Perforated Aluminum Research Articles

On the cyclic elastoplastic shakedown behavior of an auxetic metamaterial: An experimental, numerical, and analytical study

This article presents the first experimental, numerical, and analytical study of the elastoplastic shakedown response of an auxetic metamaterial structure that elucidates interactions between auxeticity and maximum shakedown loading capacity. The study aims to determine the safe elastoplastic shakedown limit of perforated auxetic aluminum sheet structures (AA5083-TO) with fixed void fraction (16.4%) under ambient cyclic asymmetric uniaxial loading conditions. The motivation is that shakedown-based designs can be used to expand the feasible design space under cyclic loading conditions compared to conventional yield-limited designs. Finite element analyses with calibrated hardening models are used to develop Bree load-interaction diagrams that are experimentally validated. It is found that shakedown occurs at stress levels up to almost four times the elastic limit of the structure for a fixed allowable equivalent strain level near three percent. This shakedown multiplier is also sensitive to the extent of auxeticity in the structure and a parametric study and analytical model are used to identify underlying mechanisms and a potential maximum condition.

Moment capacity of perforated cold-formed aluminium channels–Tests, analysis, and design

This paper investigates the moment capacity of perforated cold-formed aluminium alloy (CFAA) channel sections through a combination of experimental and numerical studies. In total, 12 new experimental tests were conducted on CFAA with different cross-section sizes, web hole spacing, and numbers of web holes, under pure bending, followed by a numerical study comprising 601 validated finite element (FE) models. In the numerical study, the effects of various parameters were examined, namely web hole size, the number of web holes, section thickness, web depth, and the grade of aluminium alloy. The moment capacities obtained from both the experimental tests and finite element analysis (FEA) were utilized to evaluate the design guidance provided in the Aluminium Design Manual (ADM), Eurocode (EC), Australian and New Zealand Standard (AS/NZ), and the American Iron and Steel Institute (AISI) standards. Along with the Direct Strength Method (DSM), the Continuous Strength Method (CSM) was also evaluated. The results from both the experimental tests and their FEA indicate that DSM and EC9 are slightly unconservative, by 1% and 9%, respectively. In contrast, ADM is found to be conservative by 10%, whereas CSM is found to be unconservative by 50%.

Development of an electrocoagulation method using alternating pulse current to treat wastewater generated by tanneries

ABSTRACT Direct current electrocoagulation has various drawbacks, including electrode passivation, heat creation from energy consumption, and high sludge formation. The restrictions limit its usage in tannery wastewater treatment. Therefore, alternating pulse current EC (APC-EC) was developed to solve these obstacles. The study was empirically examined, considering high-frequency (3,000–11,000 Hz), stirring speed (400–1,200 rpm), and reaction time (15–30 min). This research examined how factors affect chemical oxygen demand (COD) removal efficiency, turbidity from trivalent chromium (Cr+3), and energy consumption for perforated aluminum electrodes. The central composite design in the surface response design approach has improved various operational parameters in the APC-EC process for tannery wastewater treatment. The employment of mathematical and statistical methods resulted in optimal removal of COD, Cr+3, and turbidity while reducing energy usage. Using mathematical and statistical methods, we achieved maximum COD, Cr+3 ion, and turbidity reduction while reducing energy use. The investigation found that COD (70.3%), Cr+3 (89.56%), and turbidity (96%) were the most rapidly removed components at 11,000 Hz, 576 rpm, and 30 min. Surface response data explain high-frequency APC-EC dynamics.

Application of Scirpus grossus fiber as a sound absorber

The application of Scirpus grossus (SG) fiber as a sound absorber is important to reduce the level of noise affected the physical and mental wellbeing of people. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) of the SG specimen were evaluated based on a typical model-based design using the data analysis with MATLAB. The results showed that SG specimen with a thickness of 20 mm coated with the perforated aluminum sheet (PAS) compared to that without coating can improve the capability of sound absorption by 14% at the frequency of 4000 Hz. SG specimen coated with PAS that has a NRC value of 0.39 can absorb 39% of sound and thus reflects 61% of sound wave while SG specimen without coating that has a NRC value of 0.23 absorbs 23% of sound and can reflect 77% of sound wave. The sound absorption class of D for SG specimen coated with PAS should be better that of E for SG specimen without coating, which permits us to get better understanding on the applications of SG fiber as a sound adsorber in the future.

Evaluation of nonlinear interface areas in a multiple scattering medium by Nonlinear Coda Wave Interferometry (NCWI): Experimental studies

This paper aims to investigate the application of the Nonlinear Coda Wave Interferometry (NCWI) method in evaluating the nonlinear interface areas in highly heterogeneous materials. An experimental protocol is proposed for quantitatively analyzing the nonlinear interface effects in a multiple scattering medium. The experimental design involves a perforated aluminum plate with a surface ratio of circular voids equal to 17.63%, some of which are threaded to accommodate screws. The nonlinear contacts between the screws and the perforated plate are highlighted by a strong pump wave and investigated using the coda waves. Drawing upon prior numerical simulation findings (Chen et al., 2021), it is anticipated that the CWI observables (namely, the relative variation of coda wave velocity θ and the remnant decorrelation coefficient Kd) will be proportional to the change in crack length within the heterogeneous medium. In this study, the change in crack length through numerical simulation can be simulated by considering the different nonlinear interface areas between the screws and the perforated aluminum plate in the experimental design. Experimental findings demonstrate that the CWI observables are proportional to the nonlinear interface areas, which essentially aligns with previous numerical simulation results. In this paper, suggestions for refining the experimental setup are provided. This guidance is instrumental for further conducting quantitative research on nonlinear interface effects in complex media.

Simulation study on flexural behaviour of perforated aluminium tubes

A numerical investigation was conducted to compare the flexural capacity of AA6063-T5 aluminum alloy tubes with perforations of different hole diameters (4, 6, 8, and 10 mm), hole spacing (13-26-39-52 mm) and tube wall thickness (0.5, 1, 1.5 and 2 mm) by the finite-element analysis (FEA). As the tube thickness increases, the load-carrying capacity decreases, while the LCC increases as the hole diameter increases. It was observed that the LCC increased as the distance between the holes increased. ANOVA test was used to analyze the influence of hole diameter, hole spacing, and tube wall thickness on tube load-carrying capacity. It is found from the statistical analyses that the most significant factor on maximum load is tube thickness (97.2 %) between parameters of hole diameter, hole spacing, and tube wall thickness. As a result of the second statistical analysis, the most significant factor on maximum load is hole diameter (73.14 %) between parameters of hole diameter and hole spacing. A second important factor is hole spacing on maximum load.

Research on an Optimized Quarter-Wavelength Resonator-Based Triboelectric Nanogenerator for Efficient Low-Frequency Acoustic Energy Harvesting.

Sound wave is an extensively existing mechanical wave, especially in marine and industrial plants where low-frequency acoustic waves are ubiquitous. The effective collection and utilization of sound waves provide a fresh new approach to supply power for the distributed nodes of the rapidly developing Internet of Things technology. In this paper, a novel acoustic triboelectric nanogenerator (QWR-TENG) was proposed for efficient low-frequency acoustic energy harvesting. QWR-TENG consisted of a quarter-wavelength resonant tube, a uniformly perforated aluminum film, an FEP membrane, and a conductive carbon nanotube coating. Simulation and experimental studies showed that QWR-TENG has two resonance peaks in the low-frequency range, which effectively extends the response bandwidth of acoustic-electrical conversion. The structural optimized QWR-TENG has excellent electrical output performance, and the maximum output voltage, short-circuit current and transferred charge are 255 V, 67 μA, and 153 nC, respectively, under the acoustic frequency of 90 Hz and sound pressure level of 100 dB. On this basis, a conical energy concentrator was introduced to the entrance of the acoustic tube, and a composite quarter-wavelength resonator-based triboelectric nanogenerator (CQWR-TENG) was designed to further enhance the electrical output. Results showed that the maximum output power and the power density per unit pressure of CQWR-TENG reached 13.47 mW and 2.27 WPa-1m-2, respectively. Application demonstrations indicated that QWR/CQWR-TENG has good capacitor charging performance and is expected to realize power supply for distributed sensor nodes and other small electrical devices.

Study on Sound Absorption Performance of Aluminum Foam Combination

Aluminum foam is a kind of new material with a large number of holes distributed in aluminum alloy. It has the characteristics of lightweight, sound absorption, energy absorption and vibration reduction, and other porous materials. Aluminum foam has good acoustic performance. However, its excellent sound absorption ability is only reflected in the middle and high-frequency bands. Besides, the low-frequency sound absorption ability is very poor and the frequency band is narrow. Therefore, in this paper, different types of perforated aluminum foams with different parameters are combined to explore the influence on acoustic performance and find that the combination of large porosity perforated sample and aluminum foam has a better sound absorption effect. The unperforated sample is placed in front of the perforated sample to improve the sound absorption coefficient of the low and medium frequencies. Finally, different types of perforated aluminum foam samples were properly combined, and it was found through the test that almost all sound waves in the band of 1200 HZ~2000 Hz could be absorbed by the combined structure.

Performance of Electrocoagulation Process Using Iron and Aluminum Electrodes with and without Perforations

Electrocoagulation process is widely used for the removal of pollutants from the industrial wastewater. In the present study, an attempt was made to investigate the performance of electrocoagulation process using alu-minum and iron electrodes to treat the metal ions present in the synthetic galvanic wastewater. The electrodes used are with and without perforations and it was observed that the efficiency of electrodes with perforation (80 %) was higher than without perforations (50 %). The removal efficiency of heavy metal ions increased with retention time and direct current. The optimized values of residence time, voltage, pH, current, electrode spacing were 160 min, 6 V, 5, 0.2 A, and 3 cm, respectively. The maximum removal percentage of nickel and copper ions using perforated iron electrodes was 90.7 % and 86.0 %, respectively, and for chromium using a combination of perforated iron and aluminum electrodes it was 93.1 %. The removal of metal ions followed pseudo second order kinetic model with current dependent parameters.

Structural Design for Roll-Formed Aluminium Alloy Perforated Channels Subjected to Interior-Two-Flange Web Crippling: Experimental Tests, Numerical Simulation, and Neural Network

This study analyses the interior-two-flange (ITF) web crippling strength of roll-formed aluminum alloy lipped channels (RA channels) with web holes employing experimental testing, numerical modeling, and deep neural network (i.e., Deep belief Network, DBN). A total of 30 experimental tests on web crippling behavior were carried out, with the results utilized to validate a finite element (FE) model, developed in this study. The experimental results were compared to the data produced by the validated FE model, which was then used to train the DBN model. The results of the DBN prediction were shown to be around 5% more conservative than the FE results. In order to evaluate the effects of associated factors on the ITF web crippling strength of RA channels, a comprehensive parametric study was conducted using the DBN. The design guidelines that are currently available in the American Iron and Steel Institute (AISI 2016), the Australian and New Zealand Standards (AS/NZS 1997; AS/NZS (2018)), and the Eurocode (CEN 2007) were found to be unreliable while determining the ITF web crippling strength of RA channels. The DBN's predictions developed new formulae for calculating the web crippling strength reduction factors. After conducting a reliability study, it was found that the developed strength reduction factor equations are reliable when calculating the ITF web crippling strength of such perforated roll-formed aluminium alloy channels.

Modelagem matemática da cinética de secagem de folhas de chicória

ABSTRACT Endive is a vegetable traditionally eaten as a raw or cooked salad. It is a source of important nutritional compounds and one of the procedures for its industrialization is drying, which increases its shelf life, preserves the nutrients and reduces losses due to microorganisms. This research evaluated the drying kinetic of endive leaves at different temperatures and adjusted the experimental data according to mathematical models. The experimental design was completely randomized in triplicate, with each sample unit being a perforated aluminum tray containing about 100 g fresh leaves. The endive leaves were dried in an oven at 50, 60, 70 and 80°C. The mathematical models were adjusted according to the experimental data; non-linear regression analysis was performed by Gauss-Newton and Quasi-Newton methods. In all conditions, the mathematical models that best fitted the drying kinetics of the endive leaves were Midilli, Logarithmic and Valcam. The Logarithmic model, under these drying conditions, can be accurately described as suitable for predicting and simulating the drying kinetic of endive leaves, as it showed the best results in the statistical parameters evaluated.

Comparing the performance of four shading strategies based on a multi-objective genetic algorithm: A case study in a university library

Through the control of excessive daylight in buildings, shading devices can reduce glare and improve occupants' visual comfort. However, shading devices may overly reduce illuminance levels. Many shading strategies are available, but they do not perform equally well, and traditionally, it has been difficult to select the most suitable shading strategy. This study proposed a parameterization method for the selection and design of a shading strategy that would reduce glare while maintaining a satisfactory daylighting level, through the construction of Pareto sets based on a multi-objective genetic algorithm. The objective function was created by combining a dynamic glare evaluation indicator, the spatial glare autonomy (sGA), and a self-constructed daylight index, the spatial daylight vote autonomy (sDVA), developed from a field survey. As a case study, the proposed method was used to compare the performance of four shading strategies, including vertical slats (Vs), a perforated aluminum sheet (PAS), serrated windows with southern orientation (Sw_S), and serrated windows with northern orientation (Sw_N) in a university library in Shanghai, China. It was found that the Sw_S and PAS had a relatively bad performance; the Vs performed better than the Sw_N in providing a more satisfactory illuminance level; and the Sw_N was more effective in reducing the glare. The multi-objective optimization process can be used to obtain near-optimal design parameters that create a visual environment with reduced glare while maintaining an acceptable illuminance level, for all four shading strategies. The developed method can be a helpful tool in the design of an appropriate daylighting environment.

Effects of the Operational Parameters in a Coupled Process of Electrocoagulation and Advanced Oxidation in the Removal of Turbidity in Wastewater from a Curtember

The tannery industry during its process generates various polluting substances such as organic matter from the skin and chemical inputs, producing wastewater with a high concentration of turbidity. The objective of this research is to evaluate the most appropriate operational parameters of the coupled process of electrocoagulation and advanced oxidation to achieve the removal of turbidity in wastewater from a tannery in the riparian zone (tannery). This process uses a direct current source between perforated aluminum electrodes of circular geometry submerged in the effluent, which causes the dissolution of the aluminum plates. For our study, an electrocoagulation unit coupled to an ozone generator has been built at the laboratory level, where the influence of five factors (voltage, inlet flow to the reactor, initial turbidity, pH, and ozone flow) has been studied with three levels with regarding turbidity, using the Taguchi experimental methodology. The optimal conditions for the removal of turbidity were obtained at 10 volts, 7.5 pH, 360 L/h of wastewater recirculation flow rate; 2400 mg/h of ozone flow rate; and 1130 NTU of initial turbidity of the sample in 60 min of treatment reaching a removal of 99.75% of the turbidity. Under optimal conditions, the removal of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) was determined, reaching a removal percentage of 33.2% of COD and 39.36% of BOD was achieved. Likewise, the degree of biodegradability of the organic load obtained increased from 0.467 to 0.553.

Assessment of end-two-flange web crippling strength of roll-formed aluminium alloy perforated channels by experimental testing, numerical simulation, and deep learning

This work presents a deep-learning model referred to as a deep belief network (DBN) to investigate the end-two-flange (ETF) web crippling behaviour of roll-formed aluminium alloy lipped channels (both unfastened and fastened to the supports) with centred and offset web circular holes. A total of 1,080 data points was generated for training the DBN, using an elasto-plastic finite element model that was validated using 30 new experimental results presented in this paper. When the DBN predictions were compared to the experimental results, they were found to be 5% conservative on an average. A parametric analysis was then carried out using the DBN predictions, to study the effects of hole size, hole position, section thickness, and the bearing plate on web crippling strength of perforated roll-formed aluminium alloy channels. The DBN predictions were utilised to evaluate the performance of the current design rules of American Iron and Steel Institute (AISI 2016), Australian and New Zealand Standards (i.e., AS/NZS 1664, AS/NZS 4600:2018), and Eurocode (CEN 2007). The current design standards were demonstrated to be over conservative in predicting the web crippling strength of roll-formed aluminium alloy perforated channels. From the parametric analysis, new web crippling strength and web crippling strength reduction factor formulae for roll-formed aluminium alloy perforated channels were proposed. Additionally, a reliability analysis revealed that the proposed equations accurately predicted the ETF web crippling strength of roll-formed aluminium alloy perforated lipped channels.

Mechanical characterization of double-skin perforated-sheet façades

The need to reduce energy consumption and related CO2 emissions within buildings requires further in-depth analysis of buildings and their components. Building envelope materials are crucial in that regard. One example is the double-skin façade, a passive energy saving alternative, the various advantages of which include increased acoustic protection, natural lighting, natural ventilation, and user comfort. This type of system can employ lightweight perforated steel or aluminium sheets, that are industrially manufactured. The metal frames in which the sheets are fixed withstand deformation due to wind forces that the perforated sheets alone might otherwise not withstand. In this research, the mechanical behaviour of the perforated sheets is analyzed to establish whether the use of frames is necessary and to determine, through experiments on sheet size materials and thicknesses, the optimal fold dimensions of the sheets to withstand deformation in the absence of frames. To do so, the sheets underwent Finite Element Method (FEM) modelling and laboratory testing, the results of which were carefully analyzed. The performance of the steel sheets was observably better than the thinner aluminium sheets. The sensitivity of the perforated sheets and their behaviour could be observed when the fold supports were attached to the inner structure.

Numerical investigation on perforated sheet metals under tension loading

Abstract Perforated sheets are used in many areas due to their high specific load, economical production, aesthetic structure, and filtering ability. Their use in industrial machinery and the construction industry can be given as examples of these areas. In this study, the mechanical behaviour of perforated metal sheets under tensile loads has been investigated numerically. The influence of material type, hole geometry, and hole arrangement were examined with finite element analyses. Stainless steel and aluminium materials are used as sheet materials. The hole geometries are circle, ellipse, triangle, square, and hexagon. As a result of the simulations, the aluminium material gave the highest values in terms of carried load capacity and absorbed energy. The sheets with the staggered hole arrangement have higher load and energy values than the sheets with the linear arrangement. The elliptical perforated aluminium sheet provided the highest load value of 28,386 N in the staggered arrangement. In both hole arrangements, the elliptical perforated sheet gave the highest load value, while the triangle perforated sheet gave the lowest load value. The elliptical perforated sheet with linear hole arrangement provided the highest values in terms of specific load (435.57 N/g) and specific energy (0.27 J/g).

A novel machine learning method to investigate the web crippling behaviour of perforated roll-formed aluminium alloy unlipped channels under interior-two flange loading

This study presents a novel machine-learning model using the eXtreme Gradient Boosting (XGBoost) tool, for assessing the web crippling behaviour of perforated roll-formed aluminium alloy (RFA) unlipped channels (both fastened and unfastened) under interior-two-flange loading. A total of 1080 data points were generated for training the XGBoost model, utilizing an elastoplastic finite element (FE) model that was validated against 30 experimental results from the literature. A comparison against the numerical failure loads was conducted, and it was found that the prediction accuracy of XGBoost model was 94%. When compared with Ramdom Forest and Linear Regression methods, it was found that the proposed XGBoost model performed better than both the before mentioned methods. The web crippling strengths obtained from the XGBoost model, tests, and finite element analysis (FEA) were utilized to evaluate the performance of current design rules from the American Iron and Steel Institute (AISI), Australian/New Zealand Standards (AS/NZS 1664.1; AS/NZS 4600:2018) and Eurocode (CEN 2007). It is shown that the current design rules are not reliable to predict the web crippling strength of perforated RFA unlipped channels. As a consequence of the parametric analysis, new web crippling strength and web crippling strength reduction factor formulae for perforated RFA unlipped channels were proposed. A reliability analysis was then conducted, which confirmed that the proposed equations are capable of accurately predicting the ITF web crippling strengths of perforated RFA unlipped channels.

LABORATORY STUDY OF ELECTROCOAGULATION FOR COD REMOVAL FROM WASTEWATER

The current work investigates the ability of the new aluminium-based electrocoagulation (EC) cell to remediate chemical oxygen demand (COD) from synthetic wastewater. The experimental work was carried out using a rectangular EC cell (10 cm in length, 9.5 cm in width, and 7 cm in depth). The EC cell was supplied with six perforated aluminium electrodes; four of these electrodes were used in the treatment methods (connected to DC electrical current), while the first and the last electrodes were used as baffle plates (to mix water). This lab-scale unit was used to treat synthetic wastewater having 300 mg/l of COD, considering the effect of the treatment time and initial pH. After 40 minutes of treatment at a pH of 7 and a current density of 10 A/m2, 51% of COD was removed by the new EC unit. The results also revealed that the removal of the COD is positively influenced by the increase of the applied current density and/or treatment time.

Damage and ballistic evaluation of ceramic-metal composite target against cylindrical projectile

The ballistic resistance of a composite ceramic–metal target has been studied by performing three–dimensional finite element computations on ABAQUS/Explicit finite code. The bi–layer alumina 95–aluminium 2024–T3 target has been subjected to impact load by a cylindrical steel projectile at varying incidence velocity in order to carry out a detailed investigation about the behaviour of a composite with a front ceramic layer. First of all the optimum thickness ratio of the front ceramic and backing aluminium layer has been found out. Subsequently, the significance of the eccentricity on the impact response has been studied by hitting the composite target at six different impact locations and the results have been compared with that of the concentric impact condition. The possibility of reducing the areal density of the composite by using the perforated backing aluminium plate has also been studied. The eccentricity in the impact load has played a significant role on the ballistic resistance of the composite. The consideration of perforated backing plate though could not enhance the ballistic efficiency. However, it has been found that a major portion of the energy of the projectile is lost during its interaction with the front ceramic tile leading to significant erosion of the projectile. The backing plate on the other hand played the role of supporting the front layer however its share of energy absorption subsequent to the comminution of ceramic was not very significant. The Johnson–Holmquist (JH–2) constitutive model has been used for simulating the material behaviour of the ceramic and the Johnson–Cook (JC) constitutive model has been used for simulating the behaviour of backing plate and the projectile.

Electrochemical Recovery to Overcome Direct Osmosis Concentrate-Bearing Lead: Optimization of Treatment Process via RSM-CCD

The use of electrochemistry is a promising approach for the treatment of direct osmosis concentrate that contains a high concentration of organic pollutants and has high osmotic pressure, to achieve the safe discharge of effluent. This work addresses, for the first time, this major environmental challenge using perforated aluminum electrodes mounted in an electrocoagulation–flotation cell (PA-ECF). The design of the experiments, the modeling, and the optimization of the PA-ECF conditions for the treatment of DO concentrate rich in Pb were explored using a central composite design (CCD) under response surface methodology (RSM). Therefore, the CCD-RSM was employed to optimize and study the effect of the independent variables, namely electrolysis time (5.85 min to 116.15 min) and current intensity (0.09 A to 2.91 A) on Pb removal. Optimal values of the process parameters were determined as an electrolysis time of 77.65 min and a current intensity of 0.9 A. In addition to Pb removal (97.8%), energy consumption, electrode mass-consumed material, and operating cost were estimated as 0.0025 kWh/m3, 0.217 kg Al/m3, and 0.423 USD/m3, respectively. In addition, it was found that DO concentrate obtained from metallurgical wastewater can be recovered through PA-ECF (almost 94% Pb removal). This work demonstrated that the PA-ECF technique could became a viable process applicable in the treatment of DO concentrate containing Pb-rich for reuse.