Increasing Plate Thickness Research Articles

PARAMETER STUDY ON WIND RESISTANT PERFORMANCE OF STANDING SEAM ROOF SYSTEM WITH ANTI-WIND CLIP

At present, the standing seam roof system with anti-wind clips is adopted in many largespan buildings to resist the action of strong wind. However, few further studies have been conducted on the changes in the deformation, stress and other characteristic responses of the standing seam roof system with anti-wind clips under wind loading. By means of experiment and numerical simulation, the influence of plate width, plate thickness, spacing between wind clips and other parameters on the characteristic response and bearing capacity of the roof system is studied. The failure criterion of the roof system is proposed and the formula for calculating the bearing capacity of the roof system is obtained by fitting. The research shows that the bearing capacity increases by about 10% for every 0.1 mm increase in plate thickness. The bearing capacity increases by 25% for every 100 mm reduction in plate width. When the anti-wind clips spacing is less than 1100 mm, the bearing capacity increases by about 20% for each reduction of 100 mm. When the anti-wind clips spacing is more than 1100 mm, the bearing capacity increases by about 10% for each reduction of 100 mm. Changing the structure of an anti-wind clip has little effect on the bearing capacity.

Stability of an anisotropic dielectric elastomer plate

A variety of methods have been proposed to improve the performance of dielectric elastomer transducers, which lead to the anisotropic electromechanical behavior of the material. This paper theoretically analyzes the effect of material anisotropy on the diffuse modes of instability in dielectric elastomer plates. As a first step, a transversely isotropic material is considered in the present study. The linearized incremental theory is used and the plate thickness is considered in the stability analysis. The bifurcation equations are solved with Wolfram Mathematica (Wolfram Research, Inc., 2019) [1] to obtain the critical stretches under different electric field. It is found that, compared to the isotropic material, material anisotropy results in larger unstable regions and higher critical stretches above which the plate is stable. It is also shown that material anisotropy has a stronger influence on a thinner plate. As the plate thickness increases, the influence decreases.

Steady natural convection Couette flow with wall conduction and thermal boundary condition of third kind

AbstractThis study theoretically investigates the effects of viscous dissipation and boundary plate thickness on an incompressible heat generating/absorbing fluid with non‐uniform internal temperature unlike lumped heat capacitance assumption. The flow, which is laminar is induced by free convection caused by asymmetric heating of the channel boundaries and internally generated energy caused by viscous dissipation. In addition, convection through the boundary plates is also considered in the flow formation. One of the plates channel moves along the flow direction while the other is stationary. Due to the non‐linear and coupling nature of the governing flow equations, homotopy perturbation method (HPM) has been adopted to analytically find the approximate solution to the problem. The effects of thermodynamic and hydrodynamic parameters are depicted in graphs and tables. It is discovered from the investigation that, both the velocity and temperature profiles increase with increase in viscous dissipation. Velocity distribution decreases with increase in Biot number while the temperature distribution near the heated plate increases with increase in Biot number. The increase in boundary plate thickness d causes a boost in the fluid flow across the medium and reduces the temperature of the fluid near the heated plate. It is further discovered that the rate of heat transfer on both plates increase with increase in Biot number while they drastically dropped when the boundary plate thickness d is increased. The shear stresses on the surface of both plates increase with increase in heat generation while reverse cases were observed with increase in heat absorption . It is further observed that the volume flow rate within the channel increases with increase in viscous dissipation .

Combustion of H2/air supersonic mixing layers with splitter plate: Flame structure and statistical characteristics

H2/air supersonic mixing layers were calculated with different splitter plates thickness. The accumulation of OH radicals between the most reactive and stoichiometric mixture fraction causes the corresponding change of reactions. With the increase of plate thickness, flame surfaces tend to be more wrinkling. Especially in the initial developing stage, the distribution of temperature, scalar dissipation, Damkohler number and Takeno index is closely related to plate thickness. However in the developed stage, the distribution shows similarity. The symmetry of scalar dissipation rate built in the initial developing zone is broken in the developed stage, corresponding to the distribution about production terms of scalar variance [1]. Different from circulation and developed zone, premixed combustion take a more important part in the initial developing stage. Same as the change of flame curvature, autoignition effect dominating heat release increases first and decreases lately along streamwise direction.

Experimental study and numerical simulation of reinforced concrete walls with lightened blocks connected with bolts

To verify the feasibility and mechanical properties of assembled composite walls, three assembled composite walls were designed. Two bolted connection specimens in horizontal joints were tested under low-cycle reversed loading and monotonic loading, respectively. Then, the failure mechanism, hysteretic behaviour, ductility, energy dissipation capacity, slip and stress distribution of the connectors were studied. A specimen with grouting sleeve connection was tested under low-cycle reversed loading as a contrast specimen. In addition, a specimen with bolted connection under monotonic loading was simulated by the finite element method to study the effects on structural performance of the connectors and walls. The results show that the bolted connection is feasible, and compared with the grouting sleeve connection, the bearing capacity of the bolted connection specimen decreases by 17%, the displacement ductility coefficient increases by 52% and the cumulative energy consumption increases by 62%. Slippage between the connectors and the wallboard occurs mainly between the yield point and the peak point of the specimens. With the increase in plate thickness, the bearing capacity and initial stiffness increased, but there was no obvious effect on the appearance of the slip section. The larger the bolt diameter, the later the slip section forms. However, the bolt diameter does not have an obvious effect on the bearing capacity of the specimens.

Resonant Transmission Through a Single Subwavelength Slit for Varied Metallic Permittivities and Its Modal Orthogonality

This article investigates resonant transmission phenomena through a single metallic subwavelength slit when the permittivity of a real metal varies. The single metallic slit is utilized as a metal–insulator–metal waveguide, and a mode-matching technique is employed to obtain the transmitted power. The periodic resonant transmission phenomena (in terms of the metallic plate thickness) are solved, and the resonances can be understood by their guide wavelengths. Even when the permittivity of the real metal includes imaginary parts (i.e., metal with loss), the resonant transmittances are obtained. However, the peaks of the transmittances decrease, as the plate thickness increases. The orthogonal relationship of an incomplete orthogonal set is maintained despite metallic loss (given a relatively small amount of loss), due to the complex permittivity of the real metal.

Experimental and Numerical Evaluation of Perfobond Rib Shear Connectors Embedded in Recycled Aggregate Concrete

In this paper, the use of recycled aggregate concrete (RAC) for the upper slabs in steel‐concrete composite beams is proposed. Perfobond rib connector (PBL), a relatively new type of shear connectors, has been widely used to ensure composite action between the steel and concrete elements in composite beams. For the past decades, several studies on assessing the performance of PBLs have been conducted, but very few focused on the PBLs that are embedded in RAC slabs. This paper presents results of an experimental and numerical simulation study that focused on characterizing the behavior of PBL fabricated using RAC. In the experimental program, a total of six standard push‐out specimens, divided into three groups, were fabricated and loaded to failure. Test results indicated that the ductility of the PBLs using RAC materials decreased as the perforated steel plate thickness decreased, while the PBL ultimate strength increased by 4.3% and 12.8% for steel plate thicknesses of 10.0 mm and 12.0 mm, respectively, as compared to specimens with 8.0 mm steel plate thickness. Finite element (FE) models for PBLs embedded in RAC were developed, and numerical results were validated by corresponding experimental results. An extensive parametric numerical analysis was conducted to assess the effects of different parameters such as transverse steel rebar diameter and perforated steel plate strength and thickness on the performance of such connectors. Numerical simulation results showed that the PBL ultimate strength obtained based on the perforated plate fracture failure mode increases linearly as the steel rebar diameter increases. Also, numerical results indicated that as steel plate strength and thickness increase, failure mode changes from steel plate fracture to rupture of reinforced concrete dowels. Furthermore, existing published analytical formulas for predicting behavior of PBLs were assessed via a comparison with experimental and numerical results developed in this study. The outcomes of this study contribute in providing fundamental knowledge in a new sustainable application of PBL in steel‐concrete composite beams with RAC slabs.

The influence of heat treatment on the microstructure of products manufactured by direct laser deposition using titanium alloy Ti-6Al-4V

The titanium alloy Ti-6Al-4V is an important alloy in the aerospace industry. The Direct Laser Deposition (DLD) allows manufacturing products of complex geometric shapes from this alloy, which are not inferior in quality to traditional methods. As a result of previous studies, it was found that the product structure does not match the specified requirements for the Ti-6Al-4V alloy and heat treatment is required. In this research, annealing of samples was carried out in different modes, where the time and annealing temperature varied. The microstructure of the products was studied. As a result of the work, it was found that at an annealing temperature of 600–650 °C, the microstructure is heterogeneous: individual grains of the β-phase are preserved. With an increase of the annealing temperature (750 °C–900 °C), the prior β-grains become less distinguishable. It was found that the length decreases with increasing plate thickness of the metastable α′-phase with increasing temperature. With an increase in the propagation time of grain boundaries, the structure becomes homogeneous. The microhardness of the samples after heat treatment decreases slightly, remains in the range of 300–400 HV0,5.

An Experimental and Numerical Study on the Flexural Performance of Over-Reinforced Concrete Beam Strengthening with Bolted-Compression Steel Plates: Part II

This study presents an experimental investigation and finite element modelling (FEM) of the behavior of over-reinforced simply-supported beams developed under compression with a bolt-compression steel plate (BCSP) system. This study aims to avoid brittle failure in the compression zone by improving the strength, strain, and energy absorption (EA) of the over-reinforced beam. The experimental program consists of a control beam (CB) and three BCSP beams. With a fixed steel plate length of 1100 mm, the thicknesses of the steel plates vary at the top section. The adopted plate thicknesses were 6 mm, 10 mm, and 15 mm, denoted as BCSP-6, BCSP-10, and BCSP-15, respectively. The bolt arrangement was used to implement the bonding behavior between the concrete and the steel plate when casting. These plates were tested under flexural-static loading (four-point bending). The load-deflection and EA of the beams were determined experimentally. It was observed that the load capacity of the BCSP beams was improved by an increase in plate thickness. The increase in load capacity ranged from 73.7% to 149% of the load capacity of the control beam. The EA was improved up to about 247.5% in comparison with the control beam. There was also an improvement in the crack patterns and failure modes. It was concluded that the developed system has a great effect on the parameters studied. Moreover, the prediction of the concrete failure characteristics by the FE models, using the ABAQUS software package, was comparable with the values determined via the experimental procedures. Hence, the FE models were proven to accurately predict the concrete failure characteristics.

Parametric study of an active solar flat-plate collector water heater

Monthly average daily weather data and solar radiations of Bauchi obtained from the weather data processor (Type 109 component) of TRNSYS 16 software were used as the input into the design equations coded using MATLAB programming language to determine the system characteristics and components sizes. Parametric study was carried out to study the effects and sensitivity of varying some design parameters such as collector area and number of glazing, length of collector tube and tube diameter, mass flow rate and volume of the water, air gap spacing between the absorber plate and glazing and the tube spacing and plate thickness on the system solar fraction (f). The results revealed that with collector area of 0.1m 2 to 5m 2 single glazing 82 % solar fraction was achieved and with double glazing, 97 % system solar fraction was achieved. Increasing the length of the tube increases the system solar fraction. This implies that as the number of turns of the flow tube increases the system solar fraction increases but the solar fraction decreases with increase in the diameter of the tank, with tank diameter of 0.1 m to 0.4m an average of 75 % system solar fraction was achieved. As the air gap increases, the top heat loss increases and decreases as the number of glazing increases, an air gap of 0.045 m (4.5 cm) to 0.05 m (5 cm) was found to be suitable for optimum system performance. Increasing the tube spacing, the system solar fraction decreases but as the plate thickness increases, the system solar fraction increases slightly. This implies that, decreasing the tube spacing leads to increase in system solar fraction. The plate thickness increase is considered very insignificant considering the system cost in relation to system performance. Keywords: Solar fraction, solar radiation, weather data, parametric study, solar collector, MATLAB programming language

Effects of Viscous Dissipation and Wall Conduction on Steady Mixed Convection Couette Flow of Heat Generating/Absorbing Fluid

This article theoretically investigated mixed convection flow of heat generating/absorbing fluid in the presence of viscous dissipation and wall conduction effects. The flow is considered to be steady in a vertical channel with some boundary thickness. One of the plates is heated while the other is kept at ambient temperature. The governing flow equations were solved analytically using Homotopy Perturbation Method (HPM). The influences of the governing parameters were captured in graphs, tables and a table was constructed for validation of the work. It is worthwhile to stress that, both the velocity and temperature profiles decrease near the heated plate with an increase in boundary thickness (<i>d</i>) while the reverse cases were observed toward the cold plate. The velocity profile increases near the heated plate with increase in mixed convection parameter (<i>Gre</i>) and decreases towards the cold plate. Rate of heat transfer has been observed to decrease with increase in boundary plate thickness (<i>d</i>) while the critical value of (<i>Gre</i>) increases with growing boundary plate thickness. The study therefore established the importance of boundary plate thickness in mixed convection investigation.

Numerical Simulation of Bending Process for Steel Plate Using Finite Element Analysis

Defects in bending processes are inevitable due to the plastic deformations created through the material pressing. Cost-effective and good quality of the V shaped die plate bending products can be produced by reducing the bending load, springback, and residual strains. In this article, a plate bending process is employed for Hy-80 steel and 304 stainless steel. A 3D explicit/dynamic finite element model is utilized for analyzing the V shaped die plate bending process. Punch load, springback, and residual strains behaviors are studied by applying various punch radiuses and plate thicknesses. The springback and residual strains behaviors are successfully predicted with respect to punch radius and plate thickness. Although bending load has a significant effect on bending process, the springback and residual strains behavior can be estimated according to the value of punch radius and plate thickness. Springback is reduced when the punch radius decreases and plate thickness increases. Recorded residual strains at the tension side were greater than at the compression side.

Ballistic performance of bioinspired nacre-like aluminium composite plates

Inspired by the hierarchical structure of nacre, an aluminium alloy (AA) 7075-T651 based composite plate is developed for ballistic applications. The proposed nacre-like composite plates are made of 5, 7 or 9 layers consisting of many ~1 mm thick AA7075-T651 tablets bonded together with toughened epoxy adhesive. Experimental ballistic tests on these composite plates, using a hemispherical nosed steel projectile at impact velocities in the range of 340–450 m/s, were performed. Both the 5-layer and 7-layer plates exhibited a better ballistic performance than their bulk counterparts based on the observation that the measured residual velocity of the projectile through the composite plate was lower than that through the corresponding bulk plate with similar areal density. However, the performance improvement is reduced as the composite plate thickness increases (from 5 to 9 layers) due to the increased likelihood of ductile failure occurring prior to perforation in the thicker bulk plates. The failure pattern analysis of the impacted specimens confirmed that the impact performance enhancement of the nacre-like composite plates can be attributed to the hierarchical structure facilitating both localized energy absorption (by tablet deformation and interlocking) and more globalized energy absorption (by inter-layer delamination and friction).

Comparative life cycle assessment of metal arc welding technologies by using engineering design documentation

The paper aims to analyze and compare the environmental performances of metal arc welding technologies: gas metal arc welding (GMAW), shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), submerged arc welding (SAW), and flux-cored arc welding (FCAW). Welding is considered one of the most energy-intensive processes in manufacturing. This study was performed in accordance with the international standard ISO 14040/14044 by using attributional life cycle assessment (aLCA). The functional unit is defined as the “the development of 1 metre of welding seam (qualified by ASME section IX requirements) to join 25 millimetres thick of metal plates made in carbon steel material and considering a V-bevel configuration.” Different configurations of base/filler materials and standardized bevel geometries have been analyzed as welding scenarios. The inventory considers all inputs (e.g., electric energy and filler material) and outputs (e.g., fume emissions and slags) involved in each welding process. A framework for data collection starting from available project documentation is presented as an innovative solution for the inventory phase. The impact assessment includes the human health, resources (midpoints/endpoint), and ecosystems (endpoint) categories from the ReCiPe (H) and cumulative energy demand (CED) methods. This study reveals a notable dominance in terms of the environmental burdens of GTAW and SMAW processes, as they present higher impacts in most of the impact categories. SMAW is the most energy-consuming process, and this aspect is reflected in the environmental performance. Conversely, GMAW presents the least environmental load, accounting for less than one third compared with GTAW in terms of the CED indicator and performing very well in terms of the ReCiPe endpoint indicator. Via analysis of different scenarios, the main outcomes are the following: (i) the use of V bevels significantly increases the environmental load when the metal plate thickness increases and (ii) the use of specific materials such as Inconel alloy exacerbates the environmental concerns associated with welding processes. The use of project documentation allows robust analysis of welding activity. Sensitivity analysis shows how the range of values for specific parameters (e.g., volts and amps) affects each technology in a different manner. Indeed, those ranges have a limited impact on the result accuracy (up to 20%) for more automatized welding processes (e.g., GMAW, SAW, and FCAW), in which only a small number of parameters are set by the operator, and the operator skills are less influential on the quality of the weld.

Experimental study on curved steel-concrete-steel sandwich shells under concentrated load by a hemi-spherical head

Steel-concrete-steel (SCS) sandwich shells, which are combined with steel plates, concrete core and shear connectors, are usually applied as protective structures in the civil engineering. In this paper, nine curved SCS sandwich shells subjected to concentrated load by a hemi-spherical head were tested to obtain the failure characteristic, ultimate strength and load–displacement response. The finite element (FE) models of curved SCS sandwich shells were also established by using LS-DYNA. The accuracies of the FE models were verified by comparing the load–displacement curves, local and global deformation between the experimental results and FE predictions. The factors influencing the ultimate strength and deformation behavior of curved SCS sandwich shells were analysed, including concrete core and steel plate thickness, top to bottom steel plate thickness ratio and spacing of shear connectors. Through experiments and numerical simulations, three failure modes could be summarized. It was also found that increasing concrete core and top steel plate thickness and reducing the spacing of shear connectors could increase yield strength and ultimate strength of curved SCS sandwich shell. The increase of concrete core and steel plate thickness also led to higher energy absorption capacity; whereas, the spacing of shear connectors showed little effect on energy absorption capacity.

Consideration on the toughness difference depending on the direction of brittle crack propagation in very thick steel

In recent years, the steel plates used in large structures such as container ships have become extremely thick, and their strength is increasing. Since the risk of brittle fracture increases as the steel plate thickness increases (T. Ishikawa et al, 2004), it is important to properly stop brittle cracks generated from the viewpoint of ensuring safety. In the discussion about fracture safety of large container ships from the viewpoint of arrest in these ten years, two fracture safety scenarios were established. Recently an important experimental fact that the brittle crack stopping toughness Kca is lower in scenario 1 than in scenario 2 was found, but the cause has not revealed yet. In order to clarify the cause of this experimental fact, the authors carried out the three-sided slitted Charpy test and the DWTT test in which the propagation direction of the crack was devised. Parameters such as mis-orientation between neighbour grains and fracture surface roughness were calculated, and the correlation with brittle crack propagation arrest properties was examined.

A Study for Brittle Crack Prevention and Fatigue Life Improvement using a Welded Stiffener

Recently, thickness of steels used in ships is increasing along the increased size of vessels, e.g. container carriers in particular. In container vessels, thick plates are applied to hatch side coaming areas, and safety is also becoming important as steel plate thickness increases. Many studies are conducted on the brittle crack arrest characteristics to prevent catastrophic failure in those areas. A number of experiments have been conducted for investigating propagation characteristics of brittle crack from classification societies. Especially, ESSO test method is commonly employed to analyze the BCA (Brittle Crack Arrest) toughness. In order to prevent brittle crack, arrest holes, weld line shift and insert plates are suggested.Various researches have been carried out to arrest brittle crack in BCA steel. However, the actual structure thickness has to be applied to the experiment, and it is difficult to carry out experiments due to the large scale specimens. Thus, in this study, crack retardation method is researched considering the thickness, length, and location of a welded stiffener. Finite element analysis was conducted on the hatch side coaming to compare the allowable crack length according to the effect of stiffener and to compare fatigue life based on the characteristics of BCA steel. Key words: Brittle crack arrest steel, Brittle crack arrest toughness, ESSO test, Fatigue crack growth rate, Stiffener

A study on the metallurgical and mechanical properties of a GMAW-welded Al-Mg alloy with different plate thicknesses

Thick plate of 5083 aluminum alloy with 8 mm, 20 mm and 30 mm thicknesses are joined by double-side GMAW method. The influence of plate thickness on the welding stability, weld bead formation, porosity formation, microstructure and mechanical properties are investigated and compared. The results reveal that, with the increase of plate thickness, the stability of GMAW process, weld bead formation of the welded joints and the results of bending tests are similar. In larger plate thickness, more welding passes resulting in more source of hydrogen, larger specific surface area caused by thinner droplet, and the high solidification rate synergistically contribute to easier formation of porosity. With the increasing of plate thickness, higher peak temperatures of thermal cycles can lead to larger grain size. Besides, lower density of second-phase particles and more porosity of welded joint in larger plate thickness result in lower strength.

In-situ measurement of surface relief induced by Widmanstätten and bainitic ferrites in low carbon steel by digital holographic microscopy

In-situ measurement by digital holographic microscopy (DHM) was employed to clarify the difference between the surface relief effects of Widmanstätten ferrite (WF) and bainitic ferrite (BF) associated with their transformations from austenite in a low-carbon steel. It was clarified that the evolution of the surface relief is totally different between WF and BF. Only in BF, the observed ratio of the relief height to the plate width converged instantly to the value predicted by the phenomenological theory of martensite crystallography (PTMC). The ratio gradually increased with increasing plate thickness and never reached the value predicted by PTMC in WF.

Optimization of excitation frequency and guided wave mode in acoustic wavenumber spectroscopy for shallow wall-thinning defect detection

In plate-like structures, wall-thinning defects resulting from corrosion may not be accompanied by any indication of damage on the surface. Thus, inspections are required to ensure that wall-thinning defects are within allowable limits. However, conventional ultrasonic techniques require physical contact to the structure. Alternatively, acoustic wavenumber spectroscopy (AWS) may be used for detecting, locating, and characterizing defects. This paper describes the performance of AWS in the estimation of a wall-thinning defect size in thinplate structures using finite element analysis (FEA). Through a series of FEAs, the structure’s steady-state response to a single-tone ultrasonic excitation is simulated, and the wall-thinning defect-size effect on the wavenumber-estimation accuracy is investigated. In general, the A0 guided wave mode is widely used to visualize defects because of the nature of the wave speed variation in relation to the plate thickness. However, it is not appropriate for the detection of relatively shallow wall-thinning defects, because the rate of change in wave speed with the thickness decreases with increasing plate thickness. To overcome this limitation, we propose a method to optimize excitation frequency and effective guided wave mode instead of utilizing the A0 mode. The results can be used to determine the size of shallow wall-thinning defects in plate-like structures.