- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhanced performance of porous silicone-based dielectric elastomeric composites by low filler content of Ag@SiO <sub/>2</sub> Core-Shell nanoparticles
摘要： In the present work, micropores and a low filler content of Ag@SiO2 nanoparticles (NPs) are synchronously introduced into polydimethylsiloxane (PDMS) film to obtain porous dielectric elastomeric composites. The morphology and dielectric and mechanical properties of the composites are investigated. The resulting composites possess high dielectric permittivity, low dielectric loss and low Young’s modulus, which is beneficial to the requirements of a dielectric elastomer actuator. This study provides an effective method to prepare high-performance PDMS-based dielectric porous dielectric elastomeric composites filled with low filler contents of Ag@SiO2 NPs.
关键词： core-shell particles,dielectric loss,Young’s modulus,dielectric permittivity,elastomer,Porous materials
更新于2025-09-23 15:22:29
-
Young’s modulus and fatigue investigation of aluminum nitride films deposited on 304 stainless steel foils using micro-fabricated cantilevers
摘要： Aluminum nitride based (AlN-based) piezoelectric vibration energy harvesters (PVEHs) have been received much attention in the power generation for the device in microelectromechanical systems (MEMS). During the long-time vibration, PVEHs are suffering cyclically dynamic stress. This may result in the defect of the materials, and finally cause the failure of the device. To achieve a reliable design of the device that can work for a long time without failure, the investigation on the mechanical properties of Young’s modulus and fatigue were conducted for AlN films deposited on 304 stainless steel (SUS 304) foils in this study. Two kinds of materials were tested, SUS 304 foils with a thickness of 50 μm (SUS 304 (50 μm)) and a composite material of AlN films deposited on both sides of SUS 304 foils (AlN (1 μm)/ SUS 304 (50 μm)/ AlN (1 μm) structure). The samples were micro-fabricated to cantilevers. Young’s modulus was measured by the micro-cantilever resonance method. The resonant bending fatigue testing method was used to investigate the fatigue properties of the materials. The displacement amplitude of the samples was recorded during the tests. A new criterion by using the change of amplitude versus number of cycles was proposed to define the fatigue life. As results, the Young’s modulus was 184.9 and 342.9 MPa, for SUS 304 foil and AlN film, respectively. Stress-cycle (S-N) curves were plotted by using the proposed criterion successfully. The fatigue strength of SUS 304 foils and the material with AlN/ SUS 304/ AlN structure was estimated to be 294 and 327 MPa, respectively. Fatigue failures of stable crack, intrusions and extrusions, and slip bands, appeared on the surface of SUS 304 foils after the long time vibration. No fatigue failure or surface defect was observed on AlN films.
关键词： 304 stainless steel foil,aluminum nitride film,Young’s modulus,fatigue,micro-fabricated cantilever
更新于2025-09-23 15:21:01
-
Modifying the thermomechanical properties of electrospun fibres of poly-vinyl cinnamate by photo-cross-linking
摘要： We explore the effects of cross-linking on some thermal and mechanical properties of polymer nanofibers of poly-vinyl cinnamate which were electro-spun from 1,2 dichloroethane. Scanning electron microscopy performed on the fibres revealed smooth fibres which were devoid of beading or ribbon-type features. When cross-linked, the Young’s moduli and glass transition temperatures of the fibres increase, owing to the formation of new covalent bonds which leads to higher overall binding energies. The glass transition temperatures increased by 20 K after 1 h of photo-polymerization while the Young’s modulus increased by 50% for the same exposure time. The glass transition temperatures as well as the heats of enthalpy indicate that a significant portion of cross-linking occurs within the first 10 min of exposure.
关键词： Photo-polymer,Young’s modulus,Enthalpy,Glass transition,Electro-spinning,Cross-linking
更新于2025-09-23 15:21:01
-
Quasi blind carrier phase estimation scheme for special-shaped circular (7,1) modulation in high-speed visible light communication
摘要： A novel digital signal processing (DSP) scheme for special-shaped circular (7,1) modulated signals based on quasi blind carrier phase estimation (QBCPE) is proposed. The results show that applying 0.33‰ overhead QBCPE provides similar performance as 3% training sequence data-aided equalization of least mean square (LMS) algorithm.
关键词： Constant Modulus Algorithm (CMA),visible light communication (VLC),least mean square (LMS),circular (7,1) modulation,quasi blind carrier phase estimation (QBCPE)
更新于2025-09-23 15:21:01
-
On Estimating the Laws of Radial Inhomogeneity in a Cylindrical Waveguide
摘要： The inverse problem about reconstruction of a function characterizing the variation of the elastic modulus in an inhomogeneous cylindrical waveguide according to information about the field of radial displacements in the far zone has been studied. A study has been carried out based on combining the Fourier transform and linearization method. Each step of the formed iteration process includes the solution of the direct problem based on the shooting method and the solution of a Fredholm integral equation of the first kind for finding the refining corrections for the sought function. The results of computational experiments are presented.
关键词： field in the far zone,cylindrical waveguide,variable Young modulus,inverse problem
更新于2025-09-23 15:19:57
-
Synthesis and investigation of structural, optical, dielectric and electronic properties of a new hybrid: [C13H21N2O2](Cd(SCN)3)
摘要： A new ferroelectric relaxor: [C13H21N2O2](Cd(SCN)3) procainium tris(thiocyanato) cadmiate(II) was synthesized and studied by single-crystal XRD. This compound crystallizes in the orthorhombic system with acentric space group Pna21. The crystal structure is formed of discrete ionic entities (C13H21N2O2)+ and [Cd(SCN)3]?. The cadmium atom has 3N3S hexa coordinated octahedral geometry. The sulfur atoms and the nitrogen atoms are in facial mode (fac). Each pair of cadmium atoms is triply bridged by μ-1,3-SCN–bridge. Consequently, a linear polymeric chain is formed. The procainium cations are bonded to these chains by hydrogen-bonding contacts and π–ring interaction. DSC measurement shows that this compound exhibits a diffuse ferro–paraelectric phase transition around 356 K. Dielectric study exhibits a relaxor behavior characterized by the transition temperature shifts toward higher temperature with the rise of frequency. This behavior was validated by the Vogel–Fulcher relationship and the modified Curie–Weiss law. The diffuseness parameter was γ = 1.96. The optical band gap Eg = 2.20 eV was estimated by diffuse reflection spectroscopy (DRS) investigation.
关键词： Ferroelectric relaxor,Structure,Conductivity,Modulus,Vogel–Fulcher model
更新于2025-09-19 17:15:36
-
Effect of Firing Temperature and Duration on Fused Silica Investment Shell Strength at Room Temperature
摘要： Fused silica is widely used in investment casting shell molds as ?our, stucco and binder for its superior properties, such as low linear thermal expansion coef?cient and high thermal shock resistance. Investment shell molds are usually ?red after the de-wax process to remove the residue pattern material, and to improve shell strength through sintering. The ?ring temperatures are generally high enough to affect the phase constituent and microstructure of the shells, which further in?uences the shell strength. Firing duration at ?ring temperature is another important factor having an impact on the shell strength due to grain coarsening, but it is often overlooked by investment foundries. In this article, the room temperature moduli of rupture of investment shells ?red at different conditions were determined. The crystallinity of fused silica shells was determined using X-ray diffraction. The differences on the shell strength were discussed and correlated with the microstructure and phase constitution in the shells after different ?ring processes.
关键词： phase transformation,modulus of rupture,firing duration,firing temperature,investment shell
更新于2025-09-19 17:15:36
-
[IEEE 2018 International Semiconductor Conference (CAS) - Sinaia (2018.10.10-2018.10.12)] 2018 International Semiconductor Conference (CAS) - Effect of the Deposition Conditions on Titanium Oxide Thin Films Properties
摘要： This paper presents the fabrication and characterization of titanium oxide thin films deposited by Pulsed Laser Deposition in different experimental conditions. The scope of this work is to investigate the effect of the oxygen pressure in the deposition chamber on the material properties. Thin films characterizations include the mechanical and tribological properties such as the modulus of elasticity, hardness and the adhesion force. The mechanical and tribological properties of the materials are experimentally determined by using the atomic force microscopy technique. The effect of the oxygen pressure on the film thickness is analyzed. As the pressure in the deposition process decreases, the thickness of the thin films increases, respectively. The surfaces roughness increases as the deposition pressure decreases that leads to a decrease of adhesion forces. Hardness and modulus of elasticity increases as the deposition pressure decreases. This study shows that the mechanical and tribological properties of the investigated thin films strongly depend on the grain size and the films density, which are influenced by the deposition conditions (the oxygen pressure in the deposition chamber).
关键词： pulsed laser deposition,thin films,adhesion force,hardness,modulus of elasticity
更新于2025-09-19 17:15:36
-
Strain coupling and dynamic relaxation in multiferroic metal-organic framework [(CH3)2NH2][Mn(HCOO)3] with perovskite structure
摘要： Strain coupling with ferromagnetism and ferroelectricity plays an important role in the development of multiferroic metal-organic frameworks (MOFs) with strong magnetoelectric coupling, but the underlying mechanisms have not been well understood. Strain coupling and dynamic relaxation in multiferroic MOF with perovskite structure [(CH3)2NH2][Mn(HCOO)3] were investigated using X-ray diffraction (XRD), Raman spectroscopy, Infra-red (IR) spectroscopy, differential scanning calorimetry (DSC), magnetic measurements and dynamic mechanical analysis (DMA). DSC results showed peaks at 183 K and 190 K at the rate of 5 K/min during cooling and heating processes, respectively. Magnetic measurements showed magnetic transition at ~ 8.5 K at the heating rate of 2 K/min. Temperature and frequency dependences of elastic properties studied by DMA at frequencies of 0.5 Hz to 10 Hz between 140 K and 300 K at heating rate of 2 K/min indicated that the minimum in storage modulus and the maximum in loss modulus and loss factor occurred near 190 K. The peak height of loss modulus and loss factor decreased at higher frequency, and the peak temperature was independent of frequency, showing the features of first-order phase transition. Near 190 K, paraelectric to ferroelectric phase transition triggered by disorder–order transition of alkylammonium cations located in the framework cavities occurred accompanied by the structural phase transition from rhombohedral space group R c to monoclinic space group Cc. The elastic anomalies and large energy loss near 190 K were associated with the coupling of the local strain with the freezing of dimethylammonium cation and the freezing of twin walls.
关键词： Elastic modulus,Energy loss,Metal-organic framework (MOF),Phase transition,Dynamic mechanical analysis (DMA)
更新于2025-09-19 17:15:36
-
Estimation of temperature-dependent yield strength and modulus of elasticity during laser bending
摘要： In this work, an inverse method is developed to estimate the temperature-dependent value of yield strength (Y) and modulus of elasticity (E) of the material during a laser bending process. The method requires measurement of bend angle of the laser scanned workpiece. The inverse model uses the bend angle computed by a direct model. The temperature-dependent Y and E are inversely estimated by minimizing the difference between actual and direct model predicted bend angles. The validation of the proposed method is demonstrated with the help of two examples. For this purpose, inversely estimated values of E and Y are used to predict bend angles for various processing conditions and predicted values are compared with actual values. In examples, actual data has been obtained from a detailed FEM simulation in lieu of shop floor experiments. Later on, the proposed method is also validated by performing shop floor experiments for AH36 steel.
关键词： Inverse technique,Finite element method,Yield strength,Laser bending,Modulus of elasticity
更新于2025-09-19 17:13:59