Metal Beam Research Articles

Features of restoration of precast reinforced concrete ribbed slabs of coverings of industrial buildings destroyed by bombardment

With the beginning of the fullscale war launched by the Russian invaders, buildings and structures of industrial purposeand critical infrastructure were damaged and destroyed. In case of partial damage to the supporting structures of the coating, it is possible to restore them or replace them with new ones.To replace the destroyed slabs with new ones, it is necessary to use tower cranes. With the existing development and high height of the buildings, it is not possible and economically unprofitable to use tower cranes. In addition, thework must be performed in a short time and with high quality, ensuring sufficient bearing capacity. To solve this problem, it was decided to use monolithic reinforced concrete slabs on corrugated flooring and metal beams. In such slabs, the corrugated flooring plays the role of both permanent formwork and external reinforcement. The arrangement of such slabs is performed on a coating of individual elements.To reduce the time for the work, quickhardening concrete is used [11, 12]. In this case, it is possible to use light lifting mechanisms. It is also necessary to ensure the dimensions of the slabs that existed. These are prefabricated ribbedreinforced concrete slabs with dimensions in plan of 6.0×1.5 m and a section height of 300 mm. For example, the results of the survey and reinforcement of the covering of two buildings of industrial and administrative purpose,performed by employees of the Department of Reinforced Concrete Construction of the KNUBA, were used. The paper presents a methodology for calculating a reinforced concrete slab covering on corrugated board and a complex metal-reinforced concrete beam. The calculations were performed at the construction stage and at the operation stage according to thecurrent standards for this type of structures [1…6, 13…25].

Low dose contrast enhancement of biodegradable low-density stents by an approach balancing radiopaque coatings and beam filtration.

Biodegradable cardiovascular stents made of thin, low atomic number metals (e.g. Zn, Mg, Fe) are now approved for clinical use. However, poor contrast under X-ray imaging leads to longer surgical times, high patient exposure, and sometimes stent misplacement. This study aimed at enhancing the visibility of low-Z metal stents under X-ray imaging, by combining high-Z metal coatings and beam filtration. Photon energy spectra from W-anode X-ray beams operated at 80 and 120 kVp, were generated by the SpekCalc and BEAMnrc softwares. The contrast produced by Fe stent struts (50-µm; 10 m W coatings), as well as dose and air kerma values (by BEAMnrc), were simulated. Several types of beam hardening filters (Sn: 0.1, 0.2 mm; Cu: 0.2, 0.7 mm) were also applied. Then, Fe foils (50-µm) with W coatings (2-3 µm-thick) were fabricated by magnetosputtering. These samples were X-ray visualised, for quantification of contrast between W-coated and uncoated Fe samples. Fe struts (50-µm) were also coated with W (3.8 ± 0.2 µm), and stent-like objects were X-ray visualised. Fe samples attenuate 6.4% (120 kVp) and 10.1% (80 kVp) spectra photons, and 25% and 34.5% for W-coated Fe samples (SpekCalc). BEAMnrc calculations revealed the highest contrast improvement in a 120 kVp beam (36.4, and 38.5%) for W-coated and uncoated Fe samples with Sn (0.2 mm), and Cu + Sn (0.2 + 0.2 mm) filters. Experimentally, the highest contrasts between Fe and W-Fe foils, were obtained with 0.2 mm Sn (580  5 % increase). The dose was also strongly reduced (70 and 75%, for 80 and 120 kVp beams). Finally, for 3D Fe stents visualised at 80 kVp, the highest CNR and CNRD values were achieved with 0.1 mm Sn (18.5 x and 20.1 mGy⁻¹; compared to 15.0 x and 12.0 mGy⁻¹ in no-filter condition). The contrast of Fe-based stents in X-ray imaging is improved by addition of a thin layer of W and beam filtration with Sn. The precision and rapidity of biodegradable stents implantation would be improved thereby, as well as the dose to patients.

Numerical study of cellular beams under different types of loading

The integration of cellular metal beams in high-rise buildings allows for optimized space utilization for technical equipment, while also reducing floor height and, consequently, the overall weight of the superstructure. However, while these openings provide design flexibility, they can also decrease structural stability by causing deformations in the web posts, especially under concentrated loads. This study focuses on evaluating the strength and stability of open-section beams under various load conditions, using numerical simulations and three-point bending tests. Specific reinforcement solutions were developed to counter instability phenomena and enhance mechanical performance. The results indicate that the finite element model used in simulations provides accurate and consistent predictions with experimental data, validating its utility for in-depth analysis of displacements and failure modes. Notably, the addition of stiffeners proved effective in reducing displacements and enhancing beam stability. This work, still in its exploratory phase, aims to develop a theoretical formula to estimate the contribution of supports to elastic stiffness, paving the way for advances in the use of reinforced metal beams in high-rise construction.

Experimental Investigation of Energy Harvesting by Employing Piezoelectric Element and Metallic Cantilever Beam

In this paper, in response to the worldwide energy crisis, a piezoelectric element (0.2*35*50) mounted on a host metallic cantilever beam (0.8*37*220) will be presented as a unique contribution to power generation via the micro-electrical mechanical system. It's made out of aluminium and low carbon steel, both of which have a Young modulus of elasticity of 6.8 and 196 GPa, respectively. In order to take advantage of the engine's vibration as an exciting external force to collect energy in the aforementioned piezoelectric device, the whole rig has been coupled to a diesel engine 5kw 3000 rpm (50 Hz). The average power generated by the aluminium beam was 943 microWatts, while the power generated by the low carbon steel beam was 335 microWatts, an increase of 256%. In addition, for both scenarios, (45) mm from the cantilever beam's fixed point was where the engaged piezoelectric element performed best. The used two metals have different stiffnesses, and this accounts for the obtained difference between the induced powers; increasing the stiffness will result in relatively more power created, and vice versa.

Finite element method numerical modeling of the crack's impact on the free vibration of 2D functionally graded beams on the Pasternak-Winkler elastic foundation

The study's contribution is to examine, while taking into account pinned-pinned boundary conditions, the free vibration response of multi-cracks Euler-Bernoulli perfect FG beams structure on Pasternak-Winkler elastic foundations. The finite element approach is used to discretize the equations. The material properties are taken into account using a power-law form, and they differ in the thickness and width directions of the beam structure. The 2D FG beam's reduced cross section is used to calculate the stiffness of the cracked structure. On the other hand, the Pasternak-Winkler type foundation has a longitudinal distribution and makes the system stiffer. For convergence research, the numerical results are compared with the outcomes of earlier investigations in terms of dimensionless fundamental frequencies. Case studies were carried out to examine the effects on the natural frequencies of the beams structure of the power law index, multi-cracks, depths, location, and Pasternak-Winkler-elastic foundation. These studies demonstrate the benefits of the two-dimensional FG beam in the presence of cracks over the unidirectional FG and pure metallic beams.

Improving resonant ice protection systems with substrate optimization

Electro-mechanical de-icing systems are low-energy ice protection solutions based on ice fracture mechanisms. This article focuses on resonant electro-mechanical de-icing systems that actuate modes of flexion, which require low energy compared to extension modes. However, fracture propagation limits are encountered when using such flexural modes, preventing the ice from being completely detached from the substrate. This study demonstrates the feasibility of extending the ice detachment area by optimizing the thickness of the substrate. First, the interest and the limits of flexural resonant modes are discussed. Then the de-icing of a simple metallic beam in free conditions using a flexural mode is improved owing to the parametric optimization of the substrate thickness. The optimization is verified by tests on aluminum prototypes. The optimization results are then extended to a clamped composite plate and then to a NACA profile, showing interest in the approach to fully de-ice structures with modes of flexion, even in the case of complex geometries. With this last example, the study also demonstrates the feasibility of electro-mechanical ice protection systems for carbon fiber reinforced Polymer composite structures.

ДОСЛІДЖЕННЯ МІЦНОСТІ БЕТОНУ НЕРУЙНІВНИМИ ТА РУЙНІВНИМИ МЕТОДАМИ

Introduction. As a result of the military aggression of the Russian Federation against Ukraine, there is an urgent need to restore damaged and destroyed structures. Depending on the material of the span structure, bridges are divided into reinforced concrete, metal, steel-reinforced concrete, stone and wooden. Reinforced concrete bridges are the most common in Ukraine. Such structures account for almost 94 % of the total number of all bridges. Even if the bridge span is made of metal beams, such structures often have a reinforced concrete overlay slab, which means that reinforced concrete is also an integral load-bearing part of the bridge that requires proper maintenance during operation and, if necessary, repair or restoration work. In order to determine the technical condition of span structures, it is first of all necessary to inspect the structure. Typically, the list of inspection activities includes testing the concrete of structures for compressive strength. Therefore, determining the physical and mechanical characteristics of concrete is an integral part of planning for major repairs, reconstruction or new construction. This paper investigates different methods for determining the concrete strength of bridge elements. The accuracy of the results of different methods in laboratory conditions is analyzed. Problem statement. The use of a particular method has its advantages and disadvantages, which, in turn, can affect the accuracy of the data obtained.

ASTERICS, a new 28 GHz electron cyclotron resonance ion source for the SPIRAL2 accelerator

A new A/Q=7 injector is under development for the SPIRAL2 accelerator at Caen, France (NEWGAIN project). A new 28 GHz superconducting electron cyclotron resonance ion source named ASTERICS is under design for this project. The source features a modern cryostat and a large plasma chamber (91 mm radius and 600 mm length). The physical and technical motivations for a larger plasma volume are detailed and estimates of expected beam intensities enhancement are discussed. The source will mainly produce metallic ion beams: the concept of a temperature-controlled liner (up to 900°C) to stabilize high vapor pressure metal re-evaporation in the source is presented. The preliminary design of the ion source and its superconducting magnet are described.

Shakedown of metallic sandwich beams when subjected to repeated impact loadings

When a monolithic metallic beam/plate subjected to repeated dynamic loadings with fixed impact level experiences elastoplastic deformation, its measurable deformations may cease to develop for further repetitions of the same dynamic load: this phenomenon was referred to as “pseudo-shakedown” in previous studies (Jones, 2014; Shen and Jones, 1992). Would pseudo-shakedown occur in a metallic sandwich structure under repeated shock loadings remains elusive. A combined experimental and numerical study was carried out to explore whether dynamic shakedown could occur in all-metallic ultralightweight corrugated core sandwich beams. For repeated impact tests, the sandwich beams were fabricated via the sequential process of cutting-stamping-vacuum brazing. When subjected to repeated impact loads (achieved via aluminum foam projectiles launched from a light gas gun), the dynamic responses of each sandwich specimen - including structural evolutions, beam deflections, and deformation/failure modes - were measured. Experimental results revealed that, depending upon the level of impact momentum applied to the sandwich beam, either dynamic shakedown or progressive failure could occur. The method of finite elements (FE) was subsequently employed to simulate the repeated shock tests, which was validated against experimental measurements, with good agreement achieved. To explore the physical mechanisms underlying the observed dynamic shakedown, the FE results of final plastic energy and effective plastic strain distribution in the sandwich beam were extracted and analyzed. When shakedown occurred, the measurable permanent deformation of the sandwich beam kept a relatively stable state, but its plastic energy remained positive, which is different from its monolithic beam/plate counterpart (i.e., plastic energy dropping to zero during dynamic shakedown). Such difference is mainly attributed to stress concentration occurring at the connecting joint points between the corrugated core and face sheets of sandwich and clamped endings, which produces plastic deformations that are difficult to reflect in overall large deformations of the beam. Consequently, the dynamic shakedown of metallic corrugated core sandwich beam captured in this study appears to be inexhaustive and hence may be termed as the “apparent pseudo-shakedown” (with danger lurking in the welding joints as well as clamped endings). Finally, based on a simplified bi-linear hardening constitutive law, the mechanisms underlying the dynamic shakedown of sandwich beam were further discussed from a purely base material point of view.

Analyzing effects of damping materials on automotive bumper beam assembly under different velocity conditions

Automotive bumper beams play a very crucial role in absorbing impact energy during crash collisions and reducing damage from the front or rear ends of the vehicle during low or high-velocity impact. This paper discusses the impact of different energy-absorbing materials introduced between the fascia and the metallic beam. A novel recipe, with combinations ranging from 0% to 50% and 20% to 80% of Polypropylene (PP) with Ethylene vinyl acetate (EVA) and Polypropylene (PP) with Ethylene propylene diene monomer (EPDM), was prepared by weight and comparative study based on their impact strengths was done both experimentally and numerically. The mechanical properties of the polymer blends have been determined under tensile, compressive, and impact testing. Results obtained from numerical simulation analysis lie in reasonable agreement with the experimental findings. The tensile and compression test results show that polymer blend PP/EPDM-50/50 is the best selection as an energy absorber due to its ductility and toughness properties which is evident from experimental testing. The introduction of this blend in front of the metallic strip (bumper beam) has significantly supported the improvement in the energy-absorbing capacity and impact strength.

Internal damping measurements of additive manufactured metal beams

Modern additive manufacturing (AM) techniques have created an endless number of new design possibilities. Naturally, it is important to understand how the material properties, including internal damping, differ for AM structures. An experimental procedure has been developed to measure an upper bound for the internal damping of metal beams by minimizing the effects of energy dissipation at the supports and acoustic radiation into the surrounding air. In this talk, measurements for the loss factor of several common metals will be compared to equivalent samples constructed by powder bed fusion at varying angles. The results will also be compared to Zener’s thermoelasticity model, developed for isotropic Euler beams in flexure. Reasons for deviation from theory which arise from the manufacturing technique will be explored.

Measuring the internal damping of thin metal beams in flexure

Since the internal damping of most metals is a relatively small quantity, precise measurement requires that both acoustic radiation damping and boundary condition damping be either eliminated or highly minimized. In this talk, an experiment setup will be described which can measure the internal damping of metal beams in flexure. To perform a measurement, a beam specimen is placed on wire supports within a vacuum chamber and excited by an autonomous force hammer located within the chamber. The wire supports are located exactly at the nodal lines of the beam mode of interest, so that the frictional losses created by the wire supports are minimized. Once excited, the beam deflection is measured with a single point laser vibrometer. The signal decay measured by the vibrometer is used to estimate damping of the mode of interest using either the Hilbert transform or the half- power method. The wire supports are then moved, and the procedure is repeated for the next mode of interest. Results for several metal specimens will be presented and compared to Zener’s thermoelastic model, which describes the losses created by thermal currents for a beam in flexure, to demonstrate the accuracy of the measurement method.

Detecting damages in metallic beam structures using a novel wavelet selection criterion

Structural damage detection using wavelet transform is effective if a suitable wavelet function is selected. However, the selection of the appropriate wavelet function can be a challenging task. This paper introduces a novel and efficient criterion for selecting the proper wavelet function. It is emphasized that there is a relationship between the accuracy of damage detection using wavelet detail coefficients and the correctness of the approximation of the original function. Accordingly, we define a ratio function and then a novel wavelet selection criterion called WSC in this study. After applying the proposed WSC criterion for 128 wavelet functions, it is found that the wavelet functions selected via the proposed criterion (both in numerical and experimental scenarios) can detect the position of damages in the beam structure with high accuracy.

Порівняльний аналіз стану опорних тканин при використанні різних ортопедичних конструкцій для негайного навантаження на дентальних імплантатах при втраті зубів на одній із щелеп

Abstract. The use of fixed prosthetic structures supported by implants in case of partial or complete tooth loss remains relevant. Thanks to the use of intraoral welding of temporary prosthesis elements, the method of manufacturing temporary prosthetic structures has been integrated into the practice of prosthetic dentistry, which allows them to be fixed during dental implantation surgery. The aim of the study is to compare the condition of supporting tissues when using different orthopedic structures for immediate loading on dental implants in case of partial or complete loss of teeth in one of the jaws. For the comparative evaluation of different orthopedic structures on implants for immediate loading, temporary structures made of polymethyl methacrylate, composite structures reinforced with metal beams using intraoral welding, acrylic structures with dentures reinforced with a cast beam were selected. Computed tomography and orthopantomography were used to assess the condition of the bone tissue before implantation, 3 days and 1, 6, months after implantation. The study resulted in the following conclusions. Restoration of complete tooth loss in one of the jaws with fixed orthopedic composite structures reinforced with metal beams using intraoral welding is a promising method that allows to reduce the time of patient rehabilitation, the number of surgical stages and the trauma of the surgical stage of treatment. In this regard, soft and bone tissue trophism is less disturbed, which affects the subsequent osseointegration and functioning of implants. At the same time, the risks of bone resorption are minimized. Clinical evaluation of the tissues around the implants and X-ray analysis of the bone in patients with acrylic structures with set teeth reinforced with cast metal beams showed almost similar results. However, the technique involves additional surgical intervention, which negatively affects the trophism and healing of soft and bone tissues, increases the risk of complications, and extends the rehabilitation period. The use of temporary structures made of polymethyl methacrylate is less appropriate due to their less stable fixation, which can lead to inflammation of the soft tissues surrounding the implants and bone resorption. Key words: fixed structures, occlusal relations of the jaws, digital technologies, dental implantation.

Low Elastic Torsional Resonator Supported by a Thin Metallic Glass Beam

Low Elastic Torsional Resonator Supported by a Thin Metallic Glass Beam

Vision based control strategy to suppress residual vibration of flexible beams for robotic assembly using wrist motion

Automated assembly tasks require industrial robots to improve the efficiency of the manufacturing process. Most rigid or flexible objects handled by robots vibrate due to motion and transient disturbance. This work proposes an active vision-based vibration suppression strategy for flexible beams by providing motion to the wrist of a robot during robotic assembly process, which reduces the time to suppress vibration. The proposed method uses a cheap monocular camera to identify objects through a virtual marker and measure their dimensions. Subsequently, finite element method based mathematical model of a flexible beam predicts the maximum error. The proposed second stage controller determines the controller input in terms of wrist motion based on the predicted maximum error. The performance of the controller is assessed through simulations and experiments on metallic beams with different material characteristics and dimensions. The controller suppresses vibration amplitude within a safe limit so that object is inserted into the slot. It was observed from experiments that the controller can reduce vibration amplitude by ~96% in less than 2 s and decrease suppression time up to ~97%. These improvements were achieved without disturbing the internal robot controller.

The effect of an explosive shock wave on the plate of a protective structure of a critical infrastructure

The article presents the outcomes of an analysis on the stress-strain conditions of reinforced concrete structures subjected to an explosive shock wave resulting from the detonation of a combat unit from a kamikaze drone against a protective screen. When designing protective structures for critical infrastructure, employing computer simulation enables an assessment of the genuine impact of explosive loading on the structural elements' strength. The active phase of explosive loading is exceptionally brief, lasting only a fraction of a second. Under such circumstances, modeling is best performed using explicit methods of direct integration in time.
 The structure considered in this work is a reinforced concrete slab supported by a metal beam cage with I-beam cross-sections, topped with a sand backfill. The study was executed within the SIMULIA Abaqus software suite, incorporating models depicting nonlinear material behavior in a three-dimensional context. Discretely positioned reinforcement was considered for reinforced concrete structures, and the "Concrete Damage Plasticity" model was applied for concrete, accounting for damage accumulation. The devised computational scheme for the shelter represents a section of the protective structure's roof under conditions of cyclic symmetry.
 The article elucidates the core principles of incorporating explosive loading according to algorithm CONWEP.The results demonstrate that during the detonation of a kamikaze drone, an explosive wave created a crater in the sand backfill, exposing the slab. The study illustrates the development of damage in the reinforced concrete slab at various time intervals. Despite the identified damage to the slab, the protective structure overall withstood the explosive load. The intensity of the explosive shock wave diminishes significantly as it propagates away from the explosion site.

Damage quantification of a metallic beam under thermo-mechanical loads using novel empirical correlations and neural network

This research examines the interactions between fracture depth and crack location on a cantilever beam’s dynamic response under thermomechanical loads. The structure’s stiffness is significantly influenced by temperature, and changes in stiffness can alter the response’s damping, frequency, and amplitude. The basis for measuring damage to an Aluminium 2024 specimen under thermomechanical loads is provided by these variations. Cantilever beams are used in experiments that are carried out at elevated temperatures, such as 50°C, 100°C, 150°C, and 200°C, as well as at room temperature (non-heating). This analysis takes into account a cantilever beam with different initial fracture depths and positions. The outcomes of the experimental, analytical, and numerical work are found to be in good accord. This research mainly fill the gaps of recent techniques for structure health monitoring of metallic structures where the coupled loads exist. Dynamic response formulation is presented experimentally on beam for the first time under thermo-mechanical loads. The dynamic parameters vary with material stiffness, thus; this change is also investigated by introducing the temperature as a key variable using a specially designed temperature controller. A novel technique is presented for damage estimation in metallic structures using the experimental data that is currently accessible which is later compared with the neural network approach. This tool helps in finding out and quantifying damagesusing dynamic response, temperature along withfinding of subsurface cracks. The results establisha clearway of diagnosing the crack growth at any particular instant under thermo-mechanical loads within the operational condition.

Dynamic coupling of multi-degrees of freedom constrained-layer vibration neutralizers: A new methodology

Dynamic neutralizers, also known as dynamic absorbers, are efficient means of mitigating vibrations in structures. They have been particularly effective in addressing broad-band passive vibration control in structures with high modal density through the use of multi-degrees of freedom (MDoF) and viscoelastic materials (VEMs). Therefore, sandwich-type or constrained-layer beams can offer great potential when used as MDoF control devices. However, there is limited literature exploring these structures as auxiliary systems, with coupling typically assumed to be single-point and limited to only translational degrees of freedom (DoFs). In this context, this article presents a methodology to determine the dynamic behavior of a compound system, coupling the displacement and rotation DoFs between a metal structure–referred to as the primary system–and a MDoF auxiliary system. The coupling is achieved by utilizing an equivalent dynamic stiffness obtained at the base of the auxiliary system through ANSYS finite-element software, providing a robust and comprehensive approach. A Matlab code transfers the auxiliary system's geometry and properties to ANSYS, where the dynamic stiffness at the base is determined and subsequently coupled to the primary system. A MDoF auxiliary system of the constrained-layer type with VEM was studied, and both single-point and distributed coupling were analyzed. The auxiliary system was attached to a cantilever metal beam for numerical and experimental validation. The proposed generalized equivalent dynamic stiffness model accurately estimates the response of the compound system, offering a 25% reduction in response computation time compared to the finite-element model of the complete compound system. This methodology enables the accurate representation of compound system dynamics while minimizing computational time, making it valuable for the optimal design of a set of MDoF viscoelastic dynamic neutralizers.

A Methodology for Determining the Design Variables of a Metal Beam to Minimize Economic and Environmental Costs

AbstractNowadays, the minimization of energy, costs, and resource consumption of industrial products through their lifecycle is at the center of the industry and research community attention. Ideally, all these factors should be considered during the design phase of the component. Although there are many efforts to formulate indicators that can establish the ecological and economic performance of an artifact, less frequent are the attempts to formalize methods that allow for the identification of design variables as the output of an optimization process that previously includes environmental, energy, and cost requirements. This work is an attempt to formulate a methodology that allows the determination of design variables to be obtained downstream of the analysis, which, bound to the fulfilment of predefined structural requirements, are such as to optimize certain objectives of minimizing monetary and environmental costs. The proposed approach has been specified for a case of study dealing with metal section beams, on which a database has been collected about the environmental and economic characteristics of the sources of supply, the usable materials, and the technological processes. This method allows an accurate modeling of the possible production cycles and, on the basis of this, to formulate functional links between the mechanical properties of the structure and the most representative quantities related to environmental impact and costs.