Finite Model Research Articles

Human tactile sensing and sensorimotor mechanism: from afferent tactile signals to efferent motor control

In tactile sensing, decoding the journey from afferent tactile signals to efferent motor commands is a significant challenge primarily due to the difficulty in capturing population-level afferent nerve signals during active touch. This study integrates a finite element hand model with a neural dynamic model by using microneurography data to predict neural responses based on contact biomechanics and membrane transduction dynamics. This research focuses specifically on tactile sensation and its direct translation into motor actions. Evaluations of muscle synergy during in -vivo experiments revealed transduction functions linking tactile signals and muscle activation. These functions suggest similar sensorimotor strategies for grasping influenced by object size and weight. The decoded transduction mechanism was validated by restoring human-like sensorimotor performance on a tendon-driven biomimetic hand. This research advances our understanding of translating tactile sensation into motor actions, offering valuable insights into prosthetic design, robotics, and the development of next-generation prosthetics with neuromorphic tactile feedback.

Finite element method numerical modeling of the crack's impact on the free vibration of 2D functionally graded beams on the Pasternak-Winkler elastic foundation

The study's contribution is to examine, while taking into account pinned-pinned boundary conditions, the free vibration response of multi-cracks Euler-Bernoulli perfect FG beams structure on Pasternak-Winkler elastic foundations. The finite element approach is used to discretize the equations. The material properties are taken into account using a power-law form, and they differ in the thickness and width directions of the beam structure. The 2D FG beam's reduced cross section is used to calculate the stiffness of the cracked structure. On the other hand, the Pasternak-Winkler type foundation has a longitudinal distribution and makes the system stiffer. For convergence research, the numerical results are compared with the outcomes of earlier investigations in terms of dimensionless fundamental frequencies. Case studies were carried out to examine the effects on the natural frequencies of the beams structure of the power law index, multi-cracks, depths, location, and Pasternak-Winkler-elastic foundation. These studies demonstrate the benefits of the two-dimensional FG beam in the presence of cracks over the unidirectional FG and pure metallic beams.

Finite Difference Model of Substrate Channeling in TCA Cycle Enzymes

The Tricarboxylic Acid (TCA) cycle is a highly optimized metabolic pathway. Of particular interest in the TCA cycle is the malate dehydrogenase—citrate synthase (MDH-CS) complex, which accomplishes citrate production from malate with an oxaloacetate intermediate. This complex was studied experimentally by Bulutoglu et al, who showed that mutation of positively-charged residues on the complex surface effected the dynamic response of citrate production as measured by lag time experiments.1 More recently, we have created a Markov State model that was used to predict the transfer efficiency of each complex and determine the reaction pathways on the surface.2 Utilizing the kinetic parameters of both the recombinant and mutant complexes determined experimentally1and Markov state transition matrix produced by previous modeling2, we report a finite difference model to calculate time trajectories of the surface and bulk occupancies by OAA. Solution of a system of differential mass balance equations, based on the transient matrix, provide the occupancy probability at each node in the network. The lag time of MDH-CS was determined computationally to be comparable to experiment for both the recombinant and mutant complex with lag times of 0.44 and 2.1 seconds, respectively.1 Using the model, the dynamics of each of the four possible reaction pathways between the the two source (MDH) active sites and the two sink (CS) sites could be studied independently. This analysis provides a dynamic model for intermediate transport in an electrostatically channeled system, and can be used as a predictive tool to provide mechanistic insight into pathway dominance. We gratefully acknowledge support from the Army Research Office MURI (#W911NF1410263) via The University of Utah. References B. Bulutoglu, K. E. Garcia, F. Wu, S. D. Minteer, and S. Banta, ACS Chemical Biology, 11, 2847–53 (2016). doi:10.1021/acschembio.6b00523Y. Xie, S. D. Minteer, S. Banta, and S. Calabrese Barton, ACS Nanoscience Au, 2, 414-421 (2022). doi:10.1021/acsnanoscienceau.2c00011 Figure 1

The Aqueous Aluminium-Ion Battery: Optimising the Electrode Compression Ratio through Image-Based Modelling

The aqueous Al-ion battery potentially has improved safety and environmental advantages over the incumbent lithium-ion technology [1,2]. Using 3D carbon-felt matrix electrodes, the performance of these batteries can be optimised. Typically, the electrodes are compressed to improve electrical conductivity by improving contact between adjacent fibres, which also closes the electrolyte pores, reducing the ionic diffusivity [3]. In this work, we set out to understand the role of electrode compression on the interplay between these key performance parameters for the aq. Al-ion battery.Synchrotron X-ray computed tomography was used to examine the 3D morphology of the carbon felt electrodes under 11 different compression ratios [4]. A bespoke in-situ tensile/compression rig was used to measure displacement and loading for three electrode types: raw carbon felt, positive electrodes loaded with a copper hexacyanoferrate ink and negative electrodes loaded with TiO2 anatase powder. Data was acquired using two voxel sizes (330nm, and 540nm) to compare the effects of spatial resolution and imaged volume size on subsequent image analysis. The tomograms were reconstructed using Paganin phase retrieval, to improve the contrast of the weakly attenuating carbon, and a filtered back projection algorithm. A U-net convolutional neural network was trained on uncompressed, fully compressed and partially compressed (three volumes) data, and then used to fully segment all tomograms.A high-throughput, image-based model was then used to analyse how compression affects the porosity, tortuosity, volume-specific area, ionic diffusivity, and electrical conduction of the electrodes. A finite differences-based model was used to solve the equilibrium partial differential equations directly on the voxel datasets, with no additional regularisation [5]. The heterogeneity of the electrode samples is quantified by comparing the effect of representative elementary volume on the value of the computed parameters [6]. Finally, aq. Al-ion batteries are manufactured using the predicted optimal compression ratio and compared to the simulated results.This is the first in-situ study of the compression effect on the aqueous aluminium-ion battery, and the largest XCT-based modelling study known to the authors (99 XCT tomograms). This work aims to improve the understanding of the effect of manufacturing parameters on the aqueous Al-ion battery and other similar batteries, and ultimately, its performance.[1] Melzack, N. "Advancing battery design based on environmental impacts using an aqueous Al-ion cell as a case study." Scientific Reports 12, no. 1 (2022): 8911.[2] Melzack, Nicole, R. G. A. Wills, and Andrew Cruden. "Cleaner energy storage: Cradle-to-gate life cycle assessment of aluminum-ion batteries with an aqueous electrolyte." Frontiers in Energy Research 9 (2021): 699919.[3] Mckerracher, R. D., A. Holland, A. Cruden, and R. G. A. Wills. "Comparison of carbon materials as cathodes for the aluminium-ion battery." Carbon 144 (2019): 333-341.[4] Reinhard, Christina, Michael Drakopoulos, Sharif I. Ahmed, Hans Deyhle, Andrew James, Christopher M. Charlesworth, Martin Burt et al. "Beamline K11 DIAD: A new instrument for dual imaging and diffraction at Diamond Light Source." Journal of Synchrotron Radiation 28, no. 6 (2021): 1985-1995.[5] Le Houx, James, and Denis Kramer. "Openimpala: Open source image based parallisable linear algebra solver." SoftwareX 15 (2021): 100729.[6] Le Houx, James, Siul Ruiz, Daniel McKay Fletcher, Sharif Ahmed, and Tiina Roose. "Statistical Effective Diffusivity Estimation in Porous Media Using an Integrated On-site Imaging Workflow for Synchrotron Users." Transport in Porous Media 150, no. 1 (2023): 71-88.

Predicting fatigue failure in five‐axis machined ball‐end milled components through FKM local stress approach

AbstractComponents created with five‐axis machining show a multi‐scale surface character due to cusps created on the surface and feed and tool marks within the cusps. Therefore, it becomes difficult to incorporate the effects of surface character on fatigue life for such components. In this work, an Forschungskuratorium Maschinenbau (FKM) guideline is adapted to develop a fatigue prediction model which considers cusps as notches and marks within the cusps as surface roughness (characterized by parameter R10z). The assessment uses stresses obtained from an finite element analysis model to predict the fatigue life of components whilst considering stress concentration, stress gradient, mean stress, and surface roughness effects. When cusps are regarded as surface roughness within the conventional FKM approach, fatigue life is considerably underestimated. In comparison, fatigue life predictions that take into consideration the roughness within cusps and treat cusps as stress‐raising notches are closer to experimental life.

Model for the Failure Prediction Mechanism of In-Service Pipelines Based on IoT Technology

With the rapid increase in pipeline mileage in China, the accurate prediction of corrosion issues in in-service pipelines has become crucial for ensuring safe pipeline operation. Traditional pipeline leakage monitoring methods are significantly limited by human factors and equipment precision, making it challenging to predict and identify leakage points accurately. Therefore, aligned with the trend of intelligent pipeline development, this study aims to construct a failure pressure prediction mechanism model for corroded pipelines based on IoT technology. This model leverages intelligent sensing and prediction to assess the safety status of corroded pipeline sections. Ultrasonic phased array technology detects specific corrosion points and detailed defect parameters within pipeline sections. The parameters are then utilized in the Simdroid domestic finite element analysis model to simulate the ultimate burst pressure of the pipeline. A single-variable approach is employed to analyze the sensitivity of different parameters to the pipeline’s ultimate burst pressure, with the minimum burst pressure point of multi-point corroded sections selected as the overall segment failure pressure. Finite element simulation data are integrated into a neural network database to predict the pipeline failure pressure. The real-time operational data of the pipeline are monitored using negative-pressure wave sensing. The operational pressure of the corroded points is compared with the algorithm-predicted failure pressure; if the values approach a critical threshold, an alarm is triggered. Moreover, the remote control terminals evaluate the pipeline’s self-rescue time, providing a buffer for pipeline leakage self-rescue. The failure prediction mechanism model for in-service pipelines was applied to the Fujian–Guangdong branch of the West–East Gas Pipeline III to verify its accuracy and feasibility. The research results offer technical support for the maintenance and emergency repair of pipeline leakage scenarios, leveraging intelligent pipeline technology to reduce costs and increase the efficiency of pipeline operations, thereby supporting the sustainable development of China’s oil and gas pipelines with theoretical and technical backing.

Progressive fatigue modelling of composite pipes with a hole

Composite pipes are increasingly used in demanding applications thanks to their light weight and corrosion resistance. To manage their integrity, tools able to predict their fatigue life and residual properties under cyclic loads are required. A finite element progressive fatigue model was applied to filament-wound composite pipes with a hole submitted to tensile cyclic fatigue. The fatigue model combined continuum damage mechanics for intra-laminar failure mechanisms and cohesive zone modelling for inter-laminar and selected macroscopic cracks. A linear fatigue damage accumulation law was used along with an empirical sudden-death residual strength model, relying solely on the material S-N curve. The fatigue simulation was conducted by an external cycle-jump procedure. After calibration on one load level, the model was able to describe the fatigue life at other load levels within one standard deviation (0.63 decade) of the experiments and resulted in a S-N curve slope of −0.084 while the experimental one was −0.072.

Assessment by finite element analysis modelling of tissue strains associated with the use of two different nasogastric tube securement devices.

Nasogastric tube use can lead to pressure injury. Some nasogastric tube securement devices (NG-SD) include hard plastic components. In the current study, we assessed the differences in strain profiles for two NG-SD, one with hard segments and one without hard segments, using finite element analysis (FEA) to measure strain and deformation occurring at the nasogastric tube-tissue interface. FEA in silico models of devices were based on device mechanical test data and clinically relevant placements. Peak strain values were determined by modelling different scenarios using Abaqus software whereby the tubing is moved during wear. The modelling showed peak strains ranging from 52% to 434% for the two NG-SD depending on the tubing placement and device type. Peak strain was always higher for the hard plastic device. Tissue strain energy was a minimum of 133.8 mJ for the NG-SD with no hard parts and a maximum of 311.6 mJ for the NG-SD with hard parts. This study provided evidence through in silico modelling that NG-SD without hard components may impart less strain and stress to tissues which may provide an option for tube securement that is less likely to cause medical device-related pressure injury.

Simulating carbon dioxide diffusion during airflow merging in Y-shaped bifurcated tunnels after blasting operations

This research aims to evaluate the dilution and discharge effects of noxious gas produced by the drilling and blasting method under the merging of airflows during the ventilation of Y-shaped bifurcated tunnels. A finite volume model was utilized to simulate the overall diffusion process of explosion and noxious gas in the tunnel after blasting, taking into account various parameters of bifurcated structures. The flow field characteristics and the temporal and spatial evolution of the CO concentration field was analyzed under parameters including the bifurcating angle θ and cross-sectional area ratio F, as well as air supply ratio Q. The results show that the CO concentration decreases in a negative exponential manner with the ventilation time and it reaches the concentration limit within 480–610 s. By comparing conditions under different bifurcating angles θ of the main transverse tunnel, the dilution effect of CO is optimal when θ is 90° and the CO concentration reaches the safety threshold after ventilation for 489 s. Considering the influence of the cross-sectional area ratio (F) of the main transverse tunnel, the CO concentration reduces most rapidly when F is 0.7 and it reaches the safety threshold after ventilation for 476 s. Upon estimating the influence of the air supply ratio (Q) on the CO diffusion process, it is found that Q of 0.4 is most conducive to the dilution and discharge of CO and the CO concentration reaches the safety threshold after ventilation for 485 s. The results provide technical and theoretical support for the ventilation and smoke discharge during the construction of a Y-shaped bifurcated tunnel.

Soft Sensors for Industrial Processes Using Multi-Step-Ahead Hankel Dynamic Mode Decomposition with Control

In this paper, a novel data-driven approach for the development of soft sensors (SSs) for multi-step-ahead prediction of industrial process variables is proposed. This method is based on the recent developments in Koopman operator theory and dynamic mode decomposition (DMD). It is derived from Hankel DMD with control (HDMDc) to deal with highly nonlinear dynamics using augmented linear models, exploiting input and output regressors. The proposed multi-step-ahead HDMDc (MSA-HDMDc) is designed to perform multi-step prediction and capture complex dynamics with a linear approximation for a highly nonlinear system. This enables the construction of SSs capable of estimating the output of a process over a long period of time and/or using the developed SSs for model predictive control purposes. Hyperparameter tuning and model order reduction are specifically designed to perform multi-step-ahead predictions. Two real-world case studies consisting of a sulfur recovery unit and a debutanizer column, which are widely used as benchmarks in the SS field, are used to validate the proposed methodology. Data covering multiple system operating points are used for identification. The proposed MSA-HDMDc outperforms currently adopted methods in the SSs domain, such as autoregressive models with exogenous inputs and finite impulse response models, and proves to be robust to the variability of systems operating points.

Study on calculation method for dynamic load distribution of thread pair of planetary roller screw mechanism

To reveal the dynamic load distribution characteristics of planetary roller screw mechanism under the high-speed operating conditions, based on the spiral surface equation and deformation coordination relationship, a static contact force calculation method of the roller-screw and roller-nut thread at the contact point is proposed, and a formula for calculating the contact angle after bearing is derived. On this basis, further considering the inertial force generated by using high-speed operation, a dynamic load distribution model for planetary roller screw mechanism thread was established. By comparing with the finite element contact model of planetary roller screw mechansim, the error is below 5%, which verifies the correctness of the model established. Finally, the influence of the parameters such as screw speed, axial load, pitch, and tooth flank angle on the distribution of dynamic load was analyzed. The results show that the inertia force causes the roller to have a tendency to move closer to the nut and away from the screw resulting in a decrease in dynamic contact force on the roller screw side and an increase in dynamic contact force on the roller nut side. The degree of uneven distribution of dynamic load is positively correlated with the screw speed and pitch, and negatively correlated with the tooth side angle. The size of axial load has a significant impact on the distribution of dynamic load.

UNVEILING THE INFLUENCE OF ONE-LEG STANCE AND STANDING UP FROM A CHAIR ON HUMAN HIP JOINT PROSTHESIS USING FINITE ELEMENT CONCEPTS

The hip joint plays an important role in providing stability to the human body. Factors such as aging, wear, and tear, make the hip joint degenerate and, in such cases, the same to be replaced through hip arthroplasty surgeries. The background of this study aims to investigate the contact consequence between the artificial femoral head and the acetabular cup for different bearing couples during one-leg stance and standing up from a chair, utilizing the finite element method. The three-dimensional finite dynamic contact model has been developed with different material combinations. The results obtained by the present finite element model align well with the previously available literature. The parameters investigated include maximum von Mises stress, maximum contact pressure and deformation for different material combinations. The results reveal that the pair i.e., Alumina on Ultra-high molecular weight polyethylene (UHMWPE) exhibits lower contact pressure, von Mises Stress and deformation. Therefore, the material pair i.e., Alumina on UHMWPE can be employed in the Total hip replacement (THR) to mitigate contact consequences under both static and dynamic loading conditions, thereby enhancing the durability of the artificial joints.

Statistical inference for innovation distribution in ARMA and multi-step-ahead prediction via empirical process

The kernel distribution estimator (KDE) is proposed based on residuals of the innovation distribution in the autoregressive moving-average (ARMA) time series. The deviation between KDE and the innovation distribution function is shown to converge to the Brownian bridge, leading to the construction of a Kolmogorov–Smirnov smooth simultaneous confidence band for the innovation distribution function. Additionally, an empirical cumulative distribution function (CDF) based on prediction residuals is introduced for the multi-step-ahead prediction error distribution function. This empirical process weakly converges to a Gaussian process with a specific covariance function. Furthermore, a quantile estimator is derived from the empirical CDF of prediction residuals, and multi-step-ahead prediction intervals (PIs) for future observations are established using these estimated quantiles. The PIs achieve the nominal prediction level asymptotically for the finite variance ARMA model. Simulation studies and analysis of crude oil price data confirm the validity of the asymptotic theory.

Quantifying the effect of fixed structures on rail stress management: A numerical investigation

From 2012 to 2021, FRA accident data indicate that there have been 132 derailments caused by track buckles. Out of the 132 total derailments, 59 (or 45 %) occurred within 152 m (500 ft.) of a fixed structure. Therefore, this paper presents, validates, and applies a 3D finite element-based model to study the effect of the fixed structure on the rail gap size given a rail break. Specifically, the model was used to quantify the effect of the: 1) temperature differential between the rail neutral temperature (RNT) and the actual rail temperature (dT), 2) distance of the cut to the fixed structure, and 3) fixed structure length and anchoring patterns (ETA and EOTA). Model results indicated that at low dTs (e.g., <13.9ºC (25ºF)) the effect of the fixed structure can be considered if the cut occurred at the edge of the fixed structure with EOTA anchoring pattern and the fixed structure length of at least 18.3 m (60 ft.). At a dT of 22.2ºC (40ºF), the fixed structure should be accounted for when there is an edge cut. At extreme dTs (e.g., > 44.4ºC (80°F)) the fixed structure should be considered if the cut occurs within 152.3 m (500 ft.). Therefore, it is recommended that railroads refrain from strictly following open track guidelines for CWR (continuous welded rail) management and rather, consider the influence of fixed structures in relevant situations.

Investigation of high-performance alkali-activated slag concrete-filled steel tubular members under lateral impact

This paper studied the behaviour of High-performance Alkali-activated slag Concrete-Filled Steel Tubular members under transverse impact along with axial compression. Combining alkali-activated slag concrete with concrete-filled steel tubes provides a novel composite material incorporating the benefits of alkali-activated slag concrete and steel tubes. Alkali-activated slag concrete, known for its environmentally beneficial traits compared to traditional concrete, improves sustainability, while concrete-filled steel tube increases structural stability. Seven specimens composed of one hollow tube and six high-performance alkali-activated slag concrete-filled steel tubular specimens were tested using a drop hammer test setup to enhance our understanding of the structural performance of high-performance alkali-activated slag concrete-filled steel tubular members. A finite element analysis model was then established to broadly compare the impact resistance of circular high-performance alkali-activated slag concrete-filled steel tubular members. The mid-span displacement and impact test durations of specimens subjected to lateral impact and axial compression were assessed using a high-speed video camera called Phantom V411. This analysis includes the examination of maximum impact load, impact plateau value, maximum displacement, residual displacement, indentation, impact duration and strain responses, and an investigation into the failure modes of the specimens. The obtained results closely align with the experimental outcomes, indicating the effectiveness of the FEA model in predicting the behaviour of circular high-performance alkali-activated slag concrete-filled steel tubular members.

Biomechanical effects of deltoid muscle atrophy on rotator cuff tissue: a finite element study

The deltoid muscle and rotator cuff tissue are structural components that maintain the dynamic stability of the shoulder joint. However, atrophy of the deltoid muscle may affect the stability of the shoulder joint, which in turn alters the mechanical distribution of rotator cuff tissue. Currently, the effect of muscle volume changes in the deltoid muscle on reducing the load on the rotator cuff tissue is still unknown. Therefore, this paper intends to analyze the mechanical changes of rotator cuff tissue by deltoid muscle atrophy through finite elements. Based on previously published finite element shoulder models, the deltoid muscle was modeled by constructing deltoid muscle models with different degrees of atrophy as, 100% deltoid muscle (Group 1), 80% deltoid muscle (Group 2), and 50% deltoid muscle (Group 3), respectively. The three models were given the same external load to simulate glenohumeral joint abduction, and the stress changes in the rotator cuff tissue were analyzed and recorded. In all three models, the stress in the rotator cuff tissue showed different degrees of increase with the increase of abduction angle, especially in the supraspinatus muscle. At 90° of glenohumeral abduction, supraspinatus stress increased by 58% and 118% in Group 2 and Group 3, respectively, compared with Group 1; In the subscapularis, the stress in Group 3 increased by 59% and 25% compared with Group 1 and Group 2, respectively. In addition, the stress of the infraspinatus muscle and teres minor muscle in Group 2 and Group 3 were higher than that in Group 1 during the abduction angle from 30° to 90°. Deltoid atrophy alters the abduction movement pattern of the glenohumeral joint. During glenohumeral abduction activity, deltoid atrophy significantly increases the stress on the rotator cuff tissue, whereas normal deltoid volume helps maintain the mechanical balance of the rotator cuff tissue.

Modified Vector-Controlled DFIG Wind Energy System Using Robust Model Predictive Rotor Current Control

AbstractAs wind energy (WE) technologies become more prevalent, there are significant concerns about the electrical grid’s stability. Despite their many advantages, a WE system based on a doubly fed induction generator is vulnerable to power grid disruptions. Due to being built on traditional controllers, the generator systems with standard vector control (VC) cannot resist disturbances. This paper seeks to provide a novel VC that is resistant to outer perturbations. For this purpose, a finite state space model predictive control (FS-MPC) is utilized instead of the internal current loop of the standard VC. The objective of the proposed system is to minimize the error between the measured currents and their reference values and, also, reduces the total harmonic distortion (THD) of the current. The cost function can optimize this requirement, which reduces the computation time. The VC-FS-MPC was implemented using the MATLAB, where a 1.5-MW generator operating under different conditions was used. The necessary graphical and numerical results were extracted to show the efficiency, effectiveness, and ability of the VC-FS-MPC to improve the characteristics of the studied energy system. The results show the flexibility and distinctive performance of the VC-FS-MPC in the various tests used, as the THD of stator current was reduced in the second test compared to the first test by an estimated percentage of 61.79%. Moreover, the THD of rotor current was reduced compared to the first test by an estimated percentage of 23.56%. These ratios confirm the effectiveness of the VC-FS-MPC in improving the characteristics of the proposed system.

ECSW hyperreduction of hyper-viscoelastic components via co-simulation with Abaqus

Rubber components are widely spread in engineering due to their mechanical properties such as high strength, elongation, and dissipation characteristics. Modeling rubber behavior poses challenges because of its complex visco-elastic properties and various nonlinear effects. As high fidelity simulations become increasingly challenging, reduction techniques such as subspace projection and hyper-reduction have emerged, which seek to achieve efficient use of complex models while reducing computational demands.This article presents a Python-Abaqus co-simulation framework to perform the Energy Conserving Sampling and Weighting (ECSW) hyperreduction on nonlinear finite element hyper-viscoelastic models. A novel approach based on incremental elementary work is formulated to optimize the element selection in ECSW in the attempt of exploiting the rate dependent material characteristics. The successful implementation of the co-simulation framework underscores the beneficial use of commercial code capabilities in the development of nonlinear reduction algorithms. A numerical cantilever beam subjected to dynamic loading is employed to explore the potential of the newly proposed ECSW variant.

Seismic Response and Mitigation Analysis of a Subway Station in the Site with Weak Interlayers

Challenges related to seismic performance and seismic mitigation are more pronounced in the presence of weak interlayers compared to typical layered soil conditions. This study focuses on a double-layer double-span rectangular frame subway station structure. A coupled static–dynamic finite element analysis model of the soil-structure system is established by using the finite element software ABAQUS/CAE V 6.14. The research investigates the influence of factors such as interlayer thickness, location, and strength on the seismic response of subway station structures. Furthermore, in order to evaluate the effectiveness of FPB in mitigating seismic effects in the weak interlayer ground, two different schemes are proposed in this paper. One is the structure without FPB and the other is the structure with FPB on the top of the central column. The findings reveal that weak interlayers exert a significant influence on the seismic response of subway station structures, especially when these lower-strength weak interlayers are located within the central portion of the subway station structure and exhibit considerable thickness. The FPB on the top of the central column can reduce the overall lateral stiffness of the subway station structure. This, in turn, results in a slight increase in the deformation of sidewall and inter-story displacement angles, accompanied by a marginal exacerbation of sidewall damage. However, the implementation of FPB effectively reduces the deformation of the central column and substantially mitigates the extent of damage to the central column.

Investigation on electromagnetic and heat transfer coupling of heating susceptor for selective microwave hybrid soldering: 3D multi-physics simulation and experiment

The utilization of microwave hybrid heating as an emerging technique in the field of low-temperature joining presents a notable benefit of delivering both selective and rapid heating, a feature that is not commonly observed in traditional soldering methods. However, due to the complex multi-physical coupling problem, the factors and mechanisms affecting the heating effect of the susceptors have not been clearly explained. To examine the effect of susceptor shape, size, and process parameters on heating efficiency, a numerical model of electromagnetic and thermal coupling was created to analyze silicon carbide susceptor heating under microwave action. The response surface method examined how microwave frequency, power, and exposure time affect susceptor heating efficiency. The model’s three process parameters are used to selectively heat Cu/SAC305/Cu joints, and the connection mechanism is studied. The results reveal that cylindrical susceptors heat more efficiently and uniformly than cubic ones. The heating efficiency is the highest when the height of the susceptor is 30 mm. Moreover, the heating effect is optimum at 2.45 GHz. Microwave power and exposure period positively linked with susceptor heating efficiency. The finite element simulation model shows that energy consumption at 2.45 GHz\\2 kW210 s is 78.38 % of that at 2.45 GHZ\\1 kW370 s, and the maximum temperature difference is 73.44 % of that at 2.45 GHz\\3k W\\90 s. MHS experiments show that as exposure duration increases, Cu6Sn5 grew and the growth orientation becomes consistent and perpendicular to the {0 0 0 1} family of crystal planes. Under process settings of 2.45 GHz \\ 2 kW \\ 210 s, the joint can achieve 16.55 MPa shear tensile strength. The results can serve as references for the study on selective microwave hybrid soldering and provide a new idea for selective and efficient soldering.