Electromechanical Research Articles

An integrated gear tooth crack analysis of coupled electromechanical model: A complexity-based approach

This paper presents a novel approach by conducting a complexity-based study of an electromechanical (EM) gearbox system with tooth root cracks, utilizing an analytical model and motor current signals for the first time, in contrast to existing studies that primarily use experimental vibration data for complexity-based analyses. The coupled EM model is developed using the modified Lagrangian approach and by incorporating improved time-varying mesh stiffness and gear crack models. Refined composite multiscale dispersion entropy (RCMDE) is employed to evaluate system complexity at various crack depths. The analysis focuses on residual current signals and uncovers an inverse correlation between RCMDE values and the severity of cracks. To demonstrate the efficacy of the proposed approach, a comparison study is conducted between RCMDE and multiscale dispersion entropy (MDE) on both residual current and vibration signals. The results show that RCMDE provides superior stability and effectiveness compared to MDE. Additionally, it has been found that residual current signals offer more robust insights into system complexity than residual vibration signals. This study contributes valuable insights into the behavior of gearbox systems experiencing crack-induced faults, especially concerning short-time series data, highlighting the advantages of using motor current signals and RCMDE for complexity-based analyses.

Piezoelectric Transducers: Complete Electromechanical Model with Parameter Extraction.

This paper presents a complete electromechanical (EM) model of piezoelectric transducers (PTs) independent of high or low coupling assumptions, vibration conditions, and geometry. The PT's spring stiffness is modeled as part of the domain coupling transformer, and the piezoelectric EM coupling coefficient is modeled explicitly as a split inductor transformer. This separates the coupling coefficient from the coefficient used for conversion between mechanical and electrical domains, providing a more insightful understanding of the energy transfers occurring within a PT and allowing for analysis not previously possible. This also illustrates the role the PT's spring plays in EM energy conversion. The model is analyzed and discussed from a circuits and energy harvesting perspective. Coupling between domains and how loading affects coupled energy are examined. Moreover, simple methods for experimentally extracting model parameters, including the coupling coefficient, are provided to empower engineers to quickly and easily integrate PTs in SPICE simulations for the rapid and improved development of PT interface circuits. The model and parameter extractions are validated by comparing them to the measured response of a physical cantilever-style PT excited by regular and irregular vibrations. In most cases, less than a 5-10% error between measured and simulated responses is observed.

Enhancement of PZT-based damage detection in real-scale post-tensioned anchorage under ambient conditions

Varying ambient temperature significantly affects electromechanical (EM) impedance responses of PZT sensors, leading to inaccurate damage detection results. In this study, we investigate temperature influences on the PZT's EM impedance response and introduce a filtering method to enhance PZT-based damage assessment of a real-scale post-tensioned anchorage. Firstly, the principles of the PZT-based damage identification technique are outlined. Next, the sensitivity of the PZT's EM impedance under simultaneous damage and temperature effects are extensively analyzed and quantified using finite element modelling. Thirdly, a 10-day long-term impedance monitoring of a real-scale anchorage specimen is conducted under ambient temperature conditions and different strand-looseness scenarios. The issues on damage detection performance of the PZT under varying ambient temperature are discussed. Finally, a temperature filtering technique based on principal component analysis is adopted to enhance the accuracy of strand looseness detection in the test anchorage. The numerical and experimental outcomes show that the impact of ambient temperature can overshadow the effect of strand looseness, leading to false damage diagnosis. By removing the influence of temperature on the EM impedance response, the strand looseness in the test anchorage was successfully diagnosed.

On a Nonlinear Locally Resonant Metamaterial With Resistance-Inductance Shunt

Abstract Numerous recent works have established the potential of various types of metamaterials for simultaneous vibration control and energy harvesting. In this paper, we investigate a weakly nonlinear metamaterial with electromechanical (EM) local resonators coupled to a resistance-inductance shunt circuit, a system with no previous examination in the literature. An analytical solution is developed for the system, using the perturbation method of multiple scales, and validated through direct numerical integration. The resulting linear and nonlinear band structures are used for parametric analysis of the system, focusing on the effect of resonator and shunt circuit parameters on band gap formation and vibration attenuation. This band structure analysis informs further study of the system through wavepacket excitation as well as spectro-spatial analysis. The voltage response of the system is studied through spatial profiles and spectrograms to observe the effects of shunt inductance, nonlinearity, and their interactions. Results describe the impact of adding a shunted inductor, including significant changes to the band structure; multiple methods of tuning band gaps and pass bands of the system; and changes to wave propagation and voltage response. The results demonstrate the flexibility of the proposed metamaterial and its potential for both vibration control and energy harvesting, specifically compared to a previously studied system with resistance-only shunt.

Comparison of performance and tribological properties of electromechanical brake with magnetorheological fluid and magnetic powder

Brakes, which are the safety component of any automobile used to control the motion of the vehicle as per the driver's choice. In conventional brakes, friction lining materials are used, which affect the health of human beings and pollute the environment. Hence, there is a need to look for new types of brake systems. In the present work, a new type of electromechanical (EM) drum brake is designed that does not use friction lining materials for brake application. It can use magnetorheological (MR) fluid as well as magnetic powder (MP) for brake application. The presented brake has been designed to operate in hybrid mode that is, shear plus compression mode. When MR fluid is used, these brakes face the problem of the leakage of MR fluid which motivates to use of MP. In addition to the design of the new brake, the performance of the new brake has been tested with MR fluid and MP separately on a full-scale brake inertia dynamometer. The performance test results have been compared for both MR fluid and MP and compared with conventional friction brakes. 14.56% and 11.38% more braking torque have been observed for MP compared to that of MR fluid in shear and hybrid mode respectively. In addition to the performance study, the effect of MR fluid and MP on brake shoe surface properties has been studied.

MEMS strapdown inertial attitude measurement system using rotational modulation technology.

Attitude determination involves the integration of methodologies and systems for estimating the time varying attitude of moving objects. Strapdown Inertial Attitude Measurement System (SIAMS) is among the most widely used navigation systems. The development of cost effective Micro Electro Mechanic System (MEMS) based inertial sensors has made attitude measurement system more affordable. However, MEMS sensors suffer from various errors that have to be calibrated and compensated to get acceptable attitude results. Given the auto-compensation of inertial sensor bias in rotation error modulation, the objective of this paper is to develop a MEMS-based rotary SIAMS, in which the significant sensor bias is automatically compensated by rotating the IMU, to offer comparable performance with respect to a tactical-grade Inertial Measurement Unit (IMU). With the analysis of the relationship between the MEMS error and misalignment, a MEMS calibration model is derived, and a combined calibration method of multi position rotation is applied to estimate the deterministic sensor errors such as bias, scale factor, and misalignment. Simulation and experiment results indicate that the proposed method can further modulate and compensate the MEMS errors, thereby improving the MEMS attitude accuracy.

Determination of Gait Events and Temporal Gait Parameters for Persons with a Knee-Ankle-Foot Orthosis.

Gait event detection is essential for controlling an orthosis and assessing the patient's gait. In this study, patients wearing an electromechanical (EM) knee-ankle-foot orthosis (KAFO) with a single IMU embedded in the thigh were subjected to gait event detection. The algorithm detected four essential gait events (initial contact (IC), toe off (TO), opposite initial contact (OIC), and opposite toe off (OTO)) and determined important temporal gait parameters such as stance/swing time, symmetry, and single/double limb support. These gait events were evaluated through gait experiments using four force plates on healthy adults and a hemiplegic patient who wore a one-way clutch KAFO and a pneumatic cylinder KAFO. Results showed that the smallest error in gait event detection was found at IC, and the largest error rate was observed at opposite toe off (OTO) with an error rate of -2.8 ± 1.5% in the patient group. Errors in OTO detection resulted in the largest error in determining the single limb support of the patient with an error of 5.0 ± 1.5%. The present study would be beneficial for the real-time continuous monitoring of gait events and temporal gait parameters for persons with an EM KAFO.

Bulging of dielectric elastomer tubes considering residual stress and viscoelasticity

This paper investigates the impacts of residual stress and viscoelasticity on the bifurcation and post-bifurcation behaviors of dielectric elastomer tube actuator (DETA) with finite thickness. A theoretical model with residual stress is developed to analyze the electromechanical (EM) behavior of a DETA under a combined effect of voltage, internal pressure, and axial force loadings. A mathematical derivation of the bifurcation condition for the DETA under EM coupling loadings is presented, and a coexistence phase transition condition for steady bugle propagation is established. The effects of voltage, axial force, and residual stress on the bifurcation and coexistence phase transition conditions are studied. To validate the theoretical predictions, finite element (FE) simulations are performed on a closed-ended DETA subjected to the EM loadings. The results reveal a competitive relationship between the localized bugling and electric breakdown (EB). The large residual stress can inhibit the localized bugling and enhance the stability of the tube. Additionally, we explore the bifurcation behavior of the viscoelastic DETA, revealing that the viscoelastic effect significantly influences the critical pressure of bifurcation and the loading/unloading paths. It is observed that snap-back instability can occur during the unloading process under high loading rates or voltages. This work provides valuable insights into the finite deformation and bifurcation behaviors of the DETA under complex EM coupling loadings.

Low-voltage dielectric elastomer actuators by electro-mechanical resonance syntonization

Generally, a serious practical limitation of dielectric elastomer (DE)-based capacitors is the need for high voltage supply (in the order of 1 kV) to activate them. High voltages require a power level that is currently challenging due to the limit in the operating range of existing function generators. These high voltages are also dangerous for humans, thereby overshadowing many applications of dielectric elastomers. The purpose of this work is to develop a new simple actuation technique to introduce low-voltage driven DE-based capacitors, in which the electrical resonant frequency is syntonized to the mechanical natural frequency by tuning the circuit inductance. This results in extensive voltage amplification across the DE capacitor. In turn, this leads the DE membrane to oscillate with a remarkable large motion using a small voltage which is of one-tenth the magnitude of the input voltage required to drive such systems in the absence of electro-mechanical (EM) resonance syntonization. The efficiency of the proposed approach is demonstrated in the context of nonlinear vibration analysis. The results show that the voltage amplitude across the DE capacitor is amplified substantially while the electrical mode is syntonized with the mechanical one, and as a result, the DE motion’s amplitude is at least two hundred times greater than that of the unmatched system. Furthermore, for unbiased AC voltages with large amplitudes, the electro-mechanical modal interaction causes the system to exhibit the formation of frequency combs in the frequency spectrum of the system’s response. The implementation of this method using a simple electrical circuit just requires adequate matching between the electrical and the mechanical natural frequencies that depends on the inductance value. Our proposal effectively eliminates the need for a high source voltage generator which has been the main limitation in designing DE-based capacitors.

Influence of annealing temperature on ferroelectric and electromechanical responses of P(VDF-TrFE-CFE-FA) tetrapolymer

We study the influences of the annealing temperatures on the ferroelectric and electromechanical (EM) responses of the relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene- fluorinated alkyne) (PVDF-TrFE-CFE-FA) tetrapolymer. The results show that only within a narrow annealing temperature window (<10 °C) around 120 °C, the tetrapolymer exhibits a pure relaxor phase and displays the highest EM response. Films annealed outside of this narrow temperature window contain a small amount of local polar-phase mixed with the relaxor phase. These results reveal that the tetrapolymer composition in the study is near a critical transition region between polar (ferroelectric) and non-polar (relaxor) chain condensed state which has vanishingly small energy barriers between different chain condensed state, thus a small electric field generates a large EM response. The films annealed outside of the narrow temperature window have a broad energy landscape that includes both non-polar and polar chain condensed state. Hence, small changes in annealing temperature result in different ferroelectric and electromechanical responses.

Mechano-electrical interactions and heterogeneities in wild-type and drug-induced long QT syndrome rabbits.

Electromechanical reciprocity - comprising electro-mechanical (EMC) and mechano-electric coupling (MEC) - provides cardiac adaptation to changing physiological demands. Understanding electromechanical reciprocity and its impact on function and heterogeneity in pathological conditions - such as (drug-induced) acquired long QT syndrome (aLQTS) - might lead to novel insights in arrhythmogenesis. Our aim is to investigate how electrical changes impact on mechanical function (EMC) and vice versa (MEC) under physiological conditions and in aLQTS. To measure regional differences in EMC and MEC in vivo, we used tissue phase mapping cardiac MRI and a 24-lead ECG vest in healthy (control) and IKr-blocker E-4031-induced aLQTS rabbit hearts. MEC was studied in vivo by acutely increasing cardiac preload, and ex vivo by using voltage optical mapping (OM) in beating hearts at different preloads. In aLQTS, electrical repolarization (heart rate corrected RT-interval, RTn370) was prolonged compared to control (P<0.0001) with increased spatial and temporal RT heterogeneity (P<0.01). Changing electrical function (in aLQTS) resulted in significantly reduced diastolic mechanical function and prolonged contraction duration (EMC), causing increased apico-basal mechanical heterogeneity. Increased preload acutely prolonged RTn370 in both control and aLQTS hearts (MEC). This effect was more pronounced in aLQTS (P<0.0001). Additionally, regional RT-dispersion increased in aLQTS. Motion-correction allowed us to determine APD-prolongation in beating aLQTS hearts, but limited motion correction accuracy upon preload-changes prevented a clear analysis of MEC ex vivo. Mechano-induced RT-prolongation and increased heterogeneity were more pronounced in aLQTS than in healthy hearts. Acute MEC effects may play an additional role in LQT-related arrhythmogenesis, warranting further mechanistic investigations. KEY POINTS: Electromechanical reciprocity comprising excitation-contraction coupling (EMC) and mechano-electric feedback loops (MEC) is essential for physiological cardiac function. Alterations in electrical and/or mechanical heterogeneity are known to have potentially pro-arrhythmic effects. In this study, we aimed to investigate how electrical changes impact on the mechanical function (EMC) and vice versa (MEC) both under physiological conditions (control) and in acquired long QT syndrome (aLQTS). We show that changing the electrical function (in aLQTS) results in significantly altered mechanical heterogeneity via EMC and, vice versa, that increasing the preload acutely prolongs repolarization duration and increases electrical heterogeneity, particularly in aLQTS as compared to control. Our results substantiate the hypothesis that LQTS is an ‛electro-mechanical', rather than a 'purely electrical', disease and suggest that acute MEC effects may play an additional role in LQT-related arrhythmogenesis.

Mutations affecting electro-mechanical coupling in KCNQ channels alter kinetics and voltage dependence of activation.

The KCNQ voltage-gated potassium channel family serves multiple physiological functions, from regulating heartbeat (by KCNQ1) to controlling neuronal excitability (by KCNQ2-5). In KCNQ1 channels, two steps of voltage sensor activation lead to two functionally distinct open states, the intermediate-open (IO) and activated-open (AO), which define the gating, pharmacology, and physiology of KCNQ1. However, whether all KCNQ channels share the same mechanism is unclear. Here, we provide functional evidence that KCNQ2/3 only conducts at the AO state, but the electro-mechanical (E-M) coupling mechanism is conserved between KCNQ1 and KCNQ2/3. We demonstrate that this conserved E-M coupling can be compromised by select epilepsy-linked mutations in KCNQ2/3 and also can be effectively targeted by the antiepileptic prototype drug retigabine, suggesting E-M coupling as a therapeutic target for epilepsy treatment. Interestingly, KCNQ1 and KCNQ2/3 exhibit distinct kinetics and voltage dependence of activation for the AO state. While these differences may have important implications for the primary physiological roles of KCNQ2/3 (modulation of neuronal excitability) versus KCNQ1 (repolarization of cardiac action potential), it remains unclear where they originate from. Here, we find that analogous mutations in the distal S6 of KCNQ1 and KCNQ2 both affect the AO state E-M coupling and lead to delays in current activation kinetics and right shifts in voltage dependence of activation. KCNQ2 mutations near this location are also found to be associated with epileptic encephalopathy. These results further support a common regulatory mechanism for KCNQ currents via E-M coupling and indicate the physiological relevance of altering AO state activation properties in KCNQ channels.

Review on Investigation of Shear Lag Effect for EMI and PZT Technique by Using Analytical Approach

Abstract: The advent of smart materials such as piezoelectric (PZT) sensors has helped to revolutionize the field of structural health monitoring (SHM) based on NDT techniques. Currently, the effect of the thickness of the adhesive layer (Shear lag Effect) is considered insignificant in the practical application of EMI technology. Although a relatively new NDT method known as the electromechanical (EMI) technique has been studied for more than two decades, there are still a number of issues that must be resolved before it can be applied to real structures. A technique with significant potential to advance one of the most efficient SHM systems involves the use of a single PZT to excite and sense the host structure. This article reviews the research related to EMI technology over the past decade to understand its trend. It also compares new concepts and ideas proposed by other authors and ends the work with a discussion of possible directions for future work.

Optimal design of a single-point electromechanical cable subsurface mooring

ABSTRACT Single-point electromechanical (EM) cable subsurface mooring (EMC-SSM) is an innovative subsea structure used to measure several ocean parameters throughout a water column in real time. However, designing an EMC-SSM that can adapt to rough sea conditions is challenging owing to the relative fragility of EM cables. In this study, an optimisation design method based on parameter sensitivity analysis was proposed to improve the responses of EMC-SSM. The unreasonable design and optimisation value were determined by evaluating the slopes of the sensitivity curves of four response parameters: the minimum and maximum tensions, maximum declination angle, and maximum curvature to the net buoyancy of the main float and big sensor package (BSP); drag; added mass coefficient of the BSP; and net weight and hydrodynamic coefficient of small sensor packages. We found that the proposed optimisation design method is effective in identifying and optimising the unreasonable configurations of mooring similar to the EMC-SSM.

Giant Electrostriction Enabled by Defect-Induced Critical Phenomena in Relaxor Ferroelectric Polymers

Polymers that generate large shape changes under electric stimulation are of great interest for many applications. Recently, it was shown that converting a small amount of chlorofluoroethylene (CFE) in relaxor ferroelectric poly(vinylidene fluoride–trifluoroethylene–CFE) (PVDF-TrFE-CFE) terpolymer into fluorinated alkyne (FA) creates P(VDF-TrFE-CFE-FA) tetrapolymers with giant electromechanical (EM) response at ultralow electric fields (<50 MV/m). We investigate the microscopic origin of this effect and show that converting the bulky CFE into small-size FA defects dramatically weakens the relaxor behavior. Importantly, P(VDF-TrFE-CFE-FA) tetrapolymers with near 2 mol % FA exhibit a diffused critical endpoint transition region at which the energy barriers for switching from nonpolar to polar molecular conformations become small. Consequently, a small change of the electric field induces a large electroactuation, which can enable novel applications. This work opens up a totally new approach to designing ferroelectric polymers that generate large responses at ultralow electric fields.

Identifying novel phenotypes of elevated left ventricular end diastolic pressure using hierarchical clustering of features derived from electromechanical waveform data.

IntroductionElevated left ventricular end diastolic pressure (LVEDP) is a consequence of compromised left ventricular compliance and an important measure of myocardial dysfunction. An algorithm was developed to predict elevated LVEDP utilizing electro-mechanical (EM) waveform features. We examined the hierarchical clustering of selected features developed from these EM waveforms in order to identify important patient subgroups and assess their possible prognostic significance.Materials and methodsPatients presenting with cardiovascular symptoms (N = 396) underwent EM data collection and direct LVEDP measurement by left heart catheterization. LVEDP was classified as non-elevated ( ≤ 12 mmHg) or elevated (≥25 mmHg). The 30 most contributive features to the algorithm output were extracted from EM data and input to an unsupervised hierarchical clustering algorithm. The resultant dendrogram was divided into five clusters, and patient metadata overlaid.ResultsThe cluster with highest LVEDP (cluster 1) was most dissimilar from the lowest LVEDP cluster (cluster 5) in both clustering and with respect to clinical characteristics. In contrast to the cluster demonstrating the highest percentage of elevated LVEDP patients, the lowest was predominantly non-elevated LVEDP, younger, lower BMI, and males with a higher rate of significant coronary artery disease (CAD). The next adjacent cluster (cluster 2) to that of the highest LVEDP (cluster 1) had the second lowest LVEDP of all clusters. Cluster 2 differed from Cluster 1 primarily based on features extracted from the electrical data, and those that quantified predictability and variability of the signal. There was a low predictability and high variability in the highest LVEDP cluster 1, and the opposite in adjacent cluster 2.ConclusionThis analysis identified subgroups of patients with varying degrees of LVEDP elevation based on waveform features. An approach to stratify movement between clusters and possible progression of myocardial dysfunction may include changes in features that differentiate clusters; specifically, reductions in electrical signal predictability and increases in variability. Identification of phenotypes of myocardial dysfunction evidenced by elevated LVEDP and knowledge of factors promoting transition to clusters with higher levels of left ventricular filling pressures could permit early risk stratification and improve patient selection for novel therapeutic interventions.

Environmental management begins in the family

The Institito Tecnológico de Toluca, is a higher level educational institution, which belongs to the National Technological System of Mexico, which has 9 degrees, in the engineering area, citing: Industrial (IE), Chemical (CI), Logistics (LE), Electromechanical (EE), bussines management’s (BME), Electronics (EE), Mechatronics (MI), Computational Systems (CSI) and Information and Communication Technologies (ICTE,) and 3 postgraduate degrees: Master of Engineering Sciences (MES), Master of Sciences in Environmental Engineering (MSEE) and Doctorate in Environmental Sciences (DES), with a population of 5,408 students. Being a proudly public institution and classified as the best, by its employers at the state level, within which there is a Coordination called Institutional Environmental Program (IEP), which manages various strategies for the care, protection, remediation of the environment. But, in Mexico, since March 2019, educational institutions have been closed due to the context of the pandemic caused by covid-19. Academic activity being carried out, since then to date, via virtual. Faced with such a complicated, difficult and uncertain scenario. An environmental management model was developed, so that students from their homes develop prevention programs, protection and care of the ecosystem, developing sustainable strategies. Starting from the premise: If there is a polluting society it is because there are families that pollute, the family is the mirror of what happens in society. Within this program, an amalgam of strategies was considered, starting with motivation, awareness, reflection, knowledge and self-management to detonate a new environmental culture, starting from their homes and extending it to their families and neighbors. To carry out a multiplier effect, in geometric progression, having an excellent response from the students of the Instituto Tecnológico de Toluca (ITT). Among the various strategies within an application scenario, the following are cited: Responsible-reflective consumption, no generation of unnecessary waste (organic food waste reduction), no use of Unicel (expanded polystyrene), use of single-use containers (elimination of PET), no oil disposal used from the kitchen (application of a collection program), induction to the modification of nutritional intake by substituting beef for chicken, fish and vegetables, separation and classification of garbage, application of the use of compost for the organic food remains, water saving and leak elimination program, collection of cigarette butts thrown in public roads and gardens. Turning off lights in homes when they are not necessary (energy saving), only use of a motor vehicle in very necessary cases (mitigation of the effects of climate change). With these actions that began in this year 2021, we consider that we are working towards the reduction of negative environmental impacts, detonating a new culture and environmental awareness, among higher-level students (undergraduate), having a participation and involvement of 1,700 families and a number that continues to grow. Additionally, we are contributing to the 2030 Agenda, of the Sustainable Development Goals (SDG), especially regarding the objectives: 4.- Quality education, 11.- Sustainable cities and communities and 13.- Actions for the climate.Keyword: family, environmental culture, awareness, virtual scene, pollutants

Electro-mechanical coupling of KCNQ channels is a target of epilepsy-associated mutations and retigabine.

KCNQ2 and KCNQ3 form the M-channels that are important in regulating neuronal excitability. Inherited mutations that alter voltage-dependent gating of M-channels are associated with neonatal epilepsy. In the homolog KCNQ1 channel, two steps of voltage sensor activation lead to two functionally distinct open states, the intermediate-open (IO) and activated-open (AO), which define the gating, physiological, and pharmacological properties of KCNQ1. However, whether the M-channel shares the same mechanism is unclear. Here, we show that KCNQ2 and KCNQ3 feature only a single conductive AO state but with a conserved mechanism for the electro-mechanical (E-M) coupling between voltage sensor activation and pore opening. We identified some epilepsy-linked mutations in KCNQ2 and KCNQ3 that disrupt E-M coupling. The antiepileptic drug retigabine rescued KCNQ3 currents that were abolished by a mutation disrupting E-M coupling, suggesting that modulating the E-M coupling in KCNQ channels presents a potential strategy for antiepileptic therapy.

A coupling strategy for a first 3D-1D model of the cardiovascular system to study the effects of pulse wave propagation on cardiac function

A key factor governing the mechanical performance of the heart is the bidirectional coupling with the vascular system, where alterations in vascular properties modulate the pulsatile load imposed on the heart. Current models of cardiac electromechanics (EM) use simplified 0D representations of the vascular system when coupling to anatomically accurate 3D EM models is considered. However, these ignore important effects related to pulse wave transmission. Accounting for these effects requires 1D models, but a 3D-1D coupling remains challenging. In this work, we propose a novel, stable strategy to couple a 3D cardiac EM model to a 1D model of blood flow in the largest systemic arteries. For the first time, a personalised coupled 3D-1D model of left ventricle and arterial system is built and used in numerical benchmarks to demonstrate robustness and accuracy of our scheme over a range of time steps. Validation of the coupled model is performed by investigating the coupled system’s physiological response to variations in the arterial system affecting pulse wave propagation, comprising aortic stiffening, aortic stenosis or bifurcations causing wave reflections. Our first 3D-1D coupled model is shown to be efficient and robust, with negligible additional computational costs compared to 3D-0D models. We further demonstrate that the calibrated 3D-1D model produces simulated data that match with clinical data under baseline conditions, and that known physiological responses to alterations in vascular resistance and stiffness are correctly replicated. Thus, using our coupled 3D-1D model will be beneficial in modelling studies investigating wave propagation phenomena.

Relaxor ferroelectric polymer exhibits ultrahigh electromechanical coupling at low electric field.

Electromechanical (EM) coupling-the conversion of energy between electric and mechanical forms-in ferroelectrics has been used for a broad range of applications. Ferroelectric polymers have weak EM coupling that severely limits their usefulness for applications. We introduced a small amount of fluorinated alkyne (FA) monomers (<2 mol %) in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) terpolymer that markedly enhances the polarization change with strong EM coupling while suppressing other polarization changes that do not contribute to it. Under a low-dc bias field of 40 megavolts per meter, the relaxor tetrapolymer has an EM coupling factor (k33) of 88% and a piezoelectric coefficient (d33) >1000 picometers per volt. These values make this solution-processed polymer competitive with ceramic oxide piezoelectrics, with the potential for use in distinct applications.