Finite Element Method Calculations Research Articles

Research on the calculation method of grinding temperature field of spiral bevel gear based on generative machining

At present, the process parameter setting of spiral bevel gear grinding is mainly based on an empirical method, and the tooth surface temperature is difficult to estimate effectively during grinding, which may lead to excessive tooth surface temperature and surface burn caused by improper selection of process parameters. Aiming at the above problems, this paper presents a method for calculating the temperature field of spiral bevel gear forming based on a combination of analytical and numerical methods. The motion equation of spiral bevel gear grinding is derived based on the method of tooth surface development. The time-varying heat flow calculation method in tooth surface grinding was developed through the discrete and two-dimensional contact zone. The time-varying temperature field analysis method of spiral bevel gear forming is developed using the time-varying heat flow and finite element calculation method. The related research can realize the temperature prediction of grinding tooth surfaces and provide the basis for improving grinding technology.

The Influence of Physical Properties of C55 Alloy on Geometry of Flow in the Process of Shaping

The paper presents analysis of influence of change of physical parameters such as: temperature, friction coefficient and load, during the process of die forging. Optimization of the process effects in achieving high quality products, decreasing shaping resistance, and what follows – lower energy consumption. Temperature is the basic factor affecting the process of plastic working. Analyzing that influence in individual die fragments, allows to engineer the flow of shaped material. The QForm3D commercial program for finite element method calculations was used for numerical simulations. The paper presents multi-variant analysis of forging process with the usage of numerical simulation, which provided many valuable information concerning changes of key parameters, such as: temperature, stress and strain distribution and variations of technological parameters, as well as their mutual influence, difficult to obtain in analysis of industrial process.

Study on the Mechanical Properties and Design Method of Frame-Unit Bamboo Culm Members Based on Semi-Rigid Joints

The frame-unit bamboo culm structure system offers a novel approach to bamboo structure, combining advantages like reduced construction times and simplified joint designs. Despite its benefits, there is limited research on its mechanical properties and computational methodologies. This study conducted bending performance tests on simply supported frame-unit bamboo culm structures, revealing that the bending stiffness of the structure increases with the number of bolts in the edge joints, though with diminishing efficiency. Based on the experimental observations, a calculation model for this type of structure was established, proposing formulas to describe the stiffness relationships between the corner joints, edge joint, and the overall structure. Numerical simulations calculated the stiffness of the edge joint as a function of the number and placement of bolts, indicating that positioning bolts closer to the outer side enhances edge joint stiffness. By inputting the various rotational stiffness values of corner joints into the simulations and stiffness formulas, consistent total stiffness values were obtained, validating the proposed stiffness relationship formulas. The average stiffness values of the corner joints were derived from these formulas and experimental data, and the rotational stiffness of other types of corner points can also be obtained using this method. Furthermore, a finite element computational method tailored for this structural system was introduced, converting the actual structure into a beam element model for calculation. The equivalent joint forces can be distributed to various components of the actual structure, resulting in the internal force distribution of bamboo culms and bolts in the actual structure, thus achieving the design of the components. The calculated displacement values obtained from this method are close to the displacement values in the experiment, proving the feasibility of this method.

Ramalan Kestabilan Cerun yang Diperkukuhkan Menggunakan Cerucuk Menggunakan Model Sistem Inferens Neuro-Fuzzy Adaptif (ANFIS)

Predictive analysis using artificial intelligence (AI) has transformed the landscape of forecasting analysis in various research fields. The advancements in AI modelling algorithms have enhanced decision-making, trend identification, and process optimization. In geotechnical engineering, AI assists in predicting soil behaviour, structural stability, and slope stability. The AI model discussed in this paper is the Adaptive Neuro-Fuzzy Inference System (ANFIS). In this study, the ANFIS model predicts slope stability by examining the Factor of Safety (FOS) value. Slope stability analyses reinforced with continuous bored pile walls generated by the numerical computation of the finite element method (FEM) in two dimensions (2D) and three dimensions (3D) are compared with the predictions of the ANFIS model. The numerical FEM computations employ PLAXIS 2D and PLAXIS 3D software. Meanwhile, the ANFIS model is designed within the MATLAB software platform involving 112 data samples. With six input pile parameters and one output, the finding shows that the ANFIS model can learn complex non-linear data and accurately predict the output. This is supported by the R² values of 0.9771 and 0.9965 from comparing the forecasting output with the 2D and 3D FEM outputs, respectively. Meanwhile, the low RMSE values of 0.0187 and 0.0180 each confirm this.

Metro Monolithic Track Bed Vibration Characterization

With the rapid development of cities, metro transportation has also developed rapidly to solve the congestion problems caused by urban development. However, with the continuous development of metro transportation, the vibration problems caused by it have become increasingly obvious. Based on the phonon crystal theory, this paper investigates the vibration characteristics of the metro track structure. It analyzes the influence of the track structure parameters on the band gap characteristics to regulate the metro vibration band gap range. To study the band gap characteristics of metro monolithic bed track structure, establish the double-layer Euler beam model and use the plane wave expansion method (PWE) to calculate its energy band structure; use the finite element method (FEM) to calculate to get its band structure, frequency response function, and time domain analysis. The calculation of PWE shows that there is a band gap in the range of 0–300[Formula: see text]Hz for the metro monolithic track bed, which is 0–194.5[Formula: see text]Hz; the calculation of FEM shows that the range of band gap is 0–193.7[Formula: see text]Hz. Fastening spacing, stiffness, and sub-slab support stiffness will have an impact on the band gap, so appropriate fastening and spacing need to be selected for effective vibration damping of the track structure. The results show that the band gap characteristics of the metro monolithic track bed can be calculated effectively and accurately by using the phononic crystal theory.

ANALYSIS SAFETY FACTOR KUALANAMU RAILWAY EMBANKMENT USING FINITE ELEMENT METHOD

Analysis of the soil's bearing capacity for the loads acting on the railway tracks is one of the most important parts of planning the structure of the railway to be built. Considering that train activity is very intense and imposes a significant live load on the soil layer beneath it, it is necessary to ensure that the soil layer under the railroad track is able to withstand the entire load. This analysis aims to ensure that the subgrade is able to support the entire load acting on it by calculating the safety factor for the layers of soil and ballast on the railroad track. The calculation method used to obtain the load value is analytical, while the calculation of safety factors and soil settlement is carried out using the finite element method (FEM) calculation concept. From the results of analysis using the finite element method (FEM) using Plaxis 2D, it can be concluded that at the operational stage the maximum drop in the vertical direction was -5.96 mm while the maximum movement in the horizontal direction was 1.12 cm. This is smaller than the maximum drop permitted by Minister of Transportation Regulation No. 60 of 2012, namely 10 cm. The safety factor during train operations is 2.902, so the railroad construction can be declared safe.

Telemetric angle and position sensing using millimeter-wave metamaterial and a frequency-modulated continuous-wave (FMCW) chip

Abstract. We present a fully telemetric sensor concept for angle and position measurement. It is based on single-layer millimeter-wave metamaterials that exhibit an anisotropic resonant behavior in interaction with incident electromagnetic waves. The angle of rotation is determined from the reflected millimeter waves of the metamaterial target using a millimeter wave chip transceiver. We use a metamaterial geometry exhibiting anisotropic Fano-type resonant behavior. The Fano-type resonance shows a distinct minimum in the reflection spectrum, even with a single layer of metamaterial. The metamaterial target is manufactured on a printed circuit board (PCB) laminate with low-cost standard manufacturing methods. We present an analytical model estimating the resonance frequency of the metamaterial used. The model allows us to assess whether with the Fano-type metamaterial unit cell structure resonance frequencies in the millimeter wave regime are achievable and compliant with standard PCB manufacturing design rules. We performed proof-of-principle experiments with the metamaterial targets and a vector network analyzer, assisted by a detailed analysis of the sensor effect by means of finite-element method calculations. Finally, we implemented a demonstrator setup containing a state-of-the-art frequency-modulated continuous-wave (FMCW) radar chip and a metamaterial target manufactured with standard PCB manufacturing processes.

An in-situ magnetising holder achieving 1.5 T in-plane field in 200 kV transmission electron microscope

A strong in-plane magnetic field is required for Lorentz transmission electron microscopy (LTEM) to observe the evolution of the magnetic domain structure of materials with high coercivity, particularly for research on rare-earth permanent magnets. However, the maximum field of the present in-situ magnetising holder applied in 200-kV or 300-kV TEM does not exceed 0.1 T. In this study, the reason for the low field was analysed, and the field strength was significantly elevated by reducing the field application area of the field generator. From finite element method calculations and experimental measurements, a 1.5 T in-plane field was achieved by our new holder in a 200-kV TEM, and images with good quality could still be obtained. Using the newly developed holder, the magnetisation process of hot-pressed NdFeB magnets was observed. The in-situ magnetising holder can be used in research on a wide variety of magnetic materials.

Probabilistic Design Method for Aircraft Thermal Protective Layers Based on Surrogate Models

In this study, a probabilistic method was proposed for an aircraft’s thermal protective layers. The uncertainties of material properties, geometric dimensions, and incoming flow environments were considered for the design inputs. To accelerate the design efficiency, Latin hypercube sampling and surrogate models were built based on finite element method calculations to enhance the simulation efficiency. Thus, the Monte Carlo method can be implemented with such a fast simulation method and produce a massive number of samples for the uncertainty quantification and sensitivity analysis, exploring their impact on the back temperature of the thermal protection layer. Compared to the deterministic method with the extreme deviation design, the probabilistic design yields a weight reduction of 15.61%. This indicates that probabilistic design is an efficient approach to enhance the performance of aircraft and reduce the overall weight of the aircraft. The general goal of this study is to provide a new design method for the coating film of thermal protection systems by considering multiple sources of uncertainties.

Stretchability dependency on stiffness of soft elastomer encapsulation for polyimide-supported copper serpentine interconnects

For conventional flexible printed circuit board widely used in industry, jointing islands of electric components with polyimide-supported copper serpentine interconnects is an effective approach to ensure circuit stretchability. The stretchability of the interconnects varies significantly due to the soft elastomer encapsulating the interconnect, as the encapsulation essentially constrains the lateral buckling of the serpentine structure during stretching. Previous studies have indicated that thin encapsulation with a low Young’s modulus is required to maximize stretchability. However, extremely low modulus and thinness lead to the elimination of the encapsulation function, and the design criteria for maximizing stretchability while maintaining adequate modulus and thickness are still unclear. This study investigates the dependence of stretchability on encapsulation stiffness, an index that simultaneously considers modulus and thickness. The interconnects with core–shell and single-elastomer encapsulations, each with a different stiffness, were prepared. The relationships between the elongation to failure of the interconnect and the tensile and bending stiffness of the encapsulation were investigated through experiments and finite element method calculations. The results indicate that the tensile stiffness is a more useful index in encapsulation design than the bending stiffness because the elongation to failure monotonically decreases as the tensile stiffness increases. The results also indicate that the required tensile stiffness to maximize interconnect stretchability, essentially making the interconnect almost freely deformable, ranges from 5 to 34 N m−1 when the interconnects use an 18 μm thick copper and 50 μm thick polyimide.

Fretting Behavior of WC-Co-Cr Coatings Against QT Steel in Bolted Joint

Fretting damage on contacting surfaces introduces major challenges in mechanical assemblies. Thermal sprayed hardmetal coatings are extensively used for surface modification in tribological applications under demanding conditions and may also be subjected to fretting-inducing loading. In the present work, the fretting behavior of High Velocity Oxy-Fuel (HVOF) and High Velocity Air–Fuel (HVAF) sprayed WC-10Co-4Cr coatings against quenched and tempered (QT) steel was studied by using a single bolt joint-type fretting experiment. This experimental approach was selected to obtain realistic data on the fretting fatigue performance of the contact pairs (both coating-to-steel and coating-to-coating). Experimental results were completed with continuum-scale linear elastic finite element method (FEM) calculations.

(152) Energy Absorption Simulation During Low Intensity Shockwave Therapy

Abstract Introduction Low intensity shockwave therapy (LiSWT) has been used to treat erectile dysfunction since 2010 by inducing mechanotransduction. The greater the shockwave energy absorbed in cavernosal erectile tissue, the greater the opportunity for mechanotransduction regenerative mechanisms to occur and improve erectile function. Effectiveness of LiSWT depends, in part, on applied energy (mJ/mm2) and number of applications (total shocks). Although intensity of LiSWT energy cannot be arbitrarily increased due to side effects, energy absorption may be improved by performing treatment to an erect vs flaccid penis. Intracavernosal pressure and penile volume are both determinants of velocity of the energy wave in tissue and therefore absorption of shockwave energy in tissue. Intracavernosal penile pressure when erect (100 mmHg) is 16-fold higher than flaccid (6 mmHg), and blood volume when erect (142.6 cm3) is >2 times more than flaccid (62.18 cm3), therefore LiSWT in the erect state with larger blood-filled lacunar spaces should be associated with greater shockwave energy absorption. Use of a symmetry-matched secondary reflector can further increase the energy absorption of each applied shockwave by reflecting the wave back. Objective The aim of this study was to perform a simulation of energy absorption during LiSWT with a reflector in both the flaccid and erect penis. Methods This energy model used the MTS UroGold electrohydraulic shockwave device [Softwave TRT]. When sound waves pass through an interface between 2 media with different impedances, sound propagation can be significantly altered. If impedances of the media are different, part of the sound energy is reflected into the incident medium; the rest of the sound energy is transferred to the second medium. Sound propagation in tissue can be illustrated via computer simulation by mathematically calculating the damping and deflection of the sound wave by different tissue structures. Finite Element Method (FEM) simulation models are particularly suitable for the mathematical description of complex processes of shockwave propagation, such as in the flaccid and erect penis. Based on results, a “prediction” of propagation of LiSWT in tissue is possible. This patient-specific procedure is based on consideration of individual anatomical structures: corporal lacunar spaces and physical-acoustic laws. For FEM modeling of LiSWT propagation, program systems ANSYS, MATLAB and PZFLEX/ONSCALE were used. Results Using the FEM calculation model of the simulation analyses, the shockwave pulse is applied at the bottom edge of the model (Fig 1). It propagates through the erect (Fig 2a) and flaccid (Fig 2b) states, with the most energy absorption in the erect penis, shown in red. The effect of increased penile pressure on energy absorption with a constant volume is shown in Fig 3. Conclusions More energy is absorbed in cavernosal tissue during erection than in the flaccid state, with a further increase in absorption with use of a symmetric reflector. This provides greater opportunity for beneficial mechanotransduction regenerative mechanism due, in part, to increased intracavernosal pressure and tissue volume with larger blood-filled lacunar spaces during erection. LiSWT to treat erectile dysfunction should be more effective when performed in the erect state utilizing a reflector. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: MTS Medical, Softwave TRT.

Relative Entropy Application to Study the Elastoplastic Behavior of S235JR Structural Steel.

The main issue in this work is to study the limit functions necessary for the reliability assessment of structural steel with the use of the relative entropy apparatus. This will be done using a few different mathematical theories relevant to this relative entropy, namely those proposed by Bhattacharyya, Kullback-Leibler, Jeffreys, and Hellinger. Probabilistic analysis in the presence of uncertainty in material characteristics will be delivered using three different numerical strategies-Monte Carlo simulation, the stochastic perturbation method, as well as the semi-analytical approach. All of these methods are based on the weighted least squares method approximations of the structural response functions versus the given uncertainty source, and they allow efficient determination of the first two probabilistic moments of the structural responses including stresses, displacements, and strains. The entire computational implementation will be delivered using the finite element method system ABAQUS and computer algebra program MAPLE, where relative entropies, as well as polynomial response functions, will be determined. This study demonstrates that the relative entropies may be efficiently used in reliability assessment close to the widely engaged first-order reliability method (FORM). The relative entropy concept enables us to study the probabilistic distance of any two distributions, so that structural resistance and extreme effort in elastoplastic behavior need not be restricted to Gaussian distributions.

Evaluation of the Applicability of Digital Photogrammetry-Based Initial Imperfections on NLFEM Ultimate Strength Analysis of Ship- Type Stiffened Plates

In this study, the effects of initial imperfections on the ultimate strength values of ship-type stiffened plate structures are discussed and analysed from the point of view of how the initial imperfection forms are obtained. Ship stiffened panels are subjected to complex loading conditions during their operational lifespan. Accurate prediction of their strength and failure modes necessitates a thorough understanding of the effects of various imperfections on their behavior. Two primary sources of initial imperfections are considered: the buckling mode shapes resulting from linear eigenvalue buckling analysis and measurements based on digital photogrammetry. Buckling mode shapes, arising from the manufacturing process are extracted using linear static structural analysis. Digital photogrammetry is employed to capture and quantify imperfections by analysing high-resolution images of the physical structure. Numerical investigation is conducted by incorporating these two types of initial imperfections into non-linear finite element method (NLFEM) calculations. The buckling mode imperfections are applied as geometric perturbations, while the photogrammetry-based imperfections are incorporated as statistically representative deviations from the ideal geometry. Stiffened panel's structural response is analysed under longitudinal uniaxial compression. A new NLFEM project schematic has been utilized instead of the procedure outlined in the technical circular S.P 01/19 by Türk Loydu, which has been discontinued after ANSYS® Workbench™V.2019R2. This is proven by two validation case studies in ANSYS® Workbench™2022R2 version for considering buckling mode initial imperfections. A case study is then conducted using a 3D model of a stiffened plate panel, which is fabricated in a shipyard located in Trabzon, created by Photomodeler V. 2023.3.0.238 employing the digital photogrammetry method.NLFEM analysis is carried out for both initially deflected model after eigenvalue buckling analysis and naturally deflected model after welding operations. The comparative ultimate strength results are quite consistent, and this shows that the digital photogrammetric modelling method can be used in the analysis of ship structural elements.

Investigation of efficiency and temperature dependence in RbGeBr3-based perovskite solar cell structures

This study is centered on the exploration of the inorganic perovskite material RbGeBr3 as an absorbing layer in various configurations of perovskite solar cells (PSCs). The Poisson, continuity, and transport equations are solved using the finite element method for calculation. Systematic variations in the thicknesses of the RbGeBr3 absorber layer and the electron transfer layer are performed, with gold (Au) and silver (Ag) utilized as metal contacts for the electrodes. The study also delves into the impact of temperature variations on the efficacy of these structures. Among the tested configurations, the FTO/TiO2/RbGeBr3/P3HT/Au configuration emerges as the most efficient, achieving a power conversion efficiency of 11.89 %, with a short-circuit current of 14.47 mA/cm2 and an open-circuit voltage of 0.96 V. Additionally, two alternative structures, FTO/ITO/RbGeBr3/PEDOT:PSS/Au and FTO/ITO/RbGeBr3/PEDOT:PSS/Ag, are investigated, yielding comparable power conversion efficiencies of 11.374 %. The findings of this study can serve as valuable insights for the design of more advanced and efficient perovskite solar cells based on mineral perovskite layers.

Analysis of the thermal effect of two external parallel printed circuit board conductors set on a metal base and operating in a space vacuum on each other

Background. The need to analyze the thermal effect of two external parallel conductors is due to an increase in the density of the conductive pattern. For printed circuit boards set on a metal base and operating in the vacuum of space, this need is aggravated by the weakness of the issue's development. 
 Aim. Analysis of the mutual influence of two external parallel printed circuit board conductors set on a metal base and operating in a space vacuum on each other to identify the dependence of their temperature on the distance between them and determine the distance at which this dependence practically disappears.
 Methods. To achieve the purpose, a finite element method calculation implemented in the ANSYS program, the Steady-State Thermal module, was used. Three multilayer printed circuit boards were calculated: 4-layer, 6-layer, 8-layer. The temperature coefficient of resistance was taken into account separately, by recalculation.
 Results. Graphs of the dependence of overheating (the difference between the temperature of the printed conductor and the metal base) on the distance between the printed conductors were constructed. The approximation of the obtained results is carried out. According to the approximated dependencies, the minimum values of the distances between printed conductors are found, at which the cross influence of printed conductors practically disappears. As the thickness of the printed circuit board increases, this distance increases.
 Conclusion. The results obtained can help to assess the influence of neighboring printed conductors in the design of the boards of the onboard equipment of spacecraft.

Fatigue Analysis of a Cracked Shaft: a Finite Element Modeling Approach

Shafts are typically used in sophisticated mechanisms and machinery which highly depend on shafts for rotatory motion which could lead to the failure. In today’s contemporary, damages caused by cracking on mechanical components and structures have increased, causing crack and structural failure. The failure could be examined by the calculation of stress intensity factor (SIF). Once the shaft reaches the critical SIF (SIFIC), the flaw is initiated and has a potential to propagate upon loading. Typically, the flaw would spread in many patterns and tenders to the formation and initiation of different types of cracks. Thus, the objective of this research work is to analyse fatigue cracked shafts. Prediction of crack growth via SIF calculation. SIF is usually adapted to predict the stress intensity near the crack tip where crack propagation occurs. Thus, SIF is used to study and analyse the cracked surface in relation to crack initiation and propagation. The SIF is calculated through finite element method (FEM) since the FEM is capable simulating complex geometry. The SIF is calculated based on the deformation in FEM calculation. The results show the predicted crack propagation and SIF calculation. It is crucial to study the resistance of cracked shafts towards cyclic loading for maintenance preceding and retirement of the structure.

GPGPU Programming for Dipolar Field Calculation

Abstract Accelerating computational processes is paramount in numerical infrastructure development, particularly in applications such as the finite element method (FEM) and extensive calculations for simulating 3D processes in materials. In this work, we introduce a novel technique for computing the magnetostatic field of an ellipsoid particle, leveraging CUDA on a graphical card for parallel processing. The implementation on a GPU resulted in a remarkable 20-fold improvement in calculation speed. This achievement not only expedites research tasks, but also enables the exploration of larger and more intricate simulations, facilitating quicker model refinements and deeper insights into material behaviours under various conditions. The utilization of GPU computing aligns with the broader trend in scientific research and engineering, offering a versatile solution for diverse computational challenges beyond this specific task of magnetism. Overall, our work contributes to the ongoing effort to harness high-performance computing (HPC) technologies for accelerated and more efficient simulations in materials science and related fields.

RESEARCH ON FRACTAL HEAT FLOW CHARACTERIZATION OF FINGER SEAL CONSIDERING THE HEAT TRANSFER EFFECT OF CONTACT GAPS ON ROUGH SURFACES

Finger seal is a new flexible dynamic sealing technology, and its heat transfer characteristics and seepage characteristics are one of the main research hotspots. In this paper, based on the fractal theory, a fractal model of the total thermal conductance of the finger seal considering the heat transfer effect of the contact gap of the rough surface is established, a fractal model of the effective gas permeability of the adjacent finger seals annulus considering the gas slip effect and the temperature change is established, and a finite element calculation method of the two-way thermo-mechanical coupling for the finger seal is proposed. The results show that the solid-phase thermal conductance decreases with the increase of the scale coefficient. When the axial pressure difference is greater than 0.4[Formula: see text]MPa, the rotor speed is greater than 11,000[Formula: see text]r/min, the radial displacement excitation is [0.03[Formula: see text]mm, 0.09[Formula: see text]mm], and the temperature is less than 600[Formula: see text]K, the gas-phase thermal conductance between the finger seal and the rotor shows an increasing trend. The gas-phase thermal conductance of the finger seal and the rotor is always the main position under different working conditions. Under different fractal dimensions, the solid-phase thermal conductance gradually occupies the dominant position. Temperature has a certain effect on the effective gas permeability, and fractal dimension, scale coefficient, and axial pressure difference have less effect on the effective gas permeability. At an axial pressure difference of 0.08[Formula: see text]MPa, the numerical calculation results of the two-way thermo-mechanical coupling calculation method for finger seal are closer to the experimental results, with a maximum error rate of 1.96%. The above results further improve the theoretical research system of the heat transfer characteristics of the finger seal.

Description of component distortion in aluminum gravity die casting as a result of hindered shrinkage and evaluation of numerical predictions

AbstractDeviation from the nominal dimension in the sense of component distortion is a quality‐reducing phenomenon in the foundry. This distortion problem as a result of impeded solidification and cooling shrinkage is of particular importance for permanent mold casting with its mechanically stiff and thermally well‐conducting molds. In studies, the temperature when the mold constraint is removed has already been identified as one of the dominant factors influencing the dimensional deviations of the casting. So far, however, no clear dependencies have been described. In the present work, the temperature up to the removal of the mold constraint is varied from near solidus to ambient temperature on a specially designed permanent mold casting made of AlSi7Mg0.3. This is compared with thermally and mechanically coupled finite elements method calculations of the investigated test geometry and the resulting component distortions. Finally, the applicability of the distortion prediction for the development of compensation strategies is evaluated.