Structural Design Research Articles

Multitask Learning Deep Neural Networks Enable Embedded Design of Active Metamaterials.

In this study, we propose and implement a deep neural network framework based on multitask learning aimed at simplifying the forward modeling and inverse design process of photonic devices integrating active metasurfaces. We demonstrate and validate our approach by constructing a continuously tunable bandpass filter that is effective in the midwave infrared region. The key to this filter is the combination of a metasurface and Fabry-Perot (F-P) cavity structure of the tunable phase-change material Ge2Sb2Se4Te (GSST) and the precise control of the crystallinity of the GSST by a silicon-based heater. With the help of a deep learning framework, we are able to independently model the crystallinity and geometric parameters of the filter to maximize the use of GSST tuning for bandpass filtering. Our model discusses the self-attention mechanism and the effect of noise and compares several existing popular algorithms, and the results show that a multitask deep learning strategy can better assist the on-demand reverse design of photonic structures with phase change materials. This opens up new possibilities for personalization and functional extension of optical devices.

Piezoelectric Energy Harvester Technologies: Synthesis, Mechanisms, and Multifunctional Applications.

Piezoelectric energy harvesters have gained significant attention in recent years due to their ability to convert ambient mechanical vibrations into electrical energy, which opens up new possibilities for environmental monitoring, asset tracking, portable technologies and powering remote "Internet of Things (IoT)" nodes and sensors. This review explores various aspects of piezoelectric energy harvesters, discussing the structural designs and fabrication techniques including inorganic-based energy harvesters (i.e., piezoelectric ceramics and ZnO nanostructures) and organic-based energy harvesters (i.e., polyvinylidene difluoride (PVDF) and its copolymers). The factors affecting the performance and several strategies to improve the efficiency of devices have been also explored. In addition, this review also demonstrated the progress in flexible energy harvesters with integration of flexibility and stretchability for next-generation wearable technologies used for body motion and health monitoring devices. The applications of the above devices to harvest various forms of mechanical energy are explored, as well as the discussion on perspectives and challenges in this field.

Seismic and Wind Resillence Study of a 15 Story High-Rise Building with Floating Columns in Seismic Zones II & V

The use of floating columns in the construction of high-rise buildings, specifically in the context of G+15 structures in metropolitan cities, as per Indian standards. The structural design of a building is crucial for its durability, strength, stability, and lifespan. Floating columns play a significant role in transferring loads from the floors to the beams, affecting the overall stability of the building.Several factors impact the structural design, including bending moments, shear forces, torsion, and deflection. Due to the growing population in metropolitan areas, there is a need for high-rise buildings that can accommodate both commercial and residential spaces on a single platform. Commercial and residential floors have different load requirements. Therefore, floating columns are specifically used for residential floors to address these varying load demands. The structural analysis considers seismic and wind forces as per Indian standards (IS 1893-2016 for seismic analysis and IS 875-2015 for wind analysis) for different seismic zones (Zone- Ⅱ, Ⅲ, Ⅳ, and Ⅴ). The materials used in the construction include concrete with a grade of M40 and steel with a grade of Fe550. These material grades are commonly used in construction for their respective strength properties. The floor height for residential floors is 3 meters, while commercial floors have a height of 4 meters. This distinction in floor height is considered in the structural design. The design of high-rise buildings, especially in seismic-prone regions, requires a thorough understanding of structural engineering principles and adherence to local building codes and standards to ensure the safety and stability of the structure. The use of floating columns can be a part of a structural design strategy to address varying load requirements in different parts of the building.Safety is paramount in the design and construction of high-rise buildings, particularly in areas susceptible to seismic activity and strong winds.

Ternary heterostructure-driven photoinduced electron-hole separation enhanced oxidative stress for triple-negative breast cancer therapy

Zinc oxide nanoparticles (ZnO NPs) stand as among the most significant metal oxide nanoparticles in trigger the formation of reactive oxygen species (ROS) and induce apoptosis. Nevertheless, the utilization of ZnO NPs has been limited by the shallowness of short-wavelength light and the constrained production of ROS. To overcome these limitations, a strategy involves achieving a red shift towards the near-infrared (NIR) light spectrum, promoting the separation and restraining the recombination of electron-hole (e−-h+) pairs. Herein, the hybrid plasmonic system Au@ZnO (AZ) with graphene quantum dots (GQDs) doping (AZG) nano heterostructures is rationally designed for optimal NIR-driven cancer treatment. Significantly, a multifold increase in ROS generation can be achieved through the following creative initiatives: (i) plasmonic Au nanorods expands the photocatalytic capabilities of AZG into the NIR domain, offering a foundation for NIR-induced ROS generation for clinical utilization; (ii) elaborate design of mesoporous core-shell AZ structures facilitates the redistribution of electron-hole pairs; (iii) the incorporation GQDs in mesoporous structure could efficiently restrain the recombination of the e−-h+ pairs; (iv) Modification of hyaluronic acid (HA) can enhance CD44 receptor mediated targeted triple-negative breast cancer (TNBC). In addition, the introduced Au NRs present as catalysts for enhancing photothermal therapy (PTT), effectively inducing apoptosis in tumor cells. The resulting HA-modified AZG (AZGH) exhibits efficient hot electron injection and e−-h+ separation, affording unparalleled convenience for ROS production and enabling NIR-induced PDT for the cancer treanment. As a result, our well-designed mesoporous core-shell AZGH hybrid as photosensitizers can exhibit excellent PDT efficacy.

Breaking piezoelectric limits of molecules for biodegradable implants

AbstractIn the quest for optimizing biodegradable implants, the exploration of piezoelectric materials stands at the forefront of biomedical engineering research. Traditional piezoelectric materials often suffer from limitations in biocompatibility and biodegradability, significantly impeding their in vivo study and further biomedical application. By leveraging molecular engineering and structural design, a recent innovative approach transcends the conventional piezoelectric limits of the molecules designed for biodegradable implants. The biodegradable molecular piezoelectric implants may open new avenues for their applications in bioenergy harvesting/sensing, implanted electronics, transient medical devices and tissue regeneration.

Comparative analysis of thermal behaviour in functionally graded material fin under convective-radiative heat transfer: Homotopy perturbation method

In this study, the thermal characteristics of a fully wet, moving longitudinal fin made from linear Functionally Graded Material (FGM) is explored. The fin response to convective-radiative heat transfer is examined through three distinct FGM scenarios namely, a Homogeneous material (HM), Functionally Graded Material I (FGM I) having greater thermal grading near the base, and Functionally Graded Material II (FGM II) having increased thermal grading towards the tip. The derived energy equation is a second-order nonlinear ordinary differential equation is solved using the Homotopy Perturbation Method (HPM) compared with results found in the existing literature. The fin thermal profile has been graphically analysed for the thermal conductivity grading parameter (β), Peclet number (Pe) and other pertinent parameters. It is found that the temperature distribution along the fin is highest for the FGM II fin and lowest for the HM fin, with the FGM I fin displaying intermediate values. Efficiency of the fin (η) is discovered to be lowest in the case of HM fin structures followed by FGM I and FGM II fin structures at the base and vice versa at the tip. The results show significant potential of HPM which benefits the manufacture and design of FGM fin structures.

Developments of photo‐/electro‐catalysis based on covalent organic frameworks: A review

AbstractPhoto‐/electro‐catalysis has the characteristics of low cost, high performance, and zero pollution, which meet the policies on environment and energy. Covalent organic frameworks (COFs), a type of crystalline organic skeleton polymers, have been widely applied and investigated in the area of photo‐/electro‐catalysis owing to their advantages of large specific surface area, regular pore size, excellent stability, flexible structural design, and massive active sites. This article reviews the structural characteristics of COFs and the strategies for strengthening the photo‐/electro‐catalytic activity of COF materials. Subsequently, deep insights were put into the photo‐/electro‐catalysis application of COF materials. In the end, the development prospects and challenges faced by COF materials in photo‐/electro‐catalysis are discussed.

The engineering legacy of the FIFA World Cup Qatar 2022™: Stadium 974 – Reuse as driving force for sustainable stadium design

Stadium 974, located on the east shore of the Doha Bay in the municipality of Ras Abu Aboud, is the first fully demountable, transportable, and reusable stadium of its kind. Modular systems in construction have a long track record in the industry but developing and delivering an entire scheme for such a complex venue under the requirements of a FIFA World Cup Stadium was never achieved before. The basis of the innovative concept of a temporary venue is to create a highly repetitive grid of identical structural frames, supporting standardised components: bleachers, concourse slabs and modules carrying containers pre-equipped with all required functions. The venue can then be easily demounted after the event and completely re-installed in another location or repurposed into many small stadia at different locations. The structure consists of a series of steel frames resembling the appearance of a high-bay warehouse separated in different blocks, which e.g. include the stands, concourses, and sanitary fittings. All elements fit in specially modified and certified shipping containers. All individual elements can be dismantled and transported within the certified shipping containers to the next destination. This enables efficient reuse of the material and hence results in a reduced lifetime carbon dioxide footprint due to less construction material and reduced waste. This pioneering scheme posed significant challenges and constraints for the structural design, and required a comprehensive approach, from the development of suitable structural concepts to the implementation in the structural detailing. This paper describes some of those challenges and the design solutions adopted.

A Journey from Structured Emulsion Templates to Multifunctional Aerogels

AbstractInterfacial jamming and assembly, facilitated by nanoparticle surfactant (NPS) complexation, demonstrate a remarkable efficacy in stabilizing multiphase systems, evident in structured liquid streams and structured Pickering emulsions. However, the utilization of structured liquid templates to tune multiple porosity levels of ultra‐flyweight aerogels is barely discussed. In this study, a structured Pickering emulsion is prepared through mixing an aqueous dispersion of graphene oxide (GO) with an organic (hexane) solution containing an active ligand. The emulsion is jetted into the same organic phase, resulting in “dual jamming”. This process produced worm‐like aerogels with porosity that can be precisely tailored at four different levels: i) voids between filaments, ii) cavities produced by evaporation of trapped hexane droplets, iii) pores generated from sublimation of water in the bulk of GO emulsion, and iv) microscopic regions trapped between GO flakes or fractures/holes within GO nanosheets. These aerogels exhibit ultra‐low density (1.67–2.3 mg cm−3), high compressibility, and shape recovery. The multi‐scale porosity, created by structural design, endows aerogels with a record‐level fluid sorption capacity (e.g., 615 g g−1 for chloroform). Additionally, the aerogels demonstrate an absorption‐dominant electromagnetic interference (EMI) shielding mechanism, achieving a remarkable specific EMI shielding (SSE/t) of 67 178 dB cm2 g−1.

Structural Design and Analysis of Home Guard Intelligent Housekeeper Robot

Structural Design and Analysis of Home Guard Intelligent Housekeeper Robot

Neural networks-based spring element for second-order analysis of pile-supported structures with nonlinear soil- structure interaction

This paper proposes a novel structural analysis approach, the neural networks-based spring element (NNSE) method, to synergize machine learning (ML) techniques with the line finite element method (LFEM) for the second-order analysis method of pile-supported structures. Traditional LFEM, widely used in upper structure design, showcases limitations in efficiently modeling complex Soil-Structure Interaction (SSI) along piles since it requires dense element mesh for accuracy. Conversely, ML offers a mesh-free alternative for analyzing single piles but struggles in simulating pile-supported structures as the training sample collection for large-scale problems might be unbearable. This paper addresses these challenges by proposing a new analysis framework to utilize the neural network (NN) model, which only describes structural responses of single piles, for the simulation of entire pile-supported structures. In the proposed method, the NN model is not directly used for structural analysis but employed to formulate a new spring element named the NNSE to model single piles in pile-supported structures. This NNSE can be seamlessly implemented within the existing LFEM framework to analyze pile-supported structures, eliminating the dense mesh requirement for single piles and thereby significantly improving the computational efficiency. Extensive examples are provided to verify the effectiveness of the proposed method, indicating its potential in promoting the second-order analysis method to the design of pile-supported structures.

Dynamic Analysis of the Bolted Joint Structure with Interval Uncertainties

This paper investigates the dynamic influence of joint interfaces in bolted joint structures subjected to uncertain-but-bounded parameters. Firstly, applying the thin layer elements (TLE) represents the contact interfaces with nonuniform stiffness distribution. The stochastic model updating method is employed to identify the uncertain parameters of TLE. Secondly, the Legendre interval method (LIM) is applied to calculate the natural frequencies of bolted lap joints with uncertain parameters. By introducing the elastic modulus of TLE as interval vectors, relations between the natural frequencies and uncertain parameters could be analyzed using the LIM. Furthermore, the dependence of the dynamic response on TLE parameters can be established based on the modal superposition principle. Considering the influence of uncertain parameters, an uncertain acceleration frequency response surrogate function (UAFRSF) is proposed to predict the dynamic behavior and qualitatively analyze the parameter sensitivity of the bolted lap joints. The elastic modulus of TLE in different contact regions is selected as the interval variable. The acceleration frequency responses of the bolted lap joints under uncertain parameters are investigated. Compared with MCs simulations with 200 samples and Chebyshev interval method results, the effectiveness of the proposed method for solving the uncertain acceleration frequency response of bolted lap joints is verified. This research will provide theoretical support for improving the design of aero-engine joint structures.

Development of correlations between various engineering rockmass classification systems using railway tunnel data in Garhwal Himalaya, India

Engineering rockmass classifications are an integral part of design, support and excavation procedures of tunnels, mines, and other underground structures. These classifications are directly linked to ground reaction and support requirements. Various classification systems are in practice and are still evolving. As different classifications serve different purposes, it is imperative to establish inter-correlatability between them. The rating systems and engineering judgements influence the assignment of ratings owing to cognition. To understand the existing correlation between different classification systems, the existing correlations were evaluated with the help of data of 34 locations along a 618-m-long railway tunnel in the Garhwal Himalaya of India and new correlations were developed between different rock classifications. The analysis indicates that certain correlations, such as RMR-Q, RMR-RMi, RMi-Q, and RSR-Q, are comparable to the previously established relationships, while others, such as RSR-RMR, RCR-Qn, and GSI-RMR, show weak correlations. These deviations in published correlations may be due to individual parameters of estimation or measurement errors. Further, incompatible classification systems exhibited low correlations. Thus, the study highlights a need to revisit existing correlations, particularly for rockmass conditions that are extremely complex, and the predictability of existing correlations exhibit high variations. In addition to augmenting the existing database, new correlations for metamorphic rocks in the Himalayan region have been developed and presented that can serve as a guide for future rock engineering projects in such formations and aid in developing appropriate excavation and rock support methodologies.

Image‐based inertial impact test for viscoelastic constitutive identification: A digital replica for error quantification

AbstractPolymers find widespread use in applications where they are subjected to impact loading. Therefore, understanding the time dependence of their mechanical response is critical to the design of structures subjected to these high strain rate environments. However, characterising these materials on microsecond time scales has proven challenging. Traditional experimental techniques rely on satisfying a number of limiting assumptions and typically do not provide direct measurements of the material parameters. Here, we propose a novel implementation of the image‐based inertial impact (IBII) test to extract viscoelastic constitutive parameters on these microsecond time scales using the stress gauge implementation of the virtual fields method. We validate the experiment using a digital replica approach in which the constitutive parameters are first extracted on a finite element model of an IBII test on a viscoelastic material. The finite element data are then used to synthetically deform computer‐generated grid images, which are then polluted with grey‐level noise to simulate the images that would be captured in a real‐life experiment. These images are processed identically to a physical experiment, and the identification is repeated using the full‐field displacements extracted from the computer‐generated images to determine the ideal processing parameters. Parameter identification was found to strongly depend on the processing parameters used to extract the kinematic fields from full‐field images, emphasising the need for computational validation before attempting a physical experiment to extract constitutive parameters. The IBII experimental method was found to be capable of simultaneously identifying the bulk modulus and the shear modulus along with their associated time constant.

Freestanding Ammonium Vanadate Composite Cathodes with Lattice Self-Regulation and Ion Exchange for Long-Lasting Ca-Ion Batteries.

Calcium-ion batteries (CIBs) have emerged as a promising alternative for electrochemical energy storage. The lack of high-performance cathode materials severely limits the development of CIBs. Vanadium oxides are particularly attractive as cathode materials for CIBs, and preinsertion chemistry is often used to improve their calcium storage performance. However, the room temperature cycling lifespan of vanadium oxides in organic electrolytes still falls short of 1000 cycles. Here, based on preinsertion chemistry, the cycling life of vanadium oxides is further improved by integrated electrode and electrolyte engineering. Utilizing a tailored Ca electrolyte, the constructed freestanding (NH4)2V6O16·1.35H2O@graphene oxide@carbon nanotube (NHVO-H@GO@CNT) composite cathode achieves a 305 mAh g-1 high capacity and 10000 cycles record-long life. Additionally, for the first time, a Ca-ion hybrid capacitor full cell is assembled and delivers a capacity of 62.8 mAh g-1. The calcium storage mechanism of NHVO-H@GO@CNT based on a two-phase reaction and the exchange of NH4 + and Ca2+ during cycling are revealed. The lattice self-regulation of V─O layers is observed and the layered vanadium oxides with Ca2+ pillars formed by ion exchange exhibit higher capacity. This work provides novel strategies to enhance the calcium storage performance of vanadium oxides via integrated structural design of electrodes and electrolyte modification.

A study on the optimal design of UAM seats

The objective of this study is to enhance the efficiency of urban air mobility (UAM) air transportation by determining the optimal design, materials, and processes of seven different manufactured fiber-reinforced plastics (FRP), and to confirm their applicability for next-generation UAM aircraft seats. Structural designs for the aircraft seat models were carried out using carbon fiber-reinforced plastic (CFRP), glass fiber-reinforced plastic (GFRP), and GFRP chop materials, employing Autoclave, Hot-press, and vacuum-assisted resin transfer molding (VaRTM) processes, resulting in a total of seven FRP configurations. It was confirmed that CFRP seats were 50% lower weight than aluminum models, while GFRP seats showed a 30% reduction. Although Autoclave processing resulted in the highest tensile strength at 985[Formula: see text]MPa, VaRTM processing also produced strength levels comparable to Autoclave processing. Structural integrity assessments of the seat models, utilizing the Korean aviation standards (KAS), confirmed that the designed seat models exhibited no failure or deformation under the conditions required by the technical standards. This study provides insights into the potential application of the seven types of FRP materials in the design of aircraft seats, offering weight reduction benefits and meeting the structural integrity requirements outlined by KAS.

Numerical Simulation of Flow Field Structure of Vanadium Redox Flow Battery and its Optimization on Mass Transfer Performance

Abstract The structural design of the flow channel of a redox flow battery directly affects ion transport efficiency, electrode overpotential, and stack performance during charge-discharge cycles. A tapered hierarchical interdigitated flow field design that has independent flow channel structures for different levels of flow was developed in this work. Especially, the secondary branch channels are the tapered type and the corresponding cross-sections are gradually reduced along the flow direction, which is beneficial for improving the flow rate at the end of channels and enhancing mass transfer. The performances of a vanadium redox flow battery with interdigitated flow field, hierarchical interdigitated flow field, and tapered hierarchical interdigitated flow field were evaluated through 3D numerical model. The results showed that at 240 mA/cm2 and 6 mL/s, the pump-based efficiency of the hierarchical interdigitated flow field increased by 4%-7% compared with the interdigitated flow field. Furthermore, the pump-based efficiency with tapered hierarchical interdigitated flow field increased by 1.6%-3% compared with the hierarchical interdigitated flow field. This indicates that the tapered hierarchical interdigitated flow field shows further advantages in redox flow battery applications.

Strength classes of brazilian hardwoods for structural design

For the elaboration of projects on timber structures, the Brazilian standard (ABNT, in Portuguese Associação Brasileira de Normas Técnicas) 7190 (ABNT 1997) ensures the correct application of physical-mechanical properties according to strength classes of lignocellulosic materials. This procedure eliminates the need for botanical identification of woods, since these strength classes support the efficient utilization of a wide range of woody varieties available in Brazil. Due to high mechanical resistances, the hardwoods are usually applied for structural projects of timber construction. This Brazilian standard document prescribes four strength classes (C20, C30, C40 and C60) for these woods, which are determined by characteristic value from the compressive strength parallel to the grain (fc0,k). But, these classes were obtained from experimental outcomes using a few wood varieties. The reorganization of strength classes should result in the best use of mechanical potentials of woods since the updating of these categories leads to the optimization of structural projects for timber construction in order to reposition this biomaterial at even more competitive levels. In this context, the present study aims to verify the current strength classes of hardwoods and if they lead to a good allocation of the fc0,k characteristic values. Otherwise, new strength classes can be determined for better allocations for efficient structural uses. As a result, 56 hardwoods were considered using 672 experimental determinations. Statistically, the current categories can lead to 12,5 % of incorrectly allocated values. The inclusion of C50 and C70 classes allow greater representation for these categories, in order to optimize the use of the hardwoods given the new strength classes. These findings ought to support future revisions of this Brazilian standard document.

Fast Aerodynamic Prediction of Airfoil with Trailing Edge Flap Based on Multi-Task Deep Learning

Conventional methods for solving Navier–Stokes (NS) equations to analyze flow fields and aerodynamic forces of airfoils with trailing edge flaps (TEFs) are known for their significant time cost. This study presents a Multi-Task Swin Transformer (MT-Swin-T) deep learning framework tailored for swift prediction of velocity fields and aerodynamic coefficients of TEF-equipped airfoils. The proposed model combines a Swin Transformer (Swin-T) for flow field prediction with a multi-layer perceptron (MLP) dedicated to lift coefficient prediction. Both networks undergo gradient updates through the shared encoder component of the Swin Transformer. Such a trained network model for computational fluid dynamics simulations is both effective and robust, significantly improving the efficiency of complex aerodynamic shape design optimization and flow control. The study further investigates the impact of integrating multi-task learning loss functions, skip connections, and the network’s structural design on prediction accuracy. Additionally, the effectiveness of deep learning in improving the aerodynamic simulation efficiency of airfoils with TEF is examined. Results demonstrate that the multi-task deep learning approach provides accurate predictions for TEF airfoil flow fields and lift coefficients. The strategic combination of these tasks during network training, along with the optimal selection of loss functions, significantly enhances prediction accuracy compared with the single-task network. In a specific case study, the MT-Swin-T model demonstrated a prediction time that was 1/7214 of the time necessitated by CFD simulation.

METHOD FOR CALCULATING THE BEARING CAPACITY OF A SCREW PILE WITH A SPIRAL BLADE BY THE SOIL

Purpose. The purpose of the scientific article is to study and substantiate the principle methodology for calculating the bearing capacity of a screw pile with a spiral blade on the basis of field tests of a prototype pile using existing methods of theoretical calculation of similar piles. Determination of the bearing capacity of a pile with a spiral blade by the soil according to the first limit state. Also, the goal is to determine certain regularities in the modeling of pile structure. Methodology. A metal elements pile is used as a test sample. Determination of the theoretical bearing capacity of the pile in the vertical direction is conducted using formulas and calculation data from Appendix H.5 (DBN B.2.1-10-2009, 2011). The basic solution is that the load-bearing capacity of the pile is achieved due to the adhesion of each individual blade to the soil, which in total reflects the final value of the load-bearing capacity of the pile. Findings. Six experimental piles were installed and tested with static axial compressive and pullout loads. The estimated compressive, pullout and horizontal loads allowed for test piles, turned in to the design mark and tested without soaking subsoils, were determined. In this work, on the basis of experiments, the possibility of using the calculation data existing in the regulatory documentation as a justified theoretical calculation of pile-based foundations in the design of buildings and structures in general with the use of piles with a spiral blade is proven. Originality. A refined mathematical dependence for determining the bearing capacity of a screw pile with a spiral blade by the soil is proposed and the possibility of its use is confirmed experimentally. Practical value. The proposed method makes it possible to substantiate and use screw piles with a spiral blade for pile foundations.