Lightweight Structures Research Articles

Numerical modeling and validation of auxetic cell geometries for FDM infill pattern improvement

Abstract The vehicle construction sector is constantly engaged in the pursuit of lightweight structures to reduce the overall weight of vehicles. This objective aligns well with sustainability requirements, as reducing structural weight and excessive raw material usage simultaneously lowers fuel consumption. However, these lightweight panels sometimes experience a decline in mechanical properties or exhibit unpredictable failure mechanisms due to their large internal voids. To optimize material usage, 3D printing was explored, enabling the creation of highly customized infill patterns. The innovative aspect of this research lies in developing a cellular design by selecting an optimal infill configuration capable of withstanding the expected loads. Numerical modeling was employed to analyze how different cell specifications interact with the geometry of the structure and the applied loading conditions. As a result, an auxetic design was chosen for the cellular structures. This design was fabricated using fused deposition modeling (FDM) and tested under flexural and impact loading. A comparative analysis was then conducted with samples of equivalent infill density but featuring conventional infill patterns to assess performance differences. Even if the flexural tests show a decrease in resistance and stiffness of the auxetic structures than the traditional ones, the last under-impact load shows an increase in impact rigidity which is also influenced by the angle value. Furthermore, the specimens can preserve their impact absorption capacity failure mode even if load absorption and damage are completely different. A numerical model development was useful for understanding the different behaviors and it was able to reproduce the impact behavior with high precision.

Design and performance investigation of an underwater ultrasonic percussive drill for seabed mineral exploration

Abstract To address the limitations of traditional drilling equipment, such as large size, high power consumption, and difficulties with waterproofing, an underwater ultrasonic percussive drill (UUPD) based on piezoelectric drive is proposed. The structure and size parameters of the piezoelectric actuator are designed and its performance is experimentally verified. The maximum output amplitude of the piezoelectric actuator is 78.6 μm in air and 52.3 μm in water. Additionally, the dynamic characteristics of the UUPD are calculated theoretically and analyzed by simulation, and the influence of system parameters on vibration characteristics is revealed. A prototype of the UUPD is developed, and a performance testing platform is established, and drilling comparison experiments and power consumption test are carried out to evaluate the performance of the UUPD. Experimental results demonstrate that the UUPD is capable of breaking rocks with varying hardness (5 MPa–50 MPa) under small drilling pressure (around 6 N) and low power consumption (approximately 57 W). The UUPD proposed in this paper offers advantages, including low drilling pressure, low power consumption, light weight and compact structure, showing a good application prospect and providing an effective technical means for deep-sea hard mineral rock drilling and sampling.

A hybrid springback compensation method for geometry complexity in stamping

Abstract Springback compensation is a crucial approach to maintaining the accuracy of stamping parts with complex features. It has been challenging to determine the position of a characteristic point at the geometrical features during springback compensation. The currently available numerical approaches are not always sufficiently accurate and reliable, particularly when high-strength steels are increasingly used for lightweight structures. An enhanced hybrid method named springback path–displacement adjustment (SP-DA) method has been developed based on the well-known conventional displacement adjustment (DA) method to resolve the issue. A finite element method (FEM) model of stamping owning geometry complexity was established, and ST14F, BH300 and DP500, representing low, medium and high-strength steels, respectively, were selected for the study. Springback analyses were conducted, and the springback paths were acquired in the FEM simulation, based on which the spatial position of a node on the mesh of the compensation model was obtained using the SP-DA method. Its effectiveness was first verified numerically, and then, experiments were conducted to validate that the new SP-DA method could significantly increase the accuracy of springback compensation. Stamping of high-strength steels can benefit most from the proposed SP-DA method.

Study on the thermal control performance of lightweight minimal surface lattice structures for aerospace applications

With the rapid evolution of aerospace technology and the increasing complexity of space environments, the demand for lightweight, thermally insulated, and highly efficient heat dissipation materials in aircraft equipment has surged. This study addresses this critical need by investigating Triply Periodic Minimal Surface (TPMS) lattice structures, offering a novel design approach to enhance spacecraft thermal management under extreme temperatures. Our work introduces a methodology to quantitatively assess the thermal insulation and heat dissipation performance of various lightweight lattice sandwich structures. We constructed implicit function models of low volume fractions, including Gyroid, Diamond, Primitive, and IWP, and conducted experiments using an active cooling setup under controlled heating conditions at 300 °C. Key findings reveal that, at flow velocities ranging from 0.25 to 1.5 m/s, the Diamond model exhibited the highest convective heat transfer coefficient, surpassing the Gyroid, Primitive, and IWP models by 6.9 % to 427.3 %, 87.1 % to 485.6 %, and 1.5 % to 98.7 %, respectively. Conversely, at velocities between 1.5 and 3.75 m/s, the Gyroid model demonstrated superior heat exchange performance, improving by 14.6 % to 67.2 %, 73 % to 167.7 %, and 9 % to 64.8 % compared to the Diamond, Primitive, and IWP models. During thermal insulation tests at temperatures from 200 to 400 °C, the Diamond model showed the best insulation effect, while the Primitive model performed poorly. Based on the experimental data, we established empirical relationships between the Nusselt number, friction coefficient, and Geometric Surface Ratio (GS). These findings not only underscore the significant potential of TPMS lattice structures in aerospace applications but also provide a robust theoretical framework and practical guidelines for achieving efficient thermal management in lightweight aerospace manufacturing.

Effect of addition of boron and B4C coated diamond on the microstructure and compressive behaviour of porous aluminium composites

Owing to the growing demand for lightweight materials in automotive and aerospace applications, porous aluminium composites are studied in-depth due to their high strength-to-weight ratio, higher stiffness and good compressive properties. The studies include enhancing their strength by the inclusion of strengthening reinforcements. In this study, the effect of boron addition in the matrix combined with uncoated diamond as reinforcements was compared with the effect of B4C coated diamond on the microstructure, density, porosity and compressive properties of porous AlSnMg matrix composites. The addition of boron in the matrix combined with using uncoated diamond showed least significant improvement in properties while the addition of B4C coated diamond revealed better results. The microstructure of porous composites revealed that the boron addition insignificantly affected the bonding at the interface of matrix and uncoated diamond reinforcement comparatively B4C coated diamond improved the bonding at the interface of aluminium matrix and diamond. As a result, the higher densities and compressive strength of 39.97 MPa and energy absorption capacity of 13.2 MPa were acquired for porous Al composites with 10 wt.% of B4C coated diamond suggesting the use of coated diamond in porous aluminium for enhancing their strength in applications as fillers in light weight structures for automotives.

Design and optimization of a new NiTi-based shape memory alloy structures for damping applications via additive manufacturing

Abstract Shape Memory Alloys (SMA), such as NiTi-based systems, are functional materials suitable for damping applications due to their pseudoelastic effect. This property allows to obtain simple, lightweight structures capable of absorbing energy through a mechanical hysteresis and able to recover significant deformations. For this reason, SMA are attractive candidates for the development of novel devices in many fields, such as the biomedical one or in aerospace and in automotive. Recently, the development of Additive Manufacturing (AM) of metals has considerably expanded the design and production possibilities of SMA-based devices, potentially overcoming the limited workability of these materials through conventional manufacturing techniques, which is one of the main limitations to their wider adoption. This study presents a preliminary investigation of a NiTi octahedral cell structure fabricated via Laser Powder Bed Fusion (L-PBF) starting from a NiTi powder with Ni content of 50.8 at. %. Cells of different sizes were manufactured and subjected to compression tests up to 0.8 mm displacement in order to evaluate their mechanical and functional performances. Furthermore, a numeric model was used to redesign the geometry in order to optimize the structure's damping capacity. The material input data of the numerical model were obtained from mechanical and thermal analyses on square prisms, which were printed with the primary axis oriented perpendicular and at an inclination of 60° to the building platform. Finally, the optimized cell was manufactured and mechanically tested at different temperatures. The obtained results prove the high efficiency of the structure when used for damping applications and highlight the potential of AM to produce NiTi structures that combine load-bearing capabilities and functional responses.

Performance of Structural Lightweight Reinforced Concrete Solid Slabs with FRP Bars and Contain Polypropylene Fibers

Performance of Structural Lightweight Reinforced Concrete Solid Slabs with FRP Bars and Contain Polypropylene Fibers

Intrinsic production of metal-carbon fiber reinforced plastic hybrid shafts using vacuum-assisted resin transfer molding

Over the past decades, the importance of lightweight structures in the aircraft and automotive industries has steadily increased due to regulations aimed at reducing global warming. Work hardened steel alloys are commonly used for lightweight applications, but they face stability issues when the material thickness reaches certain thresholds. Fiber Reinforced Plastics (FRP) offer a viable alternative due to their high strength-to-weight ratio, but they are often expensive due to long production cycles and high material costs. A feasible solution lies in hybrid lightweight designs that utilize expensive FRP materials only in highly stressed areas, achieving a balance between low mass and acceptable cost. These hybrid structures are lighter than metal components and more cost-effective compared to fully FRP structures, without compromising mechanical properties. This study focuses on producing rotationally symmetrical hybrid structures using Resin Transfer Molding (RTM) combined with vacuum assistance in a single-stage process. The research examines the effects of injection pressure, mold temperature, and the interface between metal and FRP. The mechanical characterization of these hybrid structures was conducted to assess their performance under torsion, compression, and interlaminar shear strength (ILSS) loading conditions. The results indicate that hybrid designs can offer a lightweight alternative without compromising mechanical properties.

Impact penetration response of fiber metal laminates padded with 3D continuous fiber-reinforced polyurethane foam

Novel composite combinations are needed to meet the broad mechanical requirements for lightweight structures by integrating various properties within a single structure. This includes high structural rigidity and impact resistance with low overall density. Fiber metal laminates (FMLs) are advanced composite materials composed of an alternating stacking sequence of metal alloys layers and fiber-reinforced polymers. However, FMLs exhibit lower puncture deformation potential compared to fiber-reinforced thermoplastics (FRTPs). To address this limitation, polyurethane (PUR) foam with 3D continuous fiber-reinforcement, is investigated as padding. The FML, manufactured via thermoforming, is based on basalt fiber-reinforced polyamide 6 and two layers of aluminum alloy. The PUR foam is fabricated through structural reaction injection molding and reinforced with a spacer fabric. Subsequently, low velocity impact tests are conducted for this novel composite and its single components. The results unveil significant insights into the impact behavior of the materials. The highest perforation resistance of 81 J is achieved by the FML padded with 3D continues fiber-reinforced polyurethane foam while offering equal deformation capability as without reinforced PUR foam. These findings underscore the superior impact performance of the fiber metal laminate padded with 3D continues fiber-reinforced polyurethane foam, offering valuable insights for the advancement of impact-resistant materials in various engineering applications.

Wind-induced structural behavior and optical performance of a lightweight composite-based paraboloidal solar dish

Among the four available concentrating solar-thermal (CST) power systems, parabolic dish systems show great potential as the preferred technology for renewable electricity generation. Nonetheless, the weight of the support structure poses a major hurdle to its development. As of present, solar dishes utilize steel structures to hold the reflective panels which amount to a lot of weight, necessitating large and expensive drive units and increases energy consumption. Hence, for the dishes to advance and further become economically feasible in the near future, the structures found need to be replaced with cost-effective materials that not only diminish the weight but still maintain the structural integrity found with the steel. Hence, this investigation embodies the first effort in literature to explore the viability of utilizing honeycomb sandwich composites as a lightweight and robust support structure for solar dishes, with the ability to cope with the aerodynamic loads imposed upon them during operation. Through combined fluid-structure interaction (FSI) and ray tracing analysis, the wind-induced structural behavior and optical performance of the sandwich composite-based paraboloidal solar dish were investigated under various loading scenarios at various azimuth and elevation angles. Under dissimilar operational conditions, the proposed system exhibited varying behavior characteristics, with the worst conditions being assessed according to relevant material failure and optical standards. With the worst operational condition taking place at 0° azimuth and 30° elevation, the detailed FSI-ray tracing analysis demonstrated that the dish managed to satisfy the set specifications, highlighting the potential and effectiveness of using honeycomb sandwich composites as a support structure for parabolic dish systems.

Enhancing Thyroid Nodule Detection in Ultrasound Images: A Novel YOLOv8 Architecture with a C2fA Module and Optimized Loss Functions

Thyroid-related diseases, particularly thyroid cancer, are rising globally, emphasizing the critical need for the early detection and accurate screening of thyroid nodules. Ultrasound imaging has inherent limitations—high noise, low contrast, and blurred boundaries—that make manual interpretation subjective and error-prone. To address these challenges, YOLO-Thyroid, an improved model for the automatic detection of thyroid nodules in ultrasound images, is presented herein. Building upon the YOLOv8 architecture, YOLO-Thyroid introduces the C2fA module—an extension of C2f that incorporates Coordinate Attention (CA)—to enhance feature extraction. Additionally, loss functions were incorporated, including class-weighted binary cross-entropy to alleviate class imbalance and SCYLLA-IoU (SIoU) to improve localization accuracy during boundary regression. A publicly available thyroid ultrasound image dataset was optimized using format conversion and data augmentation. The experimental results demonstrate that YOLO-Thyroid outperforms mainstream object detection models across multiple metrics, achieving a higher detection precision of 54%. The recall, calculated based on the detection of nodules containing at least one feature suspected of being malignant, reaches 58.2%, while the model maintains a lightweight structure. The proposed method significantly advances ultrasound nodule detection, providing an effective and practical solution for enhancing diagnostic accuracy in medical imaging.

Innovative lightweight flexibility test platform for RV reducer with topology optimization and 3-D printing

Abstract The majority of existing mechanical devices are only capable of measuring a single parameter. They are constructed primarily from metal processing, resulting in a substantial weight, elevated manufacturing costs, and a fixed and inflexible accuracy and assembly methodology. Accordingly, this paper presents the design of a lightweight RV reducer test platform, which enhances the flexibility of high-precision measurement. The test platform employs topology optimization lightweight structure design and 3D printing technology. Static simulation is used to lightweight the structure and add an adjustable structure. It significantly reduces cost and weight while having an adjustable self-connection structure and a wide range of application scenarios. It improves the flexibility of high-precision measurement while ensuring sufficient strength. In order to verify the measurement performance of the platform, the wavelet threshold method with excellent denoising effect was used to analyze the acceleration power spectral density of each part of the test platform at different rotation speeds. The results show that the wavelet threshold method could effectively filter noise and extract key experimental data. The accelerometer results show that the test bench has superior stability at both 0.5 r min−1 and 120 r min−1 speeds, and has practical application value. The simulation also verifies that the test platform has sufficient rigidity to meet the working conditions.

Lightweight and modular design of a hydraulically actuated quadruped robot with high payload-to-mass ratio

Load-carrying horses, climbing mountain goats, and galloping cheetahs all exhibit impressive locomotion abilities, prompting the development of quadruped robots. Among different types of quadruped robots, hydraulically actuated robots have been widely concerned with their higher speed limit and load-bearing capacity. However, hydraulic quadruped robots usually comprise numerous components and high-pressure pipes, posing challenges to the design and component layout of the robots. To tackle these problems, this paper proposes a modular design method for the Spurlos quadruped robot. Based on the design goals and required functional composition, the robot is divided into four main parts: limb leg unit, torso, onboard hydraulic system, and control hardware. The critical issues of each part are solved correspondingly, including customized lightweight actuators based on multi-material design, active joint kinematics, lightweight torso structure with mortise and tenon joint, required flow rate estimation, and reliable hardware with hierarchical control strategy. Comparison with other advanced hydraulic quadruped robots indicates that the payload-to-mass ratio of the Spurlos robot adopting modular and lightweight design is superior to those based on other design principles. The design effectiveness and dynamic performance are validated through air walking, weight-bearing squat, and trotting experiments. The results demonstrate the robot’s good load-bearing capacity and locomotion abilities. The modular and lightweight structure design approach proposed in this study provide valuable reference for the structural design of other legged robots.

A combined aperture‐coupled membrane microstrip patch antenna array

AbstractA novel lightweight L‐band combined aperture‐coupled microstrip antenna has been proposed for synthetic aperture radar (SAR) applications. The proposed antenna element is composed of only two membranes. This design innovatively integrates the coupling aperture with the radiating patch, significantly reducing the number of required dielectric layers to achieve a simplified and lightweight structure. The feed line is placed on the front side to facilitate integration with the transmit/receive (T/R) module. Simulation results demonstrate that the antenna element exhibits excellent radiation pattern performance and bandwidth. A passive antenna array utilising polyimide as the dielectric material was fabricated and measured to validate its performance. This array employs a 4‐stage Wilkinson power divider network. Measurements show that S1,1 is below −15 dB in the frequency range from 1.15 to 1.49 GHz, with a maximum efficiency of 72.87%. Additionally, an phased array antenna was fabricated and tested. This array demonstrated stable radiation pattern performance over an azimuthal scan range of and an elevation scan of . This design offers a new option for antenna modules in spaceborne SAR applications.

Structural design and safety performance of a novel high-strength steel lightweight guardrail.

Highway guardrails are critical safety infrastructure along roadways, designed to redirect vehicles back into their lanes and facilitate a gradual deceleration to a complete stop. Traditional highway steel guardrails exhibit significant limitations, including inadequate energy absorption, susceptibility to corrosion, and an increased risk of vehicles leaving the roadway during severe collisions. Furthermore, the production and transportation of these guardrails contribute to substantial carbon emissions and environmental pollution. This study presents an optimization of the cross-sectional shape of the conventional corrugated beam guardrail, proposing a lightweight structure that incorporates high yield strength steel plate HR700F to enhance energy absorption capacity. The safety performance of the proposed guardrail is rigorously assessed through finite element numerical simulations and full-scale collision tests with real vehicles. Key performance indicators-such as the maximum dynamic lateral deflection of the guardrail, occupant impact velocity, and acceleration-are utilized to evaluate the energy absorption and protective efficacy of the structure. Results indicate that the optimized guardrail not only meets SB-level safety standards but also demonstrates superior anti-collision performance and effective energy absorption and buffering characteristics. The proposed design achieves a reduction in beam plate thickness by 1.3 mm, resulting in a lightweight structure with a weight reduction of up to 44%, thereby supporting the advancement of low-carbon, environmentally sustainable transportation solutions.

Research on Advanced Material Applications for Enhancing the Performance of New Energy Vehicle Components

This study aims to explore the application of advanced materials in new energy vehicle (NEV) components and assess their contribution to enhancing the overall vehicle performance. With the growing global demand for sustainable transportation solutions, NEVs have become a significant direction for the automotive industry. Against this backdrop, the performance enhancement of components is key to achieving higher energy efficiency, longer driving range, and a better driving experience. This paper first reviews the development history of new energy vehicle technology and the classification of advanced materials, then analyzes in detail the application of advanced materials in battery systems, electric motors and electronic control systems, lightweight structures, and thermal management systems. Through experimental research and case studies, this paper evaluates the specific impact of these materials on component performance and discusses the challenges faced in practical applications and future development directions. The research results show that the application of advanced materials can significantly enhance the performance of new energy vehicles, providing strong technical support for the further development of new energy vehicles. Finally, this paper proposes solutions to the challenges and limitations of performance enhancement in the application of advanced materials and suggests future research directions.

Structure failure and strength evaluation of honeycomb-based sandwich composites under variable hydro-thermal-mechanical load

The high-strength and lightweight sandwich structures have broad application prospect in aerospace, wind turbine generator, traffic and civil engineering. The sandwich structures usually service with severe environment and complicated mechanical load, structure failure and strength prediction are crucial issues. Under time-varying and optional position hydro-thermal–mechanical loading, this paper systematically analyzes strength failure, buckling and delamination of a sandwich beam with carbon fiber-reinforced polymer face sheet and aluminum honeycomb core. Effects of elastic boundary conditions, hydrothermal stress, configuration of honeycomb cell and thickness of face sheet on failure pattern and critical failure loading are evaluated. The theoretical deformation model is verified by performing a bending experiment of cantilever beam. For the honeycomb core with small re-entrant angle and shot horizontal cell wall, the sandwich cantilever beam occurs strength failure of face sheet and delamination is happened in simply supported beam. With increase of re-entrant angle and cell wall length, buckling of horizontal cell wall becomes the primary failure pattern of sandwich beam. With thickness increase of face sheet, the failure pattern switches from face sheet’s strength failure to delamination. The critical load for delamination decreases to a volley value and then increases with thickness of face sheet.

Significantly improves the mechanical strength of aluminum alloy adhesive joint through electrochemical pretreatment in environmentally friendly medium

Adhesive bonding of aluminum alloys is extensively practiced to achieve optimum lightweight and reliable structures in the aerospace, automobile, and maritime industries. This paper represents the inaugural attempt to use neutral salt solutions as electrolytes for the electrochemical pretreatment of aluminum alloy bonding surfaces, with the aim of achieving high-performance bonding. The NaNO3 and NaCl solutions were selected carefully due to their non-toxic, easy to obtain, and inexpensive. Comprehensive experiments were conducted, and the specimen surfaces were characterized by advanced characterization methods before and after electrochemical treatment. The results demonstrated that the surface morphology of the treated aluminum alloy exhibited notable alterations, and the wettability, roughness, and chemical composition were effectively improved. Subsequently, aluminum alloy single lap joints were subjected to detailed examination in order to evaluate the effectiveness of the pretreatments on the bonding strength and fracture resistance. The results showed that under the condition of 5 A and 1 min, the specimen treated with NaCl solution demonstrated a notable enhancement in bonding performance, and its bonding strength increased by more than 200 % that of the untreated specimen joints. Moreover, this study integrates the characterization and experimental findings to provide a comprehensive analysis of the mechanisms underlying the deterioration or improvement of the bonding performances under different pretreatment conditions. This study demonstrates not only the extremely friendly characteristics to operators and environment, but also the technical advantages of low cost, high efficiency and good bonding performance.

A Hybrid Data-Driven Machine Learning Framework for Predicting the Impact Resistance of Composite Armor

Composite armor plays a crucial role as the primary defense against high-velocity impacts from fragments and projectiles. However, balancing the need for lightweight structures with the requirement for robust protection remains a significant engineering challenge. Traditional approaches for predicting the protective performance of armor typically involve a combination of experimental testing and numerical simulations, both of which can be resource-intensive and costly. In contrast, data-driven methods combined with machine learning have demonstrated the potential to significantly reduce both time and economic costs, highlighting their substantial advantages in various engineering domains. Unfortunately, a mature machine learning framework for predicting the performance of multilayer composite armor against high-velocity impacts from large fragments has yet to be established. In this paper, a novel data-driven framework for predicting the ballistic performance of composite armor using a hybrid model of Support Vector Machine and Deep Neural Network was established. This framework employed hyperparameter optimization to enhance predictive performance, yielding a model with excellent accuracy. The proposed model was adaptable to multilayered armor with varying layer thicknesses, enabling rapid predictions of armor penetration, residual projectile kinetic energy, and armor deformation.

Assessment and retrofitting of deteriorated light structure founded on expansive soil

ABSTRACT Structure damages are becoming very common when constructed in arid and semi-arid areas on problematic soil. This may be attributed to the inadequate geotechnical investigation prior to construction. The problem is most effective in case of light weight structures constructed on arid problematic soils without any special considerations for these types of soil, and the problems start to arise with the entrance of structure to the service and the seepage of water to the founded soil. In this paper, a case study for a villa in a gated compound; just after 6 months from construction, the walls of this light structure suffered severe cracks. A careful inspection and geotechnical site investigation showed that the structure’s foundations have been subjected to differential movement at its western part, due to percolation of water into bed of high potential swelling soil. In addition, the stiffness of the basement columns was very low. Some consultants recommended to demolish the villa, nevertheless, an intensive structural analysis taking into consideration conditions of the concrete skeleton had led to select proper structure’s remedial measurements to stop the heave and shrinkage problems, and to improve the structure’s stiffness. The retrofitting measures included removing the expansive clayey layer which was of limited thickness and area; modifying the foundation system, and replacing the basement columns with inadequate strength with new ones. The measurements of the monitoring process during and after finishing repair processes had shown no movements, which reflects the efficiency of implemented retrofitting techniques.