COMSOL Simulation Research Articles

Extraordinary viscous absortion by phononic supercrystals

An effective medium theory has been developed to study the viscous absorption of a doubly periodic phononic crystal, here denominated as supercrystal (SC). In practice, the SC is made of hard cylindrical scatterers embedded in a viscous fluid and consists of a combination of two phononic crystals with lattice periods, $a_1$ and $a_2$. The decay coefficient of sound due to viscosity is calculated analytically at low frequencies when both lattices homogenize. The viscous absorbance of finite SC slabs calculated with the analytical model is supported by exact calculations based on the finite element method (COMSOL simulations). In addition, results for the complex sound speed show a good agreement with the experimentally extracted sound speed.

Enhancing electromechanical conversion and motion-monitoring application of pore-oriented cellulose nanocrystal/agarose aerogel modified with flexible heterojunction structures

Oriented-porous cellulose nanocrystal (CNC)-based aerogels excel in directional energy conversion but face reduced toughness, and triboelectric performance bottlenecks owing to the absence of electron acceptors. In this work, we crosslinked quaternary ammonium CNC with another flexible carboxymethyl agarose (AG-), via borate dynamic bonds, exploiting the electron-accepting traits of boron and electrophilic modifications to boost the mechanical and triboelectric performance of aerogels. These results demonstrate that the compressive resilience and modulus of CNC/AG aerogel are improved up to 70.79 % (after 10-cycle 20 % strain) and 18.77 kPa attributing to the borate cross-linking network and oriented structure. Furthermore, the electromechanical response sensitivity and output energy density of the CNC/AG aerogel increased by 6.06 times (to 7.51 V/Hz) and 28.3 times (to 1.87 W/m2), respectively. The structure characteristics of the CNC/AG aerogel reveal that the oriented structure and heterojunction of the CNC/AG aerogel with electron transfer pathways reduce dielectric losses. The COMSOL simulation also show that oriented pores increase the polarization and charge density of the CNC/AG aerogel, thereby improving the electromechanical conversion efficiency. This work offers a synergistic approach for toughening aerogels and generating heterojunctions via flexible modification, presenting significant potential for smart devices with energy-collection ability.

Rational synthesis of vertical graphene supported TiN@N-Li4Ti5O12 as advanced high-rate electrodes for lithium-ion batteries

The Li4Ti5O12 (LTO) is demonstrated to be one of the most promising anode materials for lithium-ion batteries (LIBs) to provide safe and high-power density cells but suffer from poor electrical conductivity. In this study, we present a TiN-decorated N-LTO on a vertical graphene (VG) array (TiN@N-LTO) as a potential anode material for lithium-ion batteries (LIBs). The use of atomic layer deposition (ALD) enables the formation of a thin layer of LTO on VG, with precise control over the thickness. The VG serves as highly conductive channels, facilitating the transfer of electrons. Moreover, the introduction of nitrogen heteroatoms into the LTO under an active N2 plasma atmosphere has been shown to enhance its intrinsic conductivity, which is achieved by reducing the bandgap and expanding the diffusion pathways of ions. Concurrently, a small number of metallic TiN are formed and deposited on the surface of N-LTO, thereby further improving its conductivity. COMSOL simulations and DFT calculations demonstrate that the introduced TiN acts as a "conductive bridge", improving the charge distribution of LTO electrodes and enhancing the Li+ transport rate. The TiN@N-LTO exhibits a high rate performance (169.51, 131.61 and 101.08 mAh/g at 0.2, 2 and 20 C, respectively) and remarkable cycling stability (a capacity retention of 99.6% after 5000 cycles at 10 C).

Two-dimensional distribution experiment of ‘lattice diffraction’ using ultrasound in an educational laboratory

Abstract A device that can study the two-dimensional distribution of ultrasonic diffraction on lattice structures was developed for educational laboratories, enabling students to design the size, shape and dimension of diffraction obstacles independently. In this experiment, metal balls were used to simulate atomic lattice structures, and the two-dimensional diffraction distribution data of simple cubic, body-centered cubic, and hexagonal close-packed structure were collected. The results were compared with the sound field simulation of COMSOL, and a good consistency was found. By observing the diffraction results of complex structures, students can gain a better understanding of the concept of diffraction.

Morphology-dependent magnetic hyperthermia characteristics of Fe3O4 nanoparticles

Magnetic hyperthermia therapy (MHT) represents an innovative approach to cancer treatment, harnessing the therapeutic capabilities of magnetic nanoparticles. Fe3O4 nanoparticles are often considered ideal candidates for MHT because of their biocompatibility. However, the clinical application of Fe3O4 nanoparticles is hindered by their low heating efficiency and concerns regarding potential toxicity linked to the high concentrations required to achieve therapeutic effects. In this study, two unique structures, hollow spherical and nanoflower Fe3O4, were successfully synthesized to enhance their magnetothermal conversion efficiency. The results indicate that Fe3O4 nanoflowers exhibit an intrinsic loss power (ILP) value of 6.52, which is 1.83 times greater than the ILP of hollow spherical Fe3O4 (3.55), indicating its enhanced potential for MHT applications. The COMSOL simulation demonstrated that higher magnetic field frequencies and intensities elevate tissue temperature and damage in tumor cells, particularly at 100 kHz and 400 kHz, with tumor tissue damage scores rising to 0.28 and 0.93, respectively. Shorter heating durations, such as 6 min, minimize harm to healthy tissue and are ideal for treatments requiring multiple sessions. After 12 min, tumor scores rose to 0.85, while normal tissue scores were 0.34, suggesting that longer durations improve therapeutic effects on tumors but also heighten the risk to healthy cells. This research provides a scientific foundation for selecting materials in the context of MHT for cancer treatment, potentially paving the way for more effective and safer therapeutic strategies.

Piezoelectric Energy Harvesting in Poly(vinylidene Fluoride‐co‐hexafluoropropylene)/Barium Titanate Nanofibers and Ultrasonic Assisted Piezocatalytic Degradation of Ciprofloxacin

AbstractAn innovative approach has been adopted through the synthesis of a cost‐effective ferroelectric host polymer, which was integrated with Barium Titanate (BaTiO3) to develop an efficient electrospun Polyvinylidene Fluoride‐Hexafluoropropylene/BaTiO3 (PVdF‐HFP/BaTiO3) nanocomposite (PBT), designated for energy harvesting and piezocatalytic applications. FT‐IR affirmed the existence of the crystalline β‐phase within the nanofibers. SEM images showed that nanofiber diameter decreases as applied voltage is increased in electrospinning. The BaTiO3 nanoparticles were scattered evenly in PBT, but at lower voltages, they aggregate. PBT showed enhanced piezoelectric performance under higher voltage conditions, registering a maximum piezoelectric output of ~7.7 V and an output current of 0.77 μA. Moreover, the composite exhibited a power density of 14.15 mW/m2 at a load resistance of 20 MΩ. Fabricated piezoelectric nanogenerator (PENG) demonstrated practical utility in flexible electronics, notably in charging capacitors of 0.47 μF and 1 μF. Additionally, the piezocatalytic degradation of the antibiotic ciprofloxacin (CIP) was effectively achieved using the electrospun nanofibers, with an impressive degradation rate of up to 99.6 % within 30 minutes under acidic conditions, and the material displayed notable reusability, maintaining up to 95.5 % efficiency after five cycles. DFT calculations and COMSOL simulations alongside a comparative examination of the electronic properties of PBT.

Bandgap Control of Local Resonance Sandwich Meta-Plate with Cantilevered Archimedean Spiral Beam-Mass Resonators

In order to attenuate the various low-frequency vibrations that may cause structural fatigue and damage, impact human health and affect work efficiency, this paper presents a novel local resonance metamaterial sandwich meta-plate structure containing a cantilever spiral beam-mass resonator, and investigates vibration reduction effects of it within the obtained low-frequency bandgap range. For this purpose, a theoretical model of the low-frequency resonator being composed by a cantilever Archimedean spiral beam and cylindrical mass is established. The natural frequency of it is calculated by solving the Euler-Lagrange equation of the resonator. The accuracy and reliability of the theoretical model are verified through COMSOL simulation. The stress distribution of five types of cantilever spiral beam mass resonators (i.e. Archimedes spiral, triangle spiral, square spiral, pentagon spiral and hexagon spiral) and different cross-sectional shapes (rectangular, square, circular, diamond and triangular) are analyzed. Then, a unit cell model of a sandwich meta-plate with a cantilever Archimedean spiral beam resonator is selected. Hamilton’s principle is used to deduce the bandgap range under infinite periods, and the theoretical solutions are also verified. The parameter optimization of the substrate plate and resonator are also studied. Moreover, the effects of the various structural variables on the bandgap range are systematically explored. Finally, the dynamic responses of the sandwich meta-plate composed of [Formula: see text]-unit cells under different excitation frequencies, boundary conditions and structural damping are analyzed.

Fluorinated solid electrolyte interphase enables interfacial stability for sulfide-based solid-state sodium metal batteries

Sulfide solid electrolytes (SSEs) with high ionic conductivity and good mechanical flexibility are considered ideal for all-solid-state sodium metal batteries (ASSSMBs). Nevertheless, the detrimental interfacial issue between SSEs and Na metal presents a significant challenge for sulfide-based ASSSMBs. Herein, we demonstrate a facile and cost-effective method for constructing a controllable NaF-rich artificial interphase on the surface of sodium metal anodes by incorporating perfluoropolyether (PFPE). A stratified solid electrolyte interphase (SEI) composed a nanocrystalline NaF inner phase and organic outer shell, efficaciously seals the Na surface. The interfacial interactions between SSEs and Na metal is explored using Comsol and ab initio molecular dynamics simulations, revealing that the presence of a NaF-rich artificial interphase hinders the growth of sodium dendrites and mitigates the decomposition of the sulfide electrolytes. As a result, the symmetric cell exhibits stable Na plating/stripping cycling for 800 h at 0.1 mA cm−2. Overall, our PFPE-modified sodium metal anodes offer a promising avenue for the widespread application of high-performance ASSSMBs.

Roller-like Spore Carbon Sphere-Orientated Graphene Fibers Prepared via Rheological Engineering for Lithium Sulfur Batteries.

Flexible batteries with large energy densities, lightweight nature, and high mechanical strength are considered as an eager goal for portable electronics. Herein, we first propose free-standing graphene fiber electrodes containing roller-like orientated spore carbon spheres via rheological engineering. With the help of the orientated microfluidic cospinning technology and the plasma reduction method, spore carbon spheres are self-assembled and orientedly dispersed into numerous graphene flakes, forming graphene fiber electrodes enriched with internal rolling woven structures, which cannot only enhance the electrical contact between active materials but also effectively improve the mechanical strength and structure stability of graphene fiber electrodes. When the designed graphene fibers are combined with the active sulfur cathode and lithium metal anode, the assembled flexible lithium sulfur batteries possess superior electrochemical performance with high capacity (>1000 mA h g-1) and excellent cycling life as well as good mechanical properties. According to density functional theory and COMSOL simulations, the roller-like spore carbon sphere-orientated graphene fiber hosts provide reinforced trapping-catalytic-conversion behavior to soluble polysulfides and nucleation active sites to lithium metal, thus synergistically suppressing the shuttle effect of polysulfides at the cathode side and lithium dendrite growth at the anode side, thereby boosting the whole electrochemical properties of lithium sulfur batteries.

Simulation-Guided Preparation of Copper Chalcogenide Nanoparticle-Based Transparent Photothermal Coating with Enhanced Deicing Performance.

In this investigation, transparent photothermal coatings utilizing plasmonic copper chalcogenide (Cu2-xS) nanoparticles were designed and fabricated for the deicing of glass surfaces. Cu2-xS nanoparticles, chosen for their high near-infrared (NIR) absorption and efficient photothermal conversion, were analyzed via finite difference time domain (FDTD) simulations to optimize nanoparticle morphology, thus avoiding costly trial-and-error synthesis. FDTD simulations determined that Cu2-xS nanorods (Cu-NRs) with an optimal aspect ratio of 2.2 had superior NIR absorption. Guided by FDTD simulations, the composite coating composed of Cu-NRs in clear acrylic resin paint was brush-coated to glass, achieving 62.4% visual transmittance and over 95% NIR absorbance. Photothermal conversion tests exhibited a significant temperature increase, with the coating reaching 65 °C under NIR irradiation within 6 min. The dynamic deicing process of ice beads on the coating at -20 °C completed within 220s, in contrast to the frozen state on glass coated with clear acrylic resin paint. Furthermore, heat transfer simulations in COMSOL illustrated melting initiation at the ice-coating interface and subsequent progression through the ice layer. This simulation-driven synthesis method and photothermal testing offer a design framework for the fabrication of photothermal deicing coatings with applications for automobiles, buildings, and aircraft in cold environments.

Investigation on electromigration failure behavior of SAC305/SnPb micro-hybrid solder joints for package-on-package techniques: Experiment and simulation

The failure mechanism of electromigration (EM) for electronic packaging technology has garnered interest. Electromigration-caused voids reduce electronic device dependability. Two-step reflow at 250℃ and 210℃ was employed to create SAC305/SnPb micro-hybrid solder connections. Finite element analysis confirmed electromigration failure. After 768 h at 10A, the anode interface IMC thickness increased by 149.8 %, while the cathode IMC increased less. Polarity accelerates anode IMC growth. Electromigration of Cu from cathode to anode causes structural flaws and 44.6 % shear strength loss to 35.1 MPa. Fractures shift from inside the solder joint to the IMC layer becoming brittle. COMSOL simulation demonstrates greatest current density, temperature, and stress at the current inlet and Cu pad-solder joint junction.

Research on the solution of the thermo-hydro-mechanical-chemical coupling model based on the unified finite volume method framework

Heat extraction from hot dry rock (HDR) reservoirs involves complex thermal–hydraulic-mechanical-chemical (THMC) coupling processes, which pose significant challenges for efficient geothermal energy utilization. The current frameworks that combine the finite volume method (FVM) and finite element method (FEM) for THMC modeling based on the embedded discrete fracture model (EDFM) are separate, leading to complex implementations and hindering the development of efficient solutions. To address these issues, we propose an FVM-based THMC coupling model that solves fluid flow, heat transfer, and chemical reactions using the finite volume method (FVM), while mechanical deformation is addressed using the extended finite volume method (XFVM). The reaction module incorporates PHREEQC for multicomponent reactions under high-temperature and high-pressure conditions. The model is validated against experimental data for mineral reactions under high-temperature and high-pressure conditions, as well as XFEM and COMSOL simulations for displacement fields, confirming its accuracy and computational performance. Application results show that the temperature deviation between multicomponent and single-component models can reach up to 14 °C, underscoring the importance of incorporating multicomponent water–rock reactions in THMC coupling. This model accurately captures the spatiotemporal evolution of THMC processes and efficiently predicts long-term heat production in enhanced geothermal systems (EGS) reservoirs. It could significantly advance the ability to achieve more accurate and reliable predictions for the engineering development and efficient utilization of EGS reservoirs.

Boosting Zinc‐Ion Storage Capability in Longitudinally Aligned MXene Arrays with Microchannel Architecture

AbstractFlexible Zn2+ ion hybrid capacitors (ZHCs) will play a crucial role in developing next‐generation wearable products, which demand portability, durability, and environmental adaptability. To further meet these requirements, Ti3C2Tx MXene with exceptional conductivity and robust mechanical properties can be utilized as cathodes, except for challenges such as the dense stacking of Ti3C2Tx nanosheets. In this study, a novel MXene cathode architecture has been developed with the facilitation of an ice template, which creates longitudinally aligned Ti3C2Tx arrays with microchannels. The introduction of hydrochloric acid to the Ti3C2Tx slurry induces a crumpled morphology, increasing active sites and enhancing ion transport with expanded interlayer spacing. Interestingly, experimental results and COMSOL simulations verify that the cathode structure also has effective impacts on the Zn anode with a weakened ion concentration gradient and suppressed dendrite formation. Consequently, the ZHCs exhibit enhanced electrochemical performance with excellent rate performance and long‐term cycling stability (enduring over 50 000 cycles at 5 A g−1) and further deliver a reliable low‐temperature operation by applying an anti‐freezing electrolyte. Moreover, flexible ZHCs assembled with gel electrolytes demonstrate excellent flexibility, improved rate performance, and mechanical stability, making them well‐suited for flexible electronics that power flexible LED panels.

Constructing stress-release layer on Si nanoparticles for high-performance lithium storage

Tailing structures of silicon anode to alleviate the mechanical stress has an important significance in the development of lithium-ion batteries (LIBs). Herein, the stress-released layer of N-doped cubic carbon on the surface of Si nanoparticles (Si@NCC) is explored to stabilize the electrode. Endowed with the unique superiority, the Si@NCC electrode delivers an impressive lithium storage performance with high specific capacity of 630 mAh/g at 0.1 A/g, excellent cycling stability (72.0 % capacity retention after 100 cycles at 0.1 A/g) and good rate capability (375 mAh/g at 2 A/g). It has been demonstrated that the N-doped cubic carbon shell with high conductivity can effectively limit the expansion and agglomeration of Si nanoparticles. Besides, the COMSOL simulations of the stress distributions in materials confirm that the N-doped cubic carbon layer could remarkably decrease the stress originated from the volume expansion of Si nanoparticles during the lithiation. Therefore, this work provides ideas for the mechanical effect of Si-based anodes for lithium storage and sheds lights on the designing advanced materials toward high-performance energy storage devices.

Investigating resonance frequency in advanced composite structures as the main part of bridge construction: a multi-physics simulation approach

This paper investigates the nonlinear vibration characteristics and resonance frequencies of a graphene oxide powders (GOP) reinforced beam structure, which is in contact with fluid, serving as a crucial component in bridge construction. Utilizing a multi-physics simulation approach, this study integrates both mathematical modeling and COMSOL simulations to analyze the behavior of the GOP-reinforced beam. The fluid in the analysis is modeled as incompressible, non-viscous, and irrotational, contributing to the interaction with the beam structure. The isogeometric approach, coupled with the harmonic balance method and the arc-length technique, is employed to solve the complex nonlinear partial differential equations (PDEs). This coupled method ensures the accurate capture of the nonlinear response and resonance frequencies of the beam, which are critical for the safe design and performance of bridge structures. The findings reveal the significant influence of GOP reinforcement on the vibration and stability characteristics of the beam, highlighting its potential to enhance structural performance under dynamic loading conditions. The study also emphasizes the importance of considering fluid-structure interactions in the design process, as the fluid’s presence substantially affects the vibration behavior. This research contributes to the understanding of the dynamic behavior of advanced composite structures in fluid environments, offering valuable insights for the design and analysis of bridge components. The results demonstrate the efficacy of the proposed simulation approach in addressing the complexities of nonlinear vibrations in fluid-structure interaction systems, paving the way for future developments in civil engineering applications.

Experimental studies of H2/Ar plasma in a cylindrical inductive discharge with an expansion region

Abstract The electrical parameters of H2/Ar plasma in a cylindrical inductive discharge with an expansion region are investigated by a Langmuir probe, where Ar fractions range from 0% to 100%. The influence of gas composition and pressure on electron density, the effective electron temperature and the electron energy probability functions (EEPFs) at different spatial positions are present. In driver region, with the introduction of a small amount of Ar at 0.3 Pa, there is a rapid increase in electron density accompanied by a decrease in the effective electron temperature. Additionally, the shape of the EEPF transitions from a three-temperature distribution to a bi-Maxwellian distribution due to an increase in electron–electron collision. However, this phenomenon resulting from the changes in gas composition vanishes at 5 Pa due to the prior depletion of energetic electrons caused by the increase in pressure during hydrogen discharge. The EEPFs for the total energy in expansion region is coincident to these in the driver region at 0.3 Pa, as do the patterns of electron density variation between these two regions for differing Ar fractions. At 5 Pa, as the discharge transitions from H2 to Ar, the EEPFs evolved from a bi-Maxwellian distribution with pronounced low energy electrons to a Maxwellian distribution in expansion region. This evolve may be attributed to a reduction in molecular vibrational excitation reactions of electrons during transport and the transition from localized electron dynamics in hydrogen discharge to non-localized electron dynamics in argon discharge. In order to validate the experimental results, we use the COMSOL simulation software to calculate electrical parameters under the same conditions. The evolution and spatial distribution of the electrical parameters of the simulation results agree well with the trend of the experimental results.

Artificial neural network enabled photovoltaic-thermoelectric generator modelling and analysis

Photovoltaic-Thermoelectric Generator (PV-TEG) system has emerged as a promising approach to significantly enhance the efficiency of conventional PV cells. However, optimizing the performance of these hybrid systems presents a formidable challenge due to their complex structure and multitude of design parameters. This study tackles such challenge by developing a machine learning based Artificial Neural Network (ANN) model which comprises two sub-ANN models that can work independently for PV and TEG modules or in combination through a cyclic approach for the hybrid PV-TEG system. The model demonstrates remarkable versatility, allowing control over various parameters such as PV coating, device geometry, and environmental conditions. Compared to COMSOL simulations, the ANN model achieves over 97.6 % accuracy with a 6000-fold increase in simulation speed, enabling extensive parameter sweeps and insightful system analysis. Within 18 min, the model conducted a real-time simulation using 8712 weather data entries from Singapore in 2022 and predicted that the hybrid PV-TEG system would generate a total power of 265 kWh/m2, 6.4 % more than that of the standalone PV system with an average system temperature reduction of 7 K. The model's rapid processing capabilities and high accuracy are particularly beneficial for large-scale simulations and practical applications in renewable energy technology.

Remediation of seawater polluted by oil spills via integrating porous materials with phase-change materials

The cleanup of viscous oil spills, especially in frigid regions, presents significant challenges due to the low fluidity of the oil. While the integration of absorption materials with photo/electric thermal conversion has shown significant promise, its effectiveness can be greatly influenced by environmental factors. To address these challenges, this study introduces an innovative solution: three-dimensional porous materials (3D-PMs) combined with phase change materials (PCMs). By utilizing energy pre-stored in PCMs through sunlight irradiation or electric heating, heat can be efficiently released when 3D-PMs come into contact with crude oil. A novel superhydrophobic melamine sponge (PPCPP@MS), composed of polypyrrole (PPy) and polyethylene glycol (PEG), has been developed for this purpose. The PPy polymerization layer reliably converts light/electricity into heat, while the PEG‑carbon nanotube (CNT) composite coating layer facilitates heat storage and release. This innovative design significantly enhances safety, energy utilization efficiency, and operational effectiveness. Furthermore, COMSOL simulation was employed to the interfacial heat transfer and phase transformation process of PPCPP@MS during crude oil absorption. Demonstrating stable heat release and oil-adsorbing performance in simulated low-temperature marine environments, PPCPP@MS exhibits great potential for addressing oil spills in extreme climates. The innovative design of PPCPP@MS offers crucial insights for managing viscous oil spills, particularly in frigid regions, providing a promising approach in environmental protection and remediation efforts.

Purification of industrial toluene from technical to reagent grade using Diahope activated carbon in a pilot-scale fixed-bed column

The removing organic impurities from technical-grade toluene (99.1 %) to produce reagent-grade toluene (99.9 %) has been addressed by assessing the mono- and multi-component adsorption of methylbenzothiophene (MBT), ethylcyclopentane (ECP), and xylene (XYL), which represent sulfur, non-aromatic, and aromatic impurities, respectively. Laboratory-scale static-experiments conducted between 10 and 30 °C showed that although toluene sorption on granulated activated carbon (GAC) is exothermic, the sorption capacity for each impurity increased with temperature, indicating endothermic sorption for the impurities. The sorption behavior for MBT and ECP followed the Langmuir model while for XYL followed the Freundlich model with the order of sorption affinity as MBT > ECP > XYL. In pilot-scale dynamic-experiments, the breakthrough curves (BTCs) were evaluated under various bed heights (60 and 120 cm), flow rates (1–3 L min−1), sorbate inlet concentrations (200–400 mg L−1), and optimal temperature (30 °C) obtained in static experiments. In mono-component sorption, the highest sorption capacities for MBT, ECP, and XYL were 97.1, 70.7, and 65.4 mg g−1, respectively, while the corresponding values were 46.0, 43.0, and 22.9 mg g−1 respectively, in multi-component sorption under the same operating conditions. A CFD simulation in COMSOL (v.6.2) revealed sharper BTCs with time delay compared to the experimental data while a good correlation (R2 > 0.99) was observed for BT models. The narrower mass transfer zone for MBT and ECP compared to XYL indicated more effective sorption of these sorbates, respectively. Regenerating GAC up to four cycles with hot N2 (80 °C) showed a satisfactory sorption capacity for industrial toluene impurities, indicating a reversible sorption–desorption process with a cumulative sorption usage rate of 5.5 g L−1. The pilot-scale set-up used in this study successfully purified a large volume (∼475 L) of industrial toluene.

Stress Fields Distribution and Simulation in 3C-SiC Resonators

In this paper the stress field distribution in 3C-SiC (111) resonators has been studied by micro-Raman measurements and COMSOL simulations. The measurements show that the asymmetry of the anchor points configuration produce an asymmetry in the stress filed distribution. This behavior has been confirmed also by the simulations. Furthermore, from the simulations the importance of the reduction of the under etching of the anchor points of the resonators has also been observed. In fact the reduction of this under etch produces a decrease of the stress in the double clamped beams, a small reduction of the resonance frequency, and a large reduction of the Q-factor and then of the oscillation frequency stability of the resonators in closed-loop operation.