Thin Metal Sheets Research Articles

Investigation of the Effect of Morphological and Crystallographic Textures on the Ductility Limits of Thin Metal Sheets Using a Cpfem-Based Approach

Investigation of the Effect of Morphological and Crystallographic Textures on the Ductility Limits of Thin Metal Sheets Using a Cpfem-Based Approach

Development and first results of a magnetic sample environment for polarized neutron imaging of thin metal sheets

Polarized neutron imaging brings the great advantage of analyzing bulk magnetic properties with good spatial resolution. The technique is based on the interaction of the neutron spin with magnetic samples or free magnetic fields and observing the changes to a spin-polarized neutron beam. The high sensitivity to even small magnetic fields is a benefit in obtaining magnetization information but simultaneously a challenge in instrumentation, since magnetic environments for the polarized neutron beam and for the sample, as well as the fringe field from the magnetic sample itself all affect the measurement and can give rise to unwanted effects. We have used finite element simulations and ray tracing simulations, to design and analyze a magnetic sample environment devised for the measurement of ferromagnetic metal sheets. Here we show an analysis of performance of the experimental setup based on the simulation results and compare them to first experimental results on a grain oriented silicon steel sample.

Process analyses of friction drilling using the Smoothed Particle Galerkin method

As a cost-effective hole production technique, friction drilling is widely used in industrial and automotive manufacturing. Compared with the traditional bolted connection, it enables the fastening of thin metal sheets and thin-walled tubular profiles. Friction drilling results in higher thread length and joint strength, thus better fulfilling the demand for lightweight structures. However, in the numerical simulation of friction drilling, the traditional finite element method encounters difficulties caused by the extreme deformation and complex failure of the material. A large number of elements are usually deleted due to the failure criterion, which significantly reduces the solution accuracy. The development of meshless methods over the past 20 years has alleviated this problem. Especially the Smoothed Particle Galerkin (SPG) method proposed in recent years and incorporating a bond-based failure mechanism has been shown to be advantageous in material separation simulations. It does not require element removal and can continuously evolve each particle's information such as strain and stress after the material failure. Therefore, the SPG method was used in this research for the simulation of frictional drilling of HX220 sheet metal. First the particle distance and the friction coefficient were varied to investigate the applicability of the SPG method to the friction drilling process. Predicted and experimental results were compared and found to be in high agreement. Furthermore, the influence of input parameters, such as sheet thickness, feed rate and rotational speed, on axial force as well as torque of the tool and the surface temperature of the workpiece during friction drilling was investigated numerically.

A review of process parameters in friction drilling on joining of steels

Friction drilling is a unique way of creating holes in steel. In a solitary advance, a rotating conical tool is utilized to enter by penetrating as an opening on the surface of the sheet and making a bushing without making a chip. During this process, the heat produced by the frictional power linking the device and the sheet metal workpiece is used to pierce and make a bushing out of work. The goal of this novel hole-making process is to improve the bushing length in the thin-walled sheet metals by forming a bush and then combining thin sheet metals. The inconceivable utilizations of warm grating penetrating in a few modern areas will introduce another period of interfacing processes for different work materials in automobiles.Researchers have undergone numerous experiments based on the machining parameters, including spindle speed, feed rates, Friction Contact Ratio (FACR), tool angle, tool diameter, sheet thickness, and the output of the friction drilling, includes the bushing length, surface roughness, tool wear, hardness, thrust force, torque and microstructural evaluation.The crucial concerns that should be addressed and researched by researchers in the near future, such as determining the optimal machining parameters of such process and analysing, bushing length, microstructural impacts on the many aspects and their performance, are highlighted.This research paper tends to examine the advancements in research on the friction drilling method and its applications, taking into account the benefits and limits of friction drilling.The present paper identifies the machining parameters and their contribution towards the output level of various materials like Stainless steel, Brass, aluminium, titanium, tempered steel and nickel-based compounds of different thickness.The machining parameters like spindle speeds, feed rate, tool angles, thrust force, Torque, surface roundness, bushing height, frictional heat and tool diameter are optimized in the friction drilling. The incorrect bushing is formed due to the high thrust force, and Low temperatures cause ductility and softening issues.

The Impact of Direct Lightning Strike Damages on PV Modules in a Large Malaysian PV Farm

Many lightning risk analyses avoided considering the role of the PV Module’s aluminium frame as a natural lightning air termination system or if such a role is considered, assumed that the ‘thin’ aluminium frame, would not be damaged from metal melting and evaporation at the point of lightning stroke attachment. Although the IEC 62305 is not lacking in guidance on the use of thin metal sheets as air terminations, this aspect is not considered in PV farm design. To ensure correct inputs into the risk assessment calculation, the evaluation of interception and sizing efficiencies and the damage probabilities of the natural components have to be addressed. A comparative analysis is done between two types of air terminations; the PV-frame LPS and the finial-added LPS. The result indicates that for solar PV farms exceeding a certain size and operating in high ground flash density regions like Malaysia, the finial air termination may out-perform the PV-frame LPS.

Knowledge Gap Causing Discontinuance of SRI: A Study in Tribal Region of Odisha

System of Rice Intensification (SRI) method is being ideally suited to the small farmers in India where rice productivity is comparatively low. But, it has been observed that the farmers are not enthusiastic to continue the practice in spite of all efforts made. Inadequate knowledge about the practices might be the reasons for the discontinuance of the method. A study was therefore, conducted with 96 farmers in the tribal region of Sundargarh district in Odisha to assess the knowledge deficiencies that causing discontinuance of SRI. The findings revealed that the farmers had inadequate knowledge on raising nursery bed at 80-100 cms height, putting single sprouted seed in line in nursery bed, sub-matting at two meters distance, putting seedlings in a thin metal sheet for easy transplanting, use of recommended quantity of well decomposed FYM/manure per hectare, green manuring and vermicomposting to supplement organic manure, minimum of four weeding at ten days interval, alternate drying and wetting of the main field, light irrigation during hair line cracks and keeping 2-3 cms standing water after flowering. Socio – economic attributes like family size, housing pattern, social participation, education, use of agricultural implements, extension contact and annual income had significant influence in increasing knowledge level of the respondents. It is therefore suggested that the extension officials of the state department of Agriculture and Non- Government Organizations promoting SRI have to take possible approaches to expose the respondents further particularly with poor knowledge on practices enabling them to realize the benefits of all these practices and may continue SRI method of rice cultivation for better production till they get better technology.

A Near-Field Meta-Steering Antenna System With Fully Metallic Metasurfaces

In the near-field meta-steering method, the near electric-field phase distribution is dynamically altered by rotating a pair of phase-gradient metasurfaces that are typically made out of dielectric lattices or metal patterns printed on bonded dielectric substrates. As a lightweight alternate, a new class of fully metallic metasurfaces (MMs) is proposed in this article. The lack of dielectrics not only substantially reduces the cost and weight but also increases its potential in space and high-power applications. More importantly, the new MMs are designed such that they can be made by cutting narrow slots in fully planar thin metal sheets, retaining structural rigidity while reducing the complexity, cost, and weight. The same MM works for any polarization. Each cell in the new MMs has close to ideal phase shift and transmission magnitude greater than −0.9 dB. A prototype was designed and fabricated to validate this MM-based beam-steering concept in the Ku-band. The maximum measured steering range in zenith is ±42°, with a full 360° steering in the azimuth. The measured 3 dB gain bandwidth is 700–800 MHz (5.6%–6.4%), and the measured gain variation (scan loss) when steering over the whole range is 2.2–4.5 dB. The weight density and thickness of each MM are 0.88 g/cm2 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.8\lambda _{0}$ </tex-math></inline-formula> , respectively. Including the feed, the total antenna height is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.9\lambda _{0}$ </tex-math></inline-formula> .

Experimental analysis of electro-jet machining of thin metal sheets under the application of ultrasonic vibration, continuous and pulsed direct current

Electrochemical machining is considered to be suitable for precision and micromachining without the development of residual stress, mechanical distortion and thermal damage. In this work, an in-house developed electro-jet machining system, a variant of electrochemical machining, has been used for machining in thin metal sheets, where the electrolyte is supplied in the form of a fine jet, concentrically to a wire electrode, through a nozzle. Machining performance was studied for generation of through slits of sub-millimetre range in 500 μm thick aluminium sheets, under the application of continuous and pulsed direct current (DC) power sources as well as with the application of ultrasonic vibration to the workpiece, emphasizing achieving better dimensional control with minimum overcut. A detailed investigation of the effect of applied voltage, scan speed, inter-electrode gap and electrolyte concentration has been performed in the case of continuous DC supply on quality factors, kerf-width, amount of overcut and material removal rate. Furthermore, the effects of duty cycle and pulse frequency in the case of pulsed DC supply, and the effect of vibration frequency under the application of ultrasonic vibration have been analysed on the above-mentioned output factors. Though a pulsed DC power supply with a pulse frequency of more than 1 kHz and a small duty cycle was found suitable for precision machining among all conditions, ultrasonic vibrations proved beneficial for fine feature generation with tighter size control at higher frequencies (lower vibration amplitude).

Energy efficiency study of household natural gas burner using pot-bottom shield and modified pot arrangement

The study aims to design and evaluate practically applicable pot-bottom shield and finned-pot in different pot-shield arrangements for better thermal and emission performances of a conventional household radial flow NG burner to lessen the household cooking energy consumption. Eleven sets of perforated hollow cylindrical pot-bottom shields having different heights were fabricated from thin metal sheet with a provision of secondary combustion air. One of the two identical flat bottom pots was converted to spot welded finned pot. The thermal and emission performances of the NG burner were then evaluated following the standard water boiling test (WBT) protocol with four different pot arrangements, namely ordinary flat bottom pot without shield and with shield and spot welded finned pot without shield and with shield at eleven different loading heights (from 2.5 cm to 7.5 cm) and six different NG supply pressures (0.4, 0.6, 1.0, 1.4, 1.8 and 2.0 kPa) keeping the burner primary air opening fixed at 50%. The corresponding NG flow rates at SATP were 4.23, 4.30, 4.70, 4.84, 4.94, 5.15 L/min for 0.4, 0.6, 1.0, 1.4, 1.8, and 2.0 kPa, respectively. It was found that a simple inclusion of a pot-bottom shield can dramatically improve the thermal efficiency of a natural gas cooking system for the both type of pots. A 20% improved thermal efficiency was evaluated for the NG burner with ordinary pot and pot-bottom shield arrangement at 0.6 kPa pressure and 3 cm loading height corresponded to the highest efficiency of the burner at base setting (burner with ordinary pot at 0.6 kPa NG pressure and 4 cm loading height). It was also found that the operation of the burner at its highest thermal efficiency was still within the safe operation limit in terms of CO emission in comparison to international standards.

Effect of ultrasonic vibration on forming force and forming quality in micro-punching with a flexible punch

In this paper, a special ultrasonic microforming method, Micro Ultrasonic thin Sheetmetal Forming using molten plastic as a flexible punch (short as Micro-USF), was used to conduct micro-punching experiments on stainless steel sheet with thickness of 10 μm and 20 μm. The influence of ultrasonic vibration on forming force and forming quality were investigated. The experimental results showed that the forming force required for punching thin sheet metal decreased gradually as the ultrasonic time or ultrasonic power increased. By applying the ultrasonic vibration effect, the forming force could be decreased dramatically and the maximum value of forming force drop could reach 86%. Moreover, with the application of ultrasonic vibration, the size accuracy and shape accuracy of micro-holes could be increased by 36.92% and 22.65%, but the cross-section quality of micro-holes were not significantly improved.

Ductile crack propagation path depending on material properties: Experimental results and discussions based on numerical simulations

To ensure the structural integrity of advanced thin sheet metals in engineering applications, it is necessary to understand their ductile crack propagation behaviour. In this work, we clarified the governing factors for ductile crack propagation paths in sheet metals by the comprehensive investigation with experimental and numerical approaches. Using two types of sheet metals, a steel and an aluminium alloy, experiments with Arcan tests were performed, and the difference in the crack paths were observed and analysed. The strategy for simulating ductile fracture proposed by the authors was successfully validated with the experimental Arcan test results, and it was applied to a parametric study based on the numerical simulations for clarifying the governing factors for ductile crack propagation paths in sheet metals. The two factors, strain hardening ability and ductility diagram parameter, were confirmed to be dominant in controlling the ductile crack propagation. The findings in the parametric study explain the difference of the crack paths as observed in the experimental Arcan tests for the two materials, thus elucidating the inverse design philosophy that facilitates material design to achieve desired performance metrics in enhancing the integrity of engineering structures.

Multiscale model for ultrashort pulsed parallel laser structuring—part II. The macroscale model

The increasing pixel density in displays demands high quality in the production of fine metal masks (FMMs). The production process of FMMs boils down to structuring tiny holes in thin metal sheets or foils. The manufacturing requirements of FMMs are high precision in terms of the hole geometry to let enough light escape from each diode and high productivity to produce the required amount. To achieve both objectives, high power ultrashort pulse (USP) lasers can be utilized. Because USP lasers fall short of the productivity requirements, they are combined with multibeam scanners. During production, the multibeam scanners deposit a lot of heat in the metal foil, which can ultimately yield temperature-induced distortions. To understand and finally avoid such distortions, a process simulation is sought. In a preceding study, the structuring of a single hole (the microscale) was investigated, but due to the large differences in the time and spatial scales involved, it was not feasible to simulate the production of the whole part (the macroscale). Within this treatise, a multiscale approach that takes into account the necessary information from the microscale to describe temperature-induced distortions on the macroscale is described. This approach targets laser ablation processes with pulse durations ranging from picoseconds up to nanoseconds provided the ablation is not melt-driven. First, a representative volume element (RVE) is generated from the results of the microscale model. Then, this RVE is utilized in the thermo-elastic structural mechanics simulation on the macroscale. The multiscale model is validated numerically against a hole-resolved computation, which shows good agreement. Naturally, the simulation is highly dependent on the microscale model, which in turn depends on the material properties. To handle material changes well, an experimental calibration has to be performed. This calibration is not part of this treatise, but it will be described in a future publication. In addition to the calibration process, the validation with experiments will be conducted in future research. Additionally, the authors envision the automation of the whole process, resulting in a first-time-right approach for the development of FMMs. Finally, the procedure might be extended to the requirements of other filtration purposes.

A Study on Aircraft Structure and Application of Static Force

In particular, the neural network approach to Demister-Schaefer theory has been demonstrated. Different modulus adherents, so that the adhesive pressures are approximately the same part of the vertical stabilizer was selected and reconstructed using the structure design of the hybrid wing body plane during the preliminary design phase. Due to the high number of design variables and various repairs, adhesive bonded fiber-composite joints or reinforcements are a challenging optimization problem, and this sheet directly affects structurally efficient and minimal damage by lightning strikes on aircraft structures. Parent systems rather than standard repairs. In the first part, the phenomenon of lightning curve connection in aircraft was introduced. Certain bonded joints offer more effective repairs than conventional mechanical joints, which are not fully credited with reducing their performance, and have important needs in most countries of the world. This article focuses on introducing integrated structural features and background, including application for civil aviation and flight qualification requirements, and the main purpose of this study is a computer-assisted materials selection tool. - Reinforced alloy. This paper explores the distribution of dynamic load identification given the unknown but limited uncertainties in aircraft configuration. This is the second of two documents on the structure of the Northwest Pacific Hurricane This sheet describes various structures Thin metal sheets are widely used to create different types of space structures due to its flexibility and ability to easily create any type of structure. Resource based to identify damage this article discusses the use of taxonomies.

Finite Element Modeling of Additive Manufacturing in Case of Metal Parts

Metal Additive Manufacturing has grown from 3D metal printing; this technology leads to manufacturing parts using various metallic materials.Additive Manufacturing technology uses the same principle of slicing a solid model into multiple layers and creating a tool path for each layer, then uploading this data to the printing machine and building the part up layer by layer following the sliced model data using a heat source (laser, electron beam, electric arc, or ultrasonic energy, etc.) and feedstock (metal powder, wire or thin metal sheet, etc.).The Additive Manufacturing process starts with designing the prototype, continues with printer pre-processing, then with printing the prototype, and finally with post-processing to get the final part, followed by testing. This sequence has to be repeated till achieving the desired prototype. This method costs money and time. In this paper, the Simufact Additive Manufacturing software makes a virtual simulation to save time and money. In this virtual modelling, different types of materials can be used. Different approaches can be tested, such as building orientations with various parameters, changing supporting structures, and cutting and support removal to achieve a usable process, which is free from damaging effects on the first time that goes through the build. This paper deals with three types of metal alloys (TiAl6V4, AlSi10Mg, and 316L). Different types of machines, thermal analysis, mechanical calibration, thermal and thermomechanical calibration, were applied to find the set parameters such as laser power, inherent strains, exposure energy fraction, and volumetric expansion factor.

Deformation of thin metal and composite sheets by using anti-buckling fixture for large deformation under tension–compression cyclic loading

In this paper, an anti-buckling fixture was proposed to assess the deformation characteristics of DP500 and DP980 dual-phase steels, and AZ31B magnesium composite under tension–compression cyclic loading. The advantage of the device lies in the possibility of monitoring friction between the specimen and supporting blocks during the test. In consequence, it allows to avoid an error during stress determination. The full cyclic loading capacity for each material can be executed at the displacement amplitude within the range ±2.5 mm which corresponds to the maximum strain amplitude of ±0.2 for the specimen with the gauge length of 21.5 mm. It is concluded, that the technique proposed is promising since the thin sheet material can be tested under tension–compression in a wide range of deformation without the buckling effect. Furthermore, useful data for modelling cyclic deformation behaviour for shell structures can be obtained.

On the Anisotropic Mechanical Response of Ti6Al4V Sheet at High Strain Rates

In traditional sheet metal forming processes, a thin sheet metal is deformed at relatively low speeds. However, more and more the speed of production processes is increased, very often to take advantage of the beneficial implications that high strain rates can have on the formability of certain metals. In this work, the effect of strain rate on the anisotropic behavior of Ti6Al4V is investigated performing tensile tests in different orientations, namely 0o, 45o and 90o, with respect to the rolling direction (RD), and in-plane shear experiments along RD. Three nominal strain rates, i.e., , 0.5 and 1000, are considered. A novel high-speed bulge (HSB) test developed at Ghent University, designed to deform sheet metals in nearly equibiaxial loading conditions at high strain rates, is used for the dynamic bulge test. The experimental results, presented in this paper, clearly show the need of including the effect of strain rate, and eventually temperature, into the formulation of the yield function in order to correctly model and predict deformation processes performed at high speed.

Impact of Die Coatings on Forming Conditions in Electromagnetic Embossing of Thin Sheet Metal

In electromagnetic embossing, the interaction of the magnetic field and the induced current density results in body forces that enable the replication of optical microstructures into thin sheet metals. However, as the sheet metal is completely penetrated by the magnetic field, electromagnetic properties of the dies need to be considered in process design, as they influence the forming conditions by changing the field distribution, force vectors and eddy current densities. With die coatings like electroless nickel–phosphorus (NiP), the electromagnetic properties of the die change. Therefore, the effect of both - die substrate and coating material - was studied to find advantageous conditions for electromagnetic embossing. Within two-dimensional electromagnetic field simulation, the electromagnetic properties of coating and substrate material were varied in addition to the coating thickness. To validate the results, electromagnetic embossing experiments were carried out. Here, different dies were fabricated from aluminum (uncoated) and cold work steel with 200 µm and 400 µm thick electroless nickel–phosphorus coatings that were subsequently micro-structured in optical surface quality. It was demonstrated by numerical and experimental results that the coating and the substrate influence the electromagnetic embossing significantly in correspondence to their shielding behavior and field interaction due to electromagnetic properties and coating thickness.

Durable Metallic Surfaces Capable of Passive and Active De‐Icing

Ice accretion has adverse effects on several industrial sectors worldwide. Sparsely suspended, thin metallic sheets (buckling elastomer‐like anti‐icing metallic surfaces, or BEAMS) recently demonstrated extremely low ice adhesion strengths while maintaining durability. Here, BEAMS are designed using elastomeric suspension points shaped as channels, enabling active de‐icing by flowing air underneath the suspended sheet. The channel geometry is optimized using computational fluid dynamics by iterating through various channel dimensions and flow conditions. An experimental setup is constructed and utilized to assess BEAMS comprised of 1–4 channels. Active de‐icing is achieved by pressurizing the air within the channels to bulge the sheet outward and delaminate accreted ice from the interface. Active de‐icing is achieved by flowing room temperature air through the channels to heat the surface and melt the interface. Passive de‐icing is also observed under atmospheric icing conditions. Rime is accreted within an icing wind tunnel on multichannel BEAMS. Ice adhesion strengths &lt;8 kPa are maintained after ten consecutive icing/de‐icing runs, demonstrating substantial durability. The active and passive de‐icing capability of channeled BEAMS makes it a promising candidate for improving the operational efficiency of infrastructure in cold environments.

Optimization of Heat Accumulation during Femtosecond Laser Drilling Borehole Matrices by Using a Simplex Algorithm.

We report on an optimization study of percussion drilling thin metal sheets employing a high repetition rate, high power femtosecond laser with respect to the resulting heat accumulation. A specified simplex algorithm was employed to optimize the spatial drilling sequence, whereas a simplified thermal simulation using COMSOL was validated by comparing its results to the temperature measurements using an infrared camera. Optimization for drilling borehole matrices was aspired with respect to the generated temperature across the processed specimen, while the drilling strategy was altered in its spatial drilling sequence and by using multi-spot approaches generated by a spatial light modulator. As a result, we found that an optimization strategy based on limited consecutive holes in a Moore neighborhood led to reduced temperatures and the shortest process times.

Analytical solution for vibration and buckling of cylindrical sandwich panels with improved FG metal foam core

In this research paper, a novel higher-order porosity distribution is proposed, and free vibration and buckling behavior of cylindrical sandwich panels with functionally graded metal foam core are investigated. It is assumed that the sandwich panel is made of two thin face metal sheets and a moderately thick functionally graded metal foam core. The dynamic governing equations are obtained based on the third-order shear deformation theory and utilizing the Hamilton principle. It is assumed that the voids are distributed non-uniformly along the thickness of the functionally graded metal foam core. The elastic modulus of the core depends on the square of the relative density, thus is changing nonlinearly through the thickness of the core. The Navier technique is implemented to derive closed form solutions for the natural frequencies and the buckling load of the simply supported cylindrical sandwich panels. The accuracy and effectiveness of the proposed model are verified by comparison with previous researches. Results revealed that the presented higher-order porosity distribution can increase the buckling load and fundamental natural frequency by 10% and 5% in comparison to the conventional porosity distributions, respectively. In addition, it is shown that if the flexural vibration is of interest, ignoring the in-plane and rotary inertias, which can significantly reduce the computational complexity, does not have any considerable effect on the natural frequencies.