Dimensional Finite Element Model Research Articles

Investigation of hybrid ultrasonic machining process of Nomex honeycomb composite using a toothed disc cutter

Nomex honeycomb composite (NHC) has been increasingly used in the automotive, aerospace and defence applications due to its excellent thermal and mechanical properties. Its complex cellular hexagonal thin-walled configuration along with heterogeneous, soft and brittle nature pose substantial processing defects such as burr formation, tearing of walls, surface roughness, dimensional inaccuracy and low machining quality during conventional machining (CM). These surface defects have a substantial influence on the operating life and functional performance of its sandwiched structural members. Hybrid ultrasonic vibration assisted machining (HUSVAM) technology has been introduced to overcome such limitations. For an in depth research on HUSVAM of NHC using ultrasonic toothed disc cutter (UTDC), three dimensional finite element model was developed and experimental validation was carried out. The numerical simulation and experimental results were found to be in good agreement with one another. The influence of various machining parameters including the ultrasonic tool vibration amplitude (UTVA), feed rate (FR), depth of cut (DoC) and spindle angular speed (SAS) on NHC cutting forces, chip formation and surface quality was investigated using both HUSVAM and CM techniques. Furthermore, stresses, deformation and forces near tool-workpiece interaction along with the surface topography and morphologies were also analysed and compared for various operating conditions. A reduction in the cutting forces was found with the increase of SAS and UTVA (up to 65.47 % and 65.74 %, respectively). Although, the cutting forces were observed to increase by increasing the DoC and FR (up to 159.45 % and 126.33 %, respectively). DoC has a greater impact on the cutting forces among all machining parameters according to 4 levels, 4 factors (L16) orthogonal experiments based on Taguchi method. The results show that the chip formation and machining quality of NHC core can be improved with HUSVAM technique using UTDC. HUSVAM also reduced the cutting forces (up to 73 %) compared to CM. The ultrasonic toothed disc cutter generated large number of burr with very short length, no tearing defects and no uncut fibers as observed from scanning electron microscopy of NHC hexagonal cell structure, walls and triple points. A burr formation of less than 10 % was realized during HUSVAM of NHC cores for Fx≤3N, while it was found up to 20 % if Fx>3N, compared to at least 40 % during CM. The finite element model developed can be used to investigate the influence of HUSVAM on modern difficult to machine materials for enhanced surface quality.

Biomechanical behavior of implant retained prostheses in the posterior maxilla using different materials: a finite element study.

The aim of this study is to evaluate the biomechanical behavior of the mesial and distal off-axial extensions of implant-retained prostheses in the posterior maxilla with different prosthetic materials using finite element analysis (FEA). Three dimensional (3D) finite element models with three implant configurations and prosthetic designs (fixed-fixed, mesial cantilever, and distal cantilever) were designed and modelled depending upon cone beam computed tomography (CBCT) images of an intact maxilla of an anonymous patient. Implant prostheses with two materials; Monolithic zirconia (Zr) and polyetherketoneketone (PEKK) were also modeled .The 3D modeling software Mimics Innovation Suite (Mimics 14.0 / 3-matic 7.01; Materialise, Leuven, Belgium) was used. All the models were imported into the FE package Marc/Mentat (ver. 2015; MSC Software, Los Angeles, Calif). Then, individual models were subjected to separate axial loads of 300N. Von mises stress values were computed for the prostheses, implants, and bone under axial loading. The highest von Mises stresses in implant (111.6MPa) and bone (100.0MPa) were recorded in distal cantilever model with PEKK material, while the lowest values in implant (48.9MPa) and bone (19.6MPa) were displayed in fixed fixed model with zirconia material. The distal cantilever model with zirconia material yielded the most elevated levels of von Mises stresses within the prosthesis (105MPa), while the least stresses in prosthesis (35.4MPa) were recorded in fixed fixed models with PEKK material. In the light of this study, the combination of fixed fixed implant prosthesis without cantilever using a rigid zirconia material exhibits better biomechanical behavior and stress distribution around bone and implants. As a prosthetic material, low elastic modulus PEKK transmitted more stress to implants and surrounding bone especially with distal cantilever.

Numerical Simulation of Soil–Structure Interaction of RC Frame

An Attempt has been made to study the effect of soil media on the response of RC frame structure. Therefore, the present work focuses on the implementation of a two dimensional finite element model of reinforced concrete frame and pile foundation system which explicitly incorporates the soil response. The superstructure members have been represented by means of three-node isoperimetric beam elements with three degrees of freedom per node. The soil mass is idealized by the eight-node isoperimetric quadrilateral element at the near field and five nodes isoperimetric infinite element to simulate the far-field behavior of the soil media. The applicability of this model was demonstrated by analyzing a multi-story building. The results have shown that the influence of the soil behavior on the overall response of the structure.

Research on the Influence of Different Winding Forms on the Performance of Induction Motor

Background: As a component of the motor’s electromechanical energy conversion, the winding is very important. When the winding design is improper, the harmonic content is increased, which leads to an increase in the motor loss and torque ripple. Therefore, winding design is very important for motor design. Objective: The effect of winding forms on the induction motor is analysed in this paper. The variation in performance parameters of different winding forms is invesitgated. Methods: This paper takes an 11 kW, 1500 r/min induction motor as the research object; the two- dimensional transient field finite element model has been established to calculate the basic parameters, which are then compared with the experimental data to verify the correctness of the model. Finally, the magnetizing reactance, starting performance, stator leakage reactance, various losses, and efficiency under different winding forms are calculated and compared. Results: When the motor adopts double-layer winding, the magnetizing reactance, stator slot leakage reactance, and harmonic leakage reactance are less than those of the motor with single-layer winding by 13.47%, 25.37% and 20.97%, respectively, while the end-leakage reactance, starting torque, and starting current rotor copper loss are higher than those of the motor with single-layer winding by 7.14%, 9.52%, 18.54%, and 15.23%, respectively. The core loss and stator copper loss of motors with different winding forms are almost unchanged. The efficiency of the motor with single-layer winding is higher than that of the motor with double-layer winding by 1.22%. Conclusion: When the winding form is different, the magnetizing reactance, stator slot leakage reactance, harmonic leakage reactance, and end-leakage reactance are different. Leakage reactance is the main factor that causes a difference in starting torque and starting current between the two winding forms. The core loss and stator copper loss of motor with different winding forms are almost unchanged, while the difference in the rotor copper loss is obvious. In addition, the efficiency of the motor with single-layer winding is higher than that of the motor with double-layer winding.

A global–local meta-modelling technique for model updating

The finite element model updating procedure of large or complex structures is challenging for engineering practitioners and researchers. Iterative methods, such as genetic algorithms and response surface models, have a high computational burden for these problems. This work introduces an enhanced version of the well-known Efficient Global Optimisation technique to address this issue. The enhanced method, refined Efficient Global Optimisation or rEGO, exploits a two-step refinement and selection technique to expand the global search capability of the original method to a global–local, or hybrid, search capability. rEGO is tested and validated on four optimisation test functions against the original methods and genetic algorithms with different settings. Good results in terms of precision and computational performance are achieved, so an application for model updating is sought. A penalty function for the finite element model updating is identified in residuals of the modified total modal assurance criterion. Finally, rEGO for finite element model updating is implemented on a hybrid, numerical and experimental, case study based on a well-known experimental dataset and on a higher dimension finite element model of a wing spar. Satisfactory results in terms of precision and computational performance are achieved when compared to the original methods and genetic algorithms, needing two orders of magnitude fewer evaluations and achieving comparable results in terms of precision.

Development of flanking structures in layered gneissic rock: Insights from numerical modelling

Flanking structures defined by dragged planar fabrics alongside of quartzo-feldspathic veins in gneissic rocks are very common. Varieties of mesoscale flanking structures were observed in parts of the Chhotonagpur Granite Gneissic Complex (CGGC), Eastern India. Alternate thin layering of quartzo-feldspathic and mafic minerals in gneissic rock causes mechanical anisotropy in rock during deformation. This study aims to explore specially the influence of mechanical anisotropy on the development of flanking structures. With the help of two –dimensional Finite Element modelling, we attempt to understand the effect of initial orientation of cross-cutting element (θ), kinematic vorticity number (Wk) and the anisotropy factor (δ) on the development of flanking structures. Deformed shape of cross-cutting element (RN), amount (LN) and nature (antithetic or synthetic) of offset of layers and pattern of drag (reverse or normal) are considered as important parameters for their nomenclature. As the final geometry of flanking structure does not only depend on the instantaneous deformational condition, we analyze the progressive development of flanking structures by varying the above parameters. Study reveals that mechanical anisotropy has strong influence on the geometry of flanking structures in layered gneissic rock, which depends on the initial orientation of long axis of cross-cutting element and its final position with respect to the orientation of principal stress axes and pole of anisotropy. The study also reveals that the flanking structures can be used as important tool for estimating the mechanical anisotropy in layered rock. Shape of cross-cutting element, amount of offset and the shifting of the object-tip points are the most important parameters for determining the anisotropy factor.

Analysis of Geosynthetic – Reinforced Stone Piles – Supported Embankments

The low bearing capacity, high compressibility, and lack of lateral resistance of stone pile-supported embankments on soft clay deposits pose design challenges. To overcome these difficulties, geosynthetics have been widely favored by geotechnical engineers in recent years. A two and three dimensional (2D, 3D) finite element model study that simulates a geosynthetic-reinforced and geosynthetic-encased stone pile-supported embankment on soft ground is presented in this paper. To study the effect of reinforcement and encasing on the vertical displacement of stone piles and soft soil, numerical analyses are performed. The results show a significant reduction in settlement with the casing, which is believed to be a direct result of the additional containment pressure created by the geosynthetic casing. With the help of soil reinforcement, the surface settlement values ​​of the soft soil could be significantly reduced.

Present–day crustal deformation in the southeastern Tibetan Plateau: Insights from three–dimensional finite–element modeling

Quantifying the present–day kinematics of southeastern Tibet is important for understanding the tectonic evolution of the Tibetan Plateau. In this study, we established a three–dimensional finite element model to estimate fault slip and strain rates in the southeastern Tibetan Plateau based on Global Navigation Satellite Systems (GNSS) observations. Our model yields an overall good fit to the GNSS velocity field with residuals of 0.83 mm/yr and 0.85 mm/yr for the east and north components, respectively, comparable to the uncertainties of 0.67 mm/yr and 0.61 mm/yr. The model–derived strike–slip rates of the Xiaojiang fault, Nanhua–Chuxiong fault, Qujiang fault, central segment of Red River fault, southeastern segment of Red River fault and Dien Bien Phu fault are 13.7 ± 0.7 mm/yr, 1.9 ± 0.6 mm/yr, 3.4 ± 1.1 mm/yr, 1.5 ± 0.5 mm/yr, 1.2 ± 0.4 mm/yr and 1.6 ± 0.4 mm/yr, respectively, which are consistent with previous geological results, implying that the short–term fault motions estimated from GNSS data can reflect the long–term fault slip in the southeastern Tibetan Plateau. The shear strain rate is localized along the Xiaojiang fault, which agrees with predictions of the tectonic extrusion model (i.e., the lateral extrusion of internally rigid blocks along strike-slip faults). Strain orientations in the western part of southeastern Tibetan Plateau are characterized by clockwise rotation. Comparison of the surface strain rates, crustal stress, and seismic anisotropy reveals general consistency between deformation of the surface and upper crust. The eastern part of southeastern Tibetan Plateau has small residuals, and the present–day crustal deformation can be explained by rigid block motion. However, the western part of the study area has relatively large residuals, implying that other processes, such as gravitational spreading, may influence deformation in the area. We propose a hybrid model that combines rigid block motion with continuum deformation to explain the contemporary crustal deformation of southeastern Tibetan Plateau.

Mandibular bone remodeling around osseointegrated functionally graded biomaterial implant using three dimensional finite element model.

Dental implantation surgery has been progressed as one of the most efficient prosthetic technologies, however, it still fails very often and one of the main causes is the large difference between implant mechanical properties and those in welcoming bony tissues, making it problematical in osseointegration and bone remodeling. Biomaterial and tissue engineering research shows that there is a requirement in developing implants with Functionally Graded Materials (FGM). Indeed, the great potential of FGM lies not only in the field of bone tissue engineering but also in dentistry. To improve the acceptance of dental implants inside the living bone, FGM were proposed to step up the challenge of ensuring a better match of mechanical properties between biologically and mechanically compatible biomaterials. The aim of the present work is to investigate mandibular bone remodeling induced by FGM dental implant. Three-dimensional (3D) mandibular bone structure around an osseointegrated dental implant has been created to analyze the biomechanical behavior of the bone-implant system depending on implant material composition. In order to implement the numerical algorithm into ABAQUS software, UMAT subroutines and user-defined material were employed. Finite element analysis have been conducted to determine the stress distributions in implant and bony system, and to evaluate bone remodeling induced by the use of various FGM and pure titanium dental implants over the period of 48 months.

A numerical simulation approach for the residual prestress of composite barrel with non-round section of railgun with tension winding

In order to obtain the distributions of residual prestress of the filament wound composite barrel with non-round section for railgun caused by the winding tension, a new numerical approach is provided. Based on the idea of considering the fiber bundles as the main load-bearing material for each winding layer, the loading of the initial winding tension in the winding process can be simulated through loading the initial tensile stress of the fiber bundles in fiber direction of the winding layers’ elements. Firstly, combing with the element birth and death technology, a three dimension finite element model for a hybrid filament wound cylinder with metal liner is established to simulate its residual prestress caused by winding tension. Its results are compared with the ones obtained by the theoretical model, which verifies that this numerical simulation method is reliable to some extent. Then, this numerical simulation method is adopted to analyze the residual prestresses of the filament wound composite barrels with non-round section for railgun, which are under three different winding tension control modes respectively. The results can provide some references to the initial design of the filament wound composite barrel with non-round section for railgun.

Nonlinear fluid-induced vibro-impact analysis on the fatigue failure pattern of a large-scale trashrack with a reduced-order model

Under the water flow excitation, large submerged structures like trashracks of hydropower stations usually undergoes flow-induced vibration (FIV) and the ensuing fatigue damage. Due to the gap between the structure and the adjacent confinement, the structure’s vibration behavior is highly nonlinear in nature. This study proposes a reduced-order (RO) model along with a parametric optimization procedure to replace the traditional high-fidelity three dimensional (3D) finite element (FE) model for an accurate and efficient vibro-impact analysis on large-scale submerged structures. Based on this numerical model, an equivalent fluid–structure coupling method considering various fluid–structure interaction (FSI) mechanisms is developed with the empirical approach to simulate the FIV of large-scale underwater structures. With this novel numerical method, this paper conducts a fluid-induced vibro-impact analysis of a sample trashrack to fully investigate its nonlinear dynamic behavior under the flow excitation. The predicted stress and strain energy distributions match the observed localized fatigue failure pattern from the field inspection. It is also found that the dynamic response of the sample trashrack is dominated by the nonlinear vibration behavior mainly triggered by the vibro-impact event.

Experimental and Finite Element Method (FEM) of Dowelled Mortise and Tenon Joint for Kapur Species

Kapur (Dryobalanops spp.) is one of the Malaysian common species used for structural construction material. It is capable of serving as a beam and column. This study focused on the experimental mortise and tenon connection fastened with wood; glass fibre reinforced polymer (GFRP), and steel dowel. The finite element method (FEM) was used to model the behaviour of mortise and tenon joint for wood dowel subjected to pull-out loads using ABAQUS software. The experimental results were used to validate a three dimensional finite element model of mortise and tenon joint. The full structural scale ofmortise and tenon was fastened with a 21 mm diameter dowel. The investigation was carried out by applying tensile loads to the top of the tenon. This study adopted a linear elastic orthotropic material to represent the Kapur wood behaviour using the FEM. In this study, the results reveal the load carrying capacity of the mortise and tenon in a sequence of highest to the lowest is when the joint dowelled with GFRP, steel and wood. The stiffness value obtained from the FEM for wood dowel is found higher than the experimental value. Thus, the findings from finite element method (FEM) and the experimental results both had slightly dissimilar load–displacement curve shape. However, this study contributes to a better knowledge of mortise and tenon performance when secured with a wood dowel.

Investigating The Effect of Trinia and Zirconia Implant Supported Fixed Partial Denture On Stress Distribution in Peripheral Bone: A Three Dimensional Finite Element Modeling

Investigating The Effect of Trinia and Zirconia Implant Supported Fixed Partial Denture On Stress Distribution in Peripheral Bone: A Three Dimensional Finite Element Modeling

Intrusion of mandibular incisors using single mini-implant –A finite element study

A deep bite is a complex orthodontic problem that is a common feature of many malocclusions. Depending on the diagnosis, a deep overbite can be corrected. Mini implants can be used for the true intrusion of anterior teeth. FEA is a computer based numerical simulation technique used to calculate deflection, stress and displacement. To analyze stress distribution pattern and displacement of mandibular incisors when intrusive forces are applied using three dimensional finite element analysis. To compare intrusion of lower anterior teeth when ‘V’ pattern force and straight vertical pattern force are applied. A three dimensional finite element model was constructed to simulate mandibular teeth, periodontal ligament and alveolar bone. The displacement of individual tooth (central and lateral incisors) on three-dimensional planes and the von Mises stress distribution were compared. Intrusive forces when applied to four mandibular anterior teeth remarkable tipping of the labial segment was seen when straight vertical elastics were used as compared to the ‘V’ shaped elastics. Within the limits of this study, predictable intrusion with minimum labial tipping is seen using single implant using V pattern elastics.

Influence of plate size and screw distribution on the biomechanical behaviour of osteosynthesis by means of lateral plates in femoral fractures

Distal femoral fractures are fractures associated with high rates of morbidity and mortality, affecting to three different groups of individuals: younger people suffering high-energy trauma, elderly people with fragile bones and people with periprosthetic fractures around previous total knee arthroplasty. They have been classically treated with conventional plates and intramedullary nails and more recently with locked plates that have increased their indications to more types of fractures. The main objective of the present work is the biomechanical study, by means of finite element simulation, of the stability achieved in the osteosynthesis of femoral fractures in zones 4 and 5 of Wiss, by using locked plates with different plate lengths and different screw configurations, and analysing the effect of screw proximity to the fracture site. A three dimensional (3D) finite element model of the femur from 55-year-old male donor was developed, and then a stability analysis was performed for the fixation provided by Osteosynthesis System LOQTEC® Lateral Distal Femur Plate in two different fracture zones corresponding to the zones 4 and 5 according to the Wiss fracture classification. The study was focused on the immediately post-operative stage, without any biological healing process. The obtained results show that more stable osteosyntheses were obtained by using shorter plates. In the cases of longer plates, it results more convenient disposing screws in a way that the upper ones are closer to fracture site. The obtained results can support surgeons to understand the biomechanics of fracture stability, and then to guide them towards the more appropriate osteosynthesis depending on the fracture type and location.

The simulation analysis of sealing performance of cone-cone premium tubing connection under combined loads

Under the complex downhole loads, premium tubing connections often suffer from seal failure and threaded connection failure, leading to tubing string leakage and even safety accidents. Therefore, this paper focuses on the cone-cone premium tubing connection, simulating the make-up process and downhole load conditions, establishing three dimensional finite element models of premium tubing connections, analyzing the distribution of equivalent stress and contact pressure on sealing surface, shoulder and thread. The results show that the stress is mainly concentrated on the shoulder and sealing surface under the make-up torque. The equivalent stress on the shoulder shows a trend of increasing first and then stabilizing. The equivalent stress at the sealing surface tends to be stable first and then decreases. Under the combined loads, the overall equivalent stress of connection increases. The contact pressure decreases slightly in the area of sealing surface and the shoulder inflection point. It may cause joint failure and leakage, when the internal pressure is over 80MPa and the axial compressive load is greater than 800kN, which will lead to the maximum equivalent stress of the threaded part exceed 5.5% of the yield strength.

Parametric analysis on the flexural behaviour of RC beams strengthened with prestressed FRP laminates

In this paper, the effectiveness of reinforced concrete (RC) beams strengthened with prestressed basalt fibre-reinforced polymer (BFRP) laminates was parametrically studied through discrete displacement-coordinated finite element (FE) method. Three dimensional (3D) FE models were established based on experiments, and the reliability of the FE model was verified. The influences of material properties, prestress load level, reinforcement ratio, and shear span on the overall behavior were investigated. The results demonstrated that the optimal capacity of strengthened beam can be achieved in large shear span with low reinforcement ratio and high-strength concrete. The cracking load of RC beams was also significantly increased by strengthening with prestressed BFRP laminates. Then, polynomial equations were fitted to quantify the influences of different parameters on capacity enhancement. The shear span ratio was found to be the most important factor. In addition, the utilisation efficiency of BFRP is much higher than that of carbon FRP (CFRP) with the same section and prestress level due to the strong deformation ability.

The effects of erupting mandibular 3 molar on the dental arch: A FEM study

Role ofErupting Mandibular 3 molars as a cause of incisor crowding in the lower arch continues to be controversial. The relation between 3 molar and dental crowding has not been established. To determine the area of stress distribution and tooth displacement during eruption of mandibular 3 molar in mesioangular and horizontal impaction. Three dimensional finite element models were generated based on computed tomography scan data. From computed tomographic scans of a human mandible two additional finite element models were generated: a mandibular model with mesioangular impaction and second model with horizontal impaction. To investigate the stress distribution to the mandible, and tooth displacement eruptive force of 10 grams was applied.High concentration of stresses was seen at the inferior border of the mandible and lowest concentration of stress was present at symphysis for both the models. The tooth displacement for both mesio-angular and horizontal impaction caused mesial tilting of all the teeth i.e. from 2 molar to central incisor; with greatest tilting of 2 molar. Along the vertical plane, there was extrusion seen with 2 molar with mesio-angular impaction and extrusion in 2 molar and 1 molar with horizontal impaction And all the teeth exhibited buccal flaring in case of both impaction. There is significant level of tooth displacement from 2 molar towards the incisors. These changes occurring along the dental arch must be taken into consideration while planning for prophylactic extraction of third molars.

Dynamic Analysis of Historical Masonry Arch Bridges under Different Earthquakes: The Case of Murat Bey Bridge

Historical structures, which constitute an important part of our cultural heritage, should be well protected and carried into the future. Masonry arch bridges are significant part of these structures. In this study, the single-span Murat Bey Bridge in the province of Kütahya, built in 1460, was studied as a numerical application. Firstly, three dimensional finite element model of the bridge was constituted with SAP2000 finite element program. Static analysis of the bridge under its own weight was carried out. The modal analysis method was used to obtain the dynamic characteristics of the bridge. Then, time-history analysis method was applied for seismic evaluation of the bridge. For this purpose, the acceleration records of the 1998 Adana, 2003 Bingöl, 2011 Van and 2020 Elazığ earthquakes were taken into consideration. As a result of the dynamic analyses carried out, the displacement and stress graphs occurring on the bridge were examined. The highest displacement and stress values on the historical bridge were obtained from the acceleration records of the 2011 Van earthquake.

Thermal buckling analysis of thin-walled closed section FG beam-type structures

In this paper, thermal buckling analysis of thin-walled, functionally graded (FG) beam-type structures with closed cross-sections and various boundary conditions is investigated. One dimensional finite element model, based on Euler–Bernoulli–Vlasov​ theory, is employed under the assumptions of large rotations and small strains. Two cases of temperature rise across the thickness of the cross-section walls are considered, which are uniform and linear. Stability analysis has been performed in eigenvalue manner and in load–deflection manner using Newton–Raphson method. Numerical results for thin-walled box beams and trapezoidal beams for two different FG materials configurations are presented to investigate the effects of temperature distribution, boundary conditions, and material properties on the critical buckling temperature and global buckling behaviour. The accuracy and reliability of the beam model is verified by comparing it with several benchmark examples. Good agreement was observed, showing possibility of further application of the proposed model which requires reduced computational time and provides greater modelling flexibility compared to commercial codes.