Search Results (242)

The structural performance of automotive doors is highly dependent on their metallic support; however, conventional development processes often involve multiple CAD-CAE iterations, which increase lead time and engineering effort. This study presents a methodology for optimizing metallic support geometry by integrating Computer-Aided Design (CAD), Computer-Aided Engineering (CAE), and the Taguchi Design of Experiments (DOE). A Taguchi L16 orthogonal array was used to evaluate eight key geometric factors, including material thickness, fixation point configuration, and geometric reinforcements. Finite element simulations with a meshless solver significantly reduced pre-processing time without compromising accuracy. By analyzing the signal-to-noise (S/N) ratio, the optimal factor combination was identified, which maximized stiffness while minimizing displacement and ensuring robustness against material variability. The optimal design achieved a stiffness of 248 N/mm, a substantial increase over the baseline’s 39 N/mm. This design demonstrates the potential of this methodology to dramatically improve structural performance from the early stages of development and accelerate product development by reducing design iterations. Full article

Background and Objectives: Alopecia areata (AA) is an autoimmune disorder characterized by non-scarring hair loss and has been associated with systemic immune-inflammatory activity and potential cardiometabolic risk. This study aimed to evaluate cardiovascular risk markers—including ECG parameters, arterial stiffness indices, anthropometric measurements, and body composition—in patients with AA according to disease severity and duration, and to compare these findings with healthy controls. Materials and Methods: This case–control study included 50 AA patients (32 men, 18 women; mean age: 28.98 ± 9.81 years) and 50 healthy controls (30 men, 20 women; mean age: 28.00 ± 7.86 years). All participants underwent anthropometric and electrocardiographic evaluations. Body composition was assessed, and arterial stiffness was measured. Subgroup analyses were performed according to SALT score (mild vs. moderate-to-severe) and disease duration (≥10 years vs. <10 years). Results: Heart rate was lower in AA patients compared with controls (mean difference −5.14 bpm; 95% CI −10.267 to −0.013). No significant differences were found between the groups regarding anthropometric variables, body composition, or arterial stiffness indices. Among AA patients, those with moderate-to-severe disease had significantly lower body fat mass (mean difference 4.95 kg; 95% CI 0.26 to 9.644) and lower visceral fat rating (mean difference 2.428 units; 95% CI 0.800 to 4.056) compared with mild AA. Conclusions: AA patients demonstrated lower heart rate and disease-severity-related alterations in body composition, although the clinical significance of these findings remains uncertain. Larger longitudinal studies are needed to clarify whether these subclinical differences translate into meaningful cardiovascular risk over time. Full article

The construction sector faces growing pressure to reduce its environmental impact, particularly in regions with limited access to conventional materials and urgent housing needs. Bamboo, a fast-growing and renewable resource with favorable mechanical properties, offers a sustainable alternative for structural applications. This study aims to enhance the efficiency of bamboo–concrete composites by investigating shear connection methods for composite floor systems. Different connection configurations were examined: (i) notch-type, (ii) dowel-type, and (iii) combined systems. Symmetric push-out tests were conducted to evaluate the load transfer mechanisms between bamboo logs and concrete layers. The mechanical behavior of each configuration was characterized through load–slip responses, failure modes, stiffness, strength, and deformation capacity. The results show that notch-type connections with longer grooves provided the highest stiffness and strength. In contrast, dowel-type connections exhibited superior ductility but lower stiffness and strength. The combined configuration delivered a balanced performance, integrating favorable aspects of both systems. A predictive model for each connection type was developed and validated against the experimental data, demonstrating satisfactory accuracy and reliable prediction of failure modes. These findings highlight the potential of optimized shear connections to advance sustainable bamboo–concrete composite construction, while also revealing the significant influence of bamboo’s natural variability, such as differences in diameter, node geometry, straightness, and material properties, on structural performance. Full article

In aerospace engineering, structural lightweight remains one of the core design objectives. Here, a design methodology combining topology optimization (TO) with honeycomb materials is proposed to achieve lightweight for a typical aircraft double-lug joint structure (DLJS). The initial DLJS is topologically optimized using the variable density method to identify optimal material distribution. The optimized result is then reconstructed into a regular geometric model using the three dimensional (3D) modeling software SolidWorks 2022. In the reconstructed DLJS, the lower stress regions are replaced with honeycomb materials possessing superior mechanical properties or either removed to further enhance stiffness-to-weight ratio. Numerical strength verifications are performed on the final designed DLJS, demonstrating that the maximum stresses designed DLJS remain below the material yield strength under three typical load cases, meeting both strength requirements and safety margins. The mass of the designed DLJS is 38.44 kg, achieving a weight reduction rate of 59.7% compared to the initial DLJS (95.38 kg). Finally, the fabrication feasibility of the designed DLJS is evaluated, and a scaled-down DLJS specimen is fabricated using 3D printing technology with photopolymer resin. This work demonstrates the effectiveness and potential of TO combined with honeycomb materials in lightweighting complex 3D engineering components, providing valuable insights for the lightweight design of intricate 3D structures. Full article

Traditional solid screw rotors suffer from excessive weight, structural redundancy, low material utilization, and high energy consumption, conflicting with the growing demand for efficient, sustainable manufacturing. To address these challenges, this study proposes a lightweight design method for hollow, internally supported male screw rotors that simultaneously enhances stiffness and static–dynamic performance. A parameterized structural model with four key design variables was established, and multi-physics simulations integrating fluid flow, heat transfer, and structural mechanics were conducted to obtain mass, maximum deformation, and first-order natural frequency. Based on these simulation results, a surrogate-assisted multi-objective evolutionary optimization framework was employed: an enhanced Newton–Raphson-based optimizer (SNRBO) was used to tune the extreme gradient boosting surrogate (XGBoost 1.5.2), and the tuned surrogate then guided the Nondominated Sorting Genetic Algorithm III (NSGA-III) to perform multi-objective search and construct the Pareto front. Compared with a conventional solid rotor, the optimized design reduces mass by 64.43%, decreases maximum deformation by 4.41%, and increases the first-order natural frequency by 82.14%. These findings indicate that the proposed method provides an effective pathway to balance lightweight design with structural safety and dynamic stability, offering strong potential for green manufacturing and high-performance applications in energy, aerospace, and industrial compressor systems, and providing robust support for further advances in this field. Full article

In recent years, agricultural production activities have been advancing towards mechanization and intelligence to bridge the growing gap between the high labor intensity and time sensitivity of harvesting operations and the limited labor resources. As the component that directly interacts with target crops, the end-effector is a crucial part of agricultural harvesting robots. This paper first reviews their materials, number of fingers, actuation methods, and detachment techniques. Analysis reveals that three-fingered end-effectors, known for their stability and ease of control, are the most prevalent. Soft materials have gained significant attention due to their flexibility and low-damage characteristics, while the emergence of variable stiffness technology holds promise for addressing their issues of poor stability and fragility. The introduction of bionics and composite concepts offers potential for enhancing the performance of end-effectors. Subsequently, starting from an analysis of the biomechanical properties of fruits and vegetables, the relationship between mechanical damage and the intrinsic parameters of produce is elucidated. On the other hand, practical and efficient finite element analysis has been applied to various stages of end-effector research, such as structural design and grasping force estimation. Given the importance of compliance control, this paper explores the current research status of various control methods. It emphasizes that while hybrid force–position control often suffers from frequent controller switching, which directly affects real-time performance, active admittance control and impedance control directly convert external forces or torques into the robot’s reference position and velocity, resulting in more stable and flexible external control. To enable a unified comparison of end-effector performance, this review proposes a progressive comparison framework centered on control philosophy, comprising the ontological characteristic layer, physical interaction layer, feedback optimization layer, and task layer. Additionally, in response to the current lack of scientific rigor and systematization in performance evaluation systems for end-effectors, performance evaluation criteria (harvest success rate, harvest time, and damage rate) are defined to standardize the characterization of end-effector performance. Finally, this paper summarizes the challenges faced in the development of end-effectors and analyzes their causes. It highlights how emerging technologies, such as digital twin technology, can improve the control accuracy and flexibility of end-effectors. Full article

Material Extrusion (MEX) additive manufacturing offers a versatile platform for producing lightweight, structurally optimized components. This study investigates the simultaneous optimization of topology and infill density using three polymer composite materials, PPA-CF, PAHT-CF, and ABS, selected for their mechanical performance, cost efficiency, and printability. Cylindrical specimens were fabricated with nine mass retention levels (100% to 33%) by systematically varying topology and infill parameters. Compression testing was conducted to assess stiffness, deformation behavior, and structural integrity under simulated operational loads. Results show that combining topology optimization with variable infill density can significantly reduce material usage and manufacturing time while maintaining mechanical reliability across all three materials. PAHT-CF demonstrated the highest strength-to-weight performance, while ABS offered cost-effective alternatives for less demanding applications. The study establishes clear relationships between design strategies and material behavior, enabling the production of net-shape satellite support structures with fewer design iterations and improved throughput. These findings support the adoption of resource-efficient manufacturing practices and provide a framework for sustainable, low- to mid-volume production in high-value manufacturing industries. Overall, the integration of design and material optimization advances the potential of additive manufacturing for scalable, cost-effective, and environmentally conscious aerospace solutions. Full article

Optimizing the life cycle of buildings within the green transition must also encompass foundations, which significantly influence material consumption and the embodied carbon of structures. Accurate settlement prediction is a cornerstone of sustainable design; however, engineering practice often relies on simplifications, such as assuming a constant soil deformation modulus, that lead to oversizing of foundation elements. This paper examines two types of shallow foundations, an isolated footing and a raft, founded in sandy subsoil, and compares calculation outcomes obtained using five approaches: a code-based method, parameters derived from oedometer tests, parameters from triaxial tests, and two Janbu variants that account for stiffness increasing with depth. The results reveal substantial variability in predicted settlements, ranging from underestimation with the code-based approach to overestimation with the oedometer method. The most realistic predictions were obtained using triaxial parameters and the nonlinear model, which better capture the actual deformation mechanisms of the subsoil. Although the primary aim of this study is to improve the technical accuracy of settlement prediction, these findings also demonstrate that precise geotechnical modeling naturally supports resource efficiency and contributes to sustainable construction as a secondary, yet measurable, outcome of rational design. Full article

Cerebral aneurysm clipping remains a key surgical approach despite advancements in endovascular techniques. However, training for this procedure is complex due to the variable and fragile nature of aneurysmal tissues. This study evaluates the mechanical behaviour of human basilar arteries during clipping and compares them to 3D-printed models used for neurosurgical training. Mechanical tests were performed on ten cadaveric basilar arteries, distinguishing between healthy and plaque-affected segments. Plaque-affected regions required significantly higher clipping force (1.73 ± 0.22 N) compared to healthy segments (0.45 ± 0.19 N), confirming that atherosclerosis markedly increases arterial stiffness. Six 3D-printed phantom materials were evaluated; none accurately replicated the biomechanical response of real arteries. The Flex Anatomical material showed the highest stiffness (44.51 ± 0.98 N), while Silicone 40A was the most compliant (1.05 ± 0.12 N), yet both deviated substantially from biological performance. These findings underscore the current limitations of anatomical models that lack realistic biomechanical properties. Full article

Soft robots often suffer from insufficient load capacity due to the softness of their materials. Existing variable stiffness technologies usually introduce rigid components, resulting in decreased flexibility and complex structures of soft robots. To address these challenges, this work proposes a novel wrist-gripper composite soft end-effector based on the weaving jamming principle, which features a highly integrated design combining structure, actuation, and stiffness. This end-effector is directly woven from pneumatic artificial muscles through weaving technology, which has notable advantages such as high integration, strong performance designability, lightweight construction, and high power density, effectively reconciling the technical trade-off between compliance and load capacity. Experimental results demonstrate that the proposed end-effector exhibits excellent flexibility and multi-degree-of-freedom grasping capabilities. Its variable stiffness function enhances its ability to resist external interference by 4.77 times, and its grasping force has increased by 1.7 times, with a maximum grasping force of 102 N. Further, a grasping force model for this fiber-reinforced woven structure is established, providing a solution to the modeling challenge of highly coupled structures. A comparison between theoretical and experimental data indicates that the modeling error does not exceed 7.8 N. This work offers a new approach for the design and analysis of high-performance, highly integrated soft end-effectors, with broad application prospects in unstructured environment operations, non-cooperative target grasping, and human–robot collaboration. Full article

Soft robots demonstrate great potential for underwater exploration, particularly in tasks such as locomotion and biological sampling in fragile marine habitats. However, developing new forms of interaction with underwater life remains a challenge due to inadequate soft mechanisms for studying the behavior of marine invertebrates. We present a 7-cm in diameter anemone robot (“Soromone”) capable of performing biological sea anemones’ wiggling behavior under the water. Inspired by the body forms of adult cnidaria, we developed a morphing mechanism that serves as both structure and actuator for the Soromone’s behavior using a soft tectonics approach—a multistep, multiscale, heterogeneous soft material fabrication technique. As an actuator, the morphing mechanism can precisely control the Soromone via a fluid system; as a structure, it can reinstate the Soromone’s original shape by incorporating various degrees of stiffness or softness into a single piece of material during fabrication. Our study demonstrates the advantages of applying a Soromone under water, including increasing water flow for enhanced nutrient uptake, waste removal, and gas exchange. This cnidaria-inspired soft robot could potentially be adapted for interaction with coral reef ecosystems by providing a safe environment for diverse species. Future soft robotics design paradigms based on a soft tectonics approach could expand the variability and applicability of soft robots for underwater exploration and habitation. Full article

To conserve natural resources and reduce waste generation, the effective valorization of industrial waste and byproducts in engineering applications is becoming increasingly important. Among these materials, aluminum production residues (APRs) offer a promising and sustainable solution for road pavement applications. Unlike previous reviews, this paper uniquely examines recent research on the use of various APRs in bituminous materials across multiple scales, with particular attention to their roles as additives and fillers. The APRs examined included red mud (RM), aluminum dross (AD), and spent pot lining (SPL) residues, as well as secondary aluminum waste (SAW). These materials have been employed as additives in asphalt binders (microscale), as fillers in asphalt mastics (mesoscale), and as additives or fillers in asphalt mixtures (macroscale). Overall, this review indicates that adopting appropriate treatment approaches for APRs as asphalt modifiers can enhance their dispersion, thermal stability, rheological behavior, and leaching performance. In particular, the use of RM has been shown to improve thermal stability, tensile strength, intermediate-temperature cracking resistance, and rutting resistance, largely due to the increased stiffness it imparts to asphalt mastic and mixture phases. However, there is no clear consensus among researchers regarding other properties, as performance outcomes depend strongly on multiple factors, particularly the physicochemical characteristics of the RM, filler–binder ratios, testing methods, and reference filler types. Other APRs—such as AD, SPL, and SAW—have also shown beneficial effects on the performance of asphalt mixtures. There is still limited research on the influence of APRs physicochemical variability on asphalt–filler interactions and the performance of bituminous materials. For the safe and large-scale adoption of APRs, it is essential to establish standardized characterization procedures, testing methods, and application guidelines while considering diverse climatic conditions. Comprehensive assessments of cost and environmental impacts should also be incorporated to support informed decision-making by engineers and industrial stakeholders. Full article

Tensegrity structures, by definition composed of compressed members suspended in a network of tensile cables, are characterised by a high strength-to-weight ratio and the ability to undergo reversible deformations. Their application as cores of sandwich panels represents an innovative approach to lightweight design, enabling the regulation of mechanical properties while reducing material consumption. This study presents a finite element modelling procedure that combines analytical determination of prestress using singular value decomposition with implementation in the ABAQUS™ 2019 software. Geometry generation and prestress definitions were automated with Python 3 scripts, while algebraic analysis of individual modules was performed in Wolfram Mathematica. Two models were investigated: M1, composed of four identical modules, and M2, composed of four modules arranged in two mirrored pairs. Model M1 exhibited a linear elastic response with a constant global stiffness of 13.9 kN/mm, stable regardless of the prestress level. Model M2 showed nonlinear hardening behaviour with variable stiffness ranging from 0.135 to 1.1 kN/mm and required prestress to ensure static stability. Eigenvalue analysis confirmed the full stability of M1 and the increase in stability of M2 upon the introduction of prestress. The proposed method enables precise control of prestress distribution, which is crucial for the stability and stiffness of tensegrity structures. The M2 configuration, due to its sensitivity to prestress and variable stiffness, is particularly promising as an adaptive sandwich panel core in morphing structures, adaptive building systems, and deployable constructions. Full article

The manufacturing industry, in general, and the plastic industry, in particular, have been developing new materials and process methods that need a correct study and optimization. Nowadays, the main approach to optimize these processes is using numerical methods and, in the case of particulate materials, the Discrete Elements Method to estimate the particles interactions. But those mathematical models use some parameters that depend on the material and must be calibrated, thus requiring an important computational and experimental cost. In this study, we integrate different speed-up procedures and present a general calibration method of Low-Density Polyethylene particles, to obtain the calibrated solid density and Poisson’s ratio of the material, the restitution, static and rolling friction factors in the particle-to-particle and particle-to-wall interactions, and the contact model variables (damping factor, stiffness factor, and energy density). For this calibration, four different tests were carried out, both experimentally and with simulations, obtaining the bulk density, the repose and shear angles, and the dropped powder. All these response variables were compared between simulations and experimental tests, and using genetic algorithms, the input parameters (design variables) were calibrated after 85 iterations, obtaining a Mean Absolute Percentage Error of the response variables lower than 2% compared to the experimental results. Full article

Sports footwear is widely used across a range of physical activities. A key factor distinguishing running shoes from other types of footwear is the “drop,” the millimeter difference between the heel and the forefoot. This study aimed to analyze the influence of different drops (0, 5, and 10 mm) on ground reaction forces during walking and to examine the effects of sex and body mass index (BMI) under these conditions. An observational, descriptive, and cross-sectional study was conducted with 117 participants (56 men and 61 women). The Dinascan/IBV^® dynamometric platform (Instituto de Biomecánica de Valencia, Valencia, Spain) was used to measure ground reaction forces during walking (braking, take-off, propulsion, and swing forces), walking speed, and stance time. The descriptive analysis revealed comparable values for the left and right limbs, with slightly higher values observed in the right limb. Statistically significant differences were found in stance time, braking force, and swing force between the 0 mm and 10 mm drop conditions. Take-off force showed highly significant differences when comparing the 0–5 mm and 0–10 mm drop conditions. Sex-based differences were observed in all variables at the initial proposed drop condition of 0 mm, except for walking speed, possibly due to anatomical and physiological differences. Significant differences were found in stance time at 0 mm drop, braking force, and propulsion force. Highly significant values were obtained for take-off force and during the swing phase. A strong correlation was found between ground reaction forces and BMI with the different proposed drops in all forces studied, except for the support force, where a moderate correlation was obtained. Although shoe drop was found to influence ground reaction forces in this study, it is one of several factors that affect gait biomechanics. Other footwear characteristics, such as sole stiffness, material composition, weight, and elasticity, also play important roles in walking performance. Therefore, shoe drop should be considered an important but not exclusive parameter when selecting footwear. However, these results are limited to healthy young adults and may not be generalizable to other age groups or populations. Full article