Element Analysis Research Articles

Bionic Design of High-Performance Joints: Differences in Failure Mechanisms Caused by the Different Structures of Beetle Femur-Tibial Joints.

Beetle femur-tibial joints can bear large loads, and the joint structure plays a crucial role. Differences in living habits will lead to differences in femur-tibial joint structure, resulting in different mechanical properties. Here, we determined the structural characteristics of the femur-tibial joints of three species of beetles with different living habits. The tibia of Scarabaeidae Protaetia brevitarsis and Cetoniidae Torynorrhina fulvopilosa slide through cashew-shaped bumps on both sides of the femur in a guide rail consisting of a ring and a cone bump. The femur-tibial joint of Buprestidae Chrysodema radians is composed of a conical convex tibia and a circular concave femur. A bionic structure design was developed out based on the characteristics of the structure of the femur-tibial joints. Differences in the failure of different joint models were obtained through experiments and finite element analysis. The experimental results show that although the spherical connection model can bear low loads, it can maintain partial integrity of the structure and avoid complete failure. The cuboid connection model shows a higher load-bearing capacity, but its failure mode is irreversible deformation. As key parts of rotatable mechanisms, the bionic models have the potential for wide application in the high-load engineering field.

Modal and harmonic analysis of femur bone using different boundary conditions by Finite Element Analysis.

The longest and largest bone in the human body is the femur. Pelvic bone sustains the weight of the body to which the femur bone is connected. Many researches have been carried out to identify the behaviour of the femur bone. The study aimed to explore the natural frequencies and mode shapes of vibrating devices to gain insights into the dynamic behavior of the femur bone during various physical activities. Examining the impact of patient-specific bone shape and density on bone natural frequencies is crucial. The primary goals of femur bone analysis involve employing computer simulations for fracture detection and employing Finite Element (FE) models to determine natural frequencies and vibration modes. To obtain the natural frequency of the femur bone, different boundary conditions such as free-fixed and fixed-fixed are applied. Avoiding the coincidence of the natural frequency with external excitation frequencies is crucial to prevent femur bone fractures. Also, for different magnitude of loads, femur bone is involved in harmonic analysis is to identify the amplitude and stress against acceleration.

Structural and physiological implications of witches' broom infection in Xylopia aromatica (Annonaceae) trees

AbstractWitches' brooms are abnormal branches that can affect various tree species in the Brazilian savanna, such as Xylopia aromatica. This disease leads to biomass loss and alters growth patterns. This study investigated the anatomical and physiological impacts of witches' broom on X. aromatica, hypothesizing that the disease induces changes in both infected and noninfected branches of the same tree. Measurements included leaf area, chlorophyll content and photosystem II (PSII) functionality in control and infected plants, as well as branch types (control, uninfected and infected branches for infected plants). Water potential was assessed at predawn and midday, and stem samples were analysed for anatomical and vessel element analysis. Witches' broom disease manifests as short brown stems and small yellowish‐green leaves. While infected and uninfected plants showed no significant differences in leaf area and leaf dry biomass, infected branches had reduced leaf number, area and weight. Chlorophyll content and PSII efficiency were significantly reduced in infected branches, indicating photosynthetic disruption. Water potential was lower at predawn in infected plants but normalized by midday, suggesting an adaptive response. Anatomical changes in infected branches included alterations in vessel elements and parenchymatic rays. Overall, X. aromatica displays localized changes due to witches' broom, which aids in water stress adaptation. Despite these findings, long‐term studies are needed to evaluate the impacts on biomass reduction and reproductive investment in Brazilian savanna areas, crucial for understanding the ecological impact and developing survival strategies for affected plants.

INFLUENCE OF ABUTMENT GEOMETRY ON THE MICROGAP SIZE IN THE CONICAL CONNECTION

BACKGROUND: To provide prosthetics for patients on implants, dentists resort to using not only original, but also non-original suprastructures. Previously, the authors carried out an finite element analysis, which showed that the size of the microgap of the conical connection depends on the choice of abutments, which affects the condition of the marginal bone around the implant. AIMS: to find out the factor that distinguishes the original and non-original abutments and largely influences the size of the microgap in the conical connection. MATERIALS AND METHODS: The experiment involved implants and standard abutments of Straumann BL, BioHorizons Tapered Internal and Nobel Biocare CC implant systems, and non-original abutments of ADM Dental. At the first stage of the experiment, four main factors were identified: the material of the screw and abutment, the geometry of the screw and abutment. The calculations were based on data from the authors' previous research and were carried out through the ANSYS Workbench using the finite element analysis. The second stage of the study was carried out on the microtomography complex “Neoscan 80”, where, in order to clarify the geometric features of the samples, the size of the microgap and the length of the conical generatrices between the constituent elements were measured. RESULTS: We can talk about the predominant influence of the abutment geometry on the micro-gap of the conical connection of Straumann and BioHorizons. In Nobel, the width of the microgap depends largely on the geometry of the abutment screw. Measurements of the microtomographic complex determined the difference in the length of the conical “implant-abutment” components for Straumann (0.1 mm) and BioHorizons (0.07 mm), and did not determine it between the original and non-original abutment for Nobel. The conical generatrix of the screw with the original Nobel abutment is smaller than with the non-original one. CONCLUSIONS: As a result of the study, it was determined that the choice between the original and non-original suprastructure has a greater influence on the size of the microgap of the conical connection due to the different geometric configuration of the abutment, in particular, the geometry of its fixing screw.

Development and Comparison of Model-Based and Data-Driven Approaches for the Prediction of the Mechanical Properties of Lattice Structures

AbstractLattice structures have great potential for several application fields ranging from medical and tissue engineering to aeronautical one. Their development is further speeded up by the continuing advances in additive manufacturing technologies that allow to overcome issues typical of standard processes and to propose tailored designs. However, the design of lattice structures is still challenging since their properties are considerably affected by numerous factors. The present paper aims to propose, discuss, and compare various modeling approaches to describe, understand, and predict the correlations between the mechanical properties and the void volume fraction of different types of lattice structures fabricated by fused deposition modeling 3D printing. Particularly, four approaches are proposed: (i) a simplified analytical model; (ii) a semi-empirical model combining analytical equations with experimental correction factors; (iii) an artificial neural network trained on experimental data; (iv) numerical simulations by finite element analyses. The comparison among the various approaches, and with experimental data, allows to identify the performances, advantages, and disadvantages of each approach, thus giving important guidelines for choosing the right design methodology based on the needs and available data.

Simulation and mechanical testing of 3D printing shin guard composite materials

ABSTRACT This study critically examines the composite material's mechanical properties and performance for 3D-printed shin guards. It contains a thermoplastic polymer matrix with short carbon fibre reinforcement. Shin guard stress and deformation under impact loading were modelled using FEA models. The composite material was 3D-printed and tested for tensile, flexural, and impact properties. The entire cycle of FEA models and careful mechanical testing allows for the development and evaluation of new composite materials and designs. The finite element analysis, such as maximum von Mises stress, is 2890.5 MPa. The carbon fibre-reinforced composite's mechanical properties, including tensile strength, flexural strength, and impact resistance, showed a considerable improvement over those of the unreinforced polymer. The solid design could be heavier and less adaptable than the pattern. Compared to unreinforced polymers, carbon fibre improves strength, stiffness, and impact resistance for the 3D-printed composite. This result thus proves that 3D-printed carbon fibre-reinforced composites could make superior sports protective equipment like shin guards. The FEA calculations and extensive mechanical testing provide a dependable framework for creating and testing these new composite materials and systems.

A Novel Application of Computational Contact Tools on Nonlinear Finite Element Analysis to Predict Ground-Borne Vibrations Generated by Trains in Ballasted Tracks

Predictive numerical models in the study of ground-borne vibrations generated by railway systems have traditionally relied on the subsystem partition approach (segmented). In such a method, loads are individually applied, and the cumulative effect of the rolling stock is obtained through superposition. While this method serves to mitigate computational costs, it may not fully capture the complex interactions involved in ground-borne vibrations—especially in the frequency domain. Recent advancements in computation and software have enabled the development of more sophisticated vibrational contamination prediction models that encompass the entire dynamics of the system, from the rolling stock to the terrain, allowing continuous simulations with a defined time step. Furthermore, the incorporation of computational contact mechanics tools between various elements not only ensures accuracy in the time domain but also extends the analysis into the frequency domain. In this novel approach, the segmented models are shifted to continuous simulations where the nonlinear problem of a rigid–flexible multibody system is fully considered. The model can predict the impact of a high-speed rail (HSR) vehicle passing, capturing the key intricacies of ground-borne vibrations and their impact on the surrounding environment due to a deeper comprehension of the occurrences in the frequency domain.

Numerical analysis of magnetohydrodynamic effects on hybrid nanofluid cooling in high-density servers

This study numerically examines active CPU cooling using hybrid nanofluids in a novel heatsink design. The proposed heatsink is a parallelepiped block filled with Al2O3-CuO/water nanofluid, traversed by four strategically placed cooling tubes. It meticulously investigates the effects of CPU temperature (10³ ≤ Ra ≤ 10⁶) and magnetic field strength (0 ≤ Ha ≤ 100) on overall cooling capacity. With hybrid nanofluids, heat transfer and cooling efficiency are substantially improved, according to comprehensive finite element analysis conducted in COMSOL Multiphysics. The study provides valuable insights for designing high-performance CPU cooling systems, carefully considering nanofluid properties, diverse thermal conditions, and complex magnetic effects. The promising results show that using advanced hybrid nanofluids and an optimized magnetic field can significantly enhance the cooling performance of modern high-powered CPUs. The groundbreaking research highlights the immense potential of combining cutting-edge nanotechnology and magnetohydrodynamics in innovative thermal management solutions. This novel approach could lead to more efficient, compact, and adaptable cooling systems for next-generation electronic devices, effectively addressing the persistent challenge of heat dissipation in high-performance computing environments.

Detectability of residual stress anomalies in railway wheels with different geometries subjected to thermal overload based on back gauge change

Temperature increases of railway wheels due to frictional braking on the running surface (wheel tread) can lead to maintenance challenges such as tread wear and thermal cracking. While heating within the anticipated design range should not adversely affect the structural safety of the wheels, excessive temperature rises resulting from brake system failures can induce tensile residual stresses in the rim, potentially leading to wheel fracture. Detecting wheels with abnormal residual stresses is therefore crucial for railway safety, and monitoring residual displacements in the rim due to changes in circumferential residual stresses is an implementable approach. However, the shape of the wheel web varies, and the displacement response to thermal input differs depending on the wheel geometries. This study aims to explore general deformation behaviours related to wheel shape and elucidate the relationship between shape and heat resistance. The elastic-plastic finite element analysis employing simplified intense thermal input revealed that residual deformation after excessive thermal loading consistently results in back gauge expansion, although the deformation and stress responses differ based on the web geometry. Differences in heat resistance are indicated by the variation in the temperature at which compressive yielding due to thermal stress occurs, depending on the web shape. The residual stress detectability of each wheel is determined based on the principle that greater residual displacement at lower stress indicates higher anomaly detectability.

Effects of Stress and Strain on the Optic Nerve Head on the Progression of Glaucoma.

In primary open-angle glaucoma, the rate of retinal nerve fiber layer thickness decrease was negatively correlated with lamina cribrosa strain, which was associated with intraocular pressure and optic nerve head geometric factors. We hypothesized that the biomechanical deformation of the optic nerve head (ONH) contributes to the progression of primary open-angle glaucoma (POAG). This study investigated the biomechanical stress and strain on the ONH in patients with POAG using computer simulations based on finite element analysis (FEA) and analyzed its association with disease progression. We conducted a retrospective analysis that included patients diagnosed with early-to-moderate stage POAG. The strains and stresses on the retinal nerve fiber layer (RNFL) surface, prelaminar region, and lamina cribrosa (LC) were calculated using computer simulations based on FEA. The correlations between the rate of RNFL thickness decrease and biomechanical stress and strain were investigated in both the progression and non-progression groups. The study included 71 and 47 patients in the progression and non-progression groups, respectively. In the progression group, the factors exhibiting negative correlations with the RNFL thickness decrease rate included the maximum and mean strain on the LC. In multivariate analysis, the mean strain on the LC was associated with optic disc radius, optic cup deepening, axial length, and mean intraocular pressure (IOP), whereas the maximum strain was only associated with mean IOP. In early-to-moderate stage POAG, the rate of RNFL thickness decrease was influenced by both the mean and maximum strain on the LC. Strains on the LC were associated with mean IOP, optic disc radius, axial length, and optic cup deepening. These results suggest that not only IOP but also ONH geometric factors are important in the progression of glaucoma.

Application of artificial neural network for the mechano-bactericidal effect of bioinspired nanopatterned surfaces.

This study aimed to calculate the effect of nanopatterns' peak sharpness, width, and spacing parameters on P. aeruginosa and S. aureus cell walls by artificial neural network and finite element analysis. Elastic and creep deformation models of bacteria were developed in silico. Maximum deformation, maximum stress, and maximum strain values of the cell walls were calculated. According to the results, while the spacing of the nanopatterns is constant, it was determined that when their peaks were sharpened and their width decreased, maximum deformation, maximum stress, and maximum strain affecting the cell walls of both bacteria increased. When sharpness and width of the nano-patterns are kept constant and the spacing is increased, maximum deformation, maximum stress, and maximum strain in P. aeruginosa cell walls increase, but a decrease in S. aureus was observed. This study proves that changes in the geometric structures of nanopatterned surfaces can show different effects on different bacteria.

Optimization of Flange Design for Engine Assembly Stand using RSM and NSGA-II Based on FEA Data

This article presents the results of a research study that focused on optimizing the flange design for engine assembly stands using the Response Surface Methodology (RSM) and Nondominated Sorting Genetic Algorithm II (NSGA-II) based on finite element analysis (FEA) simulation data. The study investigated the impact of three main dimensions (d1, d2, d3) of the flange as independent variables on the mass (m, kg), Von Mises stress (V, MPa), and displacement (D, mm) as dependent variables. The regression models developed using the RSM exhibited high R2 values of 0.9896, 0.998, and 0.9997 for m, V, and D, respectively. The multi-objective optimization results obtained through NSGA-II yielded 39 Pareto solutions, with d1 ranging from 10 to 27.43 mm, d2 ranging from 30 to 50 mm, and d3 ranging from 75 to 85 mm. These values corresponded to m values ranging from 2.93 to 7.58 kg, V values ranging from 54.8 to 342.6 MPa, and D values ranging from 0.006 to 0.270 mm. For verification purposes, Solution No.17 was selected. The results showed that the redesigned flange's mass, Von Mises stress, and displacement deviated by 0.95%, 2.28%, and 1.14%, respectively, from the optimal values obtained through the optimization process. These findings provide strong evidence for the high reliability of the optimization method employed in this study.

Desain dan Analisis Finite Elemen Rangka Gantry Crane Menggunakan Software Autodesk Inventor Profesional 2024

Currently, the gantry crane still uses steel material. The steel is protected using a coating paint to minimize the impact of corrosion. However, this method is inefficient given the high rate of corrosion due to its coastal location. This also causes maintenance issues because repainting must be done regularly and periodically. Additionally, not all equipment has annual maintenance funding. The aim of this study is to design and analyze the stress of a 9-ton capacity gantry crane using Aluminium 6061 material. Finite element analysis was conducted using Autodesk Inventor Professional 2024 software. The results of this study indicate that the gantry crane frame is safe to use because the von Mises stress analysis result of 2,778 MPa is still below the yield strength of Aluminium 6061 material, which is 275 MPa. A safety factor of 2.07 shows that the gantry crane design is very safe to withstand loads up to 9 tons.

How compactness affects long bone resistance to compression-An investigation into the rhinoceros humerus.

The functional signal of bone internal structure has been widely studied. Isolated form-function relationships have often been assumed from the observation of presumed morphofunctional relationships, but have never been truly tested. Indeed, distinct bone microanatomical feature co-evolve in response to various constraints that are difficult to detangle. This study tested for the first time the impact of various microanatomical parameters taken one by one, plus some in pairs, on bone strength under compression using biomechanical modelling. We carried out finite element analyses on humerus models, obtained from a white rhinoceros, with different heterogeneous internal structures, and analysed the magnitude and distribution of von Mises stresses. These tests validated earlier hypotheses of form-function relationships about the greater resistance to compression provided by the thickening of the cortex and the filling of the medullary area by trabecular bone and highlighted the stronger impact of increasing trabecular bone compactness than of avoiding an open medullary cavity. By making it possible to estimate the relative impact of each parameter and ofcombinations of microanatomical features, they also showed the more limited impact of the trabecular bone compactness in the epiphyses to resist compression, and the fact that microanatomical changes of opposite but of similar amplitude impact can compensate each other, but that the impact of the sum of two negative microanatomical changes far exceeds the sum of the impacts of each of the two changes taken separately. These results contribute to a better understanding of bone adaptation and form-function relationships so that they later can be used with confidence for palaeobiological inferences on fossil specimens, contributing to a better understanding of skeletal evolution during the evolutionary history of vertebrates. They also highlight the potential of taking internal structure into account in the bone biomechanical analyses. In addition, they can be used in bioinspiration to design resistant structures subjected to compression.

RF NEMS switches based on graphene for low pull-in voltage and excellent RF performance

This study introduces a novel graphene RF NEMS capacitive switch and conducts an extensive analysis of its RF performance using CST and COMSOL Multiphysics software. The switch’s characteristic impedance matching is accomplished through a coplanar waveguide (CPW) structure, incorporating a dielectric layer topped with conductive graphene beam electrodes. Simulation results reveal that the monolayer graphene RF NEMS switch maintains an insertion loss of 0.003 ~ 0.015 dB and an isolation greater than 40 dB across an ultra-wideband (UWB) frequency range of DC ~ 140 GHz. Moreover, the switch demonstrates a switching time of 4.03 ps at a pull-in voltage of 1 V. The performance of multilayer graphene RF NEMS switches was also evaluated. The study further investigates the operational mechanism of the graphene RF NEMS switch and performs finite element analysis on the proposed design. The graphene RF NEMS switch discussed herein offers significant advantages, including minimal size, lightweight, cost-effectiveness, low pull-in voltage, rapid response time, excellent RF performance, and reduced space consumption in circuitry. Its potential applications span a range from L to F bands, encompassing data storage, communication systems, sensors, remote sensing and military uses.

Biomechanical characteristics of ligament injuries in the knee joint during impact in the upright position: a finite element analysis

BackgroundOur study aims to examine stress–strain data of the four major knee ligaments—the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament (LCL)—under transient impacts in various knee joint regions and directions within the static standing position of the human body. Subsequently, we will analyze the varying biomechanical properties of knee ligaments under distinct loading conditions.MethodsA 3D simulation model of the human knee joint including bone, meniscus, articular cartilage, ligaments, and other tissues, was reconstructed from MRI images. A vertical load of 300 N was applied to the femur model’s top surface to mimic the static standing position, and a 134 N load was applied to the impacted area of the knee joint. Nine scenarios were created to examine the effects of anterior, posterior, and lateral external forces on the upper, middle, and lower regions of the knee joint.ResultsThe PCL exhibited the highest stress levels among the four ligaments when anterior loads were applied to the upper, middle, and lower parts of the knee, with maximum stresses at the PCL-fibula junction measuring 59.895 MPa, 27.481 MPa, and 28.607 MPa, respectively. Highest stresses on the PCL were observed under posterior loads on the upper, middle, and lower knee areas, with peak stresses of 57.421 MPa, 38.147 MPa, and 26.904 MPa, focusing notably on the PCL-tibia junction. When a lateral load was placed on the upper knee joint, the ACL showed the highest stress 32.102 MPa. Likewise, in a lateral impact on the middle knee joint, the ACL also had the highest stress of 29.544 MPa, with peak force at the ACL-tibia junction each time. In a lateral impact on the lower knee area, the LCL had the highest stress of 22.279 MPa, with the highest force at the LCL-fibula junction. Furthermore, the maximum stress data table indicates that stresses in the ligaments are typically higher when the upper portion of the knee is affected compared to when the middle and lower parts are impacted.ConclusionsThis study recommends people avoid impacting the upper knee and use the middle and lower parts of the knee effectively against external forces to minimize ligament damage and safeguard the knee.

Development of A Workshop on the Topic of the Bionically Inspired Lightweight Design Method for 3D Printed Components

Additive manufacturing methods, particularly 3D printing, are widely utilized in research and engineering for crafting lightweight yet durable materials capable of withstanding substantial forces. Leveraging insights from biomechanical structures offers a deeper understanding of reinforcement techniques and optimal design strategies to enhance strength. This paper focuses on the development of a Draisine design, historically significant in Karlsruhe, as part of the BWSplus project "Drais3D-Trinational" workshop. Through a comprehensive analysis of bionic influences on lightweight design and 3D printing parameters, this study aims to create an optimal design framework for the workshop. Utilizing Computer-Aided Design (CAD) software such as SolidWorks and Creo Parametric, along with Finite Element Analysis using ANSYS R2023 Workbench, deformation and stress analysis are conducted. Investigation into 3D printing parameters, including infill patterns, temperature, support systems, and orientation, seeks to identify optimal solutions considering factors like processing time, robustness, and filament wastage. The objective is to explore the biomechanical influence on construction methods, concept design, and parameter construction in preparation for the Drais3D-Trinational workshop in March 2023. The expected outcomes include the presentation of two main designs with varied parameters, alongside analyses such as Finite Element Analysis and optimization of 3D printing parameters, emphasizing the role of bionic structures in defining the optimal Draisine design.

APD: An automated parameter determination system based on in-situ tests

In-situ testing has numerous applications in geotechnical engineering. The interpretation of in-situ test results includes soil stratification and determination of soil parameters. This paper presents an automated parameter determination framework that aims to determine constitutive model parameters based on in-situ tests. The ongoing research project relies on a graph-based approach for determining the parameters. The framework has two main attributes: transparency and adaptability. Transparency is achieved by illustrating how a certain parameter was computed. Adaptability is ensured by allowing users to incorporate their expertise into the framework. The system currently determines parameters based on three main workflows that utilize the results of cone penetration tests, dilatometer tests, and shear wave velocity measurements. This study employs the three main workflows to determine soil parameters for one of the Norwegian GeoTest Sites. Additionally, the connection between the parameter determination system and finite element analysis is discussed, where the parameters for the Modified Cam Clay model are evaluated. The framework is valuable in the early stages of projects, providing detailed soil information when soil data is limited. Ongoing research aims to assess the accuracy of the derived soil and constitutive model parameters and to expand the system’s capabilities by including additional in-situ tests.

Investigation of Residual Strength in CFRP Double-Adhesive Single Lap Bonded Joints after Low-velocity Impact

ABSTRACT Single lap adhesive joints are prone to debonding and delamination during impact, affecting the residual tensile strength and mechanical properties. To improve the stress distribution and withstand larger loads, this paper proposes to use Araldite 2015 ductile adhesive at both ends of the joint and AV 138 brittle adhesive in the middle. Through finite element analysis and experiments, the residual strength and damage of the joint under different impact conditions are investigated, and a three-parameter Gram-Charlier model is established. The results show that the model can fit the data points accurately with a coefficient of determination of error above 0.99. As impact energy increases, the residual strength of the joint decreases, especially the AV 138 joint is more sensitive. The residual strength on one side of the impact joint is approximately 20% higher compared to the middle of the impact joint. For the same energy, the residual strength of the secondary impact was about 13% higher than that of the single impact. The main failure mode is cohesive failure, which gradually changes to fiber tear. The numerical simulation matches the experimental results, which verifies the reliability of the simulation and analysis methods.

A Simple Method to Evaluate the Bearing Capacity of Concrete-Filled Steel Tubes with Rectangular and Circular Sections: Beams, Columns, and Beam–Columns

This study investigates the behavior and capacity of concrete-filled steel tubes (CFTs) with rectangular and circular sections under various loading conditions: axial loads, pure-bending, and combined axial load-bending moments. A finite element-based numerical model is developed and validated against existing experimental data. Using an extensive databank generated from finite element analysis, this research proposes analytical empirical relations for determining the bearing capacity of rectangular and circular composite beams, columns, and beam–columns. These relations provide a direct, concise, and efficient method for calculating the ultimate strength of CFT members, making them valuable for engineering design. Comparisons between the proposed analytical results and previous experimental studies demonstrate the high accuracy of this method in analyzing rectangular and circular CFT member behavior. The findings contribute to a better understanding of CFT structural performance and offer practical tools for designers working with these composite elements.