastic and thermal deformations of the work rolls, as well as to ensure the possibility of rolling a flat strip, the surface of the barrel of the work rolls is profiled. During the production of steel strips on a continuous mill, the initial grinding profiles of the barrel surfaces change due to their wear. According to a number of studies, the shape of the worn surface will be determined by a number of factors: by sliding the rolled metal along the roll in the deformation zone, which depends, among other things, on the length of the produced strip; temperature conditions in the deformation zone; the presence of a movable intermediate layer between the roll and the strip, for example, mill scale during hot rolling or cutting fluid during cold rolling; chemical composition of the rolled steel; quality of rolling rolls; applied steel strip reduction modes in the mill stands; uneven heating of the rolled metal over the section, as well as some other parameters. A study was carried out on the basis of experimental data on evaluating the profile of the barrel of work rolls after they were dumped and cooled from the rolling stands. It was found that the main parameter affecting the wear of the surface is the length of the strip rolled in a given stand. It has been confirmed that wear along the length of the roll barrel is uneven. A method for calculating the wear of the surfaces of the barrels of the work rolls of a wide-strip mill along their length, based on the operating mode, is proposed. The results of the study can be used to improve the shape of the grinding profiling curve of the work roll barrels and it can be used in models for controlling the shape of a strip, and calculate technological rolling conditions

Elastomer-Embedded Multiplexed Optical Fiber Sensor System for Multiplane Shape Reconstruction

This paper presents the development and application of a multiplexed intensity variation-based sensor system for multiplane shape reconstruction. The sensor is based on a polymer optical fiber (POF) with sequential lateral sections coupled with a flexible light-emitting diode (LED) belt. The optical source modulation enables the development of 30 independent sensors using one photodetector, where the sensor system is embedded in polydimethylsiloxane (PDMS) resin in two configurations. Configuration 1 is a continuous PDMS layer applied in the interface between the flexible LED belt and the POF, whereas Configuration 2 comprises a 20 mm length PDMS layer only on each lateral section and LED region. The finite element method (FEM) is employed for the strain distribution evaluation in different conditions, including the strain distribution on the sensor system subjected to momentums in roll, pitch and yaw conditions. The experimental results of pressure application at 30 regions for each configuration indicated a higher sensitivity of Configuration 1 (83.58 a.u./kPa) when compared with Configuration 2 (40.06 a.u./kPa). However, Configuration 2 presented the smallest cross-sensitivity between sequential sensors (0.94 a.u./kPa against 45.5 a.u./kPa of Configuration 1). Then, the possibility of real-time loading condition monitoring and shape reconstruction is evaluated using Configuration 1 subjected to momentums in roll, pitch and yaw, as well as mechanical waves applied on the sensor structure. The strain distribution on the sensor presented the same pattern as the one obtained in the simulations, and the real-time response of each sensor was obtained for each case. In addition, the possibility of real-time loading condition estimation is analyzed using the k-means algorithm (an unsupervised machine learning approach) for the clusterization of data regarding the loading condition. The comparison between the predicted results and the real ones shows a 90.55% success rate. Thus, the proposed sensor device is a feasible alternative for integrated sensing in movement analysis, structural health monitoring submitted to dynamic loading and robotics for the assessment of the robot structure.

Nanoscopic Characterization of Cell Migration under Flow Using Optical and Electron Microscopy.

Hematopoietic stem/progenitor cell (HSPC) and leukemic cell homing is an important biological phenomenon that takes place through essential interactions with adhesion molecules on an endothelial cell layer. The homing process of HSPCs begins with the tethering and rolling of the cells on the endothelial layer, which is achieved by the interaction between selectins on the endothelium to the ligands on HSPC/leukemic cells under shear stress of the blood flow. Although many studies have been based on in vitro conditions of the cells rolling over recombinant proteins, significant challenges remain when imaging HSPC/leukemic cells on the endothelium, a necessity when considering characterizing cell-to-cell interaction and rolling dynamics during cell migration. Here, we report a new methodology that enables imaging of stem-cell-intrinsic spatiotemporal details during its migration on an endothelium-like cell monolayer. We developed optimized protocols that preserve transiently appearing structures on HSPCs/leukemic cells during its rolling under shear stress for fluorescence and scanning electron microscopy characterization. Our new experimental platform is closer to in vivo conditions and will contribute to indepth understanding of stem-cell behavior during its migration and cell-to-cell interaction during the process of homing.

Numerical simulation on heat transfer characteristics of unstable steam jet condensation under rolling condition

Direct contact condensation technology has been widely used in nuclear power, aerospace, chemical industry, and other fields due to efficient mass and heat transfer characteristics between two phases. Rolling motion applied to offshore cases typically significantly affects dynamic flow and heat transfer characteristics. Thus, investigating the heat transfer characteristics of unstable steam jet condensation is necessary. The present study numerically explored the heat transfer coefficient of main and detached bubbles under rolling and static conditions. The relationship between pressure and heat transfer coefficient was assessed to reveal the pressure generation mechanism. The peak value of pressure oscillation was mainly caused by the rapid collapse induced by intense condensation of detached bubble instead of main bubble. The heat and mass transfer intensity could be fortified under rolling conditions. It would increase as the maximum rolling amplitude rise and the rolling period decrease, while the maximum improvement was up to 30%.

Evaluation of Powder Metallurgy Workpiece Prepared by Equal Channel Angular Rolling.

The aim of the article is to examine the workability of sintered powder material of aluminum alloy (Alumix 321) through severe plastic deformations under the conditions of the equal channel angular rolling (ECAR) process. Accordingly, the stress-strain analysis of the ECAR was carried out through a computer simulation using the finite element method (FEM) by Deform 3D software. Additionally, the formability of the ALUMIX 321 was investigated using the diametrical compression (DC) test, which was measured and analyzed by digital image correlation and finite element simulation. The relationship between failure mode and stress state in the ECAR process and the DC test was quantified using stress triaxiality and Lode angle parameter. It is concluded that the sintered powder material during the ECAR processing failure by a shearing fracture because in the fracture location the stress conditions were close to the pure shear (η and θ¯ ≈ 0). Moreover, the DC test revealed the potential role as the method of calibration of the fracture locus for stress conditions between the pure shear and the axial symmetry compression.