Aluminum Square Research Articles

Local reinforcement of adhesively bonded square shape aluminum energy absorber with CFRP under quasi-static axial loading: An experimental and numerical study

This study presents experimental and numerical investigations on the effects of composite ply angle, thickness and number of layers on energy absorption behavior of adhesively bonded carbon fiber-reinforced plastic/aluminum hybrid structure under quasi-static axial loading. This paper aims to use the advantages of adhesive bonding for the local strengthening of a square shaped aluminum energy absorber by composite and as a result achieving desirable energy absorption behavior prior to failure in the connection and without heterogeneous deformation of the structure while reducing the weight of the structure and usage of material and at the same time obtaining favorable results compared to the traditional ways like reinforcing the aluminum structure with composite globally. For this purpose, two models were made and analyzed; one reinforced with four L-shaped composites adhesively bonded using Araldite 2015 to four outside corners of the aluminum square and the other reinforced locally to four corners from within the square. Finite element model was developed for analysis of these hybrid structures. Five different ply angles for composite and multiple number of composite layers varied from 2 to 8 layers under the same and different thicknesses were investigated. Moreover an alpha factor has been determined to measure the importance of local reinforement of the square shape aluminum energy absorber by L-shaped composites. The results showed that compared to aluminum and aluminum with global composite reinforcement energy absorbers, due to the adhesive connection between aluminum and composite in the locally reinforced CFRP/aluminum specimen, the composite had better energy absorption by following the collapse pattern of aluminum and creating a continuous collapse and failure modes. The results indicated good coordination and agreement between the simulated models and the experimental tests. The findings from this experiment demonstrates significant potential for local reinforcement of structures employing adhesives. Utilizing such connections and the ability to strengthen specific areas based on arbitrary geometry and strengthening location could offer substantial opportunities in constructing lightweight structures with high energy absorption across diverse applications.

Inspiring nested modular structure for axial compression performance

Modular structures can adapt to different energy absorption scenarios by changing the assembly form. In this work, inspired by Chinese window frames, four-leaf clovers, cotton rose hibiscus, and maze, a variety of nested modular (NM) structures are proposed with aluminum square tube as base platform. The finite element model of aluminum square tube (AST) is verified through quasi-static compression experiments. Building upon the above, a hierarchical aluminum square tube (HAST) structure is further proposed for enclosing multi-module nested modular (M-NM) structures. Five nested components, namely plum octagonal nested modular structure (PONM), square fluted tube nested modular structure (SFTNM), floral layered nested modular structure (FLNM), square spiral nested modular structure (SSNM), square spiral distributed nested modular structure (SSDNM), are combined with these two platforms, thus generated ten typical NMs. These NM models exhibit two deformation modes, namely the progressive folding of multilobe flaps and the hybrid of outward expansion and progressive folding. M-PONM looks like "jackfruit" after being compressed. Furthermore, the effects of reducing nested components and employing hybrid assembly techniques are further explored. The results indicate that the proposed NM structures significantly enhance the compressive resistance and stability of AST. It is noteworthy that reducing nested components weakens the coupling effects, while hybrid assembly has the opposite effect. In summary, this work provides a series of novel NM structures, providing new ideas for the design of energy absorbing structures.

Novel thermo-mechanical triggers processed by friction stir to enhance the crashworthiness of an automobile crash-box

Thin-walled tubular structures, also known as crash-boxes, are found to be efficient in dissipating kinetic energy of external impact. It is observed that the conventional aluminium square crash-boxes are characterized by higher initial peak crushing force and low crush force efficiency. In this work, a novel concept of inducing “Thermo-Mechanical Triggers” (TMTs) at discrete locations in a conventional aluminium square crash-box to enhance its crashworthiness behaviour is studied. TMTs are induced with the help of “Friction Stir Processing” (FSP), which is a localized heat treatment. The material properties of a crash-box are modified wherever TMTs are induced using FSP. The effect of changes in the location and the number of TMTs along the length of an aluminium crash-box is examined. By triggering a conventional square crash-box with TMTs, significant improvement is observed in its crashworthiness performance. The improvements are: (1) a 24% reduction in the initial peak force and (2) a 23% increase in the crush force efficiency. Therefore, TMTed crash-boxes will prove to be effective in enhancing passenger safety, which is a major concern in the automobile industry. The crashworthiness performance of a TMTed crash-box can be improved further by optimizing both the location and the number of TMTs.

Design and implementation of an Unmanned Aerial Vehicle (UAV) for image capture in enterprise farming

Unmanned aerial vehicle (UAV), also known as drone is one of the most interesting emerging technologies with a wide range of applications including agriculture, surveillance, security, search and rescue, mapping, farmland surveying, and wildlife conservation, among others. In Nigeria, UAV is gaining popularity in applications such as in social functions for taking both moving and static pictures, military and security, mapping and agriculture. In this work, an UAV was designed, some components produced by 3D printing, coupled and tested with certain level of local content in view. The UAV is a quadcopter equipped with a camera for real-time image capture of farmlands and it can perform autonomous missions by using global positioning system (GPS) waypoints. The weight of the quadcopter was approximately calculated and hence the electrical and mechanical components selected using a standard empirical design table. The thrust to weight ratio was set at 2:1. Autodesk Maya and Inventor software were used to design the frame in two parts: the frame arms on which the propellers are mounted and the central connecting part that links the four arms. The arms are made up of aluminum square pipes while the central connecting part for the arms was printed with a 3D printer (200 x 200 x 200 Wanhao duplicator i3) using PolyEthylene Terephthalate Glycol (PETG) Filament material of 1.75mm standard gauge. Material selection was based on material strength, cost and availability. NCH Debut video and image capture software was used to record live feeds from the UAV onboard camera. Functionality tests for lift, stability, yaw, roll, pitch, loiter, auto landing, return to launch, flight time, altitude/signal, auto mission using GPS waypoints were carried out with the completed UAV on a less windy day to avoid the influence of wind. It was generally observed that the UAV successfully took off the ground, gained stability, flew to over 100m height, captured aerial photographs of the land below it while on flight at the required height and landed safely. Cost saving advantage of 45.28% was achieved when compared to imported equivalent types.

High-velocity impact performance of AA 7475-T7351 aluminum square plates struck by steel projectiles: Assessing leakage limit velocity

This paper presents numerical and experimental findings of high-velocity impact tests conducted on thin AA 7475-T7351 aluminum plates subjected to the impact of small cubical and spherical projectiles. The investigation includes an examination of the influence of different impact angles, namely edge-on, corner-on, and face-on orientations, on the target performance. Following each impact test, the damaged plates underwent a leakage test, to determine the leakage threshold caused by the impact event. To gain a deeper insight into the failure modes and penetration mechanisms of thin-walled aluminum plates, finite element models were developed for various impact scenarios. The results revealed that both the shape and orientation of the projectile significantly impact the ballistic and liquid leakage limit velocities of targets. Notably, the cubical projectile exhibited lower ballistic and leakage limits than the spherical projectile. In terms of the leakage limit, a clear correlation was identified between the sharpness of the projectile's nose and leakage limit velocity. As the projectile's nose became sharper, the consistent trend was a decrease in leakage limit velocity i.e. the corner-on impact orientation (having the sharpest nose) exhibited the lowest leakage limit velocity, while the face-on impact orientation (having a blunt nose) displayed the highest leakage limit velocity. However, in contrast to the leakage limit velocity, a definitive relationship between the projectile nose sharpness and ballistic limit velocities was not observed. This is evident as the corner-on impact orientation, associated with the sharpest nose, registered the highest ballistic limit velocity, while the edge-on impact orientation, with an intermediate nose sharpness, recorded the lowest ballistic limit velocity.

Study on the anti-frosting performance of hydrophobic fin with non-toxic for the R600a frost-free refrigerator

The finned-tube evaporator (FTE) is widely used for the freeze and cold storage (FCS) system, such as R600a frost-free refrigerator, R290 household air-conditioning, and R717 walk-in cold stores, but it has problems of low defrosting efficiency and high electric heater consumption at the low evaporating temperature. The traditional super-hydrophobic aluminum-based fin (SAF) has a good the frost retarded performance. However, the SAF is usually fabricated by the wet chemical etching, and is not suitable for FTE with non-toxic of the R600a frost-free refrigerator in the future. Meanwhile, the traditional SAF tested and fabricated has the high-cost and complicated manufacturing method. To address these issues, a novel SAF with non-toxic (surface contact angle is 151.8°) is fabricated in this paper, by the stearic acid solution on the aluminum square laser engraved, and used to improve the anti-frosting performance of the FTE for the R600a frost-free refrigerator under low temperature conditions. The anti-frosting performance should be assessed before applying the non-toxic super-hydrophobic to the FCS system. Meanwhile, there are few theoretical and experimental studies about the SAF on restraining frost formation for the FCS system, especially in the field of computational fluid dynamics (CFD) currently. Thus, a three-dimensional frosting numerical model based on the Euler multiphase flow is developed to analyze the frost formation and distribution characteristics on the SAF with non-toxic, and the numerical model has been validated by experimental date. The experimental and numerical analysis methods are used to evaluate anti-frosting performance of FTE and comparisons with the hydrophilic aluminum-based fin (surface contact angle is 8.6°) and bare aluminum-based fin (surface contact angle is 92.4°) are also discussed. The experimental results indicate that the frosting time of 240 min, and the frost thickness of the FAS with non-toxic is reduced by 41.56% and 38.25% compared to BAS and HAS, respectively. The FAS with non-toxic has a more significant effect on frost formation retarded on the cold surface compared to the HAS. In addition, the proposed frosting model predicts frost growth process, the frost temperature distribution, the moist air velocity distribution, and the frost density distribution on the SAF cold surface. This study, not only reaffirms the benefit of using the SAF with non-toxic on restraining frost formation for the FCS system, but also provides some rules of the frost growth and distribution characteristics with different factors.

Optical generation and detection of GHz longitudinal and transverse acoustic waves in solids assisted by two-dimensional metallic grating structure

Absorption of laser pulses with picosecond temporal width in a two-dimensional nano-scale metallic grating deposited on a transparent substrate launches both longitudinal and transverse acoustic waves in to the sample. The periodic metallic structure makes the generated acoustic waves propagate several different directions. The propagating acoustic waves are monitored optically by the delayed light pulses (probe light) as the transient reflectivity change which is known as the Brillouin oscillation. The probe light is also diffracted by the metallic grating, allowing the detection of the acoustic waves propagating in the multiple directions efficiently. The analysis of the Brillouin oscillation frequencies brings the longitudinal and transverse sound velocities and the optical refractive index simultaneously from a single measurement. We verify the above mentioned scheme using a sample with two-dimensional square lattice (period 380 nm) of aluminum square islands of lateral dimension 200 × 200 nm2 and thickness of 50 nm on a fused silica substrate of thickness 1 mm. From the obtained Brillouin oscillation frequencies in several tens GHz, the acoustic and optical properties of the substrate material are successfully retrieved. The technique would be applicable to investigate the acoustic and optical properties of more complicated systems, such as anisotropic and/or inhomogeneous medium.

Enhanced dual-band absorption of graphene mediated by an aluminum metastructure

Graphene absorption from the visible to infrared spectrum has great potential and broad applications in miniature of modern optoelectronic biosensors and photodetectors. However, graphene has zero bandgap energy, which limits its absorption to 2.3% in the visible and infrared spectrums. Here, we propose a metastructure to optimize graphene absorption in the visible to near-infrared frequency regions. The metastructure, comprising an array of aluminum square blocks (Al-SBs) on a graphene layer, a silica spacer, and an Al reflector, is investigated for absorption enhancement. This work deciphers the effect of the periodicity of decorated Al-SBs on the evolution of dual-band absorption in single-layer graphene under normal incidence. The electromagnetic signatures of two excited modes indicate that surface plasmons and magnetic dipole plasmons are mediators of absorption. The investigation into the impact of geometrical parameters illustrates that the coexisting phenomena of a relative broad peak and a relative sharp peak have been achieved simultaneously with high efficiency. The dynamic manipulation of surface plasmons and magnetic dipole plasmons presents great potential for a diverse range of applications, such as sensing and imaging. By controlling the periodicity of Al-SBs, it is possible to achieve active control of surface plasmon resonance, and a detection range of 300 nm is observed. Dynamic control of the magnetic dipole plasmon is successfully achieved by modifying the electrical environment of the graphene layer, which is realized by altering the underlying spacer material. Collectively, the findings of this study demonstrate the significant potential of the suggested metastructure for its prospective applications in optoelectronic devices, including biosensors, photovoltaics, and photodetectors that rely on the dynamic control of surface and magnetic plasmon resonances.

Performance analysis and optimization of square tubes with different shapes, sizes, and patterns of holes under axial compression loading

Tubular structures are common in vehicles in the form of crash energy absorbers. Inevitably, these tubes contain holes for assembling fasteners and heating sources. Though the introduction of holes in the surface of the tube minimizes the initial peak crushing force (IPF), their structural stability also gets affected, which leads to a reduction in energy absorption capacity (EA). Therefore, the shape, dimension, and patterns of the holes in the tubular structure are to be scrutinized to minimize its unstable response during the crash event. This paper addresses the hole’s position, shape, and dimensional effects on the performance characteristics of aluminum square tubes subjected to axial quasi-static compression experimentally. Numerical models were initially created using ABAQUS/CAE® code for simulating the quasi-static structural response of square tubes (without holes) and validated against experiments. Further, numerical analysis was explored to investigate the hole’s position, shape, and dimensional effects on IPF and EA. The performance characteristics of all the examined specimens were quantified based on the best performance with the help of the TOPSIS method. Finally, Response Surface Methodology (RSM) was carried out to determine the best optimal square tube with holes. It was observed that, with an increase in the hole size, the IPF gets minimized. Among all the specimens, the diamond-shaped hole exhibits the best performance characteristics. The study also reveals that the EA varied greatly with the arrangement of holes (patterns). The research findings can provide ample guidance when designing crash tubes in the automotive protective system.

Oblique compression of square tubes with walls of different thicknesses

In this paper, thin-walled aluminum square tubes with three different types of wall thickness configurations were experimentally compressed at loading angles of 0°, 10° and 15°, i.e., four walls with uniform thickness (St1t1), opposite walls with the same thickness (St1t2O and St2t1O), and opposite walls with different thicknesses (St1t2A and St2t1A). Numerical analysis was further conducted to explore the effects of wall thickness, thickness configuration and loading angle on the deformation mode and energy absorption of tubes. The results show that tubes with opposite walls of different thicknesses (St2t1A) present better energy absorption performance than tubes with uniform thickness under oblique loading. In addition, tubes with opposite walls of the same thickness (St1t2O) absorb the most amount of energy under oblique compression at larger angles (20° and 30°).

Probing Confined Vortices with a Superconducting Nanobridge

We realize a superconducting nanodevice in which vortex traps in the form of an aluminum square are integrated with a Dayem nanobridge. We perform field cooling of the traps arriving to different vortex configurations, dependent on the applied magnetic field, to demonstrate that the switching current of the bridge is highly sensitive to the presence and location of vortices in the trap. Our measurements exhibit unprecedented precision and ability to detect the first and successive vortex entries into all fabricated traps, from few hundred nm to $2\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{m}$ in size. The experimental results are corroborated by Ginzburg-Landau simulations, which reveal the subtle yet crucial changes in the density of the superconducting condensate in the vicinity of the bridge with every additional vortex entry and relocation inside the trap. An ease of integration and simplicity make our design a convenient platform for studying dynamics of vortices in strongly confining geometries, involving a promise to manipulate vortex states electronically with simultaneous in situ control and monitoring.

Analysis of hollow aluminum square tube of refitted mattresses using mathematical calculation & computerized 3-dimensional development

Analysis of hollow aluminum square tube of refitted mattresses using mathematical calculation & computerized 3-dimensional development

Experimental study on sound absorption performance of microporous aluminum square tube space absorber

The aluminum square tube is one of the ceiling materials that have been produced in recent years. It has become the most popular product in the decoration market because its lines are bright and clean with distinct layers, reflecting the simple modern style, and it is easy to install and dismantle. However, the aluminum square tube used in the market is mostly a single aluminum panel structure, mainly used for decoration, without sound absorption and noise reduction. In order to improve the sound absorption properties of the aluminum square tube, a microporous aluminum square tube space absorber is proposed. The reverberation chamber method is used to investigate the sound absorption properties of the microporous aluminum square tube. The results show that the sound absorption performance of the aluminum square tube can be greatly improved by the formation of micropores on it. The sound absorption performance of the aluminum square tube perforated on three sides is better than that of the aluminum square tube perforated on only two sides. In the case of perforation on only two sides, with the increase in the height of the perforated surface, the peak value of sound absorption is gradually increased. In addition, the sound absorption peak gradually shifts to the low-frequency direction as the distance between the perforated surfaces increases. The reasonable design of structural parameters of microporous aluminum square tube can make it have beautiful decorative effect and good sound absorbing effect.

Effect of process parameters on the deep drawing formability of aluminum and advanced high-strength steel square cups

Effect of process parameters on the deep drawing formability of aluminum and advanced high-strength steel square cups

Modelling the effect of lateral inertia on the dynamic response of aluminium square tube extrusions

Crashworthiness of automotives require the design of crush tubes installed as a frontal structure to absorb energy by deforming plastically during collision. The crushing behaviour of aluminium extrusions modelled as square tubes is investigated under quasi-static and dynamic loading conditions using the non-linear explicit finite element code LS DYNA. Previous works have attributed the dynamic increase of the peak and mean crushing load of aluminium thin-walled structures under axial compression, to inertia effects. Results of our investigation revealed that there is a considerable thickening of the shell side walls before and during progressive folding. This shell thickening is established as the cause of lateral inertia which consequently results in increased crush strength. In addition, a positive correlation was established between the shell thickening and crushing speeds. 

Impulse saturation in metal plates under confined blasts

The phenomenon of impulse saturation is revisited for metal plates subjected to confined blasts through a combination of experiments, numerical simulations, and analytical modeling. Internal blast experiments were performed on the fully-clamped aluminium square plate where its transient inelastic (mode I) response was recorded using three-dimensional digital image correlation (DIC). A methodology was proposed to idealise the confined blast induced pulse-pressure through a validated numerical model. An analytical model was developed to predict the transient central deflection of the aluminium plate under the idealised pulse pressure, where the predictions were shown to be in reasonable agreement with the DIC measurements. Parametric studies were performed to elucidate the effect of standoff distance and confinement geometry on the saturation duration, saturated impulse and deflection. It was found that both the pulse-shape and saturated impulse strongly influence the saturated deflection during internal blast loadings.

Singular value decomposition of acousto-elastic matrix for modal analysis of mechanical structures

All mechanical structures exhibit natural vibration eigenmodes, characterized by their natural frequencies, modal shapes and damping factors. For some industrial applications, the investigation of those parameters is important either to avoid resonance phenomena or to detect the apparition of flaws. However, the analysis of symmetric or periodic structures can be complex because several modes can overlap at a same frequency. Here, we propose to measure the acousto-elastic transmission matrix between an array of loudspeakers and the displacement on the structure under test recorded with a laser vibrometer. The singular value decomposition of the transmission matrix allows detecting, counting and separating overlapping modes. The method is validated on a thin aluminum square plate, a gear and a turbine wheel. The results are compared to conventional impact hammer excitation. Based on this analysis, a selective excitation of a given mode is made possible. Finally, the effect of flaws on SVD is studied on the structures.

Numerical simulation and experimental characterization of the heat transfer in a PV/T air collector prototype

PV/T systems are an emerging technology for the simultaneous production of electrical and thermal energy. In this paper, we present an experimental device modified with an arrangement of aluminum square tubes to remove thermal heat from the system and increase its electrical efficiency. A 1D analysis allowed prediction of the heat transfer in the solid components. Moreover, a 3D simulation allowed visualization of the temperature distribution in the prototype. The simulations considered the surrounding temperature, the solar irradiance and the airflow velocity inside the square tubes. The glass temperature, PV cell temperature and the outlet airflow temperature were logged. The study was performed at a low airflow (0.5 m/s) and at a high airflow (2 m/s); for both experiments, the maximum solar irradiance was 800 W/m2 and the heat fluxes were calculated. The time constant was shorter for the experiment at low airflow, because the airflow increased by 63.2% at 5400s. At a high airflow, it took 9100 s to achieve the 63.2% of the maximum increase, and the difference between the outlet temperature and the temperature of the surrounding air was significantly reduced. At 0.5 m/s and 2 m/s the PV cell reached a maximum temperature of 75 °C and 59 °C, respectively. The maximum difference in temperature between the two experiments was 20 °C. The best thermal average efficiency was 42.5%, corresponding to the high airflow experiment. Furthermore, based on the favorable air outlet temperature, at this flow rate, the outlet air could be used for drying in a subsequent process.

Axial Crush Response of Aluminium Square Tube with Origami Patterns

Thin-walled square tubes are widely used as impact energy absorber in automotive structures due to their ease of fabrication and installation, high energy absorption capacity in terms of progressive plastic deformation and long stroke. However, the main drawback of square tube is its high initial peak force during the initial stage of crushing. An origami pattern on the faces of the tube is proposed to reduce the high initial peak force and increase the energy absorption of the tube. Static and dynamic axial crushing were performed using finite element analysis to determine the initial peak force (IPF), crush force efficiency (CFE) and plastic specific energy absorption (SEA) of tubes with origami pattern. The results of simulations were validated by experimental data. Then, various combinations of origami patterns were studied using finite element simulation only. It was found that the origami pattern significantly enhanced the tubes crush performance. Comparison between plain square tube and tubes with various origami patterns was carried out and it was found that the origami patterns reduced the initial peak force and increased the crush force efficiency for both static and dynamic loading conditions.

Quasi static axial compression of empty and PU foam filled circular aluminium and light gauge square steel tubes

Abstract For structural applications, Concrete Filled Steel Tubes (CFST) proved as efficient building material. Further study on composite filled tubes to increase strength to weight ratio is evident to improve material efficiency and reduce load on structure. In the recent years, investigations on impact resistance and energy absorption of foam filled thin walled Aluminium and Steel composite tubes have gained importance for mechanical and aerospace applications and also as crash barriers to improve its dynamic characteristics. These are made by metal tube envelopes filled with Polyurethane foam infill material. Present study is carried out to understand the strength and behaviour of PU Foam Filled Tubes for structural applications. This paper presents experimental work on Quasi Static Axial Compression Tests on Empty and PU Foam filled Circular Aluminium and Light Gauge Square Steel Tubes. For Aluminium Tubes, D/t of 40.20 and 30.15 and L/D of 3.32 and for Steel Tubes, b/t of 125, 100 and 83.33 and L/b of 2, 3 and 4 were considered. High density PU foam (of density 150 kg/m3) alone, Empty tubes and Polyurethane foam-filled tubes are tested for quasi-static axial compression experimentally and validated the results with numerical simulation using ABAQUS 6.14–3 software. The mean crushing loads of hollow and polyurethane foam-filled circular Aluminium and Square Steel tubes were calculated from FEM and experimental results. The experimental and numerical values are in agreement. This study reveals that due to composite action between tube and foam, the resistance to buckling has improved significantly when compared to empty tubes even for high L/D & L/b ratios.