Dimensional Finite Element Research Articles

Exploring Nonlinear Behavior of Gasket Joints in DEF Dosing Units through Finite Element Analysis

Gaskets serve the crucial function of maintaining a durable seal within 2fixed components within a mechanical structure, even when subjected to varying pressures and temperatures during operation. Gasket joint is necessary in many mechanical systems to form a leak free joint. DEF dosing system is one of the examples where gasket joints are used to prevent exhaust gases leaking before going through SCR. Gasket joint requires certain minimum pressure to make leak free joints. If the gasket pressure goes below the pressure of the internal fluid in the assembly, then there are chances of leaking the fluid out. If the gasket pressure is increased by applying high bolt preload, then there may be chances of yielding of the flanges or this may cause damage to bolt/nut threads. So, there must be optimum gasket pressure in the assembly. The gasket pressure gets affected by many parameters. The present paper aims to avoid leak in case of gasket joints. There are number of parameters which affects the performance of the gaskets e.g. bolt preload, bolt tightening sequence, internal pressure, temperature of internal fluid, creep of gasket etc. Different analysis has been carried out to check effect of allthese parameter on the contact pressure at the gaskets joint. Initial gasket pressure was mainly controlled by bolt preload/torque. The effect of bolt torque on the performance of the gasket joint assembly was studied. A dimensional nonlinear finite element analysis was carried out on the gasket joint and sealing performance was correlated with experimental study. Different geometric configurations are studied at different bolt pre-load levels. Effect of bolt torque on gasket pressure as well as other components of the assembly was studied. The best configuration which gives gasket pressure above minimum required to maintain leak proof joint and with no yielding in the assembly has been recommended.

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.

Pullout behaviour of strip plate anchors in clay overlying sand

Plate anchors are being increasingly employed to establish mooring systems for offshore floating facilities owing to their notable efficiency and cost-effectiveness. The majority of prior studies have concentrated on plate anchors, examining the vertical to horizontal orientations, particularly when embedded in single layer clay or sand. However, it is common to encounter multiple layers of soil with varying characteristics in practical engineering, leading to inaccurate estimation of pullout capacity when based solely on the properties of a single soil layer. This paper reports pullout behaviours of strip plate anchors in clay overlying sand by adopting two dimensional finite element analysis. To simulate the hardening and subsequent softening behaviour of medium to dense sand, a modified Mohr-Coulomb model is considered. The current Finite Element (FE) results are in good agreement when compared with both previous FE simulations and physical model test data. Then, the soil flow mechanisms (e.g. the accumulated plastic shear strain, the friction angle) surrounding the anchor during pullout out are revealed. Based on a series of FE results, a calculation framework considering the effect of thickness of clay layer is designed to predict the pullout behaviour of plate anchors in clay overlying sand.

Finite element analysis of fibre reinforced timber beams under flexural loading

ABSTRACT Laminated Veneer Lumber (LVL) is a popular product used in the building and construction industry because of its high strength, serviceability, aesthetic characteristics, and cost-effectiveness. However, LVL has traditionally been limited to residential and small light commercial buildings. To expand the use of LVL and reduce the need for steel and reinforced concrete structural members, a comprehensive computational study is conducted to understand the material’s structural performance and find an optimal strengthening ratio. In this paper, a new 3-dimensional Finite Element model was introduced and evaluated to predict the structural behaviour, strength properties, and failure damage modes of LVL timber beams reinforced with a Carbon Fibre Reinforcement Polymer (CFRP) sheet. The model is validated with three experimental tests from the literature, with the reinforced timber model showing a 1.8% error compared to the plain timber model’s 7% error. Additionally, a parametric study is conducted to understand the effects of reinforcement length on the structural behaviour of the reinforced beam, with mathematical equations established to express the relationships. The study found that reinforcing 50% of the beam span generally resulted in the most significant strength improvement. This investigation is made for various strength and serviceability parameters.

Evaluation of crush performance of extruded aluminum alloy tubes based on finite element analysis with ductile fracture modeling

In this study, the crush performance of four aluminum extrusions are investigated through analysis based on finite element (FE) simulation incorporating experiment-numerical hybrid ductile fracture modeling. Tensile tests on standard and non-standard specimens, coupled with digital image correlation and FE analyses, are employed to establish constitutive models for the materials. The evaluation of crush performance is performed based on both axial crush test and corresponding 3-dimensional FE simulation, which could validate the employed plasticity and fracture laws and predict crush performance indicators with reliable accuracy. Additionally, FE modeling enables thorough analysis of highly non-proportional loading paths and potential crack initiation sites, with the crack formation mechanism elucidated through the evolution of a proposed damage variable. Furthermore, the modified crush performance indicators are newly suggested, which could explain the dependence on both the absorbed energy of tubular extrusion and properties of ductile fracture.

Dynamic amplifications in railway transition zones: performance evaluation of sleeper configurations using energy criterion

Railway transition zones present a major challenge in railway track design mainly due to abrupt jumps in stiffness and differential settlements that result from crossing stiffer structures such as bridges or culverts. Despite numerous efforts to mitigate these transition effects at both the superstructure and substructure levels, a comprehensive solution remains elusive. Substructure-level interventions have demonstrated some effectiveness but are often cost-prohibitive and challenging to implement in existing operational railway transition zones. In contrast, mitigation measures at the superstructure (rail, sleepers, rail-pads, under-sleeper pads) level can be easily installed but have shown limited improvement in site measurements. This study evaluates the influence of different sleeper configurations in transition zones and reduced sleeper spacings on the operation-driven dynamic amplifications in railway transition zones, employing a recently proposed criterion based on the total strain energy in the track-bed layers (ballast, embankment, and subgrade). In addition to this, the influence of the loss of contact between sleepers and ballast (i.e., hanging sleepers), which typically results from the differential settlement, is studied. The first part of the paper provides useful insights regarding the interventions (and/or initial design) in the sleeper configuration and spacing, whereas the second part of the work highlights the need for interventions to deal with the loss of contact between sleeper and ballast. A 2-dimensional finite element model of an embankment-bridge transition was used for the analysis. The results show that it is not possible to mitigate the transition effects completely using the interventions involving sleeper spacing and configuration.

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.

Stress distribution on teeth restored with veneers using various incisal preparation designs: A 3D finite element analysis study

Statement of problemThe type of veneer preparation is often chosen according to the patient’s tooth structure and occlusion. Taking biomechanics into account in this decision-making process provides the clinician with more technical information on how to improve the clinical longevity of restorations. However, biomechanical analyses of veneer preparation designs are sparse. PurposeThe purpose of this 3-dimensional (3D) finite element analysis with microcomputed tomography (µCT) data obtained from realistic models was to assess the influence of different preparations for ceramic and composite resin veneers on restoration and resin layer stress distribution. Material and methodsFour replicas of a central incisor were printed and prepared for laminate veneers with 4 different incisal edge designs: shoulder (SH), palatal chamfer (PC), palatal chamfer and oblique fracture involving the distal angle (OF-PC), and palatal chamfer involving horizontal incisal fracture (IF-PC). After fabrication and cementation of the veneers, the restored replicas were assessed with µCT, and 3D finite element models were built. A 100-N load was applied on the palatal surface at 60 and 125 degrees relative to the longitudinal axis. Maximum principal stress and stress distribution on the veneers, cement layer, and tooth structure were calculated and analyzed. ResultsThe SH preparation exhibited better stress distribution than the PC preparation, and the cement layer and the veneer were subjected to lower stress. The IF-PC preparation had better stress distribution than the OF-PC. The shoulder and IF-PC showed higher stress on laminate veneers, but lower stress on the cement layer. Ceramic veneers exhibited lower stress than composite resin veneers. ConclusionsThe different incisal preparations for laminate veneers influenced stress distribution on restorations and on the resin cement layer. The shoulder type preparation showed better stress distribution and the composite resin veneers showed unfavorable results compared with the ceramic veneers.

Evaluation of Stress Distributions in All Ceramic Conometric Single Crown Restorations: 3-Dimensional Finite Element Analysis

Objective: The aim of the study is to compare the effect of monolithic translucent zirconia ceramic (TZI) and monolithic lithium disilicate glass ceramic (LDS) restorative materials on stress distributions in implant components and surrounding bone tissues in implant-supported conometric single crown restorations with a conical connection system by using 3D finite element analysis.
 Methods: Restorations produced with two different all-ceramic materials using a conometric abutment and a conometric cap on the implant with a conical connection system were placed in the maxillary right second premolar region. 3D finite element analysis was used to examine the amount and distribution of stresses in implant components, in cortical and cancellous bone tissues surrounding the implant and in crowns under vertical and oblique loading. For the statistical analysis one-way ANOVA and independent samples t-test were used (p

On the validity of the Tada stress intensity factor solution for the single edge notch tension specimen with pinned ends

The validity of the Tada stress intensity factor (KTada) for pinned-ends single edge notch tension [SEN(T)] specimens is assessed via a combined experimental-modeling approach. Analysis of fatigue crack growth rate reductions during constant-ΔKTada loading demonstrates that specific combinations of alloy stiffness, geometry, and loading result in the true K deviating below KTada. Geometrically non-linear, 3-dimensional finite element calculations confirm mild-to-strong influences of these parameters, which are not captured by KTada. Most existing pinned SEN(T) data are found to use parameters where KTada is not significantly reduced, but the present results underscore the need for a more broadly applicable K solution.

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.

Scope of magnesium ceria nanocomposites for mandibular reconstruction: Degradation and biomechanical evaluation using a 3-dimensional finite element analysis approach

Magnesium/Ceria nanocomposites (Mg/xCeO2 NCs (x = 0.5 %, 1 % and 1.5 %)) prepared by using powder metallurgy and microwave sintering method are assessed for their corrosion rate for a period of 28 days. As per the immersion tests results, the addition of ceria nanoparticles to pure Mg, brought about a noteworthy improvement to corrosion resistance. A corrosion rate of approximately 0.84 mm/year for Mg/0.5CeO2 and 0.99 mm/year for Mg/1.0CeO2 nanocomposites were observed. Another aspect of the study involves employing the simulation method i.e. finite element analysis (FEA) to compare the stress distribution in magnesium-ceria nanocomposite based screws and circular bars especially for Mg/0.5CeO2 and Mg/1.0CeO2. Further, the simulation also gives a perception of the impact of masticatory forces, the biting force and shear stress exerted on the Mg/0.5CeO2 and Mg/1.0CeO2 based screws. The simulations results show that the screws showed an acceptable level of stresses for a biting force up to 300 N. The circular bar as well kept its stresses at acceptable levels for the same load of 300N. The shear stress results indicated that a biting force up to 602 N can be safely absorbed by Mg/0.5CeO2 screw. The comprehensive approach allows for a better understanding of the corrosion behavior, stress distribution, and mechanical properties of the Mg/CeO2 nanocomposites, enabling the development of effective temporary implants for craniofacial trauma fixation that can withstand normal physiological forces during mastication. The study reported in this paper aims to target Mg/xCeO2 NCs for temporary implants for craniofacial trauma fixation.

Analytical approach to the design of a high-force density double-sided linear switched reluctance motor

This paper presents an analytical approach to the design of a high–force density double-sided linear switched reluctance motor (LSRM). The design is based on an analytical formulation of the average propulsion force determined using the non-linear energy conversion loop, in which the unaligned magnetization curve is assumed to be a straight line and the aligned magnetization curve is represented by two straight lines. The main dimensions of the LSRM are determined in accordance with the machine requirements, the proposed average propulsion force formula and the geometrical relationships that were presented in a previous paper. The present paper uses two dimensional finite element analysis that has been corrected to take into account the end effects in order to refine and/or to validate the proposed design. Finally an LSRM prototype was built following the proposed design and was verified by experimental measurements.

Effect of the Geometric Shapes of Elevated Tanks on their Dynamic Response

This study examines the impacts of geometric shapes of elevated tanks owing to the seismic loading action. Four typical tank shapes have been studied, namely: intze tank with a shaft, pure conical tank with a frame, combined conical tank, and cylindrical tank with a frame through a single degree of freedom, two degrees of freedom, and three dimensional finite element method, based on the full and empty condition using computer simulation program LUSAS FEA through added mass approach for accounting fluid-structure interaction. The results revealed that the intze shape is the most suitable shape to be analyzed based on mechanical approaches. While the impossibility of applying these approaches to conical tanks.

A 3D time-dependent backward erosion piping model

Backward erosion piping (BEP) is a failure mechanism of hydraulic structures like dams and levees on cohesionless foundations subjected to seepage flows. This article models the time-dependent development of BEP using numerical simulation of the erosion process. A 3-dimensional finite element equilibrium BEP model is extended with a formulation for the sediment transport rate. The model is compared to and calibrated with small- and large-scale experiments. Finally, a large set of simulations is analyzed to study the effects of factors such as grain size, scale (seepage length) and overloading on the rate of pipe progression. The results show that the development of BEP in the small-scale experiments is predicted well. Challenges remain for the prediction at larger scales, as calibration and validation is hard due to limited large-scale experiments with sufficiently accurate measurements. The results show that the progression rate increases with grain size and degree of overloading and decreases with seepage length, which is consistent with experimental observations. The model results provide a better physical basis for incorporating time-dependent development in the risk assessment and design of levees.

What is the Optimal Nail Length to Treat Osteoporotic Subtrochanteric Fractures? A Finite Element Analysis.

Operative management with intramedullary nail fixation remains the definitive treatment of choice for osteoporotic subtrochanteric (ST) fractures; however, there remains no consensus regarding the proper nail length. We aimed to use 3-dimensional finite element (FE) analysis to determine the optimal nail length for the safe fixation of osteoporotic ST fractures. Nine modes of FE models were constructed using 9 different lengths of cephalomedullary nails (short nails: 170, 180, and 200 mm; long nails: 280, 300, 320, 340, 360, and 380 mm) from the same company. The interfragmentary motion was analyzed. Additionally, the peak von Mises stress (PVMS) in the cortical bone, cancellous bone of the femoral head, and the nail were measured, and the yielding risk for each subject was investigated. Long nails were associated with less interfragmentary motion. In the cortical bone, the PVMS of short nails was observed at the distal locking screw holes of the femoral medial cortex; however, in long nails, the PVMS was observed at the lag screw holes on the lateral cortex. The mean yielding risk of long nails was 40.1% lower than that of short nails. For the cancellous bone of the femoral head, the PVMS in all 9 FE models was in the same area: at the apex of the femoral head. There was no difference in the yielding risk between short and long nails. For implants, the PVMS was at the distal locking screw hole of the nail body in the short nails and the nail body at the fracture level in the long nails. The mean yielding risk was 74.9% lower for long nails than that for short nails. Compared to short nails, long nails with a length of 320 mm or more showed less interfragmentary motion and lower yielding risk in low-level osteoporotic ST fractures. The FE analysis supports long nails as a safer option than short nails, especially for treating transverse-type low-level osteoporotic ST fractures.

Fast Prediction and Staged Optimization of Electromagnetic Vibration in Permanent Magnet Synchronous Motor

The most common method to suppress electromagnetic vibration is to weaken the electromagnetic force harmonics (EMFHs), which are the vibration sources. Clearly, vibration is related to some other factors, too. Therefore, in this paper, modal analytical model and transmission function of a permanent magnet synchronous motor (PMSM) are studied, based on which a fast analytical method of predicting the electromagnetic vibration is proposed, so that the vibration can be preliminarily evaluated during the machine electromagnetic design. The time-consuming 3-dimensional finite element method (FEM) is not needed when predicting the vibration. Moreover, using the fast prediction method, a 15-dimensional multi-objective optimization problem for vibration, torque and efficiency performances is solved in stages. After optimization, the vibration is greatly reduced, and the torque performance is improved. The proposed methods are also proved to be applicable for different operating conditions and types of motors with various slot-pole combinations.

Numerical Study of Shape and Density Effect on Semi-Infinite Metallic Target Under Hypervelocity Impact

Numerical investigations are conducted to examine the penetration depth of ellipsoid-shaped projectiles into semi-infinite aluminum targets under conditions of hypervelocity impact. These results are then compared against empirical equations developed by various researchers for spherical projectiles. The semi-infinite aluminum target, sized at [Formula: see text][Formula: see text]mm, is composed of Al7075-T651. The projectiles are fashioned from Al-7075-T651, steel, and boron carbide. The projectile’s shape factor was determined using the L/d ratio, specifically for the symmetrical ellipsoidal shape. Employing Ansys Autodyn, a 3-dimensional finite element model (FEM) is created and calibrated using existing experimental findings from the literature. The validation utilized the Johnson–Cook (JC) and Johnson–Holmquist (JH-2) material models for both the targets and projectiles. These validated models are subsequently employed to analyze how the ellipsoid projectile’s shape and density influenced their interaction with the semi-infinite targets. Furthermore, the investigation also encompassed an analysis of the resulting crater shapes generated by the hypervelocity impact of both metallic and nonmetallic projectiles. It is observed that for a definite SF, max[Formula: see text] depth of penetration is observed due to steel project as compared to boron carbide and aluminum projectile. Both the diameter of the crater and the height of the bulge ([Formula: see text] are directly proportional to the impact velocity and density of projectiles, and inversely proportional to SF. However, for a particular material and impact velocity of the projectile, in the case of [Formula: see text], there are no clear-cut observations displayed it seems like a mixed variation.

Effect of different implant locations and abutment types on stress and strain distribution under non-axial loading: A 3-dimensional finite element analysis

Background/purposeDental implants have been a popular treatment for replacing missing teeth. The purpose of this study was to investigate the impact of engaging (hexagonal) and non-engaging (non-hexagonal) abutments in various six-unit fixed prosthesis on the stress distribution and loading located in the implant neck, implant abutment, and surrounding bone. Materials and methodsThree implants were digitally designed and inserted parallel to each other in edentulous sites of the maxillary right canine, maxillary right central incisor, and maxillary left canine. Titanium base engaging abutments, non-engaging abutments and connecting screws were designed. Five distinct models of 6-unit fixed dental prosthesis were created, each featuring different combinations of various abutments. Forces (45-degree angle) were applied to the prosthesis, allowing for the analysis of the stress distribution on the implant neck and abutments, and the maximum and minimum principal stress values on the cortical and trabecular bone. ResultsVon Mises stress values and stress distributions located in the implant neck region due to the applied loading forces were analyzed. The overall stress values were highest while employing the hexagonal abutments. The maxillary left canine with a hexagonal abutment (model 5) reported the highest von mises value (64.71 MPa) while the maxillary right canine with a non-hexagonal abutment (model 4) presented lowest von mises value (56.69 MPa). ConclusionThe results suggest that both the various abutment combinations (engaging and non-engaging) on five different models have a similar influence on the distribution of stress within the implant system.