Lattice Shell Research Articles

Infiltrated electroless deposition of gold nanoparticles on porous Prussian blue-Fe2O3 hetero-microstructures for environmental remediation applications: A novel infiltration strategy to form 3-D nano-catalytic networks

Metal and metal oxide nanocomposites are promising candidates for heterogeneous catalytic applications. In this regard, most of the metal oxide inner core volume remains as a dead volume, not participating in the catalysis, only the metal/metal oxide hetero-junctions available at the surfaces are involved in the catalysis. Herein, we report a novel strategy for the infiltration of gold nanoparticles into the inner core of 3D-porous Prussian blue/Fe2O3 hetero-microstructures (PBFHM-Au) beyond its outer surface to form an advanced heterogeneous catalyst for the environmental remediation applications. The porosity of the Prussian blue microstructures is thermally tuned for the infiltration of gold ion precursor into the inner core volume of Prussian blue/Fe2O3 hetero-microstructures to facilitate the galvanic displacement reaction between Fe and Au to enlarge the lattice shell and form Au nanoparticle 3D networks throughout the PBFHM. Notably, the resulting PBFHM-Au2 shows enhanced structural stability electron transfer kinetics and catalytic activity in comparison with the only surface-attached Au/Fe2O3 composite. The obtained PBFHM-Au2 catalyst demonstrates remarkable catalytic activity for Rhodamine-B dye degradation with rate constant (k = 3.47 × 10−2 s−1) and p-nitrophenol reduction reactions with rate constant (k = 1.199 × 10−1 s−1).

Study on static performance and dynamic characteristics of a spoke cable-truss suspen-dome system

The proposed spoke cable-truss suspen-dome structure is a new structure system based on the traditional chord-supported dome structure. In this structure, the upper lattice shell is modified to a radial cable-truss structure. The lower part of the structure is a cable network structure composed of radial cables, ring cables and radial cables. There are few research results on the mechanical properties of the new structure, so a 1:10 scale model is established, multi-condition static loading test, local cable force failure test and natural vibration characteristic test are carried out, and the measured results are compared with the finite element results. The changes of axial force and joint displacement under different loads, the changes of static properties under cable damage and the dynamic characteristics of the structure are obtained. The results show that the loading method adopted meets the test accuracy requirements. Under the action of uniform load, the upper chord, the lower chord end and the inner ring truss of the main truss are in a pure compression state. The middle bar of the lower chord span and the outer ring truss change from the compression state to the tension state with the increase of load. The structure is still in the elastic stage when part of the cable fails, and the coordinated deformation ability is strong. The base frequency of the measured structure is 7.97 Hz, and the stiffness distribution is uniform.

Intelligent Prediction of Stability Bearing Capacity of New-Type Modular Assembled Latticed Shells with Flange Connections

Intelligent Prediction of Stability Bearing Capacity of New-Type Modular Assembled Latticed Shells with Flange Connections

Experimental Study on Small-Scale Shake Table Testing of Cable-Stiffened Single-Layer Spherical Latticed Shell

The cable-stiffened single-layer latticed shell is an innovative structural design that achieves a perfect balance between lightweight and stability by combining cables and a latticed shell. However, the study on dynamic response and failure mechanism of cable-stiffened single-layer latticed shell under seismic action is still lacking. Therefore, small-scale shaking table tests of two kinds of single-layer spherical latticed shells are carried out; the dynamic response and failure mode of the two shells under sine wave earthquake are investigated by using time history analysis. The conclusions show that the introduction of the prestressed cable plays an important role in improving the seismic performance of the single-layer latticed shell, and the cable-stiffened single-layer latticed shell has better load capacity and seismic performance under earthquake action than the ordinary single-layer latticed shell structure.

Seismic vulnerability analysis of single-layer lattice shells with different rise-to-span ratios: Focusing on the selection of Sa(T1)-based intensity measures

This study conducted a detailed examination of seismic vulnerability across different limit states for Schwedler single-layer lattice shells with differing rise-to-span ratios. A comparative analysis of seismic intensity measures, particularly those centered around Sa(T1), was performed to evaluate their effectiveness in vulnerability analysis. To comprehensively address the inherent uncertainties in seismic actions, the study selected a dual set of ground motion scenarios, encompassing both far-field and pulse-type near-field events. A novel approach was employed, integrating a multi-indicator seismic performance assessment model based on the residual seismic safety framework, aiming to thoroughly quantify the cumulative seismic damage to lattice structures. Utilizing the multiple stripes analysis technique enabled the efficient generation of analytical results for vulnerability assessments at various damage thresholds. The findings revealed that lattice shells with larger rise-to-span ratios exhibit increased seismic robustness, notably with far-field seismic events causing more significant damage than their pulse-type near-field counterparts. Furthermore, the study determined that employing seismic intensity measures which consider the effects of higher modes significantly reduces variability in the vulnerability analysis when dealing with pulse-type near-field seismic activity. As a result, the use of the seismic intensity measure IM123 is recommended for assessing the vulnerability of lattice shells with varying rise-to-span ratios, under both far-field and near-field seismic conditions.

Global interactive-mode imperfection generation for K6 single-layer latticed shell using generative adversarial networks

The worst imperfection shape of K6 single-layer latticed shells corresponding to the lowest nonlinear load-carrying capacity is difficult to be obtained in design owing to significant multi-modal interaction. The global interactive buckling of the K6 single-layer latticed shell is investigated numerically, and the intelligent model for generating its worst global interactive-mode imperfection is developed via generative adversarial networks (GAN). For the cases vulnerable to interactive buckling, the load-carrying capacity is found to be reduced significantly up to 35% with two-mode interaction considered, and unstable behaviour, such as the dominant mode changing due to the deformation evolution of different modal components, is observed at the post-buckling stage. Moreover, the GAN model for generating the worst imperfection shape and the artificial neural network for evaluating the corresponding ultimate load are developed based on the data obtained from numerical analysis. The time of training model to converge is less than 30 min, and the generating process using the trained model only takes a few seconds. It is demonstrated that for the K6 single-layer latticed shells, the developed models can give the worst imperfection and the corresponding ultimate load accurately and efficiently with interactive buckling considered well. This work can be used to develop the programming module for the intelligent design of latticed shells in future.

Static Stability Behavior-Based Seismic Damage Endurance Assessment of Long-Span Single-Layer Spherical Lattice Shells

ABSTRACT This paper presents a modified evaluation approach for the structural-capacity-reserve (SCR) based on the static stability behavior of single-layer spherical lattice shells to achieve more accurate assessment results of seismic damage endurance. The SCR index in this paper is calculated by integrating the redefined residual structural capacity (RSC) ratio based on post-earthquake static stability behavior within the range of damage degrees caused by strong earthquakes. Compared with the assessment work for seismic damage endurance in the existing literature, the proposed RSC ratio in this paper could take into account both ultimate load-bearing strength and residual deformation. Additionally, the specific quantitative indicator in the proposed assessment method should also be determined according to whether the residual nodal displacement of the lattice shell after an earthquake exceeds the limit value state specified by the design code. The numerical results in the case study indicate that the residual load-bearing strength of the lattice shell remains relatively constant under the same damage state induced by different earthquakes, with residual deformation significantly impacting the assessment of seismic damage endurance. Thereby, the required RSC can be controlled by reducing the residual nodal displacements of the lattice shell under strong earthquakes to achieve a well-balanced design scheme.

Multi-objective shape-section optimization of free-form latticed shells using the RBF-NSGA-II algorithm

In this study, a novel RBF-NSGA-II optimization framework based on the response surface methodology (RSM) and the constrained NSGA-II algorithm is proposed to simultaneously improve the static, nonlinear stability and economic performance of free-form latticed shells. The bending stiffness of joints is innovatively considered one of the design variables for shape-member section coupled optimization. The augmented radius basis functions (RBFs) are adopted to develop the metamodels of both the objectives and constraints. The improved minimum distance selection method (TMDSM) is used to select the optimal solution from the Pareto optimal solution set. Moreover, three alternative solutions are presented as supplements to meet various engineering requirements. The proposed RBF-NSGA-II algorithm is validated to have high accuracy for multi-objective optimization problems with high nonlinearity. Compared with those of the initial structures, the strain energy and steel consumption of the optimal structure decreased by 82.23 % and 17.97 %, respectively, while the buckling load considering both the geometric nonlinearity and material nonlinearity increased by 1.2 times. The involvement of the joint stiffness is demonstrated to have a great influence on the multi-objective optimization results. It is necessary to consider the joint stiffness as one of the design variables during shape-member section coupled optimization.

Mechanical performance of a kind of bolted joint for single-layer latticed shells under pure bending

In this paper, a kind of bolted joint with separated joint-body is creatively proposed. The mechanical properties of the bolted joints in the pure bending state are studied through theoretical calculation, test and finite element simulation. Based on the component method, a simplified mechanical model is proposed. The formulas of the initial rotational stiffness and the yield moment of the joint are derived. For the bolted joints, seven groups of test specimens with different typical parameters are designed. The mechanical performance tests of joints under pure bending are carried out. The influences of the joint-body form and the joint parameters on the mechanical properties of joints are obtained. Finally, the determination methods and the recommended values of the key parameters of the joint are given, which provides a basis for the design of the single-layer latticed shell with new bolted joints.

Numerical investigation of three-dimensional isolator and mitigation for single-layer lattice shell structure

Three-dimensional (3D) isolators need to have capabilities to support the dead weight of superstructures and mitigate both horizontal and vertical seismic responses of structures. However, the lack of self-centering capability under horizontal loadings and large stiffness under vertical loadings of the 3D isolators might limit their isolation performance in practical engineering. This study presents a novel 3D isolator (hereinafter referred to as DS-SMA-FS) to achieve self-centering capability under horizontal loadings and quasi-zero stiffness under vertical loadings. The self-centering capability is provided by shape memory alloys U-shaped dampers (SMA-UDs), and the quasi-zero stiffness (QZS) property is realized by the negative stiffness of disc spring (DS) isolator and positive stiffness of SMA-UDs. The working mechanism and analytical model of the DS-SMA-FS isolator were developed first. The finite element model of the DS-SMA-FS isolator was furtherly established. Numerical results revealed that DS-SMA-FS can exhibit SC capability under horizontal loadings and QZS property under vertical loadings. Subsequently, single-layer lattice shells were established to explore the isolation performance of the DS-SMA-FS isolator. Structural analysis results indicated that the DS-SMA-FS isolator can prolong the natural vibration periods of the shell and effectively prevent the shells from tri-directional earthquakes.

Highly Sensitive, Stable InP Quantum Dot Fluorescent Probes for Quantitative Immunoassay Through Nanostructure Tailoring and Biotin-Streptavidin Coupling.

Nontoxic, highly sensitive InP quantum dot (QD) fluorescent immunoassay probes are promising biomedical detection modalities due to their unique properties. However, InP-based QDs are prone to surface oxidation, and the stability of InP QD-based probes in biocompatible environments remains a crucial challenge. Although the thick shell can provide some protection during the phase transfer process of hydrophobic QDs, the photoluminescence quantum yield (PLQY) is generally decreased because of the contradiction between lattice stress relaxation and thick shell growth. Herein, we developed thick-shell InP-based core/shell QDs by inserting a ZnSeS alloy layer. The ternary ZnSeS intermediate shell could effectively facilitate lattice stress relaxation and passivate the defect states. The synthesized InP/ZnSe/ZnSeS/ZnS core/alloy shell/shell QDs (CAS-InP QDs) with nanostructure tailoring revealed a larger size, high PLQY (90%), and high optical stability. After amphiphilic polymer encapsulation, the aqueous CAS-InP QDs presented almost constant fluorescence attenuation and stable PL intensity under different temperatures, UV radiation, and pH solutions. The CAS-InP QDs were excellent labels of the fluorescence-linked immunosorbent assay (FLISA) for detecting C-reactive protein (CRP). The biotin-streptavidin (Bio-SA) system was first introduced in the FLISA to further improve the sensitivity, and the CAS-InP QDs-based SA-Bio sandwich FLISA realized the detection of CRP with an impressive limit of detection (LOD) of 0.83 ng/mL. It is believed that the stable and sensitive InP QD fluorescent probes will drive the rapid development of future eco-friendly, cost-effective, and sensitive in vitro diagnostic kits.

Design of lattice cylindrical shell meta-structures for broadband vibration reduction and high load-bearing capacity

In this paper, a new type of lattice cylindrical shell meta-structure (LCSM) with broadband vibration reduction and high load-bearing ability is designed. In particular, the proposed curved shell meta-structure is constructed by combining lattice structure and mechanical metamaterial with elastic bandgap properties. The dispersion curves of shell structure are obtained by combining Bloch's theorem with the coordinate transformation method. The vibration transmission properties and load-bearing performance of the LCSM and the sandwich LCSM are studied numerically and experimentally. The results reveal that the proposed meta-structure has excellent vibration isolation performance at broadband frequencies, and the change of structural parameters can be used to regulate the frequency range of bandgap. Especially, the existence of curvature makes the bandgap of the shell structure inevitably change when the circumferential size of the shell is changed. Moreover, the meta-structure can maintain certain broadband vibration reduction properties when increasing the load-bearing capacity. This work offers an innovative method to develop multi-functional lattice shell structures with both load-bearing and broadband vibration isolation properties.

Rotational Stiffness Investigation and Parametric Analysis of a Novel Assembled Joint in Lattice Shells

Although there are currently many types of lattice shell joints with different characteristics, assessing the flexural capacity of lattice shell joints is always a great challenge. In this paper, a fan-shaped assembled joint and a welded joint for comparison were subjected to bending tests to investigate the flexural behavior and rotational stiffness of the assembled joint. The strain distribution, load–displacement curve, moment–rotation curve, and damage modes of key parts were analyzed to determine the vulnerable parts of the joints. Our test results show that, with an initial rotational stiffness of about one third of that of the welded joint, the assembled joint specimen exhibits the obvious characteristics of a semi-rigid joint. The finite element analysis results were in good agreement with the experimental results. The results of our parametric analysis show that the rotational stiffness and ultimate moment of the assembled joint increase with increases in the spacing of the bolts and the number of bolts. The performance of the high-strength bolts had a significant influence on the flexural stiffness of the assembled joints. The spacing of the bolts and the number of bolts for the assembled joint are suggested to be greater than the height of the member section and more than three, respectively. The proposed theoretical formula can approximately simulate the initial rotational stiffness of the joint. More in-depth investigations are required in the future for assessing the mechanical behavior of FSA joints subjected to combined bending–compression loads.

Composite anisogrid lattice toroidal shell: Application to a load-carrying rim of the spacecraft reflectarray antenna

A novel design of the composite transformable/foldable rim of the spacecraft reflectarray antenna is presented in the paper. The rim is made in the form of anisogrid lattice toroidal shell split into six parts that are jointed using hinges containing helical springs. The springs create the moments required to deploy the antenna in orbit. A dielectric flexible flat membrane with reflective radiating elements generating a radio signal with required directivity is stretched on the rim. An algorithm of the finite-element model generation is developed for the toroidal rim using a typical finite-element unit cell of lattice structure. The lattice toroidal shell is modelled as a three-dimensional frame composed of curvilinear ribs. The results of design analysis of the lattice rim delivering a minimal mass to its structure subject to constraints imposed on the fundamental frequency, values of stress, and the buckling load factor are presented in this work. The corresponding set of design parameters of lattice structure, including the angle of orientation of helical ribs, number of helical ribs of one orientation, and size of the ribs’ cross section are identified based on these results.

Experimental study on the hysteretic behavior of aluminum alloy gusset joint with rectangular hollow sections

Aluminum alloys were extensively applied in single-layer latticed shells owing to their exceptional mechanical properties, outstanding corrosion resistance, and aesthetic appeal. In traditional aluminum alloy grid shell structures, H-section components were widely utilized. However, the H-section components exhibited poor self-stability compared to rectangular hollow sections, whose limitation constrains the utilization of aluminum alloy single-layer latticed shells. To overcome this problem, a named ARH (Aluminum Rectangular Hollow) joint was developed using BOM bolts by some scholars, and the out-of-plane bending behavior was studied. This paper conducted out-of-plane hysteretic tests on four ARH joints with different bolt numbers and gusset thicknesses. Subsequently, a finite element model was developed to simulate the hysteretic behavior of the ARH joint. The simulation results were compared with the test results to verify the accuracy of the model. Then, a series of parameter analyses based on the developed finite element model were conducted. For the ARH joint, Analysis results showed that the decrease in bolt numbers and gusset thicknesses resulted in the weakening of the stiffness and bearing capacity, and the increase of bolt-hole diameters resulted in elevated slip deformation. Moreover, in gusset joints, joints with rectangular hollow sections have greater out-of-plane bending resistance compared to joints made from H-sections with the same section height and flange thickness.

Mechanical Properties and Energy Absorption of Integrated AlSi10Mg Shell Structures with BCC Lattice Infill

Shell-infill structures comprise an exterior solid shell and an interior lattice infill, whose closed features yield superior comprehensive mechanical performance and light weight. Additive manufacturing (AM) can ensure the fabrication of complex structures. Although the mechanical behaviors of lattice structures have been extensively studied, the corresponding mechanical performances of integrated-manufactured shell structures with lattice infills should be systematically investigated due to the coupling effect of the exterior shell and lattice infill. This study investigated the mechanical properties and energy absorption of AlSi10Mg shell structures with a body-centered cubic lattice infill fabricated by AM. Quasi-static compressive experiments and corresponding finite element analysis were conducted to investigate the mechanical behavior. In addition, two different finite element modeling methods were compared to determine the appropriate modeling strategy in terms of deformation behavior. A study of different parameters, including lattice diameters and shell thicknesses, was conducted to identify their effect on mechanical performance. The results demonstrate the mechanical advantages of shell-infill structures, in which the exterior shell strengthens the lattice infill by up to 2.3 times in terms of the effective Young’s modulus. Increasing the infill strut diameter can improve the specific energy absorption by up to 1.6 times.

Analysis of Latticed Composite Shells Taking into Account the Edge Effect

Analysis of Latticed Composite Shells Taking into Account the Edge Effect

Shaking table tests on seismic behaviors of a single-layer spherical lattice shell with shape memory alloy-controlled friction pendulum bearings

An innovative seismic isolation device incorporating a friction pendulum bearing (FPB) and vertically aligned shape memory alloy (SMA) strands is proposed for the seismic control of spherical lattice shells located in strong-earthquake regions. To validate the effectiveness of the proposed SMA-FPBs experimentally, a 1/10-scale single-layer spherical lattice shell test structure and a set of isolators were designed and fabricated. A shaking table was used to apply various three-dimensional seismic excitations to test structures equipped with and without different isolation bearings (SMA-FPBs or bare FPBs). Significant seismic behavior enhancements were observed when such isolation systems were used. However, bare FPBs cannot accommodate excessive displacements induced by high seismic intensities owing to their lack of adaptive control. In contrast, SMA-FPBs exhibited satisfactory control performance in terms of the peak and residual bearing displacements under fortification and rare seismic actions, and the adaptive properties of the SMA-FPBs protected the isolators from disassembly owing to excessive sliding displacements under extremely rare earthquakes, even though their re-centering abilities decreased slightly because of the failure of several SMA wires. Finally, the larger number of SMA wires in an SMA-FPB enhanced its restraining capacity against peak bearing displacement rather than improving the seismic responses of structural nodes and members.

Research Progress of Lattice Shell Structure based on Kagome

The composite material shell structure has the characteristics of light weight, high strength and wide application scenarios, and has been widely used in the aerospace field in recent years. This paper first summarizes the structure, preparation process and mechanical properties of Kagome; secondly, discusses the preparation process, improvement and development of the lattice shell structure and mechanical properties in detail; finally, the application outlook and development direction of the material are forcasted.

Mechanical behavior of aluminum assembled hub joints under combined bending moment and axial force

Joints in single-layer latticed shells are mainly subjected to combined bending moment and axial force. The value and direction of the axial force may have a significant influence on the flexural capacity and stiffness of the joint systems. Therefore, the combined effect of the bending moment and axial force should be fully considered when evaluating the mechanical performance of a novel joint system. In this paper, the eccentric bearing capacities and failure modes of aluminum assembled hub (AAH) joints are investigated by laboratory tests and numerical studies. The correlation formula between the axial capacity and the bending capacity of AAH joints is derived by nonlinear regression to guide the actual design. In addition, the variation in the initial bending stiffness with the axial force-to-moment ratio λ corresponding to different force states is further evaluated. The results indicate that under combined loads, the axial capacities of AAH joints are positively related to λ while the bending capacities are negatively related to λ. It is demonstrated that λ has a significant influence on the initial bending stiffness of AAH joints in large eccentric tension state and large eccentric compression state, which should be fully considered in the stability analysis of aluminum single-layer latticed shells with AAH joints.