Strip Thickness Research Articles

Validity of Thin Element Approximation in diffractometry of opaque thick objects

The Thin Element Approximation (TEA) is widely used in diffraction analyses since it can be applied in efficient plane-to-plane propagation algorithms. While refinements have been developed for dielectric objects to obtain more accurate results, TEA is assumed precise for opaque objects. However, through numerical simulations presented in this work, based on Wave Propagation Method, we analyze the tendency of TEA to overestimate the dimensions of opaque objects in diffractometry. This effect was acknowledged in the case of cylinders, and we obtain similar results for the case of rectangular thick strips. On the other hand, TEA demonstrates a high level of accuracy when applied to objects with thickness concentrated at the center and thin edges, such as the isosceles triangular obstacle. Finally, we analyze objects whose shape is defined using the superellipse function, which is chosen for its versatility in generating objects of equivalent width and maximum thickness but with different shapes just changing a single parameter. Our results highlight the importance of considering the object geometry when employing this approximation in diffraction studies of opaque three-dimensional objects.

Identification of structural defects and their impact on the magnetic memory, static and cyclic strength of VNS9-SH thin sheet trip-steel

Identification of microstructure defects, which are stress concentrators (SC) during the operation of mechanical engineering products, is an important scientific and practical task relevant for manufacturing enterprises. This problem becomes especially urgent and difficult for critical helicopter parts made of sheet TRIP steel VNS9-Sh (23Kh15N5AM3-Sh) and operating under cyclic loads due to the complex microstructure of the steel and small thickness of strips and sheets. To assess the impact of structural defects on the cyclic strength of products made of the steel under study, the specimens were preliminary sorted proceeding from the results of their testing using the method of metal magnetic memory (MMM) and metallographic studies. The MMM method is a structure-sensitive procedure which provides information about the presence of structural defects that arise during the manufacture. Magnetic anomalies in the form of sharp local changes in the intrinsic stray magnetic field (SSMF) (H) and its gradient |ΔH| along the length of the controlled section Δx, were identified on the surface of sheets cut from five different batches. A conventional classification of the identified anomalies was made according to the magnitude of the magnetic field gradient. The specimens of two types were cut in zones of magnetic anomalies and outside them: type 1 — for cyclic tests and type 2 — for metallographic studies. The geometric parameters and field gradient values of magnetic anomalies on specimens of type 1 and type 2 were the same. Metallographic studies in zones of maximum magnetic field gradient on type 2 specimens revealed defects in the form of a strip at the boundary of different structures, which is a structural stress concentrator (SSC) and a source of the inhomogeneity and changes in the magnetic properties. Type 1 specimens with similar magnetic anomalies and Type 1 specimens cut from sheets outside zones of magnetic anomalies were then selected for cyclic testing. Comparative tests for cyclic strength of the specimens with and without specified SSC were carried out. It is shown that the presence of SSC zones in the specimens reduces the number of cycles to failure during cyclic tests by 1 – 2 orders of magnitude compared to the specimens free of SSC. Based on cyclic tensile tests of specimens, a limiting value of the magnetic field gradient was determined that corresponds to the acceptable level of stress concentration on structural defects. This value is recommended for use as a rejection criterion when examining a new tape by the MMM method.

Joint prediction method for strip thickness and flatness in hot strip rolling process: A combined multi-indicator Transformer with embedded sliding window

Thickness and flatness are important quality indicators for strip. It is important that the rapid and accurate prediction of the exit thickness and flatness for the optimal control of the hot strip rolling process. Due to the fast and long rolling process, there are time delays, non-linearity and strong coupling among the variables, which cause difficulties in the establishment of prediction models. In this paper, the variables related to thickness and flatness are selected by analyzing the rolling process mechanism and data. Based on the data related to the rolling quality, a rolling exit thickness and flatness joint prediction model combined multi-indicator Transformer with embedded sliding window (SW-MTrans) is proposed. First, a sliding window is embedded into the input layer of the model in order to address the effect of the time delay among variables. Then a Transformer network is improved to achieve accurate prediction of thickness and flatness simultaneously. It is verified that the proposed method can predict the thickness and flatness at the same time with higher prediction accuracy and generalization ability compared with other methods through actual production data. The mean absolute error (MAE) for thickness prediction was reduced by 19.37% and MAE for flatness prediction was reduced by 14.03% compared to the existing prediction model.

Pulsed current-assisted twelve-roll precision rolling deformation of SUS304 ultra-thin strips with exceptional mechanical properties

Innovative pulsed current-assisted multi-pass rolling tests were conducted on a 12-roll mill during the rolling deformation processing of SUS304 ultra-thin strips. The results show that in the first rolling pass, the rolling reduction rate of a conventionally rolled sample (at room temperature) is 33.8%, which can be increased to 41.5% by pulsed current-assisted rolling, enabling the formation of an ultra-thin strip with a size of 67.3 μm in only one rolling pass. After three passes of pulsed current-assisted rolling, the thickness of the ultra-thin strip can be further reduced to 51.7 μm. To clearly compare the effects of a pulsed current on the microstructure and mechanical response of the ultra-thin strip, ultra-thin strips with nearly the same thickness reduction were analyzed. It was found that pulsed current can reduce the degree of work-hardening of the rolled samples by promoting dislocation detachment, reducing the density of stacking faults, inhibiting martensitic phase transformation, and shortening the total length of grain boundaries. As a result, the ductility of ultra-thin strips can be effectively restored to approximately 16.3% while maintaining a high tensile strength of 1118 MPa.Therefore, pulsed current-assisted rolling deformation shows great potential for the formation of ultra-thin strips with a combination of high strength and ductility.

An industrial IoT-based deformation resistance prediction and thickness control method of cold-rolled strip in steel production systems

Different from traditional analytical and numerical simulation methods, data-driven methods can more effectively describe the effects of nonlinear and coupling factors. Although the fluctuations of deformation resistance and thickness for hot-rolled strips significantly influence the thickness accuracy in strip cold rolling, the traditional deformation resistance prediction model and thickness control mode don't involve that. Thus, based on the Industrial Internet of Things (IIOT) platform and data-driven technology, this work proposed a new method for deformation resistance prediction and a new mode of feed-forward control for strip thickness. IIOT platform can collect production data from the various levels to provide a complete data set. The deformation resistance prediction model is established by adopting the differential evolutionary algorithm to optimize the bi-directional long and short-term memory network. In addition, the feed-forward control (DFFC) strategy for strip thickness is proposed based on deformation resistance prediction. An application results of a 1420 mm production line of CR indicated that the established prediction model could provide a high accuracy prediction for deformation resistance, and compared to traditional thickness gauges-based automatic gauge control methods, the DDFC can capture the effect of the fluctuations of deformation resistance and thickness for the hot-rolled strip to improve thickness accuracy effectively.

Evaluation of commercial and scrap tyre cellular reinforcement infilled with demolition waste for granular sub-base of flexible pavements: A sustainable approach

Nowadays, use of geocell is gaining more importance in pavement industry as it offers improved performance through confinement and tensioned membrane actions. In the recent years, solid waste management seeks greater attention as it poses serious issues related to their disposal, health and environmental hazards. Effective recycling and reuse of these wastes could be a viable and economical approach towards sustainable construction. In this regard, two such wastes (scrap tyres and construction & demolition (C&D) waste) are considered for investigation. The recycled concrete aggregates (RCA) obtained from the C&D waste is used as granular sub-base material and its performance is compared with conventional crushed aggregates (CCA). Scrap tyre is used as cellular reinforcement (recycled tyre cell (RTC)) and its effectiveness as a reinforcing material is compared with the commercial cellular reinforcement (commercially available geocell (CGC)). The study involves construction of laboratory pavement sections under unreinforced and reinforced conditions and testing under repeated loading. The pavement sections supplemented with CGC and RTC reinforcement shows reduced permanent deformation by 27 & 33% and 30 & 35% respectively for CCA and RCA infill materials. The comparable performance of RCA with CCA is attributed to the self-cementation effect offered by the adhered residual cement mortar. With CGC and RTC reinforcement, residual pressure at the subgrade level reduces by 30 and 37% respectively. Provision of cellular reinforcement improves the stress distribution angle than the respective unreinforced pavements and highest improvement is observed in case RTC. Improved behaviour with RTC is due to the increased strip thickness and tensile strength of recycled tyre strip than the ones used in the preparation of CGC. Irrespective of the infill material, higher strains are experienced under the loading zone than the neighbouring cells. Overall, the study promotes use of scrap tyres and RCA in bulk volume for pavement construction offering an eco-friendly, cost-effective, sustainable and long-lasting pavements.

Analytical Study of the Reduction of Contact Pressure during Cold Rolling of Thick Strips with a Single Deformation Zone

Analytical Study of the Reduction of Contact Pressure during Cold Rolling of Thick Strips with a Single Deformation Zone

Response of the root anatomical structure of Carex moorcroftii to habitat drought in the Western Sichuan Plateau of China

Main conclusionThe anatomical structures of Carex moorcroftii roots showing stronger plasticity during drought had a lower coefficient of variation in cell size in the same habitats, while those showing weaker plasticity had a higher coefficient of variation. The complementary relationship between these factors comprises the adaptation mechanism of the C. moorcroftii root to drought.To explore the effects of habitat drought on root anatomy of hygrophytic plants, this study focused on roots of C. moorcroftii. Five sample plots were set up along a soil moisture gradient in the Western Sichuan Plateau to collect experimental materials. Paraffin sectioning was used to obtain root anatomy, and one-way ANOVA, correlation analysis, linear regression analysis, and RDA ranking were applied to analyze the relationship between root anatomy and soil water content. The results showed that the root transverse section area, thickness of epidermal cells, exodermis and Casparian strips, and area of aerenchyma were significantly and positively correlated with soil moisture content (P < 0.01). The diameter of the vascular cylinder and the number and total area of vessels were significantly and negatively correlated with the soil moisture content (P < 0.01). The plasticity of the anatomical structures was strong for the diameter and area of the vascular cylinder and thickness of the Casparian strip and epidermis, while it was weak for vessel diameter and area. In addition, there was an asymmetrical relationship between the functional adaptation of root anatomical structure in different soil moisture and the variation degree of root anatomical structure in the same soil moisture. Therefore, the roots of C. moorcroftii can shorten the water transport distance from the epidermis to the vascular cylinder, increase the area of the vascular cylinder and the number of vessels, and establish a complementary relationship between the functional adaptation of root anatomical structure in different habitats and the variation degree of root anatomical structure in the same habitat to adapt to habitat drought. This study provides a scientific basis for understanding the response of plateau wetland plants to habitat changes and their ecological adaptation strategies. More scientific experimental methods should be adopted to further study the mutual coordination mechanisms of different anatomical structures during root adaptation to habitat drought for hygrophytic plants.

A Novel Model to Predict Shape Variation of Steel Strip During Feeding in Slab Continuous Casting

To comprehensively comprehend variation of strip shape (strip feeding depth and maximum steel sheath cross‐sectional area) under different process parameters (strip feeding speed, strip oscillation frequency, strip amplitude, molten steel superheat, strip width, and strip thickness), a mathematical model of feeding strip process has been developed herein. Flow near steel strip is analyzed. Meanwhile, the qualitative relationship between strip shape and process parameters is derived based on energy conservation within the system of molten steel and steel strip. The results show that strip feeding depth is positively correlated with strip feeding speed, strip width, and strip thickness, while it's negatively correlated with strip oscillation frequency, strip amplitude, and molten steel superheat; maximum steel sheath cross‐sectional area is positively correlated with strip width and strip thickness, while it's negatively correlated with strip feeding speed, strip oscillation frequency, strip amplitude, and molten steel superheat. Based on the calculated results, the quantitative relationships are proposed to predict the strip feeding depth and maximum steel sheath cross‐sectional area with aforementioned process parameters, which are suitable for the situations that the strip tip is located between the outlet of submerged entry nozzle and the end of the liquid core.

ВАРІАНТИ ВИКОРИСТАННЯ ВЛАСТИВОСТІ УНІФІКАЦІЇ ПРИ ВИБОРІ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ РІШЕНЬ З’ЄДНАНЬ “МЕТАЛ+КОМПОЗИТ”

Possibility of unification property realization in application to variants of structural-technological solutions of “metal+composite” joints.It is drawn that this property is important for up-today vehicle engineering structures at different goals of its manufacturing. It is shown that there are three possible options can be revealed in metal-composite heterogenous joints realization: with monolithic, cylindrical and sheet transversal fastening connections.Possibility of application sheet transversal fastening elements produced on metal strips is considered exactly. Also, possibility of implementation strips of different materials and thickness is analyzed.The property of unification is most fully manifested at the stages of design, technological preparation of production and production itself. Variants of technological processes for manufacturing sheet fasteners on metal strips using stamping methods or laser cutting are proposed. An analysis of the advantages and disadvantages of these technical processes showed that the most rational method is stamping with bending.Options for route technical processes for forming transversal connections on metal tips using sheet reinforcing elements are proposed.Options for equipment are proposed, with the help of which serial production of teeth on metal strips is possible. It should be noted among these equipment options metal stamps for stamping teeth and using an electro-hydraulic device for bending them.Examples of implementation of design and technological solutions with sheet micro-elements in the manufacture of high-pressure vessels and in the strengthening of bolted joints are given.

Effect of elastic deformation on the heat transfer characteristic of refrigerator gasket based on static analysis of structural assemblies

ABSTRACT Soft and hard contact deformation is most common issue of the refrigerator gasket and it has almost been ignored in previous studies. In this paper, the novelty is to propose a thermal-solid coupling simulation to study the effect of assembly states on the heat transfer of gaskets, improving the accuracy of heat transfer simulation analysis. The numerical results indicate that the calculated temperature based on physical model of assembly state is closer to measured temperature. The assembly distance affects the assembly state of the gasket by changing the contact positions and lengths of contact interfaces. As a result, the heat transfer path and condition at the gasket region also changes. As the deformation increases form −1.0 mm to 5.0 mm, the heat leakage load of gasket rises firstly and then falls, in the range of 1.61 ~ 3.33 W•m−1. The heat leakage at the transfer paths of internal cold air, outer shell and cold bridge accounts for over 20%. Thus, it is recommended to reduce the contact interface length of internal cold air, increase the thermal resistance of auxiliary air-bag, reduce the thermal conductivity and thickness of magnetic strip and increase the contact thermal resistance of cold bridge.

Stabilization of Strip Thickness in Nonstationary Stages of the Cold Rolling Process on a Multi-Stand Mill

Stabilization of Strip Thickness in Nonstationary Stages of the Cold Rolling Process on a Multi-Stand Mill

Analysis of Edge Drop on Strip Due to Bending and Elastic Deformation of Back up Rolls in a Four-High Cold Mill

The superficial quality of the strip is a very important issue in steel production. Considering the dimensions, the thickness is one of the most important variables in the production of a strip. In the present study, the elastic curve of Back Up Rolls (BURs) is analyzed, considering them as simply supported beams as well as the effect of rolls on the profile of the strip, specifically in the strip edge producing edge drop. The analysis included theoretical and numerical measurements in the mill. The results showed that there is an instability zone of 76 mm in the strip edge, and this geometry is symmetrical in both ends of the strip. This study not only provides a theoretical basis for the edge drop, but also provides a basis for the understanding of deformation on rolls used in rolling mill processes and their effect on the thickness, profile, shape, and dimensional quality of strips. To reduce the edge drop and significantly improve the surface quality of the strip, it is suggested to complement the simulation by compensating for the elastic curve of BUR, in the process applying bending on Work Roll (WR) combined with the use of positive crowns on it.

Experimental study and numerical analysis on the axial compression performance of CFRP strip reinforced round-end aluminum alloy tube concrete column

Round-end aluminum alloy tube concrete columns had good durability and were very economical, but the low strength and elastic modulus of aluminum alloy led to the need for improvement in performance. This paper proposes carbon fiber reinforced plastic (CFRP) strip reinforced round-end aluminum alloy tube concrete (CREAC) columns and investigates their mechanical properties under axial compression loads. A total of eight specimens were tested, including seven CFRP reinforced specimens and one control specimen. The effects of the width, spacing, and number of layers of CFRP strips on the axial compression performance of CREAC under the same amount of CFRP were studied. The experimental results indicate that the main failure modes of the specimen are the buckling of round-end aluminum alloy tubes and the fracture of CFRP strips. The CFRP strip can significantly improve the ultimate bearing capacity of the specimen, with a maximum increase of 15.3% in the test range. When the amount of CFRP is the same, as the number of CFRP strips decreases, the bearing capacity and ductility deteriorate. Increasing the width and thickness of CFRP strips significantly improves ductility. On the basis of the validated finite element model, parameter analysis was conducted, and the calculation method for stability coefficients was fitted. A calculation method for axial compression bearing capacity suitable for CREAC was proposed, with a maximum error of less than 1% between the predicted results and experimental results.

Real-time detecting deformation on pantograph contact strip based on image processing technique

Railway vehicles’ traction power supply system has two main components, the catenary contact and the pantograph. During the operation, contact is influenced by electromechanical wear phenomena. Deformation on the pantograph contact strip affects its power transmission quality because contact loos with the catenary reduces the railway system’s overall reliability. Their maintenance and inspection are usually done for periods of time with negative consequences in terms of costs and safety. Thus, in this study, we developed a contact strip monitoring method based on image processing for inspection to measure the contact strip thickness. The measurement system is made through a single camera that acquires images from the contact area, measuring the contact strip’s thickness using image processing techniques.

Hot-rolled strip thickness diagnosis and abnormal transmission path identification based on sub stand strategy and KPLS-MIC-TE

Multi-stand combined rolling is the key process to determine the quality of strip. The rolled piece presents different states in each stand unit, and there is information transmission and interaction between stands. To reduce the impact of quality-related faults on subsequent production systems, it is particularly important to effectively identify the transmission path of quality-related information for locating the root cause of abnormalities. However, the causes of quality defects are misidentified due to the neglect of genetic characteristics of quality in the overall quality diagnosis. Focus on hot rolled strip thickness diagnosis, an abnormal transmission path identification method based on sub stand strategy and Kernel Principal Least Square-Maximal Information Coefficient-Transfer Entropy (KPLS-MIC-TE) was proposed to improve the accurate identification of defect roots, the sub-stand was diagnosed, and the abnormal variable diagnosis of a sub stand was conducted with the KPLS algorithm. Secondly, based on the asymmetric characteristics of the transfer entropy matrix, a directed transfer topology with the causality of variables was constructed. Finally, the production data of the 1580 hot rolling line is used for industrial validation. The results show that the method can accurately diagnose process abnormal variables and identify the path of abnormal variables.

Numerical investigations of the effects of spanwise grooves on the suppression of vortex-induced vibration of a flexible cylinder

Numerical investigations of Vortex-induced Vibration (VIV) suppression of a flexible cylinder with spanwise grooves in the uniform flow have been conducted by viv3D-FOAM-SJTU solver, which imports the thick strip model into OpenFOAM. The Reynolds-averaged Navier-Stokes (RANS) method is adopted to calculate hydrodynamic forces at each fluid strip. The vibrations of cylinder are solved through the Euler-Bernoulli bending beam hypothesis and the Finite Element Method (FEM) in two directions. During simulations, four spanwise grooves are arranged equally around the cylinder with an interval of 90° at two configurations. The spanwise groove keeps a constant width of w = 0.2D and a variable groove depth among 0.08D, 0.12D and 0.16D. Specific comparisons on Root Mean Square (RMS) vibration displacements, vibration modal responses, vibration frequency responses and vortex structures are conducted to analyze suppression effects of the spanwise grooves. Numerical studies indicate that the appropriate choose of groove geometry and arrangement can effectively reduce both crossflow and inline VIV responses.

Calculation formulas for contact curves of technological machine

The problem of describing the contact curves of technological machines has been solved. At the same time, contact interaction was studied taking into account changes in the technological parameter and deformation of the materials of the contacting bodies. The obtained dependencies make it possible to find rational parameters of the technological process with sufficient accuracy. The obtained models indicate that the shape of the contact is influenced by such parameters as strip thickness, roll radii, external forces, as well as parameters characterizing the deformations of the contacting bodies.

Study of penetrating deformation along strip thickness during rolling of composite materials

Numerical modeling of the propagation of plastic deformation across the cross-section of the rolled strip is carried out, which is especially important during secondary compaction rolling of composite products, due to the existing discontinuity of such a material, consisting of individual particles of metal powders. The developed algorithm for determining оf penetrating deformation will avoid mutual overlap of compressive stresses from each roll and prevent the appearance of tensile stresses at half-height of the strip, leading to destruction of the material. The results obtained will find application in the development of sheet rolling technologies (monomaterials and composite products), as well as in modeling the stress-strain state of the material and analyzing the causes of the appearance of layer cracks in rolled products.

A Graphical Solution to Bond Capacity

This study proposes an analytical model, referred to as the "Wine Glass model", offering an elegant graphical solution to the bond capacity. It is built on the basis of two key assumptions: (i) the bond length is sufficiently long (longer than an effective bond length) and (ii) the stress-strain behavior of the adherent monotonically increases, which is typically met by the majority of engineering materials. The tensile stress-strain (σ - ϵ) curve of the adherent can be visualized as a wine glass when plotted against the vertical axis (σ-axis). In this analogy, the fracture energy of the adhesive bond divided by the thickness of the adherent strip (Gf/t) represents the wine poured into the glass. The height of the wine within the glass corresponds to the level of adherent tensile stress, with respect to the bond capacity (Fb). This Wine Glass model, which suits lap-shear joints with both linear and nonlinear adherents, is validated on experimentally measured bond capacities of various types of lap-shear joints, including carbon fiber reinforced polymer (CFRP)-to-steel joints and iron-based shape memory alloy (Fe-SMA)-to-steel joints. It unveils the mechanism of bond capacity.