Expansion Cavity Model Research Articles

A novel comprehensive framework for surface roughness prediction of integrated robotic belt grinding and burnishing of Inconel 718

Surface roughness serves as a critical metric for assessing surface integrity, directly influencing the service performance of components. Hardening burnishing is a regularly used post-grinding procedure for Inconel 718 that can simultaneously reduce surface roughness and improve surface mechanical characteristics. A novel comprehensive framework is proposed to predict the surface roughness of Inconel 718 processed by the integrated robotic belt grinding and burnishing system developed in this study. Accounting for abrasive grain conditions and material removal rate during grinding, the L-BFGS-B optimization algorithm and image processing are utilized to predict the ground surface roughness first. Building upon this foundation, theoretical models are applied to ascertain the critical burnishing force needed to enter the hardening burnishing stage. Following this, the Expansion Cavity Model and Hertz theory are used to predict the roughness of the hardening burnished surface, which is only applicable when the step-over value exceeds a critical value. The proposed framework not only enhances our comprehension of the mechanisms underlying material surface deformation but also offers a novel avenue for predicting surface roughness during integrated robotic belt grinding and burnishing with high accuracy.

A simple stress field solution for conical indentation

Classical contact mechanics has revealed the theoretical conical indentation solution of a stress field for ideal elastic–plastic materials based on the expansion cavity model and elastoplastic theory. This study proposes an equivalent stress analytical equation for the representative volume element of the median energy density point under conical indentation. For materials whose constitutive relations conform to power-law hardening, the equivalent stress solution is defined as the characteristic stress factor, and a simple stress field solution characterized by the logarithmic distribution law of dimensionless stress for conical indentation is presented. The verification results of finite element analysis showed that the proposed solution can uniformly describe the distribution of equivalent stress and three principal stresses in the material deformation region near the cone tip.

Numerical Analysis of Effect of Temperature on Ball Indentation Behaviour of Armox500T and IN718

Temperature dependence of ball indentation behaviour of Armox500T and IN718 in terms of Meyer’s hardness, constraint factor (CF) and pile-up around indentation as a function of average strain at ambient temperature and elevated temperature (673 K) has been analysed using FEA. Subsequently, FE model has been validated by experimental data for IN718 and Armox500T. The value of CF for Armox500T and IN718 at RT is found to be 2.80 and 2.75, respectively. The CF value is increased to 3.66 and 3.41, respectively, at 673 K indicating the dependence of temperature. It is also observed that pile-up at a given strain for Armox500T is higher (low strain hardening) compared to IN718 (high strain hardening) under static indentation conditions. The FEA results are in good agreement with expansion cavity model and fully plastic model.

Circuit Theory Analysis of Aperture Coupled Patch Antenna for Wireless Communication

An analysis of dual band aperture coupled microstrip patch antenna is performed using modal expansion cavity model. The theoretical investigation of antenna characteristics such as return loss, VSWR and radiation pattern is represented. The influence of geometric parameters of the aperture coupled microstrip patch antenna, such as aperture length and width, height of the substrate, dielectric constant are also investigated. It is found that antenna resonates at two distinct modes i.e. 4.39 and 5.55 GHz for lower and upper resonance frequencies respectively. The bandwidth of the aperture coupled microstrip patch antenna at lower resonance frequency is 10.23% (theoretical) and 13.33% (simulated) whereas at upper resonance frequency, it is 5.69% (theoretical) and 3.59% (simulated). The frequency ratio obtained for upper to lower resonance frequencies for theoretical and simulated results are 1.5 and 1.37 respectively. The theoretical results are compared with IE3D simulation results along with reported experimental results and they are in close agreement.

Circularly Polarized Annular Ring Microstrip Antenna for High Gain Application

ABSTRACTDesign, simulation and measurement of high gain annular ring microstrip antenna with L-shaped strip for circular polarization is presented. The simulated and experimental results are obtained using Ansoft’s commercially available High Frequency Structure Simulator (HFSS, Brookfield WI) software and the Agilen (Santa Clara, CA) vector network analyzer (N5230A.PNA-L), respectively. Parametric study of input characteristics of the proposed antenna is carried out using modal expansion cavity model and circuit theory concept. Theoretical, simulated, and measured results show good accord between each other. For the TM12 mode, measured results illustrated an impedance bandwidth and axial ratio bandwidth of 28.20 and 10.4%, respectively. With high gain, low profile, good radiation pattern, and simple structure, it can find potential industrial application in X-band to communicate between peripherals with each other.

Single Feed L-Slot Microstrip Antenna for Circular Polarization

In this paper, a single layer asymmetric L-slot loaded microstrip patch antenna for circular polarization is proposed. The suggested L-slot excites the two orthogonal patch modes in phase quadrature for circular polarization without truncating any corner of the probe feed square patch. A parametric study has been carried out to investigate the effects caused by different arm length and width of the L-slot. Theoretical analysis using modal expansion cavity model is developed for the L-slot antenna and result are verified with simulated and experimental results. The 3-dB axial ratio bandwidth of the proposed antenna is 1.8 %. The overall antenna size is 46 mm × 46 mm × 1.6 mm.

Orthogonal slot-loaded coaxially stacked annular ring antenna with circular patch for multiband application

A coaxially stacked annular ring microstrip antenna (ARMSA) and circular microstrip antenna using L-probe feed and orthogonally slot-loaded at the inner periphery of the ARMSA is designed and fabricated for multiband application. The theoretical analysis of the proposed antenna has been carried out using modal expansion cavity model and circuit theory concept. Simulation of the proposed antenna has been performed using Ansoft HFSS software. The experimental results of input characteristic are obtained using Agilent™ vector network analyzer. The proposed antenna is resonating in L-band (1.88 GHz), S-band (2.51 GHz), and C-band (3.81 and 4.88 GHz) band with 6.38, 9.96, 2.62, and 3.27% impedance bandwidth, respectively. Theoretical and simulated results are in good agreement with experimental results.

Prediction of stone column ultimate bearing capacity using expansion cavity model

The ultimate bearing capacity of an isolated column was investigated by combining a state of stress with a failure mechanism of lateral expansion in a cylindrical cavity which reproduces the stone column installation in a purely cohesive soft soil. Some analytical and empirical methods were used to determine the limit pressure of a cylindrical cavity with the assumption of varied behaviour laws of the medium around the cavity. These models permitted the calculation of the limit pressure of an expanded cylindrical cavity from which the ultimate bearing capacity was derived. Using recorded in situ data from load tests performed on 13 isolated column configurations, the model parameters are identified. A comparison between experimental data and predictions generated from several models is presented.

Design and Analysis of Cavity Backed Annular Ring Microstrip Antenna for Personal Wireless Communication

Effect of cylindrical metallic cavity enclosure on resonant frequency of the annular ring microstrip antenna (ARMSA) having air-gap between substrate and ground plane is studied. The proposed antenna is analyze theoretically using modal expansion cavity model and circuit theory concept and verified by simulated results using Ansoft HFSS simulation software and experimental results. Theoretical and measured result of input characteristics shows good agreement with simulated results. Effect of cylindrical metallic cavity backing on resonance frequency of ARMSA is investigated for different air gap height and inner patch radius. The patch miniaturization of about 15 % is achieved using cavity backed ARMSA.

Wideband and compact slot loaded annular ring microstrip antenna using L-probe proximity-feed for wireless communications

A wideband orthogonally slot cut annular ring microstrip antenna fed by L-shaped probe is investigated using modal expansion cavity model and circuit theory approach. Simulation of the proposed antenna is performed using Ansoft HFSS and simulated results are compared with the measured and theoretical results. The impedance bandwidth of about 37.46% is observed at resonant frequency 3.15 GHz. The proposed antenna realizes an improvement in bandwidth of 13.46% and miniaturization in physical dimension about 10% from earlier reported structures. An improvement in bandwidth and miniaturization is due to thick substrate, L-probe feed, and orthogonally loaded slots. The measured results of fabricated antennas are in good agreement with simulated and theoretical results.

Analysis of L-probe Proximity Fed Annular Ring Patch Antenna for Wireless Applications

In the present paper, annular ring patch antenna with L-probe feeding has been analyzed using modal expansion cavity model. The proposed antenna shows wide band and ultra wide band operation which depends on the position of L-probe feeding and position of the shorting pin. For the fundamental $$\hbox {TM}_{11}$$ TM 11 mode, the bandwidth and gain is found to be 38.85 % and 7.8 dBi while for higher order $$\hbox {TM}_{12}$$ TM 12 mode bandwidth is obtained 58.71 % with corresponding gain of 6.1 dBi. The effect of shorting pin on the proposed antenna is also studied and it is found that the radiating structure is more compact in nature and improves the bandwidth upto 47.37 % with 8.0 dBi gain. Further, the proposed antenna has broadside radiation pattern over the entire bandwidth. The theoretical results are compared with IE3D simulated results which are in good agreement.

ANALYSIS OF MICROSTRIP LINE FEED SLOT LOADED PATCH ANTENNA USING ARTIFICIAL NEURAL NETWORK

In this article, the parametric analysis of the slot-loaded microstrip line feed patch antenna is investigated using artiflcial neural network model. The bandwidths of the proposed antenna obtained at TM01, TM02, and TM03 frequency modes are 10.2GHz, 13.6GHz, and 17.2GHz, respectively. The performance of the proposed antenna is analyzed using artiflcial neural network model. The changes obtained in bandwidth due to the position of slot length and slot width are reported. The antenna parameters such as return loss, VSWR, gain and e-ciency are also calculated. The simulated results obtained with the help of IE3D simulation software are trained and tested using ANN. Theoretical results are compared with simulated and experimental ones, and they are in close agreement. Microstrip antennas have sparked interest among researchers because of their attractive features like low proflle, light weight, and conformal to mounting structures, but they have two most serious limitations, narrow bandwidth and low gain (1). Available methods for the analysis of MSA have high level of complexity. Generally, there are two methods for analysis of microstrip antenna such as numerical method and analytical method. The numerical methods is complicated compared to analytical methods and require much more time, whereas, analytical methods are easy and specifled to only some deflnite shapes of microstrip antenna. An artiflcial neural network (ANN) is used here for reducing some of these problems. ANNs are computational tools that learn from experience (training), which provide fast and accurate models for microwave modeling, simulation, and optimization. Using artiflcial neural network microstrip patch antenna was reported by Vegni and Toscano (2) in which they proposed the analysis of MSA using artiflcial neural network. Further, Mishra and Patnaik (3,4) proposed a CAD model for the design of square patch antenna and artiflcial model for efiective dielectric constant of microstrip line. Later, CAD model using spectral domain formulation (5) was also reported for the designing of rectangular patch antenna. Therefore, Guney and Sarikaya (6) proposed a comparative study of MAMDANI and Sugeno fuzzy interface system models for the resonant frequency calculation of rectangular microstrip patch antenna. Several other papers have also used ANN model to analyze and synthesize the microwave circuits (7{15). Thakare and Singhal (16) proposed the analysis of broadband slot-loaded inset feed microstrip patch antenna using ANN model. Most of these papers are based on ANN model presented only simulated and experimental results. In this paper, we provide a theoretical investigation and compare its results with simulated and experimental ones. In this paper, the microstrip line feed slot-loaded patch antenna is proposed. Its theoretical, simulated and ANN results have also been verifled experimentally. The proposed antenna is investigated for triple frequency-band operation, so that single antenna can be utilized for more than one frequency bands. The theoretical analysis of the proposed antenna is discussed using circuit theory concept based on modal expansion cavity model whereas ANN used RBFNN model.

Compact notch loaded half disk patch antenna for dualband operation

In this article, microstrip patch antenna loaded with two symmetrical vertical notches and shorting pin is investigated for dualband operation using circuit theory concept based on modal expansion cavity model. It is found that the antenna resonates at 2.84 and 6.33 GHz for upper and lower resonance frequencies respectively. The bandwidth of the compact notch loaded antenna at lower resonance frequency is 9.94 % (theoretical) and 6.67 % (simulated) whereas at upper resonance frequency, it is 12.99 % (theoretical) and 11.59 % (simulated). The compact notch loaded antenna characteristics are compared with other proposed radiating structures. The theoretical results are compared with IE3D simulation as well as reported experimental results and they are in close agreement.

Effect of temperature on constraint factor of IN718 under static indentation conditions

Static indentation and compression tests have been carried out on IN718 in the temperature range of 300–1073 K with a view to evaluate the effect of temperature on constraint factor (CF), that is the ratio of indentation hardness to flow stress. The value of CF is found to be below 3 at room temperature and above 3 at elevated temperatures. The experimental results are also compared with Expansion Cavity Model (ECM) and Fully Plastic Model (FPM).

Analysis of half E‐shaped patch for wideband application

AbstractA half E‐shaped patch antenna is analyzed using equivalent circuit model based on modal expansion cavity model. The antenna shows almost 50% reduction in size with the same performance as achieved by full E‐shaped patch. The proposed theory is verified by simulation and experimental results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1576–1580, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24367

Analysis of inclined slot‐loaded patch for dual‐band operation

AbstractThe theoretical analysis of a single feed inclined slot‐loaded rectangular microstrip patch antenna is presented using modal expansion cavity model and circuit theory concept. By cutting the inclined slot along the radiating edge of the patch, a dual‐frequency operation is obtained. The input impedance, VSWR, and return loss are calculated. It is found that the frequency ratio of two resonant frequencies can be varied from 1.92 to 2.44 by the inclination angle of the slot. The theoretical results are validated by experimental results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2436–2441, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21965

MOS capacitor loaded frequency agile microstrip antenna

A new MOS capacitor loaded frequency agile microstrip patch antenna is proposed in which the operating frequency of the rectangular microstrip antenna is electronically controlled by the bias voltage of the MOS capacitor. Theoretical investigations, based on a modal expansion cavity model as well as an improved theory of Richards et al. (1981, IEEE Transactions on Antennas and Propagation, 29, 38-41), are carried out for five different oxide (Si3N4) thicknesses from 100 Å to 500 Å for the (Au-Si3N4-Si) MOS structure. The maximum obtainable frequency tuning range (76.08%) is achieved for the lowest value of oxide thickness (100 Å); this is almost 1.5 times the value reported for the varactor loaded patch antenna. The larger frequency variation is achieved with lower variation in the bias voltage as compared with the varactor.

Input Impedance, Bandwidth and Efficiency of an Edge-Modulated Microstrip Antenna

A sinusoidally edge-modulated microstrip patch antenna has been analysed using the modal expansion cavity model. The investigations have been carried out to explore the input impedance, bandwidth and radiation efficiency of the modulated structure against its physical parameters like the modulation depth and periodicity. The simulated results clearly show that the bandwidth increases with modulation depth under certain conditions of excitation. The analysis further shows that the modulated structure provides a lot of flexibility in matching the antenna to the standard feeder lines. Experimental results tally satisfactorily with the theoretical data.

Frequency agile microstrip patch antenna

A rectangular patch loaded with shorting posts as well as varactor diodes was investigated theoretically using a Modal Expansion Cavity Model, with a view to predicting the obtainable tuning range and its effect on the radiation characteristics of the antenna. The tuning range in the shorting-posts loaded patch was found to be 450 MHz, which is almost double the earlier reported data, whereas in the varactor-loaded patch it was almost the same as reported range. The results obtained from the proposed method are in good agreement with the previously reported one.

Studies on the Radiation Pattern of a Sinusoidally Edge-Modulated Microstrip Patch Antenna

A sinusoidally edge-modulated microstrip patch antenna has been proposed and studied which provides some additional design parameters like its modulation factor r and periodicity p controlling the radiation characteristics. Both theoretical and experimental studies have been made on radiation pattern with different values of r and p for different modes of operation. The modal expansion cavity model has been employed for the analysis which shows that the physical parameters of the modulated structure have significant effects on its radiation characteristics. The property of widening of the beamwidth with the modulation factor suggests that the proposed antenna structure may find application in mobile communication systems. The theoretical data tally with the experimental results.