Structural Performance Research Articles

Micro/meso-porous Double-shell Hollow Carbon Spheres through Spatially Confined Pyrolysis for Supercapacitors and Zinc-ion Capacitor.

Energy storage in supercapacitors and hybrid zinc ion capacitors (ZIC) using porous carbon materials offers a promsing alternative method for clean energy solutions. The unique combination of hierarchical porous structure and nitrogen doping in these materials has demonstrated significant capacity for energy storage. Nevertheless, the full potential of these materials, particularly the relationship between pore structure configuration and performance, remains underexplored. Herein, a confined pyrolysis strategy based on the polymerization characteristics of polydopamine (PDA) was developed to construction of hollow carbon spheres with microporous/mesoporous dual shell structure. The depth of micropores and cavity can be controlled by adjusting the duration of heat treatment and hydrothermal treatment, in accordance with the decomposition and polymerization characteristics of PDA. Due to the elasticity of this structure, the relationship between the micro/mesoporous depth of the prepared carbon spheres and the energy storage performance in supercapacitors and ZIC is established. Through optimizing the ion transport capacity of carbon spheres and considering the influence of its internal cavity structure on energy storage, the resulting carbon spheres exhibit high specific capacitance of 389 F g-1 in supercapacitor and specific capacitance of 260 F g-1 and excellent stability with 99.3% retention after 30000 chare/discharge cycles in ZIC.

Hybridization of Polymer-Encapsulated MoS2-ZnO Nanostructures as Organic–Inorganic Polymer Films for Sonocatalytic-Induced Dye Degradation

The development of environmentally friendly technology is vital to effectively address the issues related to environmental deterioration. This work integrates ZnO-decorated MoS2 (MZ) to create a high-performing PVDF-based PVDF/MoS2-ZnO (PMZ) hybrid polymer composite film for sonocatalytic organic pollutant degradation. An efficient synergistic combination of MZ was identified by altering the ratio, and its influence on PVDF was assessed using diverse structural, morphological, and sonocatalytic performances. The PMZ film demonstrated very effective sonocatalytic characteristics by degrading rhodamine B (RhB) dye with a degradation efficiency of 97.23%, whereas PVDF only degraded 17.7%. Combining MoS2 and ZnO reduces electron–hole recombination and increases the sonocatalytic degradation performance. Moreover, an ideal piezoelectric PVDF polymer with MZ enhances polarization to improve redox processes and dye degradation, ultimately increasing the degradation efficiency. The degradation efficiency of RhB was seen to decrease while employing isopropanol (IPA) and p-benzoquinone (BQ) due to the presence of reactive oxygen species. This suggests that the active species •O2− and •OH are primarily responsible for the degradation of RhB utilizing PMZ2 film. The PMZ film exhibited improved reusability without substantially decreasing its catalytic activity. The superior embellishment of ZnO onto MoS2 and effective integration of MZ into the PVDF polymer film results in improved degrading performance.

Enhancing the Structural Integrity and Performance of an Agricultural Robot with Caterpillar Tracks: A Comprehensive Deformation Analysis

Enhancing the Structural Integrity and Performance of an Agricultural Robot with Caterpillar Tracks: A Comprehensive Deformation Analysis

Investigating post-earthquake progressive collapse resistance of irregular steel structures

Removal of load-bearing elements such as columns, can rapidly lead to structural failures and the compromise of building stability. These failures can be initiated by minor damage but can ultimately culminate in catastrophic events. In the line of progressive collapse resistance of conventional urban buildings, extensive studies have so far been performed; though relatively little attention has been paid to the impact of earthquakes on structural resilience under such failures, this is particularly the case in irregular structures as these structures have hardly received much attention. In this research, considering the presence of setback irregularities in many structures, the impact of the column removal scenario after different earthquake intensities of low, medium, and high on over 60 steel moment frame structures with 5 and 10 stories is investigated. The structures are first categorized into four vulnerability groups, from maximum to minimum resistance against progressive collapse, based on the damage percentage. After applying 12 earthquake records at the MCE level, the cases studied are assessed under column removal scenarios at different spans and stories. The results reveal that earthquakes, elevate the risk of progressive collapse. Moreover, increasing setback irregularity up to 13.33 % improves structural performance against progressive collapse, reducing responses by 21 % on average compared to regular structures. However, at higher setback irregularity percentages, responses increase by 82 % on average, diminishing structural resistance. Setting upper limits for this type of irregularity and imposing constraints on design parameters, while modifying minimum base shear and maximum period limit, can significantly reduce progressive collapse potential.

Characterization of damage to steel bridge girders subjected to over-height vehicle collision

Bridge structures that span roads and highways are often at the risk of over-height vehicle collision. Such collisions can cause structural damage to bridge girders, adversely affecting the bridge's safety and functionality, while posing an immediate hazard to traveling motorists. To ensure the structural integrity of the bridge girders, it is imperative to evaluate them in response to the loading demand induced by over-height collisions. However, current specifications and codes do not have the details necessary to predict the impact forces that steel bridge girders can experience during such collisions. To address this gap, a comprehensive investigation was conducted in this study to (i) determine impact force characteristics, (ii) evaluate various impact-induced structural response measures, and (iii) identify design parameters in need of attention to minimize the extent of impact-induced damage to steel girders. For this purpose, nonlinear finite-element models were developed and validated with experimental tests and field surveys. The structural performance of the steel bridge girders was then investigated, in terms of damage patterns, girder displacements and rotations, shear forces and bending moments, and impact forces, during a range of over-height collision scenarios. Based on the obtained results, predictive equations were developed to estimate the mean impact force. This was to facilitate the impact-resistant design of steel girders commonly used in bridge structures.

Topology Optimization Via Spatially-Varying TPMS.

Structural design with multi-family triply periodic minimal surfaces (TPMS) is a meaningful work that can combine the advantages of different types of TPMS. However, very few methods consider the influence of the blending of different TPMS on structural performance, and the manufacturability of final structure. Therefore, this work proposes a method to design manufacturable microstructures with topology optimization (TO) based on spatially-varying TPMS. In our method, different types of TPMS are simultaneously considered in the optimization to maximize the performance of designed microstructure. The geometric and mechanical properties of the unit cells generated with TPMS, that is minimal surface lattice cell (MSLC), are analyzed to obtain the performance of different types of TPMS. In the designed microstructure, MSLCs of different types are smoothly blended with an interpolation method. To analyze the influence of deformed MSLCs on the performance of the final structure, the blending blocks are introduced to describe the connection cases between different types of MSLCs. The mechanical properties of deformed MSLCs are analyzed and applied in TO process to reduce the influence of deformed MSLCs on the performance of final structure. The infill resolution of MSLC within a given design domain is determined according to the minimal printable wall thickness of MSLC and structural stiffness. Both numerical and physical experimental results demonstrate the effectiveness of the proposed method.

Design, manufacturing and experimental validation of additive manufacturing cores for bearing seats in carbon fibre reinforced polymer structures.

The integration of carbon-fibre reinforced polymers (CFRP) in structural applications offers significant advantages due to their high strength-to-weight ratio. However, these materials exhibit limitations under out-of-plane loads, particularly in bearing applications. This study explores an innovative approach to enhance the performance of CFRP structures in such scenarios by incorporating annular polyamide inserts manufactured via additive manufacturing (AM).To evaluate the mechanical performance of the AM inserts, a novel ring tensile test is designed to emulate the bearing load conditions. This test also enables the analysis of the impact of several design and manufacturing parameters of the AM inserts, including surface geometry, surface treatment, internal structure, and curing process. These are then compared with specimens made of carbon fibre sheet moulding compounds (CF-SMC), commonly used to support bearing loads. The study reveals that AM inserts provide a viable alternative to state-of-the-art CF-SMC, offering a significant enhancement in mechanical properties under specific bearing loading conditions. The test results indicate a 17.7% improvement in the first failure limit and an 8.6% increase in the ultimate strength for AM inserts compared to CF-SMC.Additionally, the study develops a simplified analytical model to predict stress distributions and potential failure mechanisms, validating its efficacy through experimental data with discrepancies of less than 6%. Economic analysis underscores the cost benefits of AM inserts due to reduced labour and higher repeatability. This research demonstrates the potential of AM inserts to improve the stability and strength of CFRP structures, paving the way for their broader application in demanding load-bearing environments.

Shell element-based prediction of process-induced deformation considering the different fabric parameters and stacking sequences of CFRP woven composites

Herein, we present a finite element method (FEM) based curing analysis for predicting the process-induced deformation (PID) of CFRP woven composites using shell-type elements. This method can efficiently consider various fabric parameters and stacking sequences, even for complex structures. For woven composite plates and L-shaped flanges, FEM-based PID prediction using shell elements reduced computation times by 50–59% compared to solid elements, while maintaining acceptable accuracy with relative errors of 0.17–7.35%. Furthermore, the impacts of various fabric parameters and stacking sequences on the PID of woven composites are analyzed in detail. The main finding is that the variation in material properties due to fabric parameters and stacking sequences significantly impacts the PID of woven composite structures. This prediction method can be applied in the design of composite structures and molds, thereby enhancing the dimensional precision and performance of composite structures.

An improved macroscopic model for sloshing flow-combined porous structure interaction

The design of the aquaculture tank system is important for fish survival, as it directly affects the behavior of farmed fish. To avoid violent liquid sloshing, this study proposes a side-mounted bracket-shaped perforated baffle and a special porous layer to explore their anti-sloshing performance. A macroscopic computational fluid dynamics (CFD) method, applicable to the combined porous structure, is developed by introducing the volume-averaged porous media theory, with corresponding experimental tests conducted. In this study, the macroscopic CFD method is first achieved to solve the fluid force on the perforated baffle by reasonably predicting the momentum flux through the porous surface. The microscopic model is also established to further verify the reliability of our proposed macroscopic model. The amplitudes of the free water surface and sloshing loads are adopted to assess the sloshing response. In addition, an index referred to as area-weighted-average velocity is introduced to quantify the kinetic energy. Results reveal that the established macroscopic model reliably replicates the free water surface and sloshing loads and greatly improves computational efficiency. Moreover, the high-frequency component of the wave energy is more easily dissipated, thus the transfer of energy from low frequency to high frequency resulting from the porous structure enhances its anti-sloshing performance, while conversely, the performance is weakened; the suppressing performance of the porous structure is closely related to the filling depth and excitation frequency, which dominate the frequency components of the sloshing behavior.

Vibro-acoustic topology optimization for improving the acoustic insulation and mechanical stiffness performance of periodic sandwich structure

Vibro-acoustic topology optimization for improving the acoustic insulation and mechanical stiffness performance of periodic sandwich structure

Unveiling Enhanced Electrochemical Performance of LiMn1-xCoxPO4/C Cathode Materials through Co-Doping Strategy

LiMnPO4(LMP), an olivine-type material, is considered as a cathode for lithium-ion battery material, but faces challenges such as the Jahn-Teller effect, poor conductivity, and low ionic conductivity. To overcome these limitations, we explored Co doping as a potential solution. By utilizing a solvothermal method, we successfully synthesized LiMn1-xCoxPO4/C (x is the mass fraction of Co doping in LiMnPO4 sample) materials with a high (200) exposed surface. Our first-principles calculations indicated that Co doping significantly impacts the material's structure and electrochemical performance. Notably, the LiMn0.95Co0.05PO4/C sample demonstrated the highest performance, delivering capacities of 164.7 mAh g-1 at 0.1C and 97.5 mAh g-1 at 1C, while maintaining a remarkable 95.4% capacity retention after 100 cycles at 0.5C. Furthermore, the preferential growth on the b-c plane results in an enhanced (200) orientation, which exposes more reactive sites and facilitates Li+ migration. This study not only offers a straightforward approach for obtaining high-performance electrode materials but also bridges the gap between theory and experiment, providing a new avenue for understanding cation doping in polyanionic cathode materials.

Evaluation of the effect of low additive V2O5/ZnO on the structural, physical, and radiation attenuation performance of borate glasses

Evaluation of the effect of low additive V2O5/ZnO on the structural, physical, and radiation attenuation performance of borate glasses

Manganese doped La0.8Ba0.2FeO3 perovskite oxide as an efficient electrode material for supercapacitor

In this study, L0.8Ba0.2Fe1-xMnxO3 (LBFM-x, x = 0.0, 0.2, 0.5, 0.8) perovskite materials were synthesized by a Sol-Gel combustion method and were investigated as an electrode material for a supercapacitor device. The morphology, crystalline structure and electrochemical performance of the samples were studied in detail. The active points, where the electrochemical redox reaction takes place to store faradaic energy, are the oxygen vacancies on the surface of perovskite oxides. Partial substitution in the B-site of the perovskite structure, which is directly related to the oxygen vacancy in BO6 octahedral, is effective in optimizing the electrochemical performance. Based on the results of structural analysis, LBFM-0.2 has the highest concentration of oxygen vacancies; thus, it showed a higher electrochemical performance compared to other samples. The supercapacitors prepared with this electrode material should have an acceptably high specific capacitance of 685F.g-1 at a current density of 2.0A.g-1. The partial substitution of Mnn+ at the B-site increases the oxidation state of Fe cations and the mobility of oxygen ions through the oxygen vacancy sites. The electrochemical stability of LBFM-0.2, was evaluated by applying long charge-discharge cycles. After 3000 charge-discharge cycles, the supercapacitor was able to maintain about 94% of its initial capacity.

Piezoelectric fibers based on silk fibroin with excellent output performance

Abstract The self-powered tissue engineering scaffold with good biocompatibility is of great significance for stimulating nerve cell growth. In this study, silk fibroin (SF)-based fibers with regulatable structure and piezoelectric performance are fabricated by dry-spinning and post-treatment. The concentration of SF and calcium ion in spinning dope and the post-treatment affect the conformation transition and crystallinity of SF. As a result, the SF fibers exhibit high piezoelectric coefficient d 33 (3.24 pm/V) and output voltage (∼ 27 V). Furthermore, these piezoelectric fibers promote the growth of PC-12 cells, demonstrating the promising potential for nerve repair and other energy harvester.

Impact of an educational intervention utilising a three-dimensional-printed model for ultrasound-guided intra-articular injections of the dislocated shoulder.

Intra-articular injection of local anaesthetic provides safe and effective analgesia for patients with shoulder dislocation. We designed a three-dimensional-printed ultrasound model of the shoulder to educate ED clinicians on use of this technique. We aimed to evaluate the impact of a 1-h training session using this model on participants' knowledge, skills and clinical practice. This was a prospective study of the clinicians working at two EDs in New Zealand. Participants (n = 20) took part in a 1-h educational session. We tested participants' performance before the session, afterwards and at 3 months using a 10-point objective structured clinical examination. We reviewed clinical records to determine whether there was increased utilisation of this technique among ED patients before and after the training. There was improvement in participants' OCSE performance (median pre-training score = 4.00, median 3-month post-training score = 7.00, P = 0.044) and self-reported competence and knowledge, which were sustained to the end of the study. There was increased use of intra-articular injection among ED patients with shoulder dislocation: 2 of 68 patients (3%) before and 11 of 76 patients (14.5%) after the study. Notably, most were performed by clinicians who did not take part in the study (n = 9). A 1-h training session using a three-dimensional-printed model improved participants objective structured clinical examination performance in ultrasound-guided injection of the shoulder joint. Although there was minimal change in the practice of participating clinicians, overall use of the procedure increased.

Dynamic response analysis of submerged floating tunnel after anchor cables forces adjustment under impact load

Submerged Floating Tunnel (SFT) is a new type of cable-supported structural system for straight crossings. In this study, the initial state of the SFT was optimized based on the existing SFT cable-force adjustment method (relatively uniform cable forces, minimizing the support reaction forces at the abutment section). The responses of the SFT under static and seismic conditions before and after cable-force adjustment were compared, further verifying the optimization effect of the cable-force adjustment method on the structural performance of the SFT. In addition, a theoretical model (flexible support model) of the anchor cables was proposed to calculate the displacement after impact by sunken ships. A finite element model of the SFT was established using ABAQUS to prove the accuracy of the flexible boundary model. In addition, the flexible support stiffnesses of anchor cables at different positions were determined based on the finite element model. Finally, the SFT after the cable-force adjustment was analyzed to study the response patterns of the anchor cables at different positions under an impact load. The results demonstrate that a correlation between the distribution pattern of the flexible boundary stiffnesses of anchor cables and the regulation of the responses of the anchor cables to impact load.

Lignin data bank: A key to clarifying aromatic structure–performance relationships

Lignin data bank: A key to clarifying aromatic structure–performance relationships

Shape and Size Optimization Framework of Stiffened Shell Using Isogeometric Analysis

A shape and size optimization framework is developed to improve the structural performance of the stiffened shell using isogeometric analysis. To accurately model the stiffened shell, the Lagrange multiplier method is employed to establish the coupling relationship of isogeometric degenerated shell elements and isogeometric degenerated beam elements. Due to the advantages of the non-uniform rational B-spline (NURBS), the unit normal direction vectors of the shell can be defined analytically, which guarantees stiffeners perpendicular to the skin. Additionally, the stiffeners can be easily generated based on the mapping relationship of the parametric space and the physical space of the shell. Analytical sensitivity is derived in detail, and the gradient-based optimization method can be used to solve the minimum compliance optimization problem owing to the high order continuity of NURBS. Three numerical illustrative examples are presented to verify the effectiveness of the proposed framework for the shape and size optimization of stiffened shells, consisting of a cylindrical shell patch, a hyperbolic shell, and a complex engineering segment. It is worth noting that the proposed framework is especially suitable for optimization problems of the stiffened shell, eliminating the need of complex feature extraction.

Topology Optimization of Smart Structures to Enhance the Performances of Vibration Control and Energy Harvesting

Abstract With the growing interest in smart materials, the utilization of shunted piezoceramics for dynamic vibration control has gained significant attention due to their unique characteristics, such as the ability to absorb strain energy from vibrating systems and convert it into electrical energy. Designing and analyzing the behavior of structures in hybrid mitigation/harvesting conditions, considering both reliability and performance, pose challenges. This paper aims to achieve optimal design parameters for the structure by employing a multiobjective optimization approach that strikes a compromise between maximizing harvested power and minimizing structural damage. To evaluate the effectiveness of the design, topology optimization was conducted in three different cases to compare the results. By systematically exploring the design space, these cases provide insights into the influence of various parameters on the structural performance. In addition, to enhance computational efficiency, the structure was represented as a metamodel using neural networks. This approach enables rapid evaluation and prediction of the structure's behavior, facilitating the optimization process. By integrating multiobjective optimization, topology optimization, and metamodeling techniques, this study aims to provide valuable insights into the optimal design of structures that simultaneously incorporate shunt circuitry for vibration control and energy harvesting, leading to improved performance and reliability.

Flexural performance of innovative thin-walled steel–timber composite floor slabs

A floor slab carries and distributes the floor load in a structure and is an important component that affects overall structural performance. Therefore, it is important to investigate the mechanical properties of such materials. In this study, flexural performance tests under static load are conducted for an innovative thin-walled steel–timber composite floor slab, and the failure mode, bearing capacity, stiffness, deflection, and strain development are investigated. The results show that the floor slab can be quickly assembled using self-tapping and wood screws and exhibits good flexural performance. Using ABAQUS finite-element software, the effects of the oriented-strand board (OSB) thickness, thin-walled–steel-plate height, steel strength, and boundary conditions on the flexural performance of composite floor slabs are investigated. Furthermore, based on the EN1995–1-1 code and equal-section conversion principle, the simplified beam-unit model is established for the theoretical calculation of the composite floor slab. The effective bending stiffness is calculated by considering the influence of the slip modulus of the connector, and the stress distribution law of the section is analysed. The results provide a reliable design basis and reference for the application of thin-walled steel–timber composite floor slabs in engineering practice.