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This study develops a thermal homogenization model for an aluminum honeycomb panel using the representative volume element (RVE) concept, considering the orthotropic nature of the structure. The RVE thermal homogenization method is a numerical approach for analyzing heterogeneous materials. It employs a constitutive model based on RVE performance to represent thermal behavior. Effective parameters are determined through averaging techniques, and the finite element method solves the thermal problem, accounting for structure topology and material behavior. The resulting heat conduction problem is solved using the finite element method (FEM) to evaluate the effective thermal characteristics. A 3D RVE is generated based on the honeycomb panel's geometry, evaluating thermal conductivity tensor and describing the medium's thermal performance. Numerical tests validate the model by comparing it with the real honeycomb structure under sinusoidal heat flux. Results show good correlation, with maximum temperatures of 1101.9 °C in the real structure and 1096.4 °C in the medium. The homogeneous medium is further used to investigate thermal performance under convective conditions with varying panel thicknesses, achieving over 77 °C temperature reduction with the thickest panel. Natural vibration behavior is considered, demonstrating strong correlation between modal responses and natural frequencies. This modeling approach efficiently analyzes thermal behavior in large honeycomb structures, reducing computational time significantly.

The custom design of a composite material requires the knowledge of its effective behavior which depends on several parameters such as the properties of the constituents, their distributions, shapes and sizes. In thermal conductivity, all these parameters have a direct and significant influence on the effective thermal conductivity (ETC) of composites. These parameters act differently on the behavior of the composite according to its use as much as a good conductor by improving its ETC or by reducing it by considering it as an insulator. The main goal of this work is an extensive study of all possible situations of ETC by a numerical homogenization technique based on the Finite Elements Method. For this purpose, the two main categories of composites, namely the periodic composites represented by the unit cell and the random RVE, are considered. For each category of composite, different contrasts, different particles' volume fractions, aspect ratios, positions, and orientations are studied. In order to ensure the simulation results are effective and representative, two boundary conditions, namely Uniform Temperature Gradient Boundary Conditions (UGT) and Periodic Thermal Boundary Conditions (PBC), were imposed on all considered microstructures. The results of this study constitute a synthesis of the effective thermal conductivities of all the possible situations which can be summarized as follows: On the one hand, the reinforcements shape effect is very important irrespective of the nature of the periodic and random composites and on the other hand, the two types of composites do not have the same behavior as that for the reinforcements with a circular or almost circular shape. This study also emphasizes the situations where the ETC can be estimated analytically and when homogenization is necessary. From a practical point of view, and on the basis of the obtained results, this study made it possible to show clearly in which situation the composite becomes more conducting and in the opposite case when it becomes more insulating. [ABSTRACT FROM AUTHOR]

To satisfy the performance and technological requirements of large-scale dynamic machines, the foundation is evolving toward considerable size and complex structure. This makes it vibrate asynchronously, and the existing relevant guidelines and specifications that consider the foundation as a rigid body are no longer applicable. Initially, by referencing the concept of the participating mass of soil (the mass of surrounding soil that vibrates synchronously), the concept of participating mass of large-scale complex dynamic machine foundations is proposed. Subsequently, the theoretical and corresponding numerical solutions are given based on the elastic half-space theory and finite element analysis. Furthermore, referring to the prototype of the foundation of the NFEES in China, a refined finite model encompassing the surrounding soil, multilayer complex machine foundations is established. After validating the numerical model, the vibration response and the participating mass of the foundation are analyzed. Additionally, parameterized analyses are conducted by varying factors such as the overall and local stiffness of the foundation, the presence of piles at the bottom of the foundation, the integration of a large shaking table foundation and an underwater shaking table foundation. Results indicate that the foundation of the large shaking table demonstrates vibration synchronization during operation, and the participating rates exceed 80%. The piles at the bottom and the separation of the large shaking table foundation from the underwater shaking table foundation perform effectively to reduce the vibration response and enhance the synchronization of the foundation vibration. The vibration response calculated by the numerical model can be directly applied to assess whether the foundation design satisfies the vibration limit requirements, and the parameterized analyses can provide suggestions for the dynamic design and analysis of similarly large-scale complex dynamic machine foundations. [ABSTRACT FROM AUTHOR]

BACKGROUND: The thin alveolar bone in the lower anterior region increases the risk of labial bone resorption when intruding the teeth with clear aligners. The effect of sagittal overcorrection design on the labiolingual control of mandibular anterior teeth intrusion has not been fully investigated. OBJECTIVE: To explore the effect of overcorrection on the changes in the displacement and stress of the mandibular anterior teeth, especially the cervical and apical regions. METHODS: Through a male volunteer cone-beam CT data, the three-dimensional reconstruction of the mandible and teeth was conducted in the MIMICS and GEOMAGIC software. Moreover, the models of periodontal ligaments, attachments, and appliances were created in the SOLIDWORKS software. First, the study was divided into canine intrusion group and incisor intrusion group. Then, the overcorrection (0°, 1°, 2°) was designed on the bilateral mandibular central and lateral incisors. A total of six models were established. The models were assembled and imported into the ANSYS software to analyze and calculate the displacement and stress level. RESULTS AND CONCLUSION: (1) In the canine intrusion group, canines intruded and tipped lingually while incisors extruded and tipped lingually. In the incisor intrusion group, canines extruded and tipped lingually while incisors intruded and tipped lingually. (2) Without overcorrection, the incisors necks moved lingually while apexes moved labially. With overcorrection, the incisors tended to be upright, followed by labial tilt. The least cervical and apical displacements were detected under 1° overcorrection. (3) With overcorrection, the incisal cervical stress concentration area shifted from labial to lingual in the canine intrusion group, whereas the stress concentration area shifted from lingual to labial in the incisor intrusion group. (4) The incisors tended to tilt lingually when intruding the mandibular anterior teeth with clear aligners. The sagittal overcorrection design was conductive to maintain the stable position of incisors. However, the amount of overcorrection should be moderate. Excessive overcorrection might increase the labial inclination tendencies of incisors. [ABSTRACT FROM AUTHOR]

This paper focuses on the methodology for evaluating the degree of total curling in concrete pavement using machine learning. Deflection induced by falling weight deflectometer (FWD) testing is known as a direct correlation to total curling including built-in and daily curling. However, deflection measurement in the in-service road is also affected by others, such as environmental conditions, pavement geometry, subgrade stiffness, and mixture design. Thus, it is challenging to determine the level of curling from FWD data due to the complexity of influencing parameters. To navigate this complexity, prominent machine learning models are exploited to identify a non-linear relationship between curling and FWD deflections. A finite-element simulation of FWD is conducted to generate a vast data set, and a robust regression model is trained to estimate the total effective temperature difference (TETD) to quantify the effects of curling. Since input parameters for testing pavements can be measurable in the field, curling from TETD can be readily obtained using the proposed methodology. Comparative simulations highlight that the proposed models, with an MAE less than 0.5 °C significantly outperform the multiple regression performance, which registers an MAE of 3.45 °C in TETD, particularly in offering cost-effective and noise-tolerant prediction. [ABSTRACT FROM AUTHOR]

ABSTRACT Estimation of the knee joint strength by maximum voluntary isometric contraction (MVIC) is a common practice to assess strength, coordination, safety to return to work or engage in sports after an injury, and to evaluate the efficacy of treatment modalities and rehabilitation strategies. In this study, we utilize a previously validated coupled finite element‐musculoskeletal model of the lower extremity to explore the sensitivity of output measures (posterior cruciate ligament [PCL]/muscle/contact forces and passive moments) in knee MVIC flexion exercises at seated position. To do so, at three knee flexion angles (KFA), input measures (resistance moment and contribution moments of quadriceps and gastrocnemii) were varied at four levels each using the Taguchi design of experiment. Our findings reveal significant increases in PCL forces with KFA (p < 0.01), net MVIC moment (p < 0.01), and resistance moment of quadriceps (p < 0.01). In contrast, they drop at larger activity in gastrocnemii (p < 0.01). Tibiofemoral (TF) contact forces increase with the net MVIC moment (p < 0.01). The passive knee flexion moment, while highly dependent on the location at which computed, also increases with the net MVIC moment (p < 0.01). Changes in KFA, MVIC moment, and proportions thereof carried by quadriceps and/or gastrocnemii substantially affect biomechanics of the joint. Compared with level walking and stair ascent, slightly larger contact forces/stresses and much greater PCL forces are computed. This study improves our understanding of the knee joint behavior during MVIC in effective evaluation and rehabilitation interventions. Besides, it emphasizes the importance of positioning the joint center in model studies. [ABSTRACT FROM AUTHOR]

Movement patterns may be a factor for manipulating the lumbar load, although little information is yet available in the literature about the relationship between this variable and intervertebral disc pressure (IDP). A finite element model of the lumbar spine (49‐year‐old asymptomatic female) was used to simulate intervertebral movements (L2–L5) of 127 asymptomatic participants. The data from participants that at least completed a simulation of lumbar vertebral movement during the first 53% of a movement cycle (flexion phase) were used for further analyses. Then, for each vertebral angular motion curve with constant spatial peaks, different temporal patterns were simulated in two stages: (1) in lumbar pattern exchange (LPE), each vertebral angle was simulated by the corresponding vertebrae of other participants data; (2) in vertebral pattern exchange (VPE), vertebral angles were simulated by each other. The k‐mean algorithm was used to cluster two groups of variables; peak and cumulative IDP, in both stages of simulations (i.e., LPE and VPE). In the second stage of the simulation (VPE), Kendall's tau was utilized to consider the relationship between different temporal patterns and IDPs for each individual lumbar level. Cluster analyses showed that the temporal movement pattern did not exhibit any effect on the peak IDP while the cumulative IDP changed significantly for some patterns. Earlier involvement in lumbar motion at any level led to higher IDP in the majority of simulations. There is therefore a possibility of manipulating lumbar IDP by changing the temporal pattern with the same ROM, in which optimal distribution of the loads among lumbar levels may be applied as preventive or treatment interventions. Evaluating load benefits, such as load, on biomechanically relevant lumbar levels, dynamically measured by quantitative fluoroscopy, may help inform interventional exercises. [ABSTRACT FROM AUTHOR]

BACKGROUND: The reciprocal force generated by the molar distalization with clear aligners can lead to anchorage loss. The effect of arch shapes and missing second premolars on anchorage has not been reported. OBJECTIVE: To analyze the effect of arch shapes and missing second premolars on anchorage during molar distalization with clear aligners using the finite element method. METHODS: Cone-beam CT data from an adult male were acquired from the database to establish the maxilla-upper dentition-periodontium-rectangular attachment-clear aligner model. The distal movement amount designed on the bilateral second molars was set to 0.25 mm. First, there were two groups in the study: second premolar bilateral presence and absence groups. Then, four subgroups in each group were created: tapered arch, ovoid arch, square Class II Division 1 arch, and Class II Division 2 arch groups. The Ansys software was used to calculate the displacement of the anchorage tooth and the stress of the periodontal ligament. RESULTS AND CONCLUSION: Mesial tipping and extrusion of first molars and premolars, labial inclination and intrusion of anterior teeth occurred during the upper second molar distalization with clear aligners. When the bilateral second premolars were missing, the mesial displacement of first molars increased significantly while that of first premolars and anterior teeth decreased in all groups. The square Class II Division 1 arch group showed the least anterior labial inclination, while the tapered arch group showed the most. There was no significant difference between the ovoid arch group and the tapered arch group. Moreover, the magnitude of tipping in the square Class II Division 2 arch group was slightly higher than that in the Class II Division 1 arch group. The stress of the periodontal ligament of the anchorage teeth was concentrated on the cervical and apical regions of the teeth. And the lowest stress level was detected in the square arch group. Compared with the other groups, the stress on the labial cervical area of the periodontal ligaments was also significantly relieved in the square arch group. To conclude, the square arch is more favorable in terms of anterior anchorage control and periodontal ligament stress distribution. Anterior labial inclination efficiency can be increased in cases of Class II Division 2 by designing the anterior labial inclination in conjunction with molar distalization. If the second premolar is missing during molar distalization, it is not conducive to opening up the space in the area of the missing tooth. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional thermal analysis of the laser sintering additive manufacturing process was conducted. Analytical heat sink methods and numerical finite element analysis in Abaqus software were employed to assess the thermal behavior of the workpiece. Comparing the analytical method used in this study with those in the existing literature reveals the superiority of the results obtained in this research. Additionally, it has been demonstrated that the numerical and analytical results in this study are in good agreement with each other. Furthermore, the proposed method in this study has yielded significant findings, indicating its applicability in addressing the complexity of the problem. The findings demonstrated that optimizing the temperature distribution is attainable through adjustments to the initial workpiece temperature and scanning speed. [ABSTRACT FROM AUTHOR]

Numerical models based on seepage-deformation coupling governing equations are often used to simulate soil hydrodynamics and deformation in unsaturated porous media. Among them, Picard iteration method with pressure head as the main variable is widely used because of its simplicity and ability to deal with partial saturation conditions. It is well known that the method is prone to convergence failure under some unfavorable flow conditions and is also computationally time-consuming. In this study, the soil–water characteristic curve (SWCC) of unsaturated soil described by the exponential function is used to linearize the coupling equations to overcome the repeated assembly of nonlinear ordinary differential equations. The finite element method with six-node triangular element is used to discretely linearize the coupling governing equations. Further, the classical Gauss–Seidel iterative method (GS) can be used to solve the linear equations generated from the linearized coupling equations. However, the convergence rate of GS seriously restricts the ill-condition of the linear equations, especially when the condition number of linear equations is much larger than 1.0. Thus, we propose an improved Gauss–Seidel iterative methods MP(m)-GSCMGI by combining multistep preconditioning and cascadic multigrid. The applicability of the proposed methods in simulating variably saturated flow and deformation in unsaturated porous media is verified by numerical examples. The results show that the proposed improved methods have faster convergence rate and computational efficiency than the conventional Picard and GS. The hybrid improved method MP(m)-GSCMGI can achieve more robust convergence and economical simulation. [ABSTRACT FROM AUTHOR]

For geomagnetic navigation technology, taking inspiration from nature and leveraging the principle of animals' utilization of the geomagnetic field for long-distance navigation, and employing biomimetic technology to develop higher-precision geomagnetic sensors and more advanced navigation strategies, has emerged as a new trend. Based on the two widely acknowledged biological magnetic induction mechanisms, we have designed a bioinspired weak magnetic vector (BWMV) sensor and integrated it with neural networks to achieve geomagnetic matching navigation. In this paper, we assess the performance of the BWMV sensor through finite element model simulation. The result validates its high measurement accuracy and outstanding adaptability to installation errors with the assistance of specially trained neural networks. Furthermore, we have enhanced the bioinspired geomagnetic navigation algorithm and proposed a more advanced search strategy to adapt to navigation under the condition of no prior geomagnetic map. A simulated geomagnetic navigation platform was constructed based on the finite element model to simulate the navigation of the BWMV sensor in geomagnetic environments. The simulated navigation experiment verified that the proposed search strategy applied to the BWMV sensor can achieve high-precision navigation. This study proposes a novel approach for the research of bioinspired geomagnetic navigation technology, which holds great development prospects. [ABSTRACT FROM AUTHOR]

The failure of bonded composite materials is accompanied by specific failure modes. These are specifically Mode I, Mode II, Mode III, and their combination (so-called mixed mode). These modes depend on the direction and type of loading. The mechanical properties describing the damage initiation and the damage evolution are unique according to the type of adhesive and present mode of failure. However, a few research studies have focused on an adhesive thicknesses greater than 0.2 mm. The main objective of this research is to investigate the mechanical properties of a bonded joint with large adhesive thickness loaded according to Modes I and II. The observed failure parameters, the cohesive and damage parameters, are identified by minimizing the difference between the force–displacement diagram obtained from the experimental data for both Mode I and Mode II. The finite element model is confronted with these parameters and is evaluated based on their agreement. Compared to other studies with a small adhesive layer thickness, the values of failure parameters are lower. The results show that the adhesive thickness has an influence on the values of cohesive and damage parameters and that these parameter values decrease significantly compared to a small adhesive thickness. The obtained parameters can be further used to predict the fracture toughness of other bonded joints loaded in any direction. [ABSTRACT FROM AUTHOR]

The characteristics of a bullet are closely related to its shooting accuracy. In actual shooting, the centroid and entry angle of the bullet always deviate from the ideal state. To study the influence of these two parameters on the movement of the bullet, a finite element model of the bullet movement inside the barrel was built based on a 5.8 mm small-caliber rifle to simulate the actual process of firing bullets. In this model, the pressure load of the real gunpowder gas on the bullet was considered. This model was also verified by experiments and the relative error is less than 1.5%. The result shows that the influence the centroid and entry angle of the bullet are mainly reflected in the amplitude and phase angle of the bullet swing angle. The larger the offsetting distance of cetroid is, the amplitude of the pitch and yaw angle are. The maximum magnitude of amplitude is 0.2°. The difference of swing angle in phase is equal to the difference in offsetting angle. The curve characteristics of different deviation angle are similar to the curve of bullet cetroid effect. The range of the pitch angle is -1°~0.9° and the range of the yaw angle is -0.9°~0.9°. [ABSTRACT FROM AUTHOR]

Objective: Multi‐segmental total en bloc spondylectomy (TES) gradually became more commonly used by clinicians. However, the choice of surgical strategy is unclear. This study aims to investigate the biomechanical performance of different prosthesis types and fixation ranges in multisegmental TES. Methods: In this study, a validated finite element model of T12–L2 post‐spondylectomy operations were carried out. The prostheses of these models used either 3D‐printed artificial vertebrae or titanium mesh cages. The fixed range was two or three segment levels. Range of motion, stress distribution of the endplate and internal fixation system, intervertebral disc pressure, and facet joint surface force of four postoperative models and intact model in flexion and extension, as well as lateral bending and rotation were analyzed and compared. Results: The type of prosthesis used in the anterior column reconstruction mainly affected the stress of the adjacent endplate and the prosthesis itself. The posterior fixation range had a greater influence on the overall range of motion (ROM), the ROM of the adjacent segment, the stress of the screw‐rod system, and adjacent facet joint surface force. For the model of the same prosthesis, the increase of fixed length resulted in an obvious reduction of ROM. The maximal decrease was 70.23% during extension, and the minimal decrease was 30.19% during rotation. Conclusion: In three‐segment TES, the surgical strategy of using 3D‐printed artificial prosthesis for anterior column support and pedicle screws for posterior fixation at both two upper and lower levels respectively can reduce the stress on internal fixation system, endplates, and adjacent intervertebral discs, resulting in a reduced risk of internal fixation failure, and ASD development. [ABSTRACT FROM AUTHOR]

The multi-stages in-fracture temporary plugging and diverting fracturing technology (ITPDF) is significant for the stimulation of unconventional oil and gas reservoirs. However, the propagation pattern of hydraulic fracture and the pressure response law after temporary plugging still lacks some understanding affected by many factors. Hence, to deeply understand the fracture diverting propagation mechanism and pressure response law after in-fracture temporary plugging, the study developed first a numerical model of cohesive zone considering in-fracture temporary plugging, seepage and fracture propagation based on the effective viscosity characterization method and the USDFLD (user defined field) subroutine. In addition, the accuracy of the numerical model is verified by comparing with laboratory results. The effect of different parameters such as temporary plugging body permeability, temporary plugging body length, temporary plugging location, temporary plugging times, and stress difference on the temporary plugging and diverting behavior of hydraulic fractures and natural fractures are deeply investigated. The fracture diverting pattern, fracture initiation sequence, and pressure response mechanism are clarified for different in-fracture plugging conditions. The results show that the physical properties of the temporary plugging body are vital to the effectiveness of the in-fracture temporary plugging fracturing. The lower the permeability of the temporary plugging body, the longer the length of the temporary plugging body, and the closer the position of the temporary plugging body, the easier it is to activate the natural fractures. In addition, when there are many natural fractures, the more times of temporary plugging, the more range and number of natural fractures are activated. This study can provide a new method to further understand the fracture behavior after in-fracture temporary plugging fracturing. Highlights: A new numerical simulation method for multi-stage in-fracture temporary plugging and diverting fracturing was developed based on modified cohesive zone model The effect of temporary plugging body properties and the formation properties are deeply investigated. The horizontal stress difference determines the plugging function of the plugging body and the turning pattern of the fracture. [ABSTRACT FROM AUTHOR]

Bentonite-based materials have emerged as a highly promising choice for engineered barriers in nuclear waste deep geological disposal. These materials are characterised by low permeability, high swelling capacity and effective radionuclide retardation, making them suitable for sealing underground galleries and canisters containing nuclear waste. However, the presence of technological gaps within the bentonite or the host rock can significantly influence their hydromechanical behaviour, potentially creating preferential pathways for radionuclide migration, thus affecting the overall performance of the engineered barrier. In this study, two different modelling strategies (namely, "gap" and "no-gap") to reproduce technological gaps and their effect on the hydromechanical behaviour of bentonite-based materials during intermediate saturation stages are proposed. The numerical model is used to simulate laboratory tests, and the numerical results are compared with experimental data coming from hydration test conducted under overall constant volume (isochoric) conditions. It is noteworthy that the specimen used in the experimental study is characterised by a localised gap between its side and the cell wall. The paper highlights the benefits of the "gap" numerical model, which employs interface elements to reproduce technological gaps at the side of the cell and exhibits satisfactory capabilities in reproducing the experimental swelling pressure evolution during bentonite hydration, especially during the transient wetting stages. Significant implications are expected for predicting site performance of engineered barrier systems in nuclear waste disposal applications. Highlights: The effect of technological gaps on the hydro-mechanical behaviour of bentonite-based materials for nuclear waste disposal is investigated. Two different modelling strategies, "gap" and "no-gap", are proposed to simulate the presence of technological gaps in the bentonite. The numerical results are compared with experimental data from a hydration test under constant volume conditions. The advantages of the "gap" numerical model, which can reproduce the experimental swelling pressure evolution more accurately, are demonstrated and its implications are discussed for the performance of engineered barrier systems. [ABSTRACT FROM AUTHOR]

The variation of temperature fields during the winding process of CFRP (Carbon Fiber Reinforced Polymer) due to fiber winding is a key factor influencing its curing and shaping. Traditional heating methods result in energy wastage and environmental pollution during the heating process. Electromagnetic induction technology, as a non-contact, pollution-free, and efficient heating method, is playing an increasingly significant role in the process of heating and curing CFRP. This study focuses on two heating methods, internal and external, for CFRP wound circular tubes. It establishes finite element analysis models for induction heating with different coil structures. The heating mechanisms of different coil-induced CFRP wound circular tube models are explained, and the effects of external arc-shaped coils and external/internal annular coils on the temperature field distribution of CFRP wound circular tubes are investigated. By comparing simulations with experiments, the correctness of the numerical analysis model in this study is demonstrated. It offers viable heating methods for different conditions in industrial production, providing theoretical support and empirical data for the induction heating of CFRP wound circular tubes. [ABSTRACT FROM AUTHOR]

The article discusses the use of rubberized concrete in reinforced concrete columns and its performance under axial and cyclic loads. The addition of crumb rubber to the concrete reduces its compressive strength and load capacity but improves its displacement ductility and damping ratio. The study suggests that rubberized concrete can enhance the performance of concrete columns under cyclic loading and delay the onset of earthquake damage. The article provides a technical analysis of various parameters and their implications for the seismic performance of rubberized concrete. [Extracted from the article]

Adeno-associated virus (AAV) is a clinically useful gene delivery vehicle for treating neurological diseases. To deliver AAV to focal targets, direct infusion into brain tissue by convection-enhanced delivery (CED) is often needed due to AAV's limited penetration across the blood-brain-barrier and its low diffusivity in tissue. In this study, computational models that predict the spatial distribution of AAV in brain tissue during CED were developed to guide future placement of infusion catheters in recurrent brain tumors following primary tumor resection. The brain was modeled as a porous medium, and material property fields that account for magnetic resonance imaging (MRI)-derived anatomical regions were interpolated and directly assigned to an unstructured finite element mesh. By eliminating the need to mesh complex surfaces between fluid regions and tissue, mesh preparation was expedited, increasing the model's clinical feasibility. The infusion model predicted preferential fluid diversion into open fluid regions such as the ventricles and subarachnoid space (SAS). Additionally, a sensitivity analysis of AAV delivery demonstrated that improved AAV distribution in the tumor was achieved at higher tumor hydraulic conductivity or lower tumor porosity. Depending on the tumor infusion site, the AAV distribution covered 3.67–70.25% of the tumor volume (using a 10% AAV concentration threshold), demonstrating the model's potential to inform the selection of infusion sites for maximal tumor coverage. [ABSTRACT FROM AUTHOR]

Numerical simulations of convective solid-liquid phase change problems have long been a complex problem due to the movement of the solid-liquid interface layer, which leads to a free boundary problem. This work develops a convective phase change heat transfer model based on the phase field method. The governing equations consist of the incompressible Navier-Stokes-Boussinesq equations, the heat transfer equation, and the Allen-Cahn equation. The Navier-Stokes equations are penalised for imposing zero velocity within the solid region. For numerical methods, the mini finite element approach (P1b-P1) is used to solve the momentum equation spatially, the temperature and the phase field are approximated by the P1b elements. In the temporal discretization, the phase field and the temperature are decoupled from the momentum equation by using the finite difference method, forming a solvable linear system. A maximum bound principle for the phase field is derived, coming with an estimation of the tolerance of the time step size, which depends on the temperature range. This estimation guides the time step choice in the simulation. The program is developed within the FreeFem++ framework, drawing on our previous work on phase field methods [1] and a mushy-region method toolbox for heat transfer [2]. The accuracy and effectiveness of the proposed method have been validated through real-world cases of melting and solidification with linear or nonlinear buyangcy force, respectively. The simulation results are in agreement with experiments in references. [ABSTRACT FROM AUTHOR]

The present work deals with evaluating the nonlinear deflections of the smart sandwich plate with agglomerated Carbon Nanotubes (CNTs) porous core and piezo-magneto-electric (PME) facings, using a novel finite element method (FEM) – artificial neural network (ANN) approach. For the first time, an ANN-based computational tool that integrates the effects of agglomeration of CNTs, porosity and pyro-coupling of the PME materials is presented. Firstly, an in-house finite element (FE) computational tool is proposed and developed using the principle of virtual work in association with higher-order shear deformation theory (HSDT) and von-Karman's nonlinearity. The data points owing to the nonlinear deflections are collected using the proposed FE formulation, which trains the ANN model using Levenberg–Marquardt algorithm. The externally applied thermal loads are assumed to vary uniformly and linearly across the thickness of the plate. The primary focus of this work is to assess the variation in the degree of pyro-coupling associated with agglomeration and porosity. Two states of agglomeration, such as partial and complete; three forms of porosity, such as uniformly distributed, and two variants of functionally graded porosity, are considered for investigation. Numerical examples are solved to understand the interrelated effects of these material properties. A significant variation in the deflection of the plate, which refers to its actuation capability, is witnessed when the parameters of agglomeration and porosity change. [ABSTRACT FROM AUTHOR]

The meniscus tissue is crucial for knee joint biomechanics and is frequently susceptible to injuries resulting in early-onset osteoarthritis. Consequently, the need for meniscal substitutes spurs ongoing development. The meniscus is a composite tissue reinforced with circumferential and radial collagenous fibers; the mechanical role of the latter has yet to be fully unveiled. Here, we investigated the role of radial fibers using a synergistic methodology combining meniscal tissue structure imaging, a computational knee joint model, and the fabrication of simple biomimetic composite laminates. These laminates mimic the basic structural units of the meniscus, utilizing longitudinal and transverse fibers equivalent to the circumferential and radial fibers in meniscal tissue. In the computational model, the absence of radial fibers resulted in stress concentration within the meniscus matrix and up to 800 % greater area at the same stress level. Furthermore, the contact pressure on the tibial cartilage increased drastically, affecting up to 322 % larger areas. Conversely, in models with radial fibers, we observed up to 25 % lower peak contact pressures and width changes of less than 0.1 %. Correspondingly, biomimetic composite laminates containing transverse fibers exhibited minor transverse deformations and smaller Poisson's ratios. They demonstrated structural shielding ability, maintaining their mechanical performance with the reduced amount of fibers in the loading direction, similar to the ability of the torn meniscus to carry and transfer loads to some extent. These results indicate that radial fibers are essential to distribute contact pressure and tensile stresses and prevent excessive deformations, suggesting the importance of incorporating them in novel designs of meniscal substitutes. The organization of the collagen fibers in the meniscus tissue is crucial to its biomechanical function. Radially oriented fibers are an important structural element of the meniscus and greatly affect its mechanical behavior. However, despite their importance to the meniscus mechanical function, radially oriented fibers receive minor attention in meniscal substitute designs. Here, we used a synergistic methodology that combines imaging of the meniscal tissue structure, a structural computational model of the knee joint, and the fabrication of simplistic biomimetic composite laminates that mimic the basic structural units of the meniscus. Our findings highlight the importance of the radially oriented fibers, their mechanical role in the meniscus tissue, and their importance as a crucial element in engineering novel meniscal substitutes. [Display omitted] [ABSTRACT FROM AUTHOR]

Assessing reservoir subsidence due to depletion involves understanding the geological and geophysical processes that lead to ground subsidence as a result of reservoir fluid extraction. Subsidence is a gradual sinking or settling of the Earth's surface, and it can occur when hydrocarbons are extracted from underground reservoirs. In this study, a time-integrated 3D coupled geomechanical modeling incorporating the fourth dimension—time—into traditional 3D geomechanical models has been constructed utilizing seismic inversion volumes and a one-dimensional mechanical Earth model (1D MEM). The 3D geomechanical model was calibrated to the 1D MEM results. Geomechanical rock properties were derived from the density and sonic log data that was distributed with conditioning to the seismic inversion volumes obtained from running pre-stack inversion. The standard elastic parameter equations were used to generate estimates of the elastic moduli. These properties are dynamic but have been converted to static values using additional equations used in the 1D MEM study. This included estimating the Unconfined Compressive Strength. In situ stresses were matched using different minimum horizontal principal stress gradients and horizontal principal stress ratios. The match is good except where the weak carbonate faults are close to the wells, where the Shmin magnitudes tend to decrease. The SHmax orientations were assessed from image log data and indicated to be 110° in the reservoir section. A time-integrated 3D coupled simulation was created using the finite-element method (FEM). The effective stresses increase while there is depletion in all directions, especially in the Z direction. The predicted compaction in the reservoir and overburden was 350 mm. Most of the compaction occurs at the reservoir level and dissipates towards the surface (seabed). Furthermore, the case displayed no shear failure that might cause or fault reactivation in the reservoir interval (Kangan–Dalan Formations) located in the simulated area. In this study, we applied an integrated and comprehensive geomechanical approach to evaluate subsidence, fault reactivation and stress alteration, while reservoir depletion was assessed using seismic inversion, well logs, and experiment data. The deformation monitoring of geological reservoirs, whether for gas storage or hazardous gas disposal, is essential due to the economic value of the stored assets and the hazardous nature of the disposed materials. This monitoring is vital for ensuring the sustainability of the reservoir by maintaining operational success and detecting integrity issues. [ABSTRACT FROM AUTHOR]

Recently, 3D printing of large, structural polymer parts has received increasing interest, especially for the creation of recyclable structural parts and tooling. However, the complexity of large-scale 3D polymeric printing often dictates resource-intensive trial and error processes to achieve acceptable parts. Existing computational models used to assess the impact of fabrication conditions typically treat the 3D-printed part as a continuum, incorporate oversimplified boundary conditions and take hours to days to run, making design space exploration infeasible. The purpose of this study is to create a structural model that is computationally efficient compared with traditional continuum models yet retains sufficient accuracy to enable exploration of the design space and prediction of part residual stresses and deformations. To this end, a beam-based finite element methodology was created where beads are represented as beams, vertical springs represent inter-bead transverse force transfer and multi-point, linear constraints enforce strain compatibility between adjacent beads. To test this framework, the fabrication of a large Polyethylene terephthalate glycol (PETG) wall was simulated. The PETG was modeled as linearly elastic with an experimentally derived temperature-dependent coefficient of thermal expansion and elastic modulus using temperature history imported from an ABAQUS thermal model. The results of the simulation were compared to those from a continuum model with an identical material definition, showing reasonable agreement of stresses and displacements. Further, the beam-based model required an order of magnitude less run time. Subsequently, the beam-based model was extended to allow separation of the part from the printing bed and the inclusion of part self-weight during fabrication to assess the significance of these effects that pose challenges for existing continuum models. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A depth investigation into the impact of high temperatures on the load‐bearing capacity of reinforced concrete beams in the case of probabilistic design is presented in this paper, employing advanced finite element analysis techniques. This study addresses a critical knowledge gap in the design of fire‐resistant concrete structures, with specific emphasis on the function of concrete cover. The research aims to enhance the overall safety and reliability of concrete buildings under high temperature conditions by providing valuable insights into the behavior of reinforced concrete beams under thermal loading. The analysis incorporates reliability‐based modeling to account for uncertainties in temperature distribution within the beams. A validated finite element model is employed to simulate the performance of reinforced concrete beams at elevated temperatures. By considering various concrete cover thicknesses and heat distribution scenarios, the influence of these factors on the load‐bearing capacity is thoroughly examined. The results underscore the importance of augmenting the concrete cover to enhance the load‐carrying capacity of the beams. Furthermore, the study examines the impact of temperature distribution uncertainties, unveiling diverse load capacities associated with different configurations of concrete cover. [ABSTRACT FROM AUTHOR]

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the drafting process, the strength and distribution of the friction field determines the fiber movement state, affecting the yarn formation process and yarn properties directly. The bottom pin, as an important part in the drafting zone, forms an elastic friction field with the top pin through the apron, which has an important influence on yarn properties. This work is aiming to compare the different friction fields generated by two bottom pins and its mechanical effect on fibers, revealing the influence of the friction field on the quality of yarns with different counts. Theoretical and experimental results show that a larger and stronger friction field was formed by the smaller surface curvature and flatter transition level of bottom pins, imposing a positive effect on the yarn evenness and strength. The difference in evenness between yarns spun with the two types of pins vary from 4.3% to 9.8%, while the yarn spun with a flatter bottom pin has higher strength (maximum difference to 17.1%). This study on the influence of the friction field on yarn properties can clarify the adaptability of different bottom pins for the production of different yarn counts, showing great significance on the actual control of yarn properties and property improvement. [ABSTRACT FROM AUTHOR]

We construct a C 1 - P 7 Bell finite element by restricting its normal derivative from a P 6 polynomial to a P 5 polynomial, and its second normal derivative from a P 5 polynomial to a P 4 polynomial, on the three edges of every triangle. On one triangle, the finite element space contains the P 6 polynomial space. We show the method converges at order 7 in L 2 -norm. By eliminating all degrees of freedom on edges of C 1 - P 7 Argyris finite element, the global degrees of freedom of the new element are reduced substantially from 27 ⁢ V to 12 ⁢ V asymptotically, where 푉 is the number of vertices in the triangular mesh. While the global degrees of freedom of the C 1 - P 6 Argyris finite element is 19 ⁢ V , the new element is equally accurate but more economic. Numerical tests are presented, showing the new element is more accurate than the existing element while having less global unknowns. [ABSTRACT FROM AUTHOR]

We construct three H-curl-curl finite elements. The P 2 and P 3 vector finite element spaces are both enriched by one common P 4 bubble and their local degrees of freedom are 13 and 21, respectively. As there does not exist any P 1 H-curl-curl conforming finite element, the P 1 H-curl-curl nonconforming finite element is constructed with three additional P 4 bubbles. Numerical tests are presented, confirming the conformity and the optimal order of convergence. [ABSTRACT FROM AUTHOR]

We consider the numerical approximation of Gaussian random fields on closed surfaces defined as the solution to a fractional stochastic partial differential equation (SPDE) with additive white noise. The SPDE involves two parameters controlling the smoothness and the correlation length of the Gaussian random field. The proposed numerical method relies on the Balakrishnan integral representation of the solution and does not require the approximation of eigenpairs. Rather, it consists of a sinc quadrature coupled with a standard surface finite element method. We provide a complete error analysis of the method and illustrate its performances in several numerical experiments. [ABSTRACT FROM AUTHOR]

In this paper, some symmetrized two-scale finite element methods are proposed for a class of partial differential equations with symmetric solutions. With these methods, the finite element approximation on a fine tensor-product grid is reduced to the finite element approximations on a much coarser grid and a univariant fine grid. It is shown by both theory and numerics including electronic structure calculations that the resulting approximations still maintain an asymptotically optimal accuracy. By symmetrized two-scale finite element methods, the computational cost can be reduced further by a factor of 푑 approximately compared with two-scale finite element methods when Ω = (0 , 1) d . Consequently, symmetrized two-scale finite element methods reduce computational cost significantly. [ABSTRACT FROM AUTHOR]

Studying the vibration behavior of the entire spine can guide the design of seat comfort and vibration safety. However, due to simplification of traditional biomechanical models, very few studies have analyzed in detail the vibration behavior characteristics of the entire spine inside a seated human body. Therefore, this study aimed to provide guidance and reference for spinal modeling and biomechanical research in ergonomics. A developed finite element model of three-dimensional seated human body was validated and adjusted based on anatomical data of human spine in detail. Static analysis, modal analysis and random response analysis (under vertical excitation between 0 and 20 Hz at 1 m/s2 r.m.s.) were conducted. The range of motion, modal frequencies and the tri-axial transmissibility of the developed models matched well with experimental results. In the vertical resonance mode, the entire spine contained both vertical deformation (60% of the total) and vertical displacement (40%), in addition, the cervical spine, especially the lumbar spine, also contained bending deformation which could alleviate the impact, but led to complex alternating stresses, increasing the risks of the spinal injuries under vertical whole-body vibration. From the bottom to the top of the spine, the frequency distribution of vertical transmissibility became steeper, the peak value increased, and the number of peaks decreased. This study provided new insights into the vibration behavior and frequency response of the entire spine inside a seated human body for improving seat comfort and vibration safety. [ABSTRACT FROM AUTHOR]

In the column strengthening under the beam support, for the columns with large section size, heavy load, and defects, a new type of load transfer system (LTS) was proposed: the bracket-type vertical load transfer system of reinforced concrete, which is composed of supporting columns. For the supporting columns on the load-leading layer, taking the column bottom pressure force and pressure distribution curves of the cross sections as two analytical indexes, the load transfer mechanism of the LTS was studied through finite element simulation. The net distance between the supporting column and the original column and the horizontal lap length ratio between the supporting columns were two important parameters, which mainly affected the variation law of the bottom pressure force. For the part of the frame beam between the supporting column and the original column, the critical position of its deformation form has been obtained, so that the maximum limit of the net distance was determined. The pressure distribution curves showed that the load transfer was in the form of an inner arched path. Through the engineering application, the real-time monitoring showed that the LTS could satisfactorily complete the load transfer work. [ABSTRACT FROM AUTHOR]

3D textile reinforced composites have some advantages over common 2D composites due to their unique mechanical properties. In this research, five composite samples with different percentages of jute and high tenacity polyethylene terephthalate fibers in the form of three-dimensional orthogonal woven fabrics were designed by TexGen software in meso and macro scales, and their tensile, flexural, and impact behaviors were analyzed by the finite element method in Abaqus software. The results were in good agreement with the experimental results. The mean errors between experimental and numerical results were 11% for tensile strain, 9% for tensile strength, 8% for Young's modulus, 9.8% for tensile toughness, 6% for elastic flexural energy, 5.7% for flexural modulus, and 19.8% for impact resistance. [ABSTRACT FROM AUTHOR]

Since 1966, China has been using apparent resistivity observation to forecast strong aftershocks of the Xingtai earthquake. Retrospective studies of subsequent strong earthquakes have shown that anomalies in apparent resistivity observation before earthquakes usually exhibit anisotropic characteristics. In addition to the anisotropic changes in apparent resistivity before earthquakes, factors such as subway operation near the observation area, metal pipeline networks, and changes in water levels have also been found to cause anisotropic changes. These factors are called environmental interference factors. Therefore, distinguishing between anisotropic changes before earthquakes and anisotropic changes caused by interference and eliminating the effects of interference is crucial for using apparent resistivity observations for forecasting. Taking the observation of Hefei seismic station in Anhui Province as an example, a model is constructed using the finite element method to try to establish a method for analyzing anisotropy in apparent resistivity before earthquakes, and the data from other provincial stations are used for verification. In the modeling process, the influence coefficient is a measure of the relationship between the variation in apparent resistivity and the changes in the medium of the measurement area. The following results are obtained by calculating the influence coefficient using the finite element method: the influence coefficient between the power supply electrode and the measuring electrode of the apparent resistivity observation is negative, and the rest are positive, and the distribution of the influence coefficient shows obvious symmetry, with the axis of symmetry being the line connecting the electrodes and its midline, and the absolute value of the influence coefficient is inversely proportional to the distance from the electrodes. In addition, according to the constructed finite element model, the amplitude of anisotropic changes caused by interference can be quantitatively calculated. Given that interference is ubiquitous in various regions of the world, this study can provide a reference for international earthquake forecasters to quantitatively remove environmental interference in anisotropy. Moreover, when building apparent resistivity stations in seismic areas for earthquake prediction, it is best to avoid areas with larger local influence coefficients to ensure that the anomalous data before the earthquake is true and reliable. [ABSTRACT FROM AUTHOR]

The study of visualization of impact damage of fruit under different thicknesses of buffer materials can provide more efficient transportation and packaging solutions, and thus the economic losses caused by fruit damage can be reduced. Pearl cotton (EPE) is commonly used as a buffer material in the market, and the impact damage behavior of honey peaches under different thicknesses of EPE buffer material was studied by using the finite element method. Firstly, the damage area, maximum contact force and damage volume during the collision of honey peaches with EPE materials of different thicknesses (2, 4, and 6 mm) were obtained by the single pendulum device, and then the Modulus of elasticity and Poisson's ratio of peach flesh were obtained by compression test. Finally, the finite element model of honey peach was built and the collision simulations were performed. The results of the study showed that the values of mechanical parameters of honey peach decreased with the increase of the thickness of the buffer material. When the collision angle was below 60°, the honey peaches were not damaged in the collision with the EPE material with a thickness of 4 mm or more. By comparing the tested values with the simulated values, it was found that the errors of the damage area, damage volume and maximum contact force were less than 19.71%, 26.82%, and 25.88%, respectively. The study not only proves the possibility of the finite element method in the quantitative prediction of honey peaches damage but also provides rational support for the packaging design of honey peaches. [ABSTRACT FROM AUTHOR]

Ratcheting analysis for cantilever beams subjected to the thermomechanical loads is presented using the finite element method. The cantilever beam is constrained along the vertical direction, and plane stress conditions are assumed according to the bilinear isotropic hardening model. Two points are considered to obtain areas of ratcheting by using linear extrapolation. The results and output diagrams for ratcheting with elastic-perfect plastic behavior are illustrated. It was revealed that the beam behaves elastically after the first considerable plastic strain, which is seen in two shakedown regimes. The numerical results are verified with known and analytical results in the literature. The results indicate a strong correlation between the outcomes from the cyclic ANSYS Parametric Design Language (APDL) model and Bree's analytical predictions. This consistency between the finite element analysis and the analytical solutions underscores the potential of finite element analysis as a powerful tool for addressing complex engineering challenges, offering a reliable and robust alternative to traditional analytical methods. [ABSTRACT FROM AUTHOR]

In this article, we aim to analyze electrically induced magnetic incompressible flow and heat transfer through a channel within the framework of micropolar continuum. Finite element method is employed to compute the numerical solution of the governing dynamics formulated in the form of PDEs along with associated boundary conditions on the channel. The weak form is presented and variational problem is implemented in FreeFem++ language. To validate, the correct implementation of the problem and obtained numerical results, a reduced micropolar magnetohydrodynamic model is taken into consideration. The analytical solution is presented. Computed numerical results are compared with the exact solution in case of reduced micropolar model and a good agreement is achieved. An excellent convergence of the numerical solution to the exact solution is shown through Tables where L 2 -norm and H 1 -errors are computed at refined meshes. Effect of different physical parameters such as magnetic Reynolds number ( R m ), Hartmann number (Ha), micorpolar constants (m and l 1 2 ), micropolar coupling number (N), Prandtl number (Pr) and Brinkmann number (Br) are studied and discussed in detail. The development of thermal, translational and micro-rotational velocity profiles over the cross-sectional domain of the channel is shown for varying values of these material parameters. Some interesting and new findings in this investigation are presented and discussed. It is observed that the maximum temperature in the medium shifts from the center of the domain toward the boundaries if the micropolar coupling constant N is increased. Maximum micro-rotations are always found near the channel's boundary where it is evidenced that the particle's micro-rotations have a direct proportionality with the micropolar constant m. Moreover, the counter rotations of the continuum particles are evidenced at the channel's boundary. Furthermore, the micorpolar coupling constant l 1 2 is found to resist the micro motions of the particles in the channel. The successful implementation of one and higher dimensional magnetohydrodynamic model in FreeFEM++ in general and within the context of micorpolar continuum in particular is delineated. This shows that it provides an efficient platform to simulate magnetohydrodynamic problems in higher order continuum which has applications in designing magneto-rheological airbags, aircraft take-off gear, mechanical heart valves and cooling systems. [ABSTRACT FROM AUTHOR]

A sensitivity analysis was conducted to evaluate several factors, including dam height, bank slope gradient, water storage times, and phased panel filling, on concrete-faced rockfill dams (CFRDs). The analysis identified the three most significant factors to examine their impacts on the stress-deformation characteristics of CFRDs. The results show that the order of influence on the dam body's stress and deformation characteristics is as follows: dam height > bank slope gradient > water storage times > panel phased construction. From the perspective of stress-deformation of the face slab, water storage times predominantly affect tensile stress, while the bank slope gradient exerts the greatest influence on compressive stress. As the bank slope gradient decreases, the panel's lateral restraint diminishes, leading to a decrease in the panel's extrusion efficacy. Consequently, there are notable variations in the panel's compressive stresses. An increase in dam height correlates with escalating stress and deformation in both the dam and face slab. As the bank slope gradient decreases, the deformation of the dam and face slab, as well as the range of tensile stress of the face slab, also increase. In contrast to a single water storage scenario, the face slab has experienced greater stress and deformation during the initial impoundment under multiple impoundment conditions. Therefore, multiple water storage schemes result in reduced deflection, axial horizontal displacement, and tensile stresses both along the slope and axial in the face slab. Furthermore, the tensile area at the bottom of the face slab transitions into a compressive area. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament (ACL) injuries are often caused by high impact loadings during competitive sports but may also happen during regular daily activities due to tissue degeneration or altered mechanics after a previous knee injury or surgery such as meniscectomy. Most existing research on ACL injury has focused on impact loading scenarios or the consequence of ACL injury on meniscus. The objective of the present study was to investigate the effects of varying degrees of medial meniscectomy on the mechanics of intact ACL by performing a poromechanical finite element analysis under moderate creep loadings. Four clinical scenarios with 25%, 50%, 75% and total medial meniscectomy were compared with the intact knee finite element model. Our results suggested that different medial meniscal resections may increase, at different extents, the knee laxity and peak tensile stress in the ACL, potentially leading to collagen fiber fatigue tearing and altered mechanobiology under normal joint loadings. Interestingly, the ACL stress actually increased during early knee creep (~ 3 min) before it reached an equilibrium. In addition, meniscectomy accelerated ACL stress reduction during knee creep, transferred more loading to tibial cartilage, increased contact pressure, and shifted the contact center posteriorly. This study may contribute to a better understanding of the interaction of meniscectomy and ACL integrity during daily loadings. [ABSTRACT FROM AUTHOR]

Background: The proximal femur is a common site of bone metastasis. The Mirels' score is a frequently utilized system to identify patients at risk for pathologic fracture and while it has consistently demonstrated strong sensitivity, specificity has been relatively poor. Our group previously developed a Modified Mirels' scoring system which demonstrated improved ability to predict cases at risk of fracture in this patient population through modification of the Mirels' location score. The purpose of the present study is to internally validate this newly developed scoring system on an independent patient series. Methods: Retrospective review was performed to identify patients who were evaluated for proximal femoral bone lesions. Patients were stratified into one of two groups: 1) those who went on to fracture within 4 months after initial evaluation (Fracture Group) and 2) those who did not fracture within 4 months of initial evaluation (No Fracture Group). Retrospective chart review was performed to assign an Original Mirels' (OM) Score and Modified Mirels' (MM) score to each patient at the time of initial evaluation. Descriptive statistics, logistic regression, receiver operating curve, and net benefit analyses were performed to determine the predictability of fractures when utilizing both scoring systems. Results: The use of the MM scoring improved fracture prediction over OM scoring for patients observed over a 4 month follow up based on logistic regression. Decision curve analysis showed that there was a net benefit using the MM score over the OM scoring for a full range of fracture threshold probabilities. Fracture prevalence was similar for current internal validation dataset when compared to the dataset of our index study with a comparable reduction in misclassification of fracture prediction when utilizing the modified scoring system versus the original. Conclusions: Use of MM scoring was found to improve fracture prediction over OM scoring when tested on an internal validation set of patients with disseminated metastatic lesions to the proximal femur. The improvement in fracture prediction demonstrated in the present study mirrored the results of our index study during which the MM system was developed. [ABSTRACT FROM AUTHOR]

AbstractIsogeometric layerwise finite element (L-IGA) formulation is a recent state-of-the-art approach integrating Non-Uniform Rational B-spline (NURBS) basis functions into the quasi-static solution process of piezolaminated composite plates. This study extends the application of the L-IGA framework to encompass free, forced vibration, and displacement control analyses of laminated composite plates with straight/curvilinear fibers and piezoelectric layers. To this end, the NURBS basis functions, utilized in geometry definition, are employed to solve electromechanically coupled differential equations following Hamilton’s variational principle. The adoption of high-order continuous NURBS shape functions throughout the IGA discretization span both in-plane and through-thickness laminate dimensions. This effectively facilitates precise geometry representation directly from Computer-Aided Design (CAD). Besides, such a discretization accelerates the convergence of displacement and electric potential solution fields toward exact results. Various benchmark problems have been solved to verify the robustness and high accuracy of the proposed dynamic L-IGA method. These include comparative analyses between L-IGA dynamic solutions (i.e. employing the Newmark-Beta method), analytical solutions, and ANSYS-Solid 226 finite element results. All the results are compared across various span-to-thickness ratios, mechanical-potential loading scenarios, and fiber orientation angles. Remarkably, the L-IGA method attains almost excellently accurate time response of various fields (displacement, stress, electric potential) and modal results, with considerably fewer mesh elements than Solid 226 solutions. Overall, such an outcome reveals the high potential and practical merits of the proposed L-IGA formulation as a proficient finite element approach for the dynamic analysis of piezolaminated plates. [ABSTRACT FROM AUTHOR]

This research aimed at studying the effect of fiber content on the flexural strength and behavior of steel fiber reinforced concrete (SFRC) beams with steel rebars. The study employed finite element (FE) analysis to simulate the behavior of SFRC beams. The simulation results of the FE model were validated against experimental data. Subsequently, the validated model was utilized to analyze the strength and crack patterns of SFRC beams with steel rebars in comparison to conventional RC concrete beams without fibers. The parametric study indicates an average 9% increase in RC beam capacity for every 1% increment in fiber volume fraction. Moreover, this study reveals more substantial effects of steel fibers on beams with low reinforcement ratios. Crack analysis shows that cracks in the SFRC beams are distributed more evenly compared to plain RC beams at regions with the same bending moment, indicating enhanced strength to sustain loads, reduced deflection, and improved beam ductility. [ABSTRACT FROM AUTHOR]

Since the helicopters are required to fulfil many different attitudes during actual flight and are exposed to low amplitude and high number of cycles of vibration loads for a long period of time, the stresses on its rotor structure will be more complicated, which will lead to the rotor blades being subjected to larger stresses and causing fatigue damage. This paper proposes a combination of fluid-solid coupling and nCode fatigue simulation of helicopter rotor blade structure to study the stress distribution, danger point and fatigue life of rotor blades in hovering and forward flight state, so as to provide a reference basis for the judgement of helicopter rotor blade fatigue damage and the enhancement of safety performance. The results show that the maximum stress of the helicopter in the forward flight state is larger than that in the hovering state, and the maximum stress of the rotor blade in the forward flight state of the helicopter is located at the root of the blade as 166.89 MPa; and the fatigue life in the two states is obtained by the joint simulation method of Workbench-nCode, and the fatigue life in the forward flight state is reduced by 0.726 % compared with that in the hovering state. Therefore, the combined method of fluid-solid coupling and nCode fatigue simulation proposed in this paper can provide an effective research method for the design and optimisation process of helicopter rotor blades. [ABSTRACT FROM AUTHOR]

The high stiffness and low mass gearbox structure design requirements were met through multi-objective optimization based on finite element modal analysis. The correlation between structural parameters and optimization objectives was identified, providing guidance for optimal design. A parametric finite element model of the box cover was established to calculate the first-order modal shape and equivalent stiffness. By using mass and equivalent stiffness as optimization objectives, a discrete data set was constructed with key dimensions of the box cover as design variables, from which a surrogate model was obtained. Standard response surface and full second-order polynomial fitted response surface function were applied after error verification. Different optimization algorithms were employed to search for the optimal value, resulting in obtaining design variables meeting the optimization objectives. The results indicated a reduction in optimized mass by approximately 6.8 %, with an error of less than 1 %. [ABSTRACT FROM AUTHOR]

Heat exchangers are necessary in most engineering systems that move thermal energy from a hot source to a colder location. The development of additive manufacturing technology facilitates the design and optimization of heat exchangers by introducing triply periodic minimal surface (TPMS) structures. TPMSs have shown excellent mechanical and thermal performance, which can improve heat energy transfer efficiency in heat exchangers. This current study intends to design and develop efficient, lightweight heat exchangers for aerospace and space applications. Using the TPMS structure, a porous construction encloses a horizontal tube that circulates heated fluid. Low-temperature water circulates inside a rectangular box that houses the complete system to remove heat from the horizontal pipe. Three porous structures, the gyroid, diamond, and FKS structures, were employed and examined. Porous models with various porosities and surface areas (15 cm2 and 24 cm2) were investigated. The results revealed that the gyroid structure exhibits the highest Nusselt number for heat removal (Nu max = 2250), confirming the highest heat transfer and lowest pressure drop among the three structures under investigation. The maximum Nusselt number obtained for the FKS structure is less than 1000, whereas, for the diamond structure, it is near 1250. A linear variation in the average Nusselt number as a function of the structure surface area was found for the FKS and diamond structures. In contrast, nonlinearity was observed in the gyroid structures. [ABSTRACT FROM AUTHOR]