Trapezoidal Grooves Research Articles

The effects of double groove type on the backing weld penetration in swing arc vertical-up MAG welding

The penetration of the bead for swing arc vertical-up backing welding was investigated by experiments and numerical simulations in the present work. Three double groove types were used: double V groove, one V-one trapezoid groove, and double compound angle groove. The molten pool behaviors and the weld-forming mechanisms for different grooves were studied. The results indicate that the groove assembly dimensions affect the penetration of the backing weld. As the root gap increases or the root face decreases, the penetration increases. For one V-one trapezoid groove, the increase of the groove width leads to the decrease of the penetration. Based on the analysis of the weld-forming mechanisms, a double compound angle groove was proposed and applied, and a better full penetration can be obtained. Through the analysis of simulation results, the optimized groove for double-sided swing arc vertical-up metal active gas (MAG) welding was obtained.

Gas sensing through evanescent coupling of spoof surface acoustic waves

An ultrasonic gas sensor based on evanescent coupling of spoof surface acoustic waves between two surface phononic crystals containing trapezoidal grooves on rigid slabs is theoretically and experimentally demonstrated. Sensing properties for carbon dioxide in dry air at 25 °C and 760 Torr are investigated as an example. Band structure analyses reveal two spoof surface acoustic wave bands with opposite parities when the separation of surface phononic crystals is 1.5 times the periodicity of grooves. The beat length varies with frequency and carbon dioxide volume fraction, where the increase of the latter results in red shift of a sharp intense output peak at 59.69 kHz at a rate of 17.70 mHz/ppm and 16.20 mHz/ppm for carbon dioxide volume fractions up to 10,000 ppm, as measured through Finite-Element Method simulations and experiments, respectively. Gas sensing can also be achieved by measuring the output acoustic intensity at constant frequency, which exhibits a steep decrease with carbon dioxide volume fraction up to 2000 ppm.

A Spectral Finite Difference Method for Analysis of a Fluid-Lubricated Herringbone Grooves Journal Bearing under a Special Case at Rectangle Groove

A spectral difference method is applied to get numerical solutions for a fluid-lubricated herringbone grooved journal bearing with trapezoidal grooves by previous work of the authors. However, an inexpedience in which Fourier series of the film profile does not converge at jump points of groove start or groove end in the case of rectangle groove was still remained. In the paper, an inexpedience of numerical analysis under a special case at rectangle groove is challenged to solve. As a result, for compensation of which Fourier series does not converge at jump points in a special case of rectangle groove, Fourier coefficient of fluid film thickness is proposed as taking the limit of which in a case trapezoidal groove at trapezoidal angle approaches 0.

Spoof Surface Plasmon Polariton-Based Reconfigurable Band-Pass Filter Using Planar Ring Resonator

In this paper, we report the design, analysis, and development of spoof surface plasmon polariton (SSPP)-based reconfigurable band-pass filter using a planar ring resonator. A transition from quasi-transverse electromagnetic (QTEM) mode of microstrip to SSPP mode was implemented which has been subsequently used to develop a reconfigurable band-pass filter. Trapezoidal shape periodically corrugated metallic grooves etched on the planar metallic surface have been used in the implementation of this transition. In the designed transition, impedance and mode matching between QTEM mode and SSPP mode have been achieved using gradient grooves. The developed transition has been used in the characterization of a ring resonator corrugated with the periodical array of the trapezoidal shape grooves. This SSPP ring resonator shows multiple passbands at different frequencies within the specified frequency range. Varactor diodes have been incorporated in the SSPP ring resonator to obtain tunable passband. Three types of varactor-tuned circuits have been experimentally implemented and characterized using SMV2019-079LF diode package. These circuits will pave the path for development of other front-end circuit elements using the concept of spoof SPP.

Microstructure and mechanical properties of HSLA-100 steel repaired by laser metal deposition

HSLA-100 steel substrates with pre-machined trapezoidal grooves were repaired by laser metal deposition with HSLA-100 and nickel base alloy (GH3536) powders. The grooves can be restored and good metallurgical bonding was achieved. The microstructure and mechanical properties were analyzed. Results showed that the microstructure of the repaired zone was typical fine columnar crystals and dendrites. The main phase in the repaired zone (RZ) was martensite confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) results. No visible micro-pores or cracks was found under optical microscopy (OM). The micro-hardness of the RZ repaired with HSLA-100 steel powder was in the range of 240–350 HV while the sample repaired with GH3536 showed a relatively smooth micro-hardness distribution. The tensile properties were comparable to that of the substrate. The average absorbed impact energy at −40 °C of specimens repaired with HSLA-100 steel and GH3536 powder reached 29.6% and 88.5% that of the base material, respectively. The fracture mechanism was revealed by the SEM fracture analysis.

Study on the Optimal Groove Shape and Glue Material for Fiber Bragg Grating Measuring Bolts.

Fiber Bragg grating (FBG) measuring bolts, as a useful tool to evaluate the behaviors of steel bolts in underground engineering, can be manufactured by gluing the FBG sensors inside the grooves, which are usually symmetrical cuts along the steel bolt rod. The selection of the cut shape and the glue types could perceivably affect the final supporting strength of the bolts. Unfortunately, the impact of cut shape and glue type on bolting strength is not yet clear. In this study, based on direct tension tests, full tensile load–displacement curves of rock bolts with different groove shapes were obtained and analyzed. The effects of groove shape on the bolt strength were discussed, and the stress redistribution in the cross-section of a rock bolt with different grooves was simulated using ANSYS. The results indicated that the trapezoidal groove is best for manufacturing the FBG bolt due to its low reduction of supporting strength. Four types of glues commonly used for the FBG sensors were assessed by conducting tensile tests on the mechanical testing and simulation system and the static and dynamic optical interrogators system. Using linear regression analysis, the relationship between the reflected wavelength of FBG sensors and tensile load was obtained. Practical recommendations for glue selection in engineering practice are also provided.

The Recessed Trapezoidal Groove Dual‐Gate AlGaN/GaN E‐Mode Transistor by Using Depletion Enhancement Effect

The recessed trapezoidal groove dual‐gate profile is achieved by the low power CF4 plasma etching based on the principle of ion‐scattering. The recessed trapezoidal groove dual‐gate architecture can increase the lateral broadening of depletion width, yielding the Enhancement‐mode operation. This device demonstrates a threshold voltage of 0.43 V, a maximum drain current of 480 mA mm−1 and a trans‐conductance of 308 mS mm−1. The device exhibits a low off‐state leakage current of ≈10−10 A mm−1 and gate induced drain leakage is effectively improved. An extrinsic current gain cut off frequency of 32 GHz and a maximum oscillation frequency of 65 GHz are deduced. The threshold voltage (Vth) stability of the Schottky gate HEMT is investigated. The recessed trapezoidal groove dual‐gate exhibits a small shift of Vth, which is attributed to the lateral extension of depletion region in the trapezoidal groove dual‐gate structure.

Analysis and Optimization of Trapezoidal Grooved Microchannel Heat Sink Using Nanofluids in a Micro Solar Cell.

It is necessary to control the temperature of solar cells for enhancing efficiency with increasing concentrations of multiple photovoltaic systems. A heterogeneous two-phase model was established after considering the interacting between temperature, viscosity, the flow of nanofluid, and the motion of nanoparticles in the nanofluid, in order to study the microchannel heat sink (MCHS) using Al2O3-water nanofluid as coolant in the photovoltaic system. Numerical simulations were carried out to investigate the thermal performance of MCHS with a series of trapezoidal grooves. The numerical results showed us that, (1) better thermal performance of MCSH using nanofluid can be achieved from a heterogeneous two-phase model than that from single-phase model; (2) The effects of flow field, volume fraction, nanoparticle size on the heat transfer enhancement in MCHS were interpreted by a non-dimensional parameter NBT (i.e., ratio of Brownian diffusion and thermophoretic diffusion). In addition, the geometrical parameters of MCHS and the physical parameters of the nanofluid were optimized. This can provide a sound foundation for the design of MCHS.

Investigation of air damping effect in two kinds of capacitive MEMS accelerometers

In this study, the air damping ratios of an unsealed chip of a capacitive accelerometer subjected to different pressures were measured by a special designed circuit in a static state test. There are total eight trapezoid grooves on the top and bottom electrode wafers aiming at reducing air damping effect. Finite element method based on energy balance method and transient blade row model is used to simulate in ANSYS/CFX with a new formula of effective viscosity of the air derived from simulation and validated by experimental results. The numerical results are in good agreement with the experimental results. With the same method and the new formula of effective viscosity, the air damping ratio of a new chip without trapezoid grooves is simulated as well. The comparison of the two kind of chips shows that the air damping ratio decreases 63.4% after four trapezoid grooves were engrooved on the top and bottom electrode wafers. As a result, engrooving on the top and bottom electrode wafers provides a new way to reduce air damping effect.

Incorporation of manufacturing constraints into an algorithm for the determination of maximum heat transport capacity of extruded axially grooved heat pipes

In this study, an algorithm is proposed which takes into account the manufacturing (EDM and extrusion) constraints as well as container design, temperature drop criterion between the evaporator and condenser together the with the vapor and liquid pressure losses for axially grooved heat pipes. The algorithm was executed for rectangular, triangular, trapezoidal and reentrant grooved heat pipes for a fixed outer diameter with and without manufacturing constraints. It was seen that for all groove types, the maximum heat transport capacity was found to be higher for the case in which manufacturing constraints are neglected. Results also show that for trapezoidal and reentrant grooves, the width and depth combinations yielding the maximum heat transport cannot be actually manufactured. On the other hand, the maximum heat transport occurs in the range where the heat pipe can actually be manufactured for rectangular and triangular grooves.

Influence of Parallel and Trapezoidal Wick Structures to the Heat Transfer Capability of MHPs

Heat transfer capability of micro heat pipe (MHP) is relied on the thermal resistance of material, the specific phase change latent heat of working fluid, and the pattern of micro structures which is served as wick. In this paper, parallel and trapezoidal micro Cu structures were designed and fabricated by UV-LIGA. The capillary pressure and the effective coefficient of heat transfer conductivity of the micro grooves were calculated and results showed that trapezoidal grooves with small dimension in evaporator and large dimension in condenser (forward trapezoidal) have the best performance, because this structure can generate larger capillary force of working fluid and enhance the heat transfer. Two MHPs based on the calculations were fabricated and tested, results demonstrated that forward trapezoidal groove had the lowest equilibrium temperature while the inversed trapezoidal groove had the highest equilibrium temperature, approved the numerical calculation results. When the input power was 10W, the equilibrium temperature of forward trapezoidal, parallel and backward trapezoidal grooved MHP was 67.2 oC, 73.4°C and 89.1 oC, respectively. The forward trapezoidal grooves enlarge the capillary pressure and benefit the heat transfer of MHP.

A new kind of spoof surface plasmon polaritons structure with periodic loading of T-shape grooves

A new kind of spoof surface plasmon polaritons (SSPPs) structure with periodic loading of T-shape grooves is introduced in this paper. Dispersion property of this proposed structure is investigated in detail, and comparisons of dispersion property of the proposed structure and that of the traditional SSPPs structures, including structure with rectangular grooves and structure with trapezoidal grooves, are also made. The SSPPs field confinement along the orthogonal directions of the proposed structure is studied. Also, some researches on the transmission loss and propagation length of the SSPPs on the proposed structure are made. All the simulation and calculations show that the proposed structure have a great improvement of SSPPs field confinement and the transmission loss is low.

Repair of 304 stainless steel by laser cladding with 316L stainless steel powders followed by laser surface alloying with WC powders

304 stainless steel substrates with a trapezoidal groove are repaired by laser cladding with 316L stainless steel powders, and then the repaired surfaces are modified with cast WC powders by laser surface alloying. The microstructure of the cladded zone consists of columnar dendrites, clusters of cells and equiaxed grains, and the microstructure of the alloyed layer consists of supersaturated austenite dendrites and homogeneous interdendritic networked carbides. Most of the WC particles are dissolved in the matrix with a few partially melted WC particles sparsely distributed in the alloyed layer. No visible macro pore or crack is observed before and after wear test, indicating a potential good fatigue performance of the repaired part. The sample with the highest WC content (24.4% wt.) exhibits the highest hardness of 550 HV0.5 and the minimum mass loss of 0.7mg. The wear performance is significantly higher than that of the substrate with mass loss of 11.9mg. With the increase of WC content, the wear mechanism transformed from adhesion to abrasion due to the hardening matrix and the increase of the un-melted WC particles.

Groove-shape-induced bandwidth expansion of spoof surface plasmon polaritons on planar corrugated Goubau line in millimeter-wave range

Surface plasmon polaritons (SPPs) do not exist naturally in millimeter-wave range, but can be assisted by plasmonic meta-materials, generally periodic corrugated Goubau lines (PCGLs) coated on ultrathin flexible dielectric films. Compared to traditional PCGLs with rectangular groove, we present two single-edge PCGLs with different corrugation groove shapes of triangle and trapezoid to realize more broadband transmission of spoof SPPs (SSPPs). Both the simulated and experimental results show that the pass-band of SSPPs is expanded for the PCGLs with trapezoidal and triangular grooves in the same actual depth and conversion efficiency, compared to the case of traditional rectangular grooves. The dispersion relation and the equivalent circuit model of the three SSPPs are investigated to explain the groove-shape-induced bandwidth expansion effect. The bandwidth expansion effect opens up another path to control the pass-band of SSPPs.

Numerical study on condensation heat transfer of trapezoid grooved surfaces

This article presents a numerical analysis and experimental study on condensation heat transfer and fluid flow for filmwise condensation on trapezoid grooved surfaces. First, a physical model was properly simplified based on some reasonable assumptions. Then, the coupled non-linear governing equations for the mass transfer, fluid flow, and two-dimensional thermal conduction were developed. The relationship between z-coordinate and heat transfer was obtained by solving the equations numerically. The influences of groove length and basic angle were discussed. The calculation results showed that the heat flux decreased with increase in groove length, and the decline range also decreased gradually. The calculation results also suggested that the heat flux through groove with α = 60° was lower than the groove with α = 75° at the top of the groove, while the opposite conclusion was obtained at the low parts. The distributions of wall temperature and heat flux on trapezoid groove were also studied systematically. The distribution of surface temperature and heat flux presents obvious lateral inhomogeneity, and the maximum wall temperature and heat flux were both obtained in region II. The thermal resistance of groove with α = 60° was lower but the liquid-discharged ability was better than that of groove with α = 75°. In order to validate the feasibility and reliability of the present analyses and to further investigate the heat transfer performance of trapezoid grooved surfaces, experiments were carried out with three condensing plates including two trapezoid grooved surfaces in different physical dimensions and one smooth surface. The experimental data obtained under various schooling were compared with the calculations, and the experimental results for different condensing plates are all in good agreement with the numerical model, with a maximum deviation less than 15%. Moreover, the trapezoid grooves can enhance the condensation heat transfer by 1.5–2.5 times higher than the smooth surface. The present analyses are feasible and can be used in the parameter design and heat transfer calculation of trapezoid grooved surfaces.

Experimentation and modeling of the steady-state and transient thermal performances of a helicoidally grooved cylindrical heat pipe

The thermal management of electronic components is one of the crucial problems in the electronics industry. Heat pipes are promising thermal devices which can be used in cooling systems. An experimental study is realized in order to determine the steady-state and transient thermal performances of a water filled copper cylindrical heat pipe including helicoidal and trapezoidal capillary grooves. A test rig is developed to determine the effects of various parameters on the heat pipe thermal performance. Experiments were carried out for different heat inputs and heat sink temperatures in steady-state and transient regimes. A model is developed in order to simulate the transient thermal response of such heat pipes. The model is based on RC network circuit. The thermal resistances are determined from the steady-state experiments and the thermal capacitances are calculated theoretically. The comparison between the experimental results and the simulated ones shows a good agreement whatever the heat sink temperature and the heat input power.

A high-power microwave circular polarizer and its application on phase shifter.

A high-power waveguide dual circular polarizer was theoretically designed and proof-of-principle was experimentally tested. It consists of two incident rectangular waveguides with a perpendicular H-plane junction, one circular waveguide with a pair of trapezoidal grooves coupled in E-plane at the top, a spherical crown located at the bottom, and an iris at the perpendicular junction of two rectangular waveguides. When wave incidents at one of the two separated rectangular waveguides, it, respectively, generates a left-hand circular polarized wave or a right-hand circular polarized wave in the circular waveguide. By adding a dumbbell-like metal plug driven with a high speed servomotor, a movable short circuit is formed along the circular waveguide to adjust the output RF phase of the rectangular port, realizing a high-speed high-power phase shifter. The C-band high power microwave (HPM) experiments were carried out, and the power capacity of the HPM polarizer and phase shifter was demonstrated to reach gigawatt level.

台形溝を有する平板間流路における圧力損失測定

台形溝を有する平板間流路における圧力損失測定

Study of heat transfer due through rib-groove channel to turbulent How of nanofluids

Nanofluids for improve characteristics flow in a rib-groove channel are investigate. The continuity, momentum and energy equations were solved by FLUENT program. The bottom wall of channel is heated while the upper wall is symmetry, the left side velocity inlet, and the right side is outlet (pressure out). Four different rib-groove shapes are used. Four different types of nanoparticles, Al2O3, CuO, SiO2, and ZnO with different volumes fractions in the range of 1% to 4% and different nanoparticle diameter in the range of 25 nm to 70 nm, are dispersed in the base fluid water are used. In this paper, several parameters such as different Reynolds numbers in the range of 10000 < Re < 40000 are investigated. The numerical results indicate that the trapezoidal with increasing height in the flow direction rib- trapezoidal groove has the best heat transfer and high Nusselt number; the nanofluids with SiO2 have the best behavior. The Nusselt number increases as the volume fraction increases and it decreases as the nanoparticle diameter increases.

Highly-confined and low-loss spoof surface plasmon polaritons structure with periodic loading of trapezoidal grooves

In this paper, we propose an ultra-thin spoof surface plasmon polaritons (SPPs) structure, periodically loaded with trapezoidal grooves. Compared to the reported SPPs with rectangular grooves, the proposed SPPs structure can support the guided surface SPP wave with enlarged propagation constant, which implies an enhanced confinement of surface wave along the spoof SPPs structure. Guided-wave characteristics of the proposed SPPs structure are theoretically investigated by virtue of a numerical short-open calibration (SOC) technique. The results show that the loss of spoof SPPs is lower than that in other reported spoof SPPs structures. Experiment on prototype in microwave frequency regime is carried out which validates the theoretical findings. It is believed that the proposed structure could be scaled to THz frequencies, and is very promising in developing the miniaturized planar surface plasmonic devices and circuitry.