Search Results (476)

Topology optimization serves as a critical method for promoting lightweight structural design. Traditional methods predominantly focus on mechanical performance evaluation, often neglecting the critical correlation between modal characteristics and structural stiffness. The Evolutionary Structural Optimization (ESO) method is extensively employed in topology optimization; however, iterative oscillations lead to issues such as grid divergence and diminished solution quality. To address issues such as iterative oscillations and mesh divergence in the traditional Evolutionary Structural Optimization (ESO) method, this study applies a Simp Evolutionary Structural Optimization (SI-ESO) methodology. This method integrates intermediate density parameters and penalty factors into the progressive structural optimization process, thereby significantly enhancing iterative convergence and model quality. This work applied the optimized SI-ESO method to the lightweight redesign of an aviation generator’s rear cover, with validation conducted through additive manufacturing. Subsequently, the back cover of an aviation generator was redesigned and fabricated utilizing additive manufacturing technology. Empirical results indicate that under maximum stress conditions and employing the same additive process, the maximum deformation of the SI-ESO-optimized model is reduced compared to that of the ESO-designed model. Compared with the original design, the SI-ESO-optimized model achieved a 31% weight reduction, while relative to the ESO-optimized model, it exhibited a 27% lower maximum stress and a 10.53% higher first-order frequency, demonstrating both lightweighting and enhanced structural stiffness. Full article

Block caving is a cost-effective mining method that enables the highly efficient mining of thick and large ore bodies. During ore extraction in block caving operations, the ore-drawing roadways require especially high safety standards. However, the complex in situ stress conditions and cyclic loading from caved ore significantly deteriorate the stability of the surrounding rock. This makes rock mass control particularly challenging, such that it is crucial to study an effective method for maintaining the long-term stability of the roadways. This research proposes a comprehensive approach combining laboratory rock mechanics testing, numerical simulation, and field engineering validation to design effective support strategies for disturbance-affected roadways. Laboratory tests provide accurate mechanical parameters for the rock mass, the numerical simulations allow for the comprehensive analysis of deformation–failure mechanisms under disturbance conditions, and field validation ensures the reliability and practical applicability of the proposed support method. This study focuses on a −285 m ore-drawing roadway in the western section of the Yanqianshan Iron Mine. The in situ stress distribution was characterized through rock mechanics testing and acoustic emission monitoring. The propagation mechanisms of ore-drawing disturbance waves within the rock mass were analyzed, and numerical simulations revealed the deformation patterns and failure modes under dynamic disturbance, upon which the support scheme was designed. The results demonstrate that the designed bolt–mesh–shotcrete support scheme can effectively control surrounding rock deformation within 5 mm and resists the deformation induced by cyclic disturbances. This study provides valuable technical support for stability management in block caving mines with similar conditions. Full article

The integration of nanomaterials within hydrogel scaffolds offers significant promise in bone tissue engineering by improving mechanical performance and modulating cellular responses through mechanotransductive and biochemical signaling. Previous studies have demonstrated that nanodiamonds (NDs) incorporated in electrospun microfibrillar meshes enhance cellular adhesion, spreading, and cytoskeletal organization through localized mechanical reinforcement. However, the effects of ND loading into soft, bioinert three-dimensional hydrogel matrices remain underexplored. Here, we developed nanostructured 3D printing inks composed of gellan gum (GG) supplemented with a low content of ND nanoadditive (0–3% w/v). ND integration improved the shear-thinning properties of the formulation, enabling consistent filament formation and reliable extrusion-based 3D printing. Structural and mechanical assessments confirmed enhanced scaffold morphology, reduced deformation, and improved morphostructural integrity under compression and increased local stiffness at 2% ND loading (GG_ND2%). Biological assessments revealed that increasing ND content enhanced murine preosteoblast viability, proliferation, and attachment, particularly in GG_ND2%. Furthermore, bioactivation of the GG_ND2% formulation with icariin (ICA), a bioflavonoid known for its osteogenic and angiogenic activity, amplified the beneficial cellular responses of MG-63 cells to ND loading, promoting enhanced surface mineralization and improved cell–matrix interactions. Collectively, these findings highlight the potential of ND-reinforced GG scaffolds bioactivated with ICA, integrating structural reinforcement and biological functionalities that may support osteogenic responses. Full article

Background/Objectives: The purpose of this review was to determine the impact of osteoporosis on outcomes after surgery for cervical deformity. Cervical deformity involves abnormal curvature or misalignment of the cervical spine, often resulting in a significant loss of quality of life and requiring surgical correction. While osteoporosis has been associated with hardware failure including screw loosening and cage migration in spine surgery, its role in cervical deformity remains unclear. Existing studies report mixed findings with regard to postoperative sequelae in patients with osteoporosis undergoing surgical correction of cervical deformity. Methods: A systematic review using PRISMA guidelines and MeSH terms involving spine surgery for cervical deformity and osteoporosis was performed. The Medline (PubMed) database was searched from 1990 to August 2022 using the following terms: “osteoporosis” AND “cervical” AND (“outcomes” OR “revision” OR “reoperation” OR “complication”). This review focused on radiographic outcomes, as well as post-operative complications. Results: Eight studies were included in the final analysis. Three papers assessed risk factors for the development of post-operative distal junctional kyphosis (DJK), but only one found osteoporosis as a predictor for DJK. Although three studies found that osteoporosis was not significantly associated with the incidence of surgical complications, one highlights osteoporosis as a predictor of complications at 90 days postoperatively (p < 0.001) and another associates osteoporosis with overall poor outcomes (p = 0.021). Furthermore, one study assessing the relationship between osteoporosis and reoperation found no association. Conclusions: Overall, our systematic review suggests that in patients undergoing surgery for cervical deformity, osteoporosis is not predictive of the need for reoperation or the development of postoperative complications, such as DJK, dysphagia, superficial infection, and others. These findings highlight the need for further study regarding the role of osteoporosis in surgical correction of cervical deformity. Full article

The dynamics of mechanical systems with fast motions and dynamic loads are strongly influenced by the deformability of kinematic elements. The finite element method and the superposition of rigid body motion with deformable body motion allow us to determine a new structure for the matrices that define the mechanical system equations of motion. Meshing the kinematic elements into finite elements causes the unknowns of the problem to no longer be displacement functions but rather nodal displacements. These displacements are considered as a linear combination of modal shapes and modal coordinates. This method is applied to a drive mechanism of an internal combustion engine with three pistons mounted in line. The system is driven by the pressure exerted by the gas on the piston head, which was experimentally determined. The longitudinal and transversal deformations of the connecting rod are determined, including the nodal displacements. These results were verified through virtual prototyping on the 3D model, using multibody system theory and the finite element method. The recorded differences are mainly explained by the type, size, and shape of the used finite elements. Experimental analysis allows us to determine the connecting rod kinematic and dynamic parameters as functions of time and frequency variation. The developed method is flexible and can be easily adapted to systems with fast motions in which, during operation, impact forces appear in joints for various reasons. Full article

Cylindrical gears are used extensively due to their significant advantages including high efficiency, high load-bearing capacity, and long lifespan. However, the machining accuracy of cylindrical gears is significantly affected by motion errors and force-induced errors of machine tools. In this study, a motion error model of the machine tools was established based on multi-body system theory and homogeneous coordinate transformation method, quantifying the contributions and variation patterns of 12 key errors in the A and B-axes to workpiece geometric errors. Then, by using the stiffness analytical model and the spatial meshing theory, the influence of the force-induced elastic deformation of the shaft of rolling wheel and the springback of the workpiece tooth flank on the geometric error was revealed. Finally, taking the through rolling of a spur cylindrical gear with a module of 1.75 mm, a pressure angle of 20°, and 46 teeth as an example, the force-induced elastic deformation model of the shaft was verified by the rolling tests. Results show that for 40CrNiMo steel, the total profile deviation, total helix deviation, and single pitch deviation in the X-direction caused by rolling forces are 32.48 μm, 32.13 μm, and 32.13 μm, respectively, with a maximum contact rebound is δ_c = 28.27 μm. The relative error between theoretical and measured X-direction spindle deformation is 8.26%. This study provides theoretical foundation and experimental support for improving the precision of rolling process. Full article

Pelvic organ prolapse (POP) cases have been rising, affecting women’s quality of life. Severe cases often require surgical mesh implants, which can cause complications like tissue erosion and infection, leading the FDA to ban transvaginal meshes for POP. To address this, polycaprolactone (PCL) mesh implants, produced via melt electrowriting (MEW), were evaluated mechanically and coated with azithromycin, an antibiotic for genitourinary infections. Uniaxial tensile and cyclic tests assessed the long-term behavior of the meshes over 100 cycles. The results show that while all PCL meshes had similar behavior, those with 1 mm pores sustained higher stress, whereas 1.5 mm pore size meshes had mechanical properties closer to vaginal tissue but remained stiffer. Cyclic tests revealed initial damage and hardening during plastic deformation, with tensile tests confirming increased stiffness, as Young’s modulus rose between 19.2% and 29.3%. Zone inhibition and biofilm assays evaluated azithromycin’s effectiveness against bacterial infection. Even though FTIR analysis could not confirm antibiotic incorporation, the drug coated meshes show inhibitory activity against E. coli biofilm formation and MSSA in its planktonic state. Scanning Electron Microscopy supported these findings. These results suggest that MEW-fabricated PCL meshes coated with azithromycin hold promise as improved implants for POP treatment. Full article

A physics-informed neural network (PINN) framework is developed to model the large deformation and coupled electromechanical response of dielectric elastomer tubes for energy harvesting. The system integrates incompressible neo-Hookean elasticity with radial electric loading and compressible gas inflation, leading to nonlinear equilibrium equations with deformation-dependent boundary conditions. By embedding the governing equations and boundary conditions directly into its loss function, the PINN enables accurate, mesh-free solutions without requiring labeled data. It captures realistic pressure–volume interactions that are difficult to address analytically or through conventional numerical methods. The results show that internal volume increases by over 290% during inflation at higher reference pressures, with residual stretch after deflation reaching 9.6 times the undeformed volume. The axial force, initially tensile, becomes compressive at high voltages and pressures due to electromechanical loading and geometric constraints. Harvested energy increases strongly with pressure, while voltage contributes meaningfully only beyond a critical threshold. To ensure stable training across coupled stages, the network is optimized using the Optuna algorithm. Overall, the proposed framework offers a robust and flexible tool for predictive modeling and design of soft energy harvesters. Full article

The mutual twisting of steel wires is widely used in construction, engineering, and everyday applications, as it is relatively easy to perform and imparts new and useful properties to the wires. Since the process involves large deformations and high stress levels, understanding the mechanical behavior of twisted pairs is essential for both their manufacturing and in-service performance. This study provides a detailed analysis of the stresses and deformations that arise during the twisting of two galvanized steel wires with a diameter of 4 mm. Comprehensive information is presented on the development and validation of a suitable finite element model, with emphasis on geometry definition, the selection of appropriate initial and boundary conditions, and the meshing strategy. Special attention is devoted to the material properties, which are obtained and processed based on original tensile and torsion tests. Both the maximum and residual stresses are investigated. It is found that, for small twist pitches, the equivalent stresses during twisting can exceed the material’s yield strength by a factor of two or more, posing a risk of failure. The residual equivalent stresses show complex spatial distributions that vary with pitch, yet their average magnitudes remain within a narrow range, indicating a consistent residual stress level across different twisting configurations. Full article

The Thin-Plate Splines (TPS) technique, using Kybic et al.’s generalized interpolation approach, is extended to differentiable manifolds. The initial application to surface mesh deformation resulting from parameterized Computer Aided Design (CAD) used in the framework of shape optimization is given. Coming to RSM (Response Surface Model), we give a comparison with Kriging and RBF (Radial Basis Functions), and an enrichment methodology is proposed. The new approach proposed is a breakthrough for UAV shape design of high-curvature areas. Full article

Background/Objectives: The breast implant exchange/explantation rate has been increasing in recent years due to various types of long-term complications or adverse effects, such as implant migration, rippling, or capsular contracture. To reduce complications such as migration and/or implant–pocket mismatch, surgical meshes may provide implant support. Here, we present a case series about the use of a non-absorbable synthetic bra-shaped mesh in revision surgery of the breast, using implants that do not adhere to the surrounding tissues. Methods: In this retrospective case series, eight patients underwent breast revision surgery between 2021 and 2024 due to implant-related long-term complications following aesthetic surgery. Surgical revision included implant exchange, total or partial capsulectomy, creation of a pre-pectoral implant pocket for the new implant, and positioning of the non-absorbable synthetic mesh, acting as an internal support for the implants. BREAST-Qs were collected from all patients. Results: Of the eight patients included, the following symptoms were observed: symptomatic capsular contracture (n = 3), implant migration (n = 4), and breast animation deformity (n = 2). After revision surgery, during the follow-up period of 6–42 months, neither infection nor seroma occurred. No implant-related complications were registered. The BREAST-Q analysis revealed the highest patient satisfaction in the domain “satisfaction with the implants” (median score 87.5%). Conclusions: In revision surgery after breast augmentation, the synthetic, non-absorbable and titanized pocket-like mesh may provide implant support and avoid recurrence of complications related to implant position. However, due to the small and heterogeneous patient group, larger studies are needed to validate these preliminary findings. Full article

This article discusses contemporary strategies to deal with immersed boundary (IB) frameworks useful for analyzing flow–structure interaction in complex settings. It focuses on immense advancements in various fields: biology, oscillation of structures due to fluid flow, deformable materials, thermal processes, settling particles, multiphase systems, and sound propagation. The discussion also involves a review of techniques addressing moving boundary conditions at complex interfaces. Evaluating practical examples and theoretical challenges that have been addressed by these frameworks are another focus of the article. Important results highlight the integration of IB methods with adaptive mesh refinement and high-order accuracy techniques, which enormously improve computational efficiency and precision in modeling complex solid–fluid interactions. The article also describes the evolution of IB methodologies in tackling problems of energy harvesting, bio-inspiration propulsion, and thermal-fluid coupling, which extends IB methodologies broadly in many scientific and industrial areas. More importantly, by bringing together different insights and paradigms from across disciplines, the study highlights the emerging trends in IB methodologies towards solving some of the most intricate challenges within the technical and scientific domains. Full article

We investigated the electrochemical properties of and conducted an electromechanical analysis on a stacked polyvinyl chloride (PVC) gel actuator, comprising a PVC gel plasticized with dibutyl adipate (DBA) sandwiched between a metal mesh and a metal disk electrode. In this study, we examined the electrochemical impedance, displacement, and electric current responses to square-wave voltage inputs. The linear motion of PVC gel actuators with and without ionic liquid (IL) additives was analyzed in relation to the mesh size and metal composition of the mesh electrode. The displacement increased with decreasing mesh numbers, indicating that displacement increases with increasing wire diameter and space length. The linear motion of the stacked PVC gel actuators with and without IL additives depended on the metal species of the mesh electrodes. The electrochemical impedance of the stacked PVC gel actuators under DC voltage application was analyzed with and without the IL. Based on the electromechanical and electrochemical results, a deformation model was developed to describe the linear motion of stacked PVC gel actuators in response to the applied voltage. The model attributed this motion to the deformation induced by Maxwell stress in the solvent-rich layer, successfully accounting for the experimental observations. Full article

Intraosseous hemangiomas (IH) are rare intrabony lesions that represent less than 1% of intraosseous tumors. IH are mostly seen in the axial skeleton and skull. Most commonly, the frontal bone, zygomatic, sphenoid, maxilla, ethmoid, and lacrimal bone can manifest IH. Currently, IH is classified as a developmental condition of endothelial origin. According to WHO, the five histological types of IH are cavernous, capillary, epithelioid, histiocytoid, and sclerosing. IH of the zygoma is an extremely rare condition with female predominance. A systematic review recently estimated that there were 78 cases published in the literature until 2023. The lesion is usually asymptomatic and presents with a gradually deteriorating deformity of the malar area, and the patient might be able to recall a history of trauma. Numbness due to involvement of the infraorbital nerve might also be present; however, atypical skin and bone sensations might also occur. Other symptoms include painful swelling, bone asymmetry, skin irritation, sinus pressure, paresthesia, diplopia, enophthalmos, or atypical neuralgia. A bony lesion with a trabecular pattern in a radiating formation (sunburst pattern) or a multilocal lytic lesion pattern created by the multiple cavernous spaces (honeycomb pattern) is commonly observed during radiologic evaluation. We present a rare case of IH of the zygoma in a 65-year-old generally healthy woman. A cyst-like bone tumor was revealed from the CT scan, which made preoperative biopsy of the lesion problematic. A careful radiological diagnostic differentiation of the lesion should always be conducted in such cases to outline a safe surgical plan and possible alternatives if needed. The patient underwent total tumor resection in the operating room, and the defect was reconstructed with the use of a titanium mesh and a synthetic hydroxyapatite bone graft based on a 3D surgical guide printed model. Full article

Cutting beech plywood using abrasive water jet (AWJ) technology represents a significant area of research due to increasing demands for precision, quality, and environmental sustainability in manufacturing processes within the woodworking industry. AWJ technology enables non-contact cutting of materials without causing thermal deformation or mechanical damage, which is crucial for preserving the structural integrity and mechanical properties of the plywood. This article investigates cutting beech plywood using technical methods using an abrasive water jet (AWJ) at 400 MPa pressure, with Australian garnet (80 MESH) as the abrasive material. It examines how abrasive mass flow rate, traverse speed, and material thickness affect AWJ lag, which in turn influences both cutting quality and accuracy. Measurements were conducted with power abrasive mass flow rates of 250, 350, and 450 g/min and traverse speeds of 0.2, 0.4, and 0.6 m/min. Results show that increasing the abrasive mass flow rate from 250 g/min to 350 g/min slightly decreased the AWJ cut width by 0.05 mm, while further increasing to 450 g/min caused a slight increase of 0.1 mm. Changes in traverse speed significantly influenced cut width; increasing the traverse speed from 0.2 m/min to 0.4 m/min widened the AWJ by 0.21 mm, while increasing it to 0.6 m/min caused a slight increase of 0.18 mm. For practical applications, it is recommended to use an abrasive mass flow rate of around 350 g/min combined with a traverse speed between 0.2 and 0.4 m/min when cutting beech plywood with AWJ. This balance minimizes jet lag and maintains high surface quality comparable to conventional milling. For thicker plywood, reducing the traverse speed closer to 0.2 m/min and slightly increasing the abrasive flow should ensure clean cuts without compromising surface integrity. Full article