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To use effectively the shell in high-performance applications, analyzing the effect of hygrothermal effects on a piezoelectric delamination event is necessary. A laminated piezoelectric cylindrical shell with delamination is first established under hygrothermal effects, followed by an internal force analysis and an energy analysis of the shell. Then, a parametric vibration equation of the Mathieu for the shell is obtained by using the energy variation of the Rayleigh-Ritz method; later on, the harmonic balance method is employed to solve this equation. Finally, the effects of delamination parameters, geometric parameters, hygrothermal effects, and piezoelectric materials on the shell under uniformly distributed axial load are discussed.

In this paper, the stiffness of carbon nanotube bundle (CNTB) reinforced composite is predicted by means of the Mori-Tanaka method and Eshelby method. The curvature of one CNTB on uniaxial aligned ...

In this paper, composites with multi-directional ellipsoidal fillers of arbitrary aspect ratio, and an interphase layer surrounding the filler, accommodating smoothly the differences in the filler and the matrix's properties, is taken into account. Each constituent of the fiber reinforced composite (FRC) is regarded to be isotropic and linear elastic, and the property of interphase is assumed to be of power-law variation across the thickness. Based on linear hygro-thermo-elastic theory and Elshelby's theory, a novel prediction scheme for effective stiffness, coefficient of thermal expansions (CTEs) and coefficient of moisture expansions (CMEs) of FRCs with functionally graded interphase (FGI) is proposed, in which the Mori-Tanaka method and piecewise method are used and novel analytical expressions for hygro-thermo-elastic of unidirectional FRCs are obtained, respectively; afterwards, a two-step homogenization technique is performed for the filler's distribution consideration. Numerical examples and analyses indicate that the effect of the thickness and mechanical properties of FGI on the overall properties of the FRC is substantial, especially for nano-filler reinforced composites; additionally, the filler content, the aspect ratio and orientation of inclusions have considerable influences on the overall properties of the hygro-thermo-elastic of FRCs.

The different loading conditions often occur in polymer matrix composites during their service life. In order to use effectively the materials in high-performance applications, analyzing the effect of hygrothermal effects on a ballistic impact event is necessary. This paper considers a heat sink and humidity sink for the hygrothermal diffusion in the composites and solves the Luikov equations by means of the differential quadrature method (DQM). Then, failure and partial failure of a projectile with high velocity into the composites are studied based on the conservation of energy. Further, as hygrothermal deformation reaches equilibrium, the effect of hygrothermal effects on the ballistic impact event is studied. Finally, based on carbon fiber reinforced composite (CFRP), the effects of the hygrothermal diffusion are discussed on the ballistic impact event.

The hygro-thermo-mechanical behavior of a ultra-high strength steel (UHSS) gasket under radial mechanical loads is investigated. By adopting an appropriate displacement function, the displacement, ...

Knotting is common in long polymers and significantly affects the polymer behavior. It is generally believed that knotting should increase polymer bending energy. However, many recent studies found...

Due to the significant differences in the properties (e.g., anisotropy, elasticity modulus, and surface roughness) of fibre-reinforced polymer (FRP) and traditional pile materials, research on bond behavior between FRP tube and concrete should be conducted to ensure that they can work together properly. Push-out tests on twenty-nine GFRP-confined concrete piles were performed, the influence of bond type, slenderness ratio of FRP tube, radius-thickness ratio of FRP tube, concrete stress and concrete type on bond behavior and distribution of axial strains were studied, and simplified bond-slip constitutive models based on test results were proposed. It was found that bond type was a critical factor influencing bond behavior. A smaller radius-thickness ratio, a higher concrete stress, and the use of expansive concrete were advantageous for achieving higher bond behavior, whereas the slenderness ratio had little influence on the bond behavior. The axial strain distribution of all FRP tubes demonstrated the following rules: the upper strain was greater than the middle strain, which was larger than the lower strain, but for normal concrete specimens, the strain was linearly distributed with height, while for expanded concrete specimens, the distribution curves were polylines.

We investigate, for the first time, the effect of line-edge roughness (LER)-induced variability for dual-metal gate (DMG) Fin field-effect transistors (FinFETs) using a computer-aided-design simulation. The Gaussian autocorrelation function is utilized for generating the LER sequence. From the standard deviations of subthreshold swing (SS), threshold voltage (VTH), and transconductance (gm), the simulation results indicate that the LER-induced electrostatic integrity variability is related to the ratio of control gate to total gate lengths. The variability caused by LER degrades with respect to the length of control gate near the source. Our work fills a gap in the study of LER-induced variability for DMG FinFETs, and suggests that the length of the control gate near the source should be greater than or equal to the screen gate near the drain in the entire gate.

A micromechanical model for short fiber-reinforced composites (SFRCs) with functionally graded interphases and a systematic prediction scheme to determine the effective properties are presented. The matrix and the fibers are regarded to be linear elastic, isotropic, and homogeneous. Fibers are assumed to be ellipsoids coated perfectly by functionally graded interphases, which is supposed to be formed chemically or physically by the constituents near the interface. First, to analyze the grading interphase effect, layer-wise concept is followed to divide the functionally graded interphases into multi-homogeneous sub-layers. Next, to take the effect of functionally graded interphases into account, a combination of multi-inclusion method and Mori–Tanaka method is applied to predict effective elastic properties of this unidirectional SFRCs with respect to the content and aspect ratio of the inclusions. By employing coordinate transformation, spatially elastic moduli are obtained. Finally, Voigt homogenization scheme is used to obtain the overall, averaged, symmetrical elastic properties of the SFRCs. Numerical examples and analyses demonstrate the applicability of the proposed method and indicate the influences of graded interphase, orientation, and aspect ratio of inclusions as well as properties and contents of the constituents on the overall properties of SFRCs.

In this work, we report an intriguing phenomenon: crowding-induced polymer trapping in a channel. Using Langevin dynamics simulations and analytical calculations, we find that for a polymer confined in a channel, crowding particles can push a polymer into the channel corner through inducing an effective polymer-corner attraction due to the depletion effect. This phenomenon is referred to as polymer trapping. The occurrence of polymer trapping requires a minimum volume fraction of crowders, ϕ^{*}, which scales as ϕ^{*}∼(a_{c}/L_{p})^{1/3} for a_{c}≫a_{m} and ϕ^{*}∼(a_{c}/L_{p})^{1/3}(a_{c}/a_{m})^{1/2} for a_{c}≪a_{m}, where a_{c} is the crowder diameter, a_{m} is the monomer diameter, and L_{p} is the polymer persistence length. For DNA, ϕ^{*} is estimated to be around 0.25 for crowders with a_{c}=2nm. We find that ϕ^{*} also strongly depends on the shape of the channel cross section, and ϕ^{*} is much smaller for a triangle channel than a square channel. The polymer trapping leads to a nearly fully stretched polymer conformation along a channel corner, which may have practical applications, such as full stretching of DNA for the nanochannel-based genome mapping technology.

Organics with the merit of renewability have been viewed as the promising alternative of inorganic electrode materials in lithium-ion batteries, but most of them display inferior performance due to the sluggish ion/electron diffusion and the potential dissolution in aprotic electrolytes. Here, covalent triazine frameworks (CTFs-1), full of vertical pores and layered spaces for Li+ transfer, have been synthesized with p-dicyanobenzene as the monomer by a facile two-step method including a prepolymerization with CF3SO3H as the catalyst and deep polymerization in molten ZnCl2. CTFs-1-400, obtained at the deep polymerization temperature of 400 °C, exhibits the superlithiation property with the specific capacities of 1626 mA h g-1 at 25 °C and 1913 mA h g-1 at 45 °C at 100 mA g-1, indicating the formation of Li6C6/Li6C3N3 in the reduction process. Electrochemical analysis and density functional theory calculation indicate that the ultrahigh capacity is mainly contributed by the capacitance of micropores and the redox capacity of benzene and triazine rings. Moreover, CTFs-1-400 displays the specific capacity of 740 mA h g-1 for 1000 cycles at 1 A g-1 with almost no capacity fading.

An enzymatic glucose sensor was fabricated and integrated into a heterodyne refractometer. A heterodyne light source was incident into the sensor which the circular birefringence refractive index of sample was changed as the chemical reaction between glucose oxidase and glucose progressed. Therefore, the phase difference before and after chemical reaction could be measured by a lock-in amplifier with phase-lock technology. The optical configuration and measurement procedures indicated that the alignment of the measurement system was straightforward and that it reduced the misalignment effect. The phase stability of the proposed system was superior to 0.04 deg within 1 min. The glucose sensor can be reused 100 times while retaining favorable performance. The results indicated that the resolutions of the proposed method were ∼1.5 and 1.29 mg / dl for the glucose solution and serum-based sample (SRM 965b), respectively. The calibration curve revealed high linearity within the dynamic range of 0 to 300 mg / dl. Based on these findings, the proposed method has a potential to measure the whole blood glucose concentration for daily monitoring.

A three-axis micro magnetic sensor (MS) is developed based on the standard 180 nm complementary metal oxide semiconductor (CMOS) technology. The MS designs two magnetic sensing elements (MSEs), which consists of an x/y-MSE and an z-MSE, to reduce cross-sensitivity. The x/y-MSE is constructed by an x-MSE and an y-MSE that are respectively employed to detect in the x- and y-direction magnetic field (MF). The z-MSE is used to sense in the z-direction MF. The x/y-MSE, which is constructed by two magnetotransistors, designs four additional collectors that are employed to increase the sensing current and to enhance the sensitivity of the MS. The Sentaurus TCAD software simulates the characteristic of the MS. The measured results reveal that the MS sensitivity is 534 mV/T in the x-direction MF, 525 mV/T in the y-direction MF and 119 mV/T in the z-axis MF.

As an intriguing phenomenon, knotting in DNA, proteins, and other molecules has been extensively investigated in recent years, not only because of fundamental interest in knotting but also because of significant effects of knotting on mechanical, rheological, chemical, and biological properties. Some polymers contain side chains, and the effects of side chains on polymer knots are not clear. In this work, we investigate the effects of side chains on knots through Langevin dynamics simulations of knot diffusion along a stretched polymer with side chains. When the gap between side chains is larger than the knot size; each side chain acts as a barrier to slow down the knot diffusion. We find that how a knot crosses the barrier by a side chain resembles how a polymer translocates a pore. Inspired by the latter, we find a simple empirical expression for the free energy barrier caused by a side chain: Fbarrier/kBT ≈ 75Rg/Lknot, where kB is the Boltzmann constant, T is the temperature, Rg is the radius of gyration of a side chain, and Lknot is the contour length of the knot core. The equations and numerical results obtained in this work can guide the rational control of knot diffusivity along a polymer by side chains. In addition, our results provide insights into the understanding of knots in peptides and single-stranded DNA where side chains are common. Furthermore, this work makes a connection between two interesting phenomena for polymers - knotting and pore translocation.

In this paper, thermo-electro–elastic behavior of a hollow cylinder made of carbon nanotubes bundles–reinforced electro-active polymer considering the hierarchical structure of carbon nanotube bund...

The design and synthesis of highly efficient thermally activated delayed fluorescence (TADF) emitters with an electroluminescence wavelength beyond 600 nm remains a great challenge for organic light-emitting diodes (OLEDs). To solve this issue, three TADF molecules, xDMAC–BP (x = 1, 2, 3), are developed in combination with the rigid planar dibenzo[a,c]phenazine (BP) acceptor core and different numbers of 9,9-dimethylacridan (DMAC) donors. All these emitters possess stable internal charge transfer and a large dihedral angle between the donors and planar BP core. The emission wavelength can be regulated from 541 to 605 nm by increasing the number of the donor DMAC units because of the controllable tuning of the intramolecular charge transfer effect and the molecular geometrical structure. The photoluminescence quantum yields of these emitters are improved from 42 to 89% with the increase in the number of DMAC units. The orange-red OLEDs employing the xDMAC–BP emitters exhibit maximum external quantum effici...

In this paper, the one-dimensional transient heat conduction problem is investigated of a coated high strength steel (HSS) plate which is composed of two coating layers and a HSS layer. As the coating is extremely thin, non-Fourier heat conduction is applied to this part, while the steel part is analyzed by Fourier conduction. Then the temperature increment equations are obtained, which can be calculated by the Newmark method. The effects of thermal relaxation time, temperature boundary conditions, and coating parameters on temperature increment distribution of the coated HSS plate are also presented. Thus, the one-dimensional transient heat conduction problem of a coated HSS plate can be solved, which contributes to practical application and engineering design.

Experiment in literature has shown the aggregation phenomenon in carbon nanotube (CNT) reinforced polymeric composites. In this paper, considering the aggregation effect of CNTs and porosity in both polymeric matrix and aggregated CNT clusters, a mechanical model to investigate the coupled conduction of temperature and moisture as well as the hygrothermal mechanical behaviors of a porous functionally graded CNT reinforced composite (FG-CRC) rotating annular plate with variable thickness is built. Numerical results of the temperature and moisture fields as well as the hygrothermal mechanical responses are achieved by combining the differential quadrature method (DQM), the Runge-Kutta method and the Newmark method. Several useful conclusions as follow are obtained through numerical examples and discussions. In the numerical examples, influences of the aggregation effect of CNTs, coupled effect of temperature and moisture, material property (graded index and porosity parameters), geometric parameters as well as the rotating conditions to the hygrothermal mechanical responses of the porous FG-CRC annular plate are studied in detail. The theoretical process and conclusions will be helpful to the design and manufacture of novel porous graded materials and structures applying in hygrothermal environment and conditions.

In this paper, two formulae that can predict the tensile strength of composites are derived. One of the formulae is suitable for predicting the tensile strength of composites in which there is no f...

The current study focuses on the single-lap adhesively bonded joint of carbon fiber reinforced resin (CFRR), a kind of carbon fiber reinforced polymers (CFRPs), and metal with/without adhesive defect under coupled hygrothermal environment. Theoretical mechanical model, containing key geometric and position parameters of the interfacial defect, is established and solved by differential quadrature method (DQM). Influences of the coupled hygrothermal condition, external mechanical loads, adhesive defect size and position as well as adherend materials to interfacial stresses are explored and discussed. Numerical examples show the significance of consideration of hygrothermal environment for the interfacial stresses, especially the importance of temperature gradient. Taking into account the hygrothermal environment makes the stress fields more complex. The current study may offer theoretical references to investigations of failure mechanisms of adhesively bonded structures of dissimilar materials operating in complex environment conditions.

In this study, the impact of orientation of metal-gate granularity on analog figures-of-merit (FOMs) in high-k/metal-gate junctionless (JL) fin-field-effect transistor (FinFET) and gate-all-around (GAA) nanowire metal-oxide-semiconductor-field-effect-transistor (NWFET), with a similar ratio of average grain size to gate area is investigated. Further, their FOMs when operating in the linear and saturated regions have been compared using three-dimensional technology computer-aided design simulation. According to the standard deviation and relative deviation of the FOMs, it is observed that their FOMs are significantly affected by the work-function variation (WFV). In addition, as expected, the influence of WFV on the JL FinFET is greater than that on the GAA NWFET. Our study provides insights for circuit design using high-k/metal-gate technology.

A rotating porous functionally graded magneto-electro-elastic (FGMEE) annular plate with variable thickness under hygrothermal environment is studied in this paper. The FG index is expressed by the volume fraction of piezoelectric component, and the porosity which depends on the volume fraction of each solid component takes various pores (inherent pores in components and structural pores at the interfaces) into account. Considering the effect of pores on both mass density and moisture of the structure, steady-state heat conduction and nonlinear moisture diffusion equations are built and solved by the differential quadrature method (DQM). Applying a linear hygrothermal electro-magneto-elastic constitutive relation, and combining the stress equilibrium equation with static electric and magnetic equations, governing equations expressed by displacement, electric and magnetic potentials are derived and also solved by DQM. In the numerical examples, influences of material property (FG index and porosity parameters), geometric structure (inner-outer thickness ratio and its change index) as well as external conditions (temperature and moisture boundary conditions) to the multi-field responses of the porous FGMEE annular plate are studied in detail. The theoretical process and conclusions will be helpful to the design and manufacture of novel porous FG structures applying in complex multi-field environment and conditions.

Magnetic seeding agglomeration (MSA), i.e., adding magnetic seeds and a low intensity pre-magnetization for fine agglomeration, was applied to the flotation of coal, pyrite and hematite ore slimes. Size analysis and flotation tests highlight that the MSA improved flotation recovery and kinetics of pyrite ore while causing some loss in selectivity, and in the presences of the polyacrylamide for coal and starch for hematite the agglomeration flotation was further strengthened due to the synergetic effect between the flocculants and magnetic seeds. Magnetism analyses and calculation confirmed the adsorption of magnetic seeds onto minerals, resulting in a decreased threshold magnetic field intensity for the MSA to happen. Then atomic force microscope (AFM) study found that there exists a long range force between magnetic seeds and minerals, which facilitates the adsorption of magnetic seeds on minerals. FTIR shows both the polyacrylamide and starch adsorbed onto minerals and magnetic seeds, thus acting as the bridging media between minerals and magnetic seeds, intensifying the agglomeration in flotation. Surface characterization of the MSA was understood by SEM imaging, and models of the MSA were proposed.

Zigzag line is a common defect in friction stir welding (FSW) joint. The formation mechanism of the zigzag line in Al–Cu alloy FSW joint and its influence on the microstructure and mechanical properties during post weld heat treatment (PWHT) were studied by scanning electron microscopy (SEM), microhardness and tensile tests. It is found that the occurrence of zigzag line for PWHT joint is determined by PWHT process which in nature depends on residual stress and thermal stress of FSW joint. The optimization of PWHT process to reduce the residual and thermal stress can trigger for the deterioration of mechanical properties of PWHT joints with zigzag line. No obvious decrease of tensile properties is observed for T6-450 and T6-495 joints although zigzag line appears in the weld. PWHT determines the sizes of zigzag line cracks and consequently determines the fracture location and characteristics of FSW joint.

A radio frequency microelectromechanical system switch (MSS) manufactured by the complementary metal oxide semiconductor (CMOS) process is presented. The MSS is a capacitive shunt type. Structure for the MSS consists of coplanar waveguide (CPW) lines, a membrane, and springs. The membrane locates over the CPW lines. The surface of signal line for the CPW has a silicon dioxide dielectric layer. The fabrication of the MSS contains a CMOS process and a post-process. The MSS has a sacrificial oxide layer after the CMOS process. In the post-processing, a wet etching of buffer oxide etch (BOE) etchant is employed to etch the sacrificial oxide layer, so that the membrane is released. Actuation voltage for the MSS is simulated using the CoventorWare software. The springs have a low stiffness, so that the actuation voltage reduces. The measured results reveal that actuation voltage for the MSS is 10 V. Insertion loss for the MSS is 0.9 dB at 41 GHz and isolation for the MSS is 30 dB at 41 GHz.

For continuous and efficient oil/water separation and adsorption of dyes, coconut shell powder was grafted onto the surface of quartz sand by dip-coating method to make coconut shell powder-covered quartz sand filter media (CSQS) with superhydrophilic and underwater superoleophobic properties and superoleophilic and underoil highly hydrophobic properties. The contact angles of the underwater oil and underoil water with CSQS were more than 151.2&deg, and 134.2&deg, respectively. A continuous oil/water separation device was designed. The separation device filled with CSQS can separate oil/water mixture (whether heavy or light oil) into water and oil at the same time with a separation efficiency of above 99.92%. The filter layer can be recovered through reverse extrusion even after lyophobic liquid penetrated the filter layer, hence, the separation efficiency of the filter layer was still above 99.99% for diesel and water mixture. Simultaneously, CSQS can effectively adsorb methylene blue with the highest removal rate as 98.94%. CSQS can maintain stable wettability under harsh environment conditions. This paper provides a new idea on continuous and efficient oil/water separation and simultaneous dye adsorption.

During the service life of polymer matrix composites, various loading conditions often occur. To use such materials effectively in high-performance applications, their behaviors under hygrothermal effects should be clearly understood. Firstly, a laminated spherical shell panel is established under hygrothermal effects, followed by geometric properties’ analysis and internal forces analysis of the shell. Then, the constitutive relations related to the hygrothermal effects are considered in the laminated spherical shell panel, and equations of motion with geometric nonlinearity are derived by employing Hamilton’s principle; thereafter, solution of equations of motion is obtained using the Navier solution technique. Finally, influences of the hygrothermal effects on nondimensionalized center deflections, nondimensionalized fundamental natural frequency, and vibration-deflection amplitude for the shell are discussed.

The fabrication and characterization of a magnetic micro sensor (MMS) with two magnetic field effect transistors (MAGFETs) based on the commercial complementary metal oxide semiconductor (CMOS) process are investigated. The magnetic micro sensor is a three-axis sensing type. The structure of the magnetic microsensor is composed of an x/y-MAGFET and a z-MAGFET. The x/y-MAGFET is employed to sense the magnetic field (MF) in the x- and y-axis, and the z-MAGFET is used to detect the MF in the z-axis. To increase the sensitivity of the magnetic microsensor, gates are introduced into the two MAGFETs. The sensing current of the MAGFET enhances when a bias voltage is applied to the gates. The finite element method software Sentaurus TCAD was used to analyze the MMS&rsquo, s performance. Experiments show that the MMS has a sensitivity of 182 mV/T in the x-axis MF and a sensitivity of 180 mV/T in the y-axis MF. The sensitivity of the MMS is 27.8 mV/T in the z-axis MF.

This study describes the fabrication of an ammonia gas sensor (AGS) using a complementary metal oxide semiconductor (CMOS)&ndash, microelectromechanical system (MEMS) technique. The structure of the AGS features interdigitated electrodes (IDEs) and a sensing material on a silicon substrate. The IDEs are the stacked aluminum layers that are made using the CMOS process. The sensing material, polypyrrole/reduced graphene oxide (PPy/RGO), is synthesized using the oxidation&ndash, reduction method, and the material is characterized using an electron spectroscope for chemical analysis (ESCA), a scanning electron microscope (SEM), and high-resolution X-ray diffraction (XRD). After the CMOS process, the AGS needs post-processing to etch an oxide layer and to deposit the sensing material. The resistance of the AGS changes when it is exposed to ammonia. A non-inverting amplifier circuit converts the resistance of the AGS into a voltage signal. The AGS operates at room temperature. Experiments show that the AGS response is 4.5% at a concentration of 1 ppm NH3, and it exhibits good repeatability. The lowest concentration that the AGS can detect is 0.1 ppm NH3

This study involves the fabrication and measurement of a flexible thermoelectric generator (FTG) using micromachining and electroplating processes. The area of the FTG is 46 &times, 17 mm2, and it is composed of 39 thermocouples in series. The thermoelectric materials that are used for the FTG are copper and nickel. The fabrication process involves patterning a silver seed layer on the polymethyl methacrylate (PMMA) substrate using a computer numerical control (CNC) micro-milling machine. Thermoelectric materials, copper and nickel, are deposited on the PMMA substrate using an electroplating process. An epoxy polymer is then coated onto the PMMA substrate. Acetone solution is then used to etch the PMMA substrate and to transfer the thermocouples to the flexible epoxy film. The FTG generates an output voltage (OV) as the thermocouples have a temperature difference (&Delta, T) between the cold and hot parts. The experiments show that the OV of the FTG is 4.2 mV at &Delta, T of 5.3 K and the output power is 429 nW at &Delta, T of 5.3 K. The FTG has a voltage factor of 1 &mu, V/mm2K and a power factor of 19.5 pW/mm2K2. The FTG reaches a curvature of 20 m&minus, 1.

Two formulas which can predict the tensile strength of hybrid composite filled with short fibers and spherical particles are derived in this paper. One of them is suitable for predicting the tensile strength of hybrid composites in which there is no cluster. And another formula is suitable for predicting the tensile strength of hybrid composites in which clusters exist. There are two vital points in this paper. One is that the influence of fiber end on the tensile strength has been quantitatively studied, while most predictions of the tensile strength of the composite from other authors neglect it. Another one is that the influence of reinforcement aggregation on the tensile strength of the composite has been quantitatively studied.

Based on the nonlinear static stability analysis, this paper establishes the governing equations of the nonlinear dynamic stability of a spherical shell panel of carbon fiber-reinforced polymer (CFRP) under the hygrothermal effects; the Galerkin method is used to solve the governing equations. Then, for the free vibration of CFRP spherical shell panel, the analytical expression of the ratio of nonlinear vibration frequency to natural frequency is obtained by employing the multiscale method; for forced vibration, the analytical expression of the ratio of excitation frequency to natural frequency is obtained by considering the harmonic excitation load. Finally, the effects of geometric parameters, boundary conditions, loads, and the hygrothermal effects on the amplitude-frequency response curves of the CFRP spherical shell panel are discussed.

A design method and corresponding fabrication procedures are proposed for a dual frusto-conical reflector of a downlight luminaire. The profile of the dual frusto-conical reflector consists of two flat-slant reflective surfaces with slightly different slopes. The optimum dual frusto-conical reflector can be obtained with the proposed design method. The finished product of the dual frusto-conical reflector is fabricated by a 3D printer and followed by surface polishing and reflection paint spraying. The measurement results show that luminaires exhibited 70% optimum illuminance confined within an illumination area of 1.8 m 2 , and the optimum illumination intensity is at 252 lux. The optimum efficiency of the proposed luminaire can reach 158 lm/W for normal-white light-emitting diode (LED) and 119 lm/W for warm-white LED, respectively.

Hygrothermal effects and periodic loading often occur in carbon nanotube-reinforced composite (CNTRC) during their service life. For the effective use of such materials for high-performance applications, their nonlinear vibration behavior under hygrothermal effects should be clearly understood. Firstly, this paper establishes a nonlinear vibration mechanical model of the CNTRC plate with different distributions of carbon nanotubes (CNTs). Then, ordinary differential equations of nonlinear vibration are given by using the Galerkin method and solved by using the harmonic balance method; additionally, a primary resonance and stability of the CNTRC plate under transverse harmonic loads are analyzed by employing the multi-scale method. Finally, for a fixed shear deformation function, effects of geometric size, volume fraction, CNT distribution, and damping coefficient on the nonlinear vibration behaviors of the CNTRC plate are discussed.

This paper shows an analytical approach to investigate buckling behavior of a carbon fiber reinforced resin (CFRR) cylindrical shell covered with a damaged porous microcapsule coating subjected to axial compressed loads under hygrothermal environment. The formulas are in view of the Donnell’s shell theory considering the von Karman geometric nonlinearity. The material parameters of microcapsule coating are predicted with the self-consistent model and Mori-Tanaka model. By utilizing Galerkin approach, the buckling behavior for simple-support damaged double-layered cylindrical shell are determined. The influence of temperature and moisture, interface debonding damages, material properties, geometry parameters of microcapsules and porosity upon the buckling behavior of the double-layered cylindrical shell are investigated. Results show moisture and geometry size of microcapsules are propitious to the critical buckling and post-buckling compressive load. In addition, the micro-structure damage greatly affects temperature and moisture. The geometric parameters of microcapsules significantly affect the buckling and post-buckling behavior of double-layered cylindrical shell.

3-(Phenylsulfonyl)pyridine (PSP), an unreported acceptor, is used to construct two thermally activated delayed fluorescent materials (TADF), PSPP and PSPBP, with rigid PXZ as donor in 3-position or 3, 5-position of PSP. Both PSPP and PSPBP have large twisted structure due to highly steric hindrance, resulting in small ΔEST. Simultaneously, the frontier molecular orbitals of PSPP and PSPBP show limited spatial overlap, which improve photoluminescence quantum yields. Both emitters have distinct TADF performance. The OLEDs based on these emitters exhibit good photoelectric properties. This work enriches the acceptor selection scope and possesses crucial significance to developing new TADF molecules.

The elastic-plastic deformation of materials provides limited displacement for metal gaskets, so as to ensure the sealing performance of flanges. In order to study the sealing performance of a novel metal gasket with a convex structure of a semi-cylindrical shell between two flanges, the compression-springback behavior of semi-cylindrical shell is investigated. By introducing the rebound and anti-coupled system consisting of the compressed body and the resilient body, meanwhile based on von Karman nonlinear theory and Mises yield criterion, the incremental thermo-elastoplastic stress-strain constitutive relation of the semi-cylindrical shell is theoretically derived. Utilizing the finite difference method in space domain and nonlinear term iteration technique, the plastic stage problem including the semi-cylindrical shell and the sheet with flattening single-corrugated structure is solved. The influence factors of material properties, temperature, geometrical parameters of semi-cylindrical shells and cyclic loads are considered. Results show that the compression-springback behavior of nickel-based alloy is better than that of stainless steel in thermal environment, while the compression-springback behavior of stainless steel is closed to that of nickel-based alloy at room temperature. The width of semi-cylindrical shell and depth of base material significantly affect the compression-springback behavior of stainless steel. In addition, the cyclic load can cause the plastic hardening of stainless steel.

Adequate micro-modeling for composites is the basic and key precondition for their property prediction. This study takes fiber-reinforced composites (FRCs) as an example and focuses on the linkages among fiber content, porosity and aggregation in the microstructure of composites, as well as their effect on the overall mechanical properties. A novel two-parameter agglomeration model is developed to take both the tightly packed filler assemblies and the porosity into account, in which the fiber weight fraction is used as an independent variable to express the volumetric composition. Meanwhile, an improved two-scale approach based on Mori–Tanaka (M–T) homogenization theory is utilized to predict the effective properties of FRCs. Three typical FRCs: three-dimensional (3D) randomly distributed FRCs, two-dimensional (2D) randomly distributed ones and unidirectionally (UD) distributed ones, are investigated in detail. The proposed model and method are validated by available experimental data. A parametric study reveals that due to the synergistic influence of fiber content, porosity and local aggregation, a maximum stiffness of FRCs can be achieved by making fibers uniformly dispersed in the matrix and setting the fiber weight fraction to be a certain transition value, which is characterized as a best possible condition with high fiber content and low porosity.

In this paper, the distributions of the temperature, moisture, displacement and stress of a functionally graded piezoelectric material (FGPM) circular disk rotating around its axis at a constant angular velocity under a coupled hygrothermal field are presented by a numerical method. The material properties of the FGPM circular disk are assumed to vary along the radial coordinate exponentially. First, the coupled hygrothermal field along the radius of a rotating circular disk is achieved by solving the coupled hygrothermal equations, and then the dynamic equilibrium is solved by utilizing the finite difference method. Finally, numerical results show the effects of functionally graded index, inner radius, angular speed and hygrothermal index on the hygrothermal behaviors of the FGPM circular disk. The results can be useful for the optimal design of rotating FGPM circular disks under a coupled hygrothermal field.

Springback prediction for a metal sheet during the forming process has always been a practical problem. In this paper, based on the mixed plastic hardening rule, which comprehensively describes the Bauschinger effect, transient behavior and permanent softening, a mechanical model considering the variable elastic modulus effect, nonlinear elastic recovery, initial anisotropy yielding criterion and damage evolution is established. Influence of damage on time-dependent springback for a U-shaped HSLA steel plate is investigated. The results obtained from numerical examples show that the hardening exponent, bending radius-thickness ratio, friction coefficient, blank holder force and damage have great influences on the springback of the U-shaped HSLA steel plate. Comparison example is conducted to verify the validity of the present model which can accurately predict the springback behavior of the U-shape HSLA steel plate.

A three-dimensional (3D) micromechanical study is performed for effective viscoelastic properties prediction of fiber reinforced polymers (FRPs) containing elastic, transversely isotropic/isotropic ellipsoidal fibers surrounded by graded interphases, embedded in an isotropic, viscoelastic matrix. Based on mean-field homogenization theory, an improved double-inclusion model for FRPs considering graded interphase and imperfect interface is established. Applying two-step homogenization technology, elastic-viscoelastic corresponding approach and Time-Temperature Superposition Principle (TTSP), effective thermo-viscoelastic moduli of FRPs are obtained with respect to the grading and geometric parameters. By solving the interface damage tensors numerically, the mathematical errors in the previously used analytical expressions are avoided, and the entire prediction scheme is extended to fillers at any aspect ratio. Comparing the results for composites with 3D randomly dispersed fibers with existing semi-analytical solutions, the accuracy and efficiency of the proposed method is verified. Parameters analyses are conducted, which indicate that the established model and the proposed method should be of great help for predicting mechanical properties of FRPs and designing micro-composites.

Temperature and relative humidity (RH) are the most important thermodynamic parameters in aerosol formation, yet laboratory studies of nucleation and growth dependencies on temperature and RH are lacking. Here we report the experimentally observed temperature and RH dependences of sulfuric acid aerosol nucleation and growth. Experiments were performed in a flow tube in the temperature range from 248-313 K, RH from 0.8% - 79%, and relative acidity (RA) of sulfuric acid from 6 × 10-5 - 0.38 (2 × 107 - 109 cm-3). The impurity levels of base compounds were determined to be NH3