scholarly journals A Modified Iterative Automatic Method for Characterization at Shear Resonance: Case Study of Ba0.85Ca0.15Ti0.90Zr0.10O3 Eco-Piezoceramics

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1666
Author(s):  
Lorena Pardo ◽  
Armando Reyes-Montero ◽  
Álvaro García ◽  
Alfredo Jacas-Rodríguez ◽  
Pilar Ochoa ◽  
...  
Keyword(s):  
Iterative Method ◽  
Piezoelectric Coefficient ◽  
Complex Impedance ◽  
Shear Mode ◽  
Rectangular Plates ◽  
Material Models ◽  
Shear Plate ◽  
Standard Plate ◽  
Shear Resonance

Coupling between electrically excited electromechanical resonances of piezoelectric ceramics is undesirable for the purpose of their characterization, since the material models correspond to monomodal resonances. However, coupling takes place quite often and it is unavoidable at the shear resonance of standard in-plane poled and thickness-excited rectangular plates. The piezoelectric coefficient e15, the elastic compliance s55E and the dielectric permittivity component ε11S for a piezoelectric ceramic can be determined, including all losses, using the automatic iterative method of analysis of the complex impedance curves for the shear mode of an appropriated resonator. This is the non-standard, thickness-poled and longitudinally excited, shear plate. In this paper, the automatic iterative method is modified. The purpose is to be able to deal with the analysis of the impedance curves of the non-standard plate as the periodic phenomena of coupling and decoupling of the main shear resonance and other resonances takes place. This happens when the thickness of the plate is reduced, and its aspect ratio (width of the excitation (w)/thickness for poling (t)) is increased. In this process, the frequency of the shear resonance also increases and meets those of other plate modes periodically. We aim to obtain the best approach for the shear properties of near coupling and to reveal both their validity and the limitations of the thus-obtained information. Finally, we use a plate of a Ba0.85Ca0.15Ti0.90Zr0.10O3 eco-piezoceramic as a case study.

scholarly journals Piezoelectric characterization of lead-free ferroelectric ceramics

2010 ◽  
Vol 4 (3) ◽  
pp. 199-207 ◽  
Author(s):  
Lorena Pardo ◽  
Alvaro García ◽  
Klaus Brebøl ◽  
Lavinia Curecheriu ◽  
Liliana Mitoseriu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Complex Impedance ◽  
Experimental Spectrum ◽  
Lead Free ◽  
Ferroelectric Ceramics ◽  
Coarse Grained ◽  
Shear Mode ◽  
Fine Grained ◽  
Accuracy Test

The challenge to develop high piezoelectric sensitivity and lead-free composition ferro-piezoelectric ceramics has recently dragged new attention to some classic ferroelectrics. Here, Ba(CexTi1-x)O3 (Ce-BT) and 0.94(Bi1/2Na1/2)TiO3-0.06BaTiO3 (BNBT6) ceramics were piezoelectrically characterized from measurements of complex impedance at electromechanical resonances and their analysis by Alemany et al. software. The reconstruction of the spectra for each resonance is used as an accuracy test of the set of calculated coefficients, quantitatively characterized by the regression factor (R2) of such reconstruction to the experimental spectrum. Piezoelectric activity at room temperature (RT) was observed for Ce-BT with x=0.06 and 0.1, ferroelectrics with T(?'max)>RT, but also for x=0.2 with T(?'max)<RT, which confirms its relaxor character (Ps?0 for T?T(?'max)). BNBT6 fine grained ceramics (~1 ?m) were prepared from nanopowder obtained by sol-gel autocombustion. Results obtained for the fine grained ceramic hot-pressed at 800?C for 2 h and recrystallized at 1050?C for 1 h are d33=148 pCN-1 and kp=26.8%. Despite of its lower grain size, the properties of this material are comparable with those reported for coarse grained ceramics obtained by sintering at T>1100?C. Some measurement issues, as the role of the mode coupling on the characterization results, illustrated for the shear mode of a thickness poled plate, are discussed.

scholarly journals Evaluation of Basement's Thermal Performance Against Thermal Comfort Model at Hot-arid Climates, Case Study (Egypt)

2017 ◽  
Vol 2 (1) ◽  
pp. 24
Author(s):  
Heba Hassan Kamel ◽  
Daisuke Sumiyoshi
Keyword(s):  
Iterative Method ◽  
Thermal Comfort ◽  
Thermal Performance ◽  
High Energy ◽  
Mean Bias Error ◽  
Comfort Levels ◽  
Diurnal Range ◽  
Energy Plus ◽  
Thermal Comfort Model

Reaching thermal comfort levels in hot-arid climates is becoming more difficult nowadays without the use of high energy consuming mechanical systems. Therefore, the need to use effective passive energy design techniques such as earth-sheltered buildings is becoming greater. This paper combines researches that uses monitoring and simulations in order to evaluate basements’ thermal performance that reached thermal comfort levels without active air-conditioning systems, despite the harsh climate conditions. The case study was conducted in Al-Minya city, Egypt, which is known for its high diurnal range. The study calibrated a non-conditioned basement simulation model versus the monitored data to simulate its thermal performance. The greatest challenge was to calculate the ground temperature. To do this successfully, we used an iterative approach between packages of the basement preprocessor and Energy Plus / Design Builder until reaching a convergence. The iterative method results showed significant agreement between the measured and modeled data; with a correlation of 98 percent and errors with mean bias error and normalized root mean square error of -1.0 and 7.6 percent; respectively. On the other hand, the Energy Plus method, integrating the Xing approach, showed significantly divergent results between the simulated models versus the measured data. The calibrated model analysis evaluation, using the Fanger’s thermal comfort model, showed satisfactory results within the thermal comfort sensation range. The research results significance indicates that the precise customized detailed iterative method is essential to create the needed inputs which subsequently lead to near-to-actual outputs compared with other ground-contact simulation methods. In fact, the precise customized detailed iterative method approach may be used as a benchmark for simulators for easy and precise ground temperatures’ calculations and earth-sheltered buildings’ simulations.

Iterative Method for Solving Rectangular Plates

1972 ◽  
Vol 98 (1) ◽  
pp. 135-151
Author(s):  
B. Sen ◽  
S. Sengupta ◽  
T. K. Nath
Keyword(s):  
Iterative Method ◽  
Rectangular Plates

scholarly journals Iterative Method in the Characterization of Piezoceramics of Industrial Interest

2006 ◽  
Vol 45 ◽  
pp. 2448-2458 ◽  
Author(s):  
L. Pardo ◽  
Miguel Algueró ◽  
K. Brebøl
Keyword(s):  
Iterative Method ◽  
Shear Mode ◽  
Element Analysis ◽  
Simulation Based ◽  
The Finite Element Analysis ◽  
The Matrix ◽  
Fea Simulation ◽  
Complex Characterization

Although characterization of piezoceramics from resonance is a customary technique, the works dealing with the determination of the ten elastic, dielectric and piezoelectric coefficients that are needed in the full matrix characterization of such 6mm symmetry materials are rather scarce. Even more, if the complex characterization is foreseen, thus accounting with the three types of losses, few are the methods avaliable to obtain the material linear coefficients. This work deals with such complex characterization by the use of Alemany et al. automatic iterative method. This method has been applied to the four modes of resonance that are sufficient for the purpose: (1) the length extensional mode of long rods, length poled, (2) the thickness extensional mode and (3) the radial mode of a thin disk, thickness poled, and (4) the thickness shear mode of a thin plate. Recent work of the authors has shown the limits in characterizing materials that arise from the use of the Standard shear geometry and, therefore, and alternative geometry is used here. This work presents the matrix characterization of some piezoceramics and the Finite Element Analysis (FEA) simulation based on such characterization, of the samples used as a reliability criteria of the results obtained by comparison of the experimental and simulated values at resonance of the electrical parameters.

Non-Rigid Variation Simulation for Ready-to-Assemble Furniture

2019 ◽  
Author(s):  
Kristina Wärmefjord ◽  
Rikard Söderberg ◽  
Lars Lindkvist ◽  
Andreas Dagman
Keyword(s):  
Future Development ◽  
Automotive Industry ◽  
Assembly Process ◽  
Furniture Industry ◽  
Contact Modeling ◽  
Material Models ◽  
Simulation Procedure ◽  
Variation Simulation

Abstract Ready-To-Assemble (RTA) furniture is becoming increasingly popular due to attractive pricing compared to standard furniture. However, for this kind of furniture to be attractive to the customer, the assembly process must be smooth. If the assembly requirements are fulfilled or not is, for this kind of assembly, ruled by the tolerances on part level. In this paper, a methodology for variation simulation of RTA furniture is presented. By predicting the fulfillment of requirement on assembly level, reasonable tolerances on part level can iteratively be set, to guarantee a smooth assembly process. The methodology includes material models, flexibility and bending during assembly, contact modeling and modeling of fastener elements between parts. Variation simulation is commonly used in the automotive industry and a comparison of variation simulation methodologies between the two kinds of industries is conducted. A major difference between RTA furniture business and automotive industry is that no fixtures are used for RTA furniture. This must be reflected in the simulation procedure. Furthermore, the results from the variation simulation need to be evaluated, and the results are dependent on the context of the assembled product. Both the assemblability and esthetical requirements, like flush, gap, and parallelism, need to be evaluated. The methodology is illustrated on a case study and future development and research needed to adapt variation simulation to furniture industry are discussed.

Residual Strength of Pitted Mild Steel Plates Subjected to Biaxial Compression

2016 ◽  
Author(s):  
Xiaoli Jiang ◽  
C. Guedes Soares
Keyword(s):  
Mild Steel ◽  
Pitting Corrosion ◽  
Residual Strength ◽  
Fem Analysis ◽  
Steel Plates ◽  
Biaxial Compression ◽  
Rectangular Plates ◽  
Nonlinear Fem ◽  
Unique Parameter

The present paper focus on the residual strength of pitted mild steel rectangular plate under biaxial compression. This paper aims to propose a general and practical formula to predict the residual strength of pitted rectangular plates under biaxial compression starting from the classic formula for intact rectangular plates and assessing whether it can be applicable to pitted plates, where the degree of pitting corrosion is modelled as one key parameter. Firstly, the numerical model is verified with an existing case study. Afterwards, a series of nonlinear FEM analysis are performed, changing geometrical attributes of both pits and plates, i.e., the radius and location of pits and the slenderness of plates. Based on those simulation results, it is found that the classic formula for intact rectangular plates can be applied reasonably well for pitting corroded plates. A unique parameter DOP (degree of pitting), which is easily determined, is employed to evaluate the effect of pitting corrosion with adequately accuracy and without bias to either longitudinal or transverse compressive stress. The proposed formula can provide guidance during the process of ship structural maintenance decision-making and strength reassessment conveniently.

scholarly journals An iterative method of statistical tolerancing based on the unified Jacobian–Torsor model and Monte Carlo simulation

2020 ◽  
Vol 7 (2) ◽  
pp. 165-176
Author(s):  
Heping Peng ◽  
Zhuoqun Peng
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Iterative Method ◽  
Iterative Process ◽  
Simulated Data ◽  
Small Displacement ◽  
Real Multiplication ◽  
Small Displacement Torsor ◽  
Statistical Tolerance

Abstract This paper focuses on exploring an iterative method of statistical tolerance design to guide designers to select tolerances more economically and effectively. After having identified the assembly functional requirement (FR) and the functional elements (FEs) of corresponding tolerance chain, the expression of a unified Jacobian–Torsor model can be derived. Monte Carlo simulation is employed to generate random variables simulating the variations of small displacement torsor associated with the FE pairs with all the generated random values being within the intervals constrained by the corresponding tolerance zones. Then, the real multiplication operations are repeatedly executed to this model, a large number of real torsor component values of FR will be obtained and we can perform statistical analysis for these simulated data to get the statistical limits of the assembly FR in the desired direction. The tolerances of critical FEs may need to be adjusted to satisfy the assembly FR imposed by the designer, and the percentage contribution of each FE to the assembly FR can help determine these critical tolerances that need to be tightened or loosened. Once the calculated FR is in close agreement with the imposed FR, the iterative process can be stopped, and the statistical tolerance redesign is achieved. The effectiveness of the proposed method is illustrated with a case study. Compared with the deterministic tolerancing method, the results show that the proposed method is more economical and that can relax significantly the precision required, manufacturing and inspection costs can then be reduced considerably.

scholarly journals Evaluation of Basement's Thermal Performance Against Thermal Comfort Model at Hot-arid Climates, Case Study (Egypt)

2017 ◽  
Vol 2 (1) ◽  
pp. 24
Author(s):  
Heba Hassan Kamel ◽  
Daisuke Sumiyoshi
Keyword(s):  
Iterative Method ◽  
Thermal Comfort ◽  
Thermal Performance ◽  
High Energy ◽  
Mean Bias Error ◽  
Bias Error ◽  
Comfort Levels ◽  
Diurnal Range ◽  
Thermal Comfort Model

Reaching thermal comfort levels in hot-arid climates is becoming more difficult nowadays without the use of high energy consuming mechanical systems. Therefore, the need to use effective passive energy design techniques, such as earth-sheltered buildings, is becoming greater.This paper describes research, that uses monitoring and simulations, to evaluate basements’ thermal performance, which reached thermal comfort levels without active air-conditioning systems, despite the harsh climate conditions. The case study was conducted in Al Minya city, Egypt, which is known for its high diurnal range. The study calibrated a non-conditioned basement simulation model versus the monitored data to simulate its thermal performance. The greatest challenge was to calculate the ground temperature. To do this successfully, we used an iterative approach between packages of the Basement preprocessor and EnergyPlus/Designbuilder until reaching a convergence.The iterative method results showed significant agreement, between the measured and modeled data, with a correlation of 98 percent, and errors with mean bias error and normalized root mean square error of -1.0 and 7.6 percent, respectively. On the other hand, the EnergyPlus method, integrating the Xing approach, showed significantly divergent results between the simulated models versus the measured data. The calibrated model analysis evaluation, using the Fanger’s thermal comfort model, showed satisfactory results within the thermal comfort sensation range.The research results significance indicates that the precise customized detailed iterative method is essential to create the needed inputs which subsequently lead to near-to-actual outputs compared with other ground-contact simulation methods. In fact, the precise customized detailed iterative method approach may be used as a benchmark for simulators for easy and precise ground temperatures’ calculations and earth-sheltered buildings’ simulations.

scholarly journals Design of a Computer-Aided Location Expert System Based on a Mathematical Approach

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1052
Author(s):  
Martin Straka
Keyword(s):  
Expert System ◽  
Iterative Method ◽  
Calculation Procedure ◽  
Graphical Display ◽  
Mathematical Approach ◽  
Classic Result ◽  
Computer Aided ◽  
X 32

This article discusses how to calculate the location of a point on a surface using a mathematical approach on two levels. The first level uses the traditional calculation procedure via Cooper’s iterative method through a spreadsheet editor and a classic result display map. The second level uses the author-created computer-aided location expert system on the principle of calculation using Cooper’s iterative method with the direct graphical display of results. The problem is related to designing a practical computer location expert system, which is based on a new idea of using the resolution of a computer map as an image to calculate location. The calculated results are validated by comparing them with each other, and the defined accuracy for a particular example was achieved at the 32nd iteration with the position optima DC[x(32);y(32)] = [288.8;82.7], with identical results. The location solution in the case study to the defined accuracy was achieved at the 6th iteration with the position optima DC[x(6);y(6)] = [274;220]. The calculations show that the expert system created achieves the required parameters and is a handy tool for determining the location of a point on a surface.

ON THE GALERKIN - ITERATIVE METHOD APPLIED TO THE NON-LINEAR VIBRATIONS OF RECTANGULAR PLATES

2011 ◽  
Author(s):  
Frederico M. A. Silva ◽  
Flávio Augusto X. C. Pinho ◽  
Zenón J. G. N. del Prado ◽  
Paulo B. Gonçalves
Keyword(s):  
Iterative Method ◽  
Rectangular Plates ◽  
Non Linear ◽  
Linear Vibrations
Sign in / Sign up

Export Citation Format

Share Document