3D Finite Element Analysis Research Articles

Centrifugal forces enable band gaps that self-adapt to synchronous vibrations in rotating elastic metamaterial

The rotation of mechanical systems can greatly change their modal and wave propagation response. In the classic example of the Foucault pendulum, the Coriolis force from the Earth’s rotation causes the pendulum path to appear deflected to an observer on Earth. More recently, Coriolis forces and gyroscopic effects from rotation have been shown to break time-reversal symmetry, induce non-reciprocity, and change the band structure of phononic crystals. However, rotation also introduces centrifugal forces that can considerably affect the vibration response through stress stiffening and spin softening effects. Although this is well studied in the field of rotor dynamics, the effects of centrifugal forces on the dynamic behavior of acoustic metamaterials (AMs) are still unexplored. In this paper, we study the dependence of torsional band gaps on rotational speed in a rotating shaft with attached local resonances. Different from previous studies, we explicitly consider the effects of stress stiffening in local resonances by introducing a stress stiffening function in a reduced order model of the rotating AM. We then calculate the stress stiffening function for beam-tip-mass resonators and show that these resonators have a resonant frequency that scales linearly with the rotational speed in the asymptotic limit, which in turn causes the band gaps of the AM to depend linearly on the rotational speed. Motivated by the presence of synchronous vibrations in rotating machinery, in which frequency is also linearly dependent on rotational speed, we show that this rotating AM supports band gaps that self-adjust to the synchronous vibration frequency, resulting in attenuation over a wide range of frequencies and thus rotational speeds. Finally, we validate the reduced order model of the rotating AM using 3D finite element analysis. This work contributes a foundational understanding of the effects of rotation in AMs and builds a connection between the AM and rotor dynamics communities, with the potential to introduce novel vibration control in rotor dynamics problems.

Detailed 3D FE modeling approach for 2D and 3D beam-column joints retrofitted with fully fastened haunch retrofit solution including anchor behavior

Fully fastened haunch retrofit solution (FFHRS) is a low-invasive method for seismic retrofitting of substandard beam-column joints. The method is quite effective provided a good performance of the anchors used for connecting the haunch elements and structural members is ensured. Therefore, to assess the performance of the joints retrofitted with FFHRS, realistic modeling of anchors connecting haunch elements to the joint members is essential. The paper presents a new numerical modeling approach for detailed 3D finite element analysis of substandard beam-column joints retrofitted with FFHRS, where bonded anchors are used to connect the haunch elements to structural members. The model includes detailed and realistic modeling of concrete, reinforcement, bond, haunch elements and anchors. A special focus is laid on the detailed modeling of anchor behavior. The model is validated against two experiments reported in the literature, by comparing the complete performance obtained in the tests and analysis in terms of load–displacement response, failure modes and forces in the haunch elements. The validated model is used to carry out parametric studies to investigate the performance of the single haunch retrofit solution and the performance of FFHRS as well as the efficacy of FFHRS in a 3D beam-column joint with transverse beams and slab.

Stress Intensity Factor Solutions for Eccentric Annular External Cracks in Notched Round Bars under Tensile Loading

In this paper, stress intensity factor (SIF) solutions of eccentric annular external cracks in elliptical notched round bars under tension loading have been obtained from 3D finite element analysis, along with their relation to the energy release rate obtained with the J-integral contour. The analysis variables have been the ligament diameter, its eccentricity, and the elliptical notch aspect ratio. The maximum SIF increases with the ligament eccentricity, the presence of the notch (compared to when the bar is smooth), and the elliptical notch axial semi-axis (for the same notch depth); it decreases with the ligament diameter. For external cracks, eccentricity induces bending of the bar subjected to tensile loading, which can produce partial and full contact of the crack surface, relevant phenomena in terms of the SIF value at the different points of the crack front.

A tunnelling crack density evolution model for FRP laminates subjected to cyclic multi-axial strain-controlled loading

A multi-scale stochastic crack density evolution model for tunnelling cracks under multi-directional cyclic loading is presented. The damage model proposed utilizes a multi-scale stress-based criterion for crack initiation and a triple unit cell approach with inputs from the GLOB-LOC model for crack-front growth rate. Biaxial cruciform specimens subjected to strain-controlled cyclic loading are used to calibrate the crack initiation SN curve and the Paris-Erdogan type of law required for crack growth. Additionally, uniaxial force-controlled cyclic tests are used to calibrate the stochastic parameters associated with crack initiation and crack growth. The performance of the damage model in predicting the crack-front growth compared well with experimental data and 3D finite element analyses. The damage model includes a crack element discretisation scheme which allows for multiple collinear cracks to initiate and coalesce. The model also accounts for the growth of damage outside the window of a primary representative volume element. The crack density predictions of the model are compared with measurements from cruciform specimens. It is shown that the damage model captures the trend of the crack density evolution well and provides a conservative prediction of the crack saturation level.

Influence of Placement of Ultrashort Implant at Sub-Crestal, Crestal and Supra-Crestal Level with Titanium or Polyetheretherketone Hybrid Abutment: 3D Finite Element Analysis

The aim of this study was to evaluate and compare the stress concentration of short dental implants supporting different conical abutments using 3D finite element analysis (3D-FEA). A tridimensional model of single-unit short dental implants (5.2 mm × 5 mm) was designed using the computer-aided design (CAD) software based on the manufacturer’s stereolithography. The short implants were positioned in a bone model to support titanium or ceramic-reinforced PEEK conical abutments considering different bone levels (supra-crestal, crestal or sub-crestal). With the aid of a computer-aided engineering (CAE) software, the finite element model was created and an axial load of 500 N was applied. Observing the mechanical response of the implant, abutment and screw, both evaluated materials resulted in homogeneous stress and could be indicated for implant-supported restorations with short fixtures. However, aiming to decrease the strain in the bone tissue, placing the implant in the sub-crestal position is a preferable option; while the supra-crestal placement decreases the stress at the screw and implant.

Finite element analysis for a deep excavation in soft clay supported by lime-cement columns

The aim of the paper is to simulate the response of a deep excavation supported by sheet pile walls and lime-cement columns. The application of the deep mixing technique using lime-cement products in deep excavations changes the initial state of the natural soil and creates substantial displacements associated with the installation effects. In this paper, the influence of lime-cement stabilisation was investigated using the finite element method for an instrumented braced excavation. The 2D finite element analyses were performed with advanced constitutive models for both natural clay and stabilised soil, exploiting the laboratory test made on both field mixed and laboratory mixed stabilised clay samples. The numerical results show that taking account of installation effects provides realistic predictions of deformation, excess pore water pressure evolution, as well as the structural forces in the struts.

Cryogenic System Preliminary Design for a 0.5m-Long, Conduction-Cooled Nb3Sn Undulator Magnet Prototype

There are several NbTi superconducting undulator (SCU) magnets currently in operation at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The development on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn-based superconducting undulator magnets at APS is underway due to the potential to further enhance the performance of the SCUs. Superconducting undulator magnets need to keep temperature gradients minimized in order to retain thermal and operating current margin. We have designed the thermal links for efficient heat conduction using 3D finite element analysis (FEA) simulation in COMSOL Multiphysics software, which was later used for the calculation of the temperature distribution across a 0.5 m long, conduction-cooled, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn undulator magnet prototype that includes both conductive heat transfer and radiative heating components. We have modelled the evolution of the thermal properties of the magnet winding as well as other cold parts during cool-down from ambient temperature with the operation of a SHI RDK-415D cryocooler to examine the estimated time that is needed for the cooldown as well as the baseline temperature we could achieve. A key result was that a maximum coil <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta $</tex-math></inline-formula> T = 0.11 K along the designed thermal links and a temperature range of 3.42 K–3.53 K for the winding were predicted at steady state. A pair of G10 support rods for carrying the magnet as well as a pair of current leads made of metals were also designed and optimized for the testing system, targeting for an operation temperature of 4 K and a coil current of 950 A DC.

A theoretical and practical framework based on plasticity theory for the drained behavior of single and multiple shallow footings

AbstractWith the shift of the offshore wind energy sector to deeper waters, demand for the development of more complex foundation solutions, particularly suction bucket – supported tripod/tetrapod and jacket foundations, has increased. This paper is divided into two main sections. The first part comprises a comprehensive review of the performance of circular surface and shallow foundations under combined loading (VHM), and how it can principally be understood in a theoretical framework of plasticity theory. Examination of the considered data suggested that the general assumption of over‐estimated non‐association degree with constant failure surface parameters and increasing vertical load may require further investigation. This may be attributed to the complex interplay of multiple properties such as stress level, soil strength profile and foundation geometry. The existing data in the literature were also used to provide practical guidance for a successful implementation of the elasto‐plastic constitutive relationships in offshore foundation design. In second part of the paper, the suitability of the non‐associated plasticity formulation for a baseline multi‐pod system in H‐M load space was investigated using three‐dimensional (3D) finite element (FE) analyses and not verified. Furthermore, the failure envelopes and hardening law for caissons with different embedment ratios differed from those recommended in the literature were established. Parametric studies of multi‐caisson foundations revealed that the failure mechanism of multi‐bucket foundations under horizontal loading depended greatly on the bucket spacing. The horizontal bearing capacities increased with the bucket spacing until they reached a threshold. Meanwhile, analyses of the multi‐bucket foundation under moment loading confirmed the occurrence of a push‐pull failure mechanism.

Evolution and optimization of a brushless doubly‐fed machine with an asymmetrical reluctance and magductance rotor

AbstractThe brushless doubly‐fed machine (BDFM) utilizes an asymmetric composite rotor featuring salient pole reluctance and magductance to effectively compensate for the phase shift in space, as well as enhance magnetic field modulation effects, and is therefore used as a modulator. This paper evaluates the modulation capability of the modulator from the perspective of the magnetic field conversion mechanism. The theoretical evolutions of the average magnetic field conversion factors and torque contributions of various airgap field harmonics are accomplished. Additionally, multi‐objective optimization is conducted for better performance, using stratified sensitivity analysis on typical 4/2 pole pair BDFMs featuring symmetrical and asymmetric composite rotors. As a result, further improved modulation of the air gap magnetic field is expected, the cross‐coupling efficiency of the rotor is improved, and a lower output torque ripple is also achieved compared to the conventional symmetrical counterpart. Theoretical investigation of the optimized BDFM, including its effectiveness in enhancing performance metrics such as coupling factor, airgap flux density, and phase shift mechanism, is verified through 2D finite element analysis. Furthermore, a proof‐of‐concept prototype for experimentation was manufactured, which achieved good agreement with the theoretical predictions.

A Novel Sleeve Design to Reduce the Eddy Current Loss of High-Speed Electrical Machines

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying the retaining sleeve to the rotor is essential. However, when using sleeves, there is a problem of reducing efficiency due to eddy current loss. In this paper, a study was conducted on a motor for a 100 kW building air conditioning system operating at a speed of 20,000 rpm. The purpose of the study is to reduce eddy current loss by optimizing the sleeve geometry. To this end, 3D finite element analysis (FEA) using JMAG 22.1 was conducted to analyze eddy current loss, the minimum safety factor was analyzed through mechanical stiffness analysis using ANSYS Workbench, and the validity of sleeve shape was proved through cause analysis. Through the research results, it is expected that the shape change of the sleeve will have the effect of reducing eddy current loss.

Edge damage prediction and analysis of ceramic restorations in ultrasonic-assisted dental grinding based on a multi-grit finite element model

Abrasive machining is heavily used to fabricate ceramic restorations in dentistry. The machining-induced edge damage on ceramic surfaces has been a persistent challenge for reliable restorations. This paper presents a new three-dimensional (3D) finite element analysis (FEA) modeling to visually evaluate and quantitatively predict edge chipping damage of ceramic restorations. In this model, a randomly distributed multi-grit model was built instead of most single-grit or uniform models widely used in the past. Meanwhile, axial ultrasonic vibration was first added to the model to investigate the effects of rotary ultrasonic on surface quality. Dental grinding testing was carried out using a robot arm and a high-speed dental handpiece with and without ultrasonic assistance. The experimentally measured results were in agreement with the FEA predictions. The results indicate that the reasonable rotary-ultrasonic assistance could achieve a clear reduction of edge chipping damage in the brittle dental ceramics, especially at high cutting depths without compromising cutting efficiency, compared with conventional dental grinding. This research has first proved the feasibility of applying the rotary ultrasonic technique to dental high-speed grinding for improving the surface quality of ceramic restorations. Furthermore, the proposed multi-grit FEA model for edge damage prediction is applicable not only to dental grinding but also to other abrasive machining in engineering.

Investigation of anchorage plate opening on bursting force

Three-dimensional (3D) Finite Element analyses were performed to investigate transverse stresses and bursting forces at the anchorage zone in post-tensioned concrete beams. The behavior of the concrete beam was investigated through linear elastic Finite Element analyses. To validate the Numerical modeling results, an experimental study was performed on a beam and results are compared in terms of ultimate strength. The effect of duct hole and eccentricity are investigated by varying diameter and eccentric distances on the concrete beam. Furthermore, the results are validated for bursting stress and bursting force. Altogether, the equation of bursting force in IS 1343:2012 hasn’t considered the effect of duct hole and eccentricity, the results are compared with IS 1343:2012, and an equation is presented considering the effect of duct and eccentricity.

3D finite element analysis of a two-surface wear model in fretting tests

This article aims at developing a computationally efficient framework to simulate the erosion of two contact surfaces in three-dimensional (3D), depending on the body resistance. The framework involves finite element (FE) resolution of a fretting problem, wear computation via a non-local criterion including a wear distribution parameter (WDP), as well as updating of the geometry and automatic remeshing. Its originality is based on the capability to capture the damage on each surface and obtain local and global results for a quantitative and qualitative analysis. Numerical simulations are carried out for two 3D contact specimens with different values of WDP. The results highlight the importance of correctly modelling wear: One-surface wear model is sufficient from a global point of view (wear volume), or whenever the wear resistance for a body is much higher than that of another one, whereas a 3D two-surface wear model is essential to capturing local effects (contact pressure, wear footprint, etc.) related to the difference in wear resistance of the bodies.

Analysis of the adhesively bonded composite double cantilever beam specimen with emphasis on bondline constraint, adherend through-thickness flexibility and fracture process zone relative size

ABSTRACT The double cantilever beam (DCB) specimen is widely used to characterise the mode I fracture of adhesive joints. This paper analyses some particular characteristics of adhesively bonded composite DCB specimens which could affect test results. Three-dimensional (3D) and two-dimensional (2D) finite element analyses (FEA) were conducted in order to evaluate the effects bondline constraint and adherend through-thickness flexibility on the specimen response. Since beam theory-based data reduction schemes are widespread, beam models were also employed to analyze the effects of adherend through-thickness flexibility and fracture process zone relative size. It is shown that, although composite adherends are usually thinner and have much lower transverse moduli than metal adherends, the level of bondline constraint is similarly high. This may: limit the level of adhesive plastic deformations in the fracture process zone; generate high bondline tractions that increase the likelihood of interface failure and interlaminar damage in the composite adherends. The present analyses also show relevant effects of adherend through-thickness flexibility in the adhesive elastic loading stage. Finally, smaller fracture process zones relative to metal adherend DCB specimens were predicted by a beam cohesive zone model. This may explain lower fracture energy values reported with composite adherends in some studies.

Outcome of Implant Diameter and Length on the Distribution of Stress with Immediate Loaded Implants: A 3D Finite Element Analysis.

To assess the outcome of implant diameter and length on THE distribution of stress using a three-dimensional (3D) finite elements (FE) analysis, with immediate loading implants. This study made use of a 3D FE model of an implant encased in a chunk of bone. The LEADER/ITALIA-Fix type implant was created specifically for immediate loading. To create a solid model of the implant and bone and to carry out the FE analysis, the ANSYS V.12 programme was used. The findings indicated that the neck of dental implants is the area of highest stress for all implant diameters and lengths, with an increase in implant length from 10 mm to 12 mm resulting in a slight raise in stress at the interface of implant-bone, and an increase in diameter from 3.75 mm to 4.25 mm having no appreciable impact on the value of stresses around dental implants. It was concluded that an increase in length has a negative effect on stress, while a diameter increase has no discernible impact on stress values.

Design and Optimization of PMSM for Injection Molding Machine

With the implementation of the “dual carbon policy”, the traditional injection molding machine transmission system pays more and more attention to improving the energy efficiency for the drive motor, and the PM motor has obvious advantages in injection molding machine drive motor because of its high efficiency and high-power density. A permanent magnet servo motor (PMSM) for an injection molding machine with a rated power of 7 kW is designed based on the theory of PMSM in this paper. The 2D finite element analysis (FEA) model of the motor is set up. The electromagnetic performance parameters are obtained, including cogging torque, torque ripple, output torque, and no-load back EMF. The cogging torque of the motor is optimized and analyzed. The results show that the optimized motor has reduced the cogging torque and torque ripple without affecting the output capacity, which is more suitable for the application in the drive system of the injection molding machine.

3D cellular characterization and finite element analysis of cork compressive behavior based on high-resolution X-ray microtomography

3D cellular characterization and finite element analysis of cork compressive behavior based on high-resolution X-ray microtomography

3D Finite Elements Analysis of Stress Distribution on the Posterior Tilted Implants on all on 4 Concept

3D Finite Elements Analysis of Stress Distribution on the Posterior Tilted Implants on all on 4 Concept

Comparison of 2D and 3D Finite Element Analysis of RC Blocks Culvert Based on Soil-Structure Interaction Using GTS

This paper presents a comparison of soil-structure interaction based on 2D and 3D finite element analyses of ‘Reinforced Concrete Box Culvert’ by using the software GTS (Geotechnical and Tunnel Analysis System). For buried Structures like Box Culvert, the soil below the structure is to be simulated by elastic spring while surrounding and overlying soil by superimposed load combinations. GTS is the most advanced software, presenting a new paradigm for Box Culvert and other specific geotechnical structures. It is based on expert analysis and advanced graphic technologies. GTS enables engineers to intuitively generate complex geotechnical models. Such modeling capabilities are armed with strong analytic features, powered by a uniquely developed multi-frontal solver with the fastest analysis speed. The difference in values of forces and moments, between 3D FEA and 2D FEA, has been found to be more in large sections (10ft x 10ft) than in small sections (5ft x 5ft) of Box Culverts.

Post-fatigue fracture load, stress concentration and mechanical properties of feldspathic, leucite- and lithium disilicate-reinforced glass ceramics

ObjectiveTo evaluate the mechanical properties of different CAD/CAM ceramic systems and the post-fatigue fracture and stress distribution when used as cemented crowns. Materials and methodsSixty (60) CAD/CAM monolithic crowns were milled using three different ceramic materials (FD – Feldspathic [Vita Mark II]), LE - Leucite-based ceramic [IPS Empress CAD] and LD - Lithium Disilicate [IPS e.max CAD]) and adhesively cemented on resin composite dyes. Specimens were stored in distillated water (37 °C) for 7 days. After, half of the crowns were submitted to immediate fracture load test while the other half was submitted to fatigue cycling. The average cement layer of approximately 80 μm was assessed using scanning electron microscopy (SEM). The average thickness was used in the three-dimensional (3D) Finite Element Analysis (FEA). For each ceramic material, the density, Poisson ratio, shear modulus, Young modulus, fracture toughness, and true hardness were assessed (n = 3). The data was used to assess the Maximum Principal Stress throughout 3D-FEA according to each material during load to fail and post-fatigue. Data were submitted to two-way ANOVA and Tukey test (α = 0.05). ResultsLD showed the highest compression load, density, shear modulus, Young modulus, fracture toughness and true hardness values. While LE presented the lowest mechanical properties values. There is no difference in the Poisson ratio between the evaluated ceramics. ConclusionLD was susceptible to aging process but presented stronger physicomechanical properties, showing the highest post-fatigue fracture load and highest stress magnitude.