3D FEM Analysis Research Articles

Effects of Non-Linear Thermal Stress on Fatigue Damage of Airport Concrete Pavements

Thermal stress caused by temperature distribution in concrete slab is important in the structural design of airport concrete pavements. Airport concrete pavement slab is very thick, therefore, temperature in the slab varies nonlinearly throughout the slab depth. In this study, a method for estimating thermal stress in a concrete slab with 3DFEM analysis and heat transfer analysis was developed. The thermal stresses for airport concrete pavements with various thicknesses and climate conditions were calculated with the method for one year period and relative frequency distributions (RFDs) of the thermal stresses were obtained. Influence lines of load stress due to aircraft gear were also calculated with 3DFEM. The fatigue damages were estimated from the RFDs, the lateral distributions of the gear, combined stresses and fatigue curve of concrete. Based on the results, effects of the nonlinearity of thermal distribution and air temperature on the fatigue damage of airport concrete pavements were investigated in terms of the optimal thickness of concrete slab.

Evaluation of Thermal Stress in Airport Concrete Pavement Slab by 3D-FEM Analysis

Evaluation of Thermal Stress in Airport Concrete Pavement Slab by 3D-FEM Analysis

Test and Analysis for Shearing Behavior of Circular CFST Columns

Concrete-filled steel tubular (CFST) structures are well known to possess high strength and ductility. CFST members are used under complex stress states, such as beam–columns, piers, caissons, or other foundation components. Recommendations for the design and construction of concrete-filled steel tubular (CFST) structures were published in 1997 and revised in 2008 in Japan. In the recommendations, calculation methods for the axial strength and flexural strength of CFST columns were established on the basis of experimental results of more than 400 specimens; however, the test results of the columns that failed in shear referred to only 12 specimens in the recommendations. It is necessary to accumulate experimental data on the shear strengths and behaviors of CFST columns. Tests and analyses have been carried out on eight circular CFST column specimens with a shear span ratio of 0.75. The diameter-to-thickness ratio of the steel tube is approximately 34. The shearing capacities of the tests were underestimated by over 20% errors using the calculation method of the CFST Recommendations in Japan. The load versus deformation relations obtained by the tests were well traced by 3D-FEM analysis. The shearing capacities were estimated as an average of 12% errors using 3D-FEM analysis.

Transient thermal 2D FEM analysis of SiC MOSFET in short-circuit operation including high-temperature material laws and phase transition of aluminum source electrode

Understanding the electrothermal behavior of SiC MOSFET power devices under extreme operation conditions, such as short circuits, is crucial for their application certification. However, simulating short circuits in electronic components is challenging due to the necessity of a comprehensive thermal and electrical Multiphysics model that incorporates material laws and respects elevated temperatures with broad ranges. It is also needed to model the melting of the topside Al electrode. The paper presents for the first time a 2D electrothermal FEM that simulates the thermodynamic behavior of SiC MOSFET at high temperatures transistors under short-circuit conditions, including wide-range temperature-dependent material property laws. This work models the Al phase transition by considering the apparent heat capacity method and including the latent heat absorbed during the Al solid-liquid phase change (PC). The geometric accuracy of this study provides significant added values compared to existing 1D models. It was deduced that including the temperature-dependent material laws highly impacted the results. The rise in SiC junction temperature led to a delay in the onset of Al melting. It also impacted the progression manner of the Al melting process after the formation of new melting fronts.

Evaluation of earth retaining wall and adjacent underground structure behavior using 3D-FEM analysis

Considering that excavation work in urban areas is often conducted close to the existing infrastructure, evaluating the impact of excavation on the surrounding area is crucial. Although step finite element method (FEM) analyses have been conducted to elucidate the behavior of the retaining wall and surrounding soil during excavation, evaluating the horizontal displacement of the retaining wall and the vertical displacement of the ground behind the retaining wall using linear elastic FEM analysis remains difficult. In this study, the behavior of the retaining wall and adjacent underground structure was evaluated by applying a three-dimensional elastoplastic step finite element method (FEM) analysis, in which the elastic modulus, considering the ground confining pressure and strain due to excavation, and the usefulness of setting the deformation coefficient were evaluated. The results indicated that the displacement behavior could be simulated using elastoplastic analysis, which sets the elastic modulus by considering the excavation effect for each region.

Sustainable Approach to Metal Coin Canceling Methods, Using 3D Modeling and Finite Element Method Analysis

Over time, many minted coins were withdrawn from circulation, being replaced with new ones. The returned, obsolete metal coins were melted in order to ensure sustainable reuse of the alloy for other purposes. Between the withdrawal and melting, some of the metal coins were canceled by the destruction of their original shape and dimensions using adequate tools. The first part of this paper is focused on presenting some insights into the canceling method used on old Romanian nickel coins; also, some examples are presented. The introduction also includes a literature review in the field of coin manufacturing, covering subjects such as metal behavior under striking load and aspects of 3D modeling and FEM analysis as well as explaining some striking errors. The main purpose of this paper is to study the particularities of canceling methods applied to coins, which is conducted on relatively valuable collection metal pieces. In the second part of the paper, an adequate 3D model is computed for the canceling dies and the coin. Then, the assembled models are introduced, corresponding to each canceling case, consisting of the obverse and reverse canceling dies with coins inside them. For each model, the finite element analysis is realized and is achieved for different initial conditions. The final part of the paper presents the analysis results as well as the discussion and conclusions.

Modelling and Thermographic Measurements of LED Optical Power.

This paper presents a simple engineering method for evaluating the optical power emitted by light-emitting diodes (LEDs) using infrared thermography. The method is based on the simultaneous measurement of the electrical power and temperature of an LED and a heat source (resistor) that are enclosed in the same plastic packaging under the same cooling conditions. This ensures the calculation of the optical power emitted by the LED regardless of the value of the heat transfer coefficient. The obtained result was confirmed by comparing it with the standard direct measurement method using an integrated sphere. The values of the estimated optical power using the proposed method and the integrated sphere equipped with a spectrometer were consistent with each other. The tested LED exhibited a high optical energy efficiency, reaching approximately η ≈ 30%. In addition, an uncertainty analysis of the obtained results was performed. Compact modelling based on a thermal resistor network (Rth) and a 3D-FEM analysis were performed to confirm the experimental results.

Cracking Resistance of Steam-Cured Precast Concrete Using High Alite Cement with Modified Fly Ash

Cement with fly ash has rarely been used in Japan, mainly because its strength development is slower than ordinary Portland cement. In this research, the effect of the new type of fly ash (which was modified by the electrostatic belt separation method) with high alite (C3S) cement on cracking resistance of precast concrete prepared by steam curing was studied. The mechanical and shrinkage properties of the proposed fly ash concrete were compared with those of concrete made using OPC cement without fly ash. In order to study the cracking tendency of precast concrete with the proposed cement with fly ash, thermal stress analysis was conducted, taking into consideration the experimental data of concrete properties with the different concrete mix proportions. A standard precast concrete box culvert model was used in this 3D FEM analysis, and the distribution of temperature and relative humidity in the cross-section and induced restraint stress during and after steam curing were discussed. Steam-cured concrete with fly ash and high alite cement developed higher compressive strength on the first day of age than concrete with OPC. The proposed fly ash concrete developed high cracking resistance in the early days. On the other hand, the results showed that the drying shrinkage at later ages was the main cause of cracking.

Effects of Prior Footprints on the Bearing Capacity of Spudcan Foundations: A Case Study

A jack-up rig is a self-elevating offshore drilling platform designed for mobile operations in the marine environment. The rig is supported by 3 or 4 legs, with spudcan foundations at the end. These spudcan provide the necessary stability and load-bearing capacity for rig foundation during drilling operations. The mobile rig sometimes revisits sites where prior installation, operation, and extraction activities have resulted in identifiable footprints on the seabed. The penetration of spudcan close to, or partially overlapping, footprints shall be carefully considered because the spudcan-footprint interaction may cause a change in the ultimate vertical bearing capacity (Fv). ISO 19905-1:2016 states that the interaction between a spudcan and a footprint is expected to be minimal when the edge-to-edge distance exceeds one spudcan diameter. This paper presents the effect of existing footprints on the vertical bearing capacity of a spudcan with various spacing variations from 0.5B to 1.75B, where B is the diameter of the spudcan. A 3D finite element method (3D FEM) is employed as the primary analysis tool in analyzing the effects of footprints on layered clay soil. The 3D FEM analysis is conducted because the analytical approach outlined in ISO 19905-1:2016 does not consider the influence of the footprint on the spudcan capacity. The analysis results show that bearing capacity may reduce by more than 50% when the center-to-center distance is less than 1B. Whereas, for distances greater than 1.5B, the influence of the footprint is relatively insignificant, only reducing less than 10% of the ultimate capacity of the spudcan.

FEM investigation of full-scale tests on DSSI, including gravel-rubber mixtures as geotechnical seismic isolation

Soil-rubber mixtures underneath foundations are an eco-sustainable and low-cost Geotechnical Seismic Isolation (GSI) solution. Using rubber grains from end-of-life tyres in the mixtures can provide a modern recycling system that reduces the stockpile of scrap tyres worldwide. In recent years, gravel-rubber mixtures (GRMs) properties have been investigated, finding good behaviour in static and dynamic conditions. Laboratory tests on GRMs advantages as GSI in the form of a layer underlying the foundation of a structure are available in the literature. Nevertheless, only one experimental campaign on a full-scale prototype structure resting on GRMs with 0% and 30% rubber content per weight was performed (SOFIA-SERA Research Programme).This paper presents 3D advanced nonlinear FEM analyses to reproduce and furnish new results about the above-mentioned full-scale test. The calibration of the parameters of the different constitutive models used for modelling the foundation soil and the GRMs was supported by an extensive geotechnical characterization. The developed FEM model was validated by the results from the above-mentioned full-scale test in terms of accelerations and velocities. Then, the dynamic behaviour of the GRMs was studied, also considering the shear strains versus the shear stresses and the horizontal and vertical displacements, quantities not investigated experimentally. Finally, the GRMs static behaviour was also investigated, considering the GRMs axial strains and the GRMs and foundation vertical displacements.The paper highlights the fundamental role of both experimental tests and numerical modelling, as invaluable tools for coupled analyses of the seismic behaviour of soil-structure systems, including innovative materials, such as GRMs, and the main advantages of using GRMs as GSI.

The Impact of Surface Discontinuities on MEMS Thermal Wind Sensor Accuracy.

A 2D calorimetric flow transducer is used to study distortions of the flow velocity field induced by small surface discontinuities around the chip. The transducer is incorporated into a matching recess of a PCB enabling wire-bonded interconnections to the transducer. The chip mount forms one wall of a rectangular duct. Two shallow recesses at opposite edges of the transducer chip are required for wired interconnections. They distort the flow velocity field inside the duct and deteriorate the flow setting precision. In-depth 3D-FEM analyses of the setup revealed that both the local flow direction as well as the surface-near distribution of the flow velocity magnitude deviate significantly from the ideal guided flow case. With a temporary leveling of the indentations, the impact of the surface imperfections could be largely suppressed. Including a yaw setting uncertainty of about ±0.5°, a peak-to-peak deviation of 3.8° of the transducer output from the intended flow direction was achieved with a mean flow velocity of 5 m/s in the duct corresponding to a shear rate of 2.4·104 s-1 at the chip surface. In view of the practical compromises, the measured deviation compares well with the peak-to-peak value of 1.74° predicted by previous simulations.

Study on the Galvanic Corrosion between 13Cr Alloy Tubing and Downhole Tools of 9Cr and P110: Experimental Investigation and Numerical Simulation

The galvanic corrosion of oil and gas production string is related to wellbore integrity and production safety. In order to study the galvanic corrosion of an oil and gas well tubing assembly and maintain production safety, this paper studied the galvanic corrosion behavior between 13Cr alloy steel tubing and the downhole tools of 9Cr and P110 in formate annular fluid via experimental and numerical simulation methods. The chemical composition, HTHP corrosion tests and electrochemical measurement of the three materials were investigated to analyze the corrosion mechanism and electrochemical parameters. Then, a full-sized 3D galvanic corrosion model of 13Cr tubing and a 9Cr/P110 joint combination was established using COMSOL Multiphysics software based on the electrochemical test results. The mechanism and current variation law of the galvanic corrosion of different tubing materials are discussed and analyzed in the paper. The results revealed that the corrosion rates obtained based on the electrochemical test are as follows: P110 (0.072 mm/y) > 9Cr (0.033 mm/y) > 13Cr (0.0022 mm/y). The current densities of a combination of 13Cr tubing with a 9Cr joint and 13Cr tubing with a P110 joint vary dramatically: the current density of the 13Cr tubing–P110 joint reach 1.6 × 10−4 A/cm2, higher than the current density of the combination of 13Cr tubing and a 9Cr joint. The results of a 3D FEM analysis show that the 13Cr tube demonstrates obvious galvanic corrosion with 9Cr and P110 joints, which is consistent with the analysis results of the polarization curve. This study therefore explains the galvanic corrosion mechanism of different tubing materials and provides guidance for the safe use of tubing in the productive process.

Design and optimization of the construction of a mobile disinfection chamber for small communication devices and small objects

Abstract This manuscript aims to familiarise readers with the development of a device for the construction of a mobile disinfection chamber for small communication devices and small objects. The conceptual design and the material of the new device play essential roles in the design process of a new device. The manuscript presents concepts based primarily on previous experience and different perspectives. The concept design is created in the 3D modelling program CREO Parametric 8.0. A multi-criteria team evaluation determined the most suitable version of the idea. For dimensioning and shape adaptation of the device was used EinScan SP device (3D scanning method). The article's aim was also to establish a suitable way of producing a prototype using tribological research in available production methods and materials within rapid prototyping. Using the ALICONA Infinite Focus G5 device, experimentally investigated the parameters characterising the surface of the parts. The end of the manuscript focused on the mechanical structure and subjecting them to FEM analysis in the program ANSYS Workbench. The design of the concept disinfection device was also for extreme cases of use. Within this issue was optimising shapes, wall thicknesses, reinforcement design and other necessary modifications using the FEM analysis. From the results, the most suitable material to produce a more significant number of parts may not be the most suitable material to create prototype devices. Tools such as 3D scanning, rapid prototyping, and FEM analysis can "significantly" help reduce mistakes before testing the device.

Design and Finite Element Analysis of a 6/4 Pole Multi-Layer Fully Pitched Switched Reluctance Motor to Reduce Torque Ripple

—In this study, the design and analysis of multi-layer fully pitched winding switched reluctance motor (MFP-SRM) for general use (submersible pump, electric vehicles, etc.) have been performed. It is seen that the multi-layer switched reluctance motor (SRM) has higher output power when compared to the single-layer SRM. In multi-layer SRM, the motors in the layers are electromagnetically independent of each other although they are identically the same motors with the same characteristics in terms of performance and geometry. Each layer of the MFP-SRM which is designed in this study consists of a 6/4 pole fully pitched SRM (FP-SRM) and these motors are magnetically independent of each other. In the MFP-SRM, which is designed as a double layer, there is a 15° phase difference between the rotor position angles and torque profile curves of each layer. With the phase difference that changes depending on the number of layers, each layer contributes to the total torque production of the profile, ensuring a smooth profile. According to the results of the 3D FEM analysis, it is seen that the proposed multi-layer motor structure has high starting torque and low torque ripple properties. In the analysis carried out in the range of 3–15 Amperes, the torque ripple of the traditional FP-SRM varies between 31.99% and 38.19%, while the torque ripple of the proposed MFP-SRM only varies between 3.23% and 7.11%.

A 2D and 3D Analysis on Electromagnetic Parameters of Spoke-shape Interior Permanent Magnet Synchronous Motor Using FEM

In industry, the most frequently used motors are induction motors (IMs), reluctance motors, and permanent magnet synchronous machines (PMSMs). Nowadays because of higher efficiency with higher power density, PMSM attracts its uses in every field of application. Hence, a spoke shape interior PM-based synchronous motor (IPMSM) with distributed winding is considered to discuss in this paper. Also, there has always been a dispute between 2D and 3D analysis of electromagnetic parameters of machines. Therefore, this paper discusses the accuracy, advantages, and difficulty level of 2D and 3D FEM analysis of the IPM motor model by considering several electromagnetic with electromechanical parameters such as torque, flux linkage, eddy current loss, etc. The performance of five different core materials is also considered for comparison. These analyses are carried out by using ANSYS Maxwell software. Spoke shape IPMSM of 0.55 kW with 220 V, 50 Hz is considered for analysis. The 2D and 3D comparison results of parameters under magnetostatic and transient conditions are presented and verified with the results reported in the literature. 2D FEM analysis has given more value in case of torque, stator current, and magnetic flux density than 3D analysis where as 3D analysis is give good performance for flux linkage, back EMF, and eddy current losses. Significant percentage changes with respect to observed materials in the results of 2D and 3D cases are reported. Silicon Steel M36 suitability for stator and rotor core is also observed. This 2D and 3D FEM analysis clarifies accuracy prior to design motor.

3D FEM analysis of stress concentrations in a rectangular thick plate with PZT inclusions under bending

3D FEM analysis of stress concentrations in a rectangular thick plate with PZT inclusions under bending

Lightweight geo-bead fill to prevent soft ground deposit failure

As a foundation for transportation infrastructure, soft ground has limited bearing capacity and high compression. To prevent embankment failure, lightweight material is suggested. In the construction of road embankments, EPS can be regarded as an environmentally sustainable lightweight fill material. The study's goal is to create a formula for GB (Geo-bead) concrete mixing as a lightweight fill ingredient. Several tests are performed on the material specimens, including bulk density, interface shear strength, unconfined compression, and a SEM of the composite material. The tests were designed to determine the physical and mechanical qualities using GB percentages (20%, 30%, and 40%). Composite material has a lower density than compacted sand. The friction angle falls between the adhesion of GB-GB and GB-cemented sand. A ductile failure pattern develops because the bond between cement paste and GB is less than that between cement sand. The composite material's CBR passed embankment specifications. In the case of an embankment on soft soil, the 2D FEM analysis expressed settlement by compacted sand and lightweight fill material. Lightweight geo bead backfill decreases soft soil settlement, preventing failure.

Analytical prediction of the cross-sectional shear flow in non-prismatic inhomogeneous beamlike solids

Non-prismatic beamlike elements are widespread in engineering applications. Unfortunately, analytical methods commonly used for stress analyses in prismatic beams provide mispredictions in non-prismatic cases. Referring for instance to components like towers and blades of large horizontal axis wind turbines, whose main length is much larger than the dimensions of the tapered transverse cross-sections, the cross-sectional taper produces shear stress distributions that are quite different from those obtainable by formulas valid in prismatic beams, notwithstanding the slender shape of such components, the limited magnitude of their tapering slopes, and the possible Navier-like distribution of their cross-sectional normal stresses. Here, we address the analytical determination of the cross-sectional stresses in elements of this kind, which are slender, non-prismatic, inhomogeneous, and susceptible to large deflections. Recalling the results of a recent work by the author, the field equations that govern the state of stress in the considered elements are exploited to obtain a new closed-form expression of the cross-sectional shear flow, which, in turn, can be used for stress predictions. Comparisons with results of non-linear 3D-FEM analyses for elements mimicking the shape of components used in applications confirm the effectiveness of the proposed analytical approach and formulas.

Design and 3D FEM Analysis of a Flexible Piezoelectric Micromechanical Ultrasonic Transducer Based on Sc-Doped AlN Film.

In this paper, a flexible piezoelectric micromachined ultrasonic transducer (PMUT) based on Scandium (Sc)-doped Aluminum Nitride (AlN) film was designed and modeled by the three-dimensional finite element method (3D-FEM). The resonant frequency of 218.1 kHz was reported. It was noticeable that a high effective electromechanical coupling coefficient (k2eff) of 1.45% was obtained when a combination of a flexible PI and a thin Si layer was used as the PMUT supporting structure layer. Compared with a pure Si supporting layer counterpart, the coupling coefficient had been improved by 110.68%. Additionally, the increase of Sc doping concentration in AlN film further enhanced the device electromechanical coupling coefficient and resulted in an improvement for transmitting/receiving sensitivity of the proposed flexible PMUT. When the doping concentration of Sc reached 30%, the emission sensitivity was as large as 1.721 μm/V, which was 2.86 times greater than that of conventional AlN film-based PMUT. The receiving sensitivity was found to be 2.11 V/KPa, which was as high as 1.23 times the performance of an undoped device. Furthermore, the bending simulation result showed that the proposed flexible PMUT device can maintain a good mechanical stability when the bending radius is greater than 1.5 mm. The simulation of sound field characteristics demonstrated that the flexible PMUT based on AlScN could receive stable sound pressure signals under the bending radius of 1.5 cm.

3D FEM Analysis of the Subsoil-Building Interaction

This paper presents the process of advanced numerical analysis of interaction between a building and the subsoil. The analysis covered a wide range of work for both computing and research. As part of the research work, field and laboratory subsoil tests were carried out, as well as geodetic measurements of building settlement and measurements of natural vibrations of an object. The computational work included the analysis of a total of 47 FEM models. The subsoil was described using the Modified Cam-Clay model, with parameters determined using field CPT and SDMT tests, as well as triaxial and edometric laboratory tests. Parts with geodetic benchmarks were separated from the building model, and then multi-variant calculations were made on smaller, partial models with parameters obtained from various methods. Calibration of the main models was performed using 8 partial models for which calculations were carried out in 4–5 variants of parameters. This gave a total of 38 partial models. Then, calculations were carried out on the full model of the building with subsoil. At each stage, the results of vertical displacements were compared to the geodetic values. The measured settlement of the real building in the time from the construction of the underground story to its use for the period of 1 year, was from 2.3 mm to 7.8 mm. The settlement from FEM calculations of small calibration models for the same benchmarks was from 2.0 mm to 9.8 mm with parameters derived from CPT tests and from 1.8 to 7.3 mm for parameters derived from SDMT. For the full building model, settlement from FEM calculations ranged from 2.2 to 8.8 for the variant with a simplified subsoil model, and from 3.7 to 10.5 for the model taking into account the inhomogeneity of the subsoil. As a result, it was found that the displacements from the numerical analysis were convergent with the geodetic values. Detailed numerical analyses also allowed to detect the deviations of the segments from the vertical and to indicate potential damage to the structure. It was also indicated how the work of the subsoil influences the stress distribution in selected structural elements. Behaviour of the subsoil has an impact on the behaviour of the building and its deformations, as well as on the distribution of stresses in the structural elements, and, as a result, on the change in the distribution of internal forces in the structure.