방사선 조사 환경에서 압전소재의 활용 및 열화 거동 문헌 연구

맹완영,박진주,문성인 한국비파괴검사학회 2022 한국비파괴검사학회지 Vol.42 No.3

Piezoelectric materials are used for accelerometers in loose part monitoring systems (LPMS), Internal vibration monitoring systems (IVMS), and reactor coolant pump vibration monitoring systems (RCP-VMS), which are systems for detecting vibration and foreign substances in nuclear power plants. Acoustic emission (AE) sensor materials (piezoelectric materials) for detecting cracks are essential for securing the reliability of nuclear power plants. In addition, piezoelectric materials are used in various ways as sensors for monitoring structure integrity and measuring properties in radiation irradiation environments such as research reactors and radioactive waste disposal sites. When radiation, such as neutrons and gamma rays, is irradiated onto piezoelectric materials, the materials are degraded by atomic displacement and ionization in the material lattice. Recently, research has been actively conducted to develop a reliable material that withstands degradation even when used for a long time in a radiation environment. To secure long-term reliability of piezoelectric materials in a radiation irradiation environment such as a nuclear power plant, understanding and verifying test data on the degradation behavior of the materials according to the radiation dose are essential. In this study, research results related to the effect of radiation on piezoelectric materials were investigated and analyzed. Data on the radiation degradation behavior of piezoelectric materials were systematically classified and summarized to be used as basic data for the development and application of new piezoelectric materials. 압전소재는 원자력발전소의 진동, 이물질 및 균열을 감지하기 위한 시스템인 LPMS(Loose Part Monitoring Systems), IVMS(Internal Vibration Monitoring Systems), RCP-VMS(Reactor Coolant Pump Vibration Monitoring System) 등에 사용되는 가속도계(acelerometers), AE(Acoustic Emision) 센서의 소재로서 원전 신뢰성 확보를 위한 필수적인 재료이다. 또한 압전소재는 연구로 및 방사성 폐기물처분장과 같은 방사선 조사 환경에서 구조물 감시 및 물성 측정 센서로 다양하게 활용되고 있다. 중성자 및 감마선과 같은 방사선이 압전소재에 조사되면 재료 격자 내부의 원자 이동(atomic displacement), 이온화 등을 통해 소재가 열화된다. 최근에는 방사선 환경에서 장기간 사용 시에도 열화에 견디는 신뢰성 있는 소재를 개발하기 위한 연구가 활발히 진행되고 있다. 원전과 같은 방사선 조사 환경에서 압전소재의 장기적인 신뢰성을 확보하기 위해서는 방사선량에 따른 소재의 열화 거동에 대한 이해 및 실증 시험 자료의 확보가 필수적이다. 본 연구에서는 압전소재에 미치는 방사선의 영향에 관련된 연구 문헌들을 조사·분석하여 압전소재의 방사선 열화 거동에 대한 자료를 체계적으로 종합하여 새로운 압전 소재 개발·응용의 기초자료로 활용하고자 하였다.

압전기법을 이용한 복합재료 손상모니터링의 가능성에 관한 연구

황희윤(Hui-Yun Hwang) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.11

Since crack detection for laminated composites in-service is effective to improve the structural reliability of laminated composites, it have been tried to detect cracks of laminated composites by various nondestructive methods. An electric potential method is one of the widely used approaches for detection of cracks for carbon fiber composites, since the electric potential method adopts the electric conductive carbon fibers as reinforcements and sensors and the adoption of carbon fibers as sensors does not bring strength reduction induced by embedding sensors into the structures such as optical fibers. However, the application of the electric method is limited only to electrically conductive composite materials. Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints because it can monitor continuously the damage of adhesively bonded structures without producing any defects. Polymeric materials for the matrix of composite materials have piezoelectric characteristics similarly to adhesive materials, and the fracture of composite materials should lead to the fracture of polymeric matrix. Therefore, it seems to be valid that the piezoelectric method can be applied to monitoring the damage of composite materials. In this research, therefore, the feasibility study of the damage monitoring for composite materials by piezoelectric method was conducted. Using carbon fiber epoxy composite and glass fiber composite, charge output signals were measured and analyzed during the static and fatigue tests, and the effect of fiber materials on the damage monitoring of composite materials by the piezoelectric method was investigated.

압전기법을 이용한 복합재료 손상모니터링의 가능성에 관한 연구

황희윤(Hui Yun Hwang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Since crack detection for laminated composites in-service is effective to improve the structural reliability of laminated composites, it have been tried to detect cracks of laminated composites by various nondestructive methods. An electric potential method is one of the widely used approaches for detection of cracks for carbon fiber composites, since the electric potential method adopts the electric conductive carbon fibers as reinforcements and sensors and the adoption of carbon fibers as sensors does not bring strength reduction induced by embedding sensors into the structures such as optical fibers. However, the application of the electric method is limited only to electrically conductive composite materials. Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints because it can monitor continuously the damage of adhesively bonded structures without producing any defects. Polymeric materials for the matrix of composite materials have piezoelectric characteristics similarly to adhesive materials, and the fracture of composite materials should lead to the fracture of polymeric matrix. Therefore, it seems to be valid that the piezoelectric method can be applied to monitoring the damage of composite materials. In this research, therefore, the feasibility study of the damage monitoring for composite materials by piezoelectric method was conducted. Using carbon fiber epoxy composite and glass fiber composite, charge output signals were measured and analyzed during the static and fatigue tests, and the effect of fiber materials on the damage monitoring of composite materials by the piezoelectric method was investigated.

Sintering Mechanism and Enhanced Piezoelectric and Crystal Structural Properties of (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 Lead Free Ceramics

오유영,이광섭,Masao Kamiko,고중혁 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.2

A lead-free piezoelectric ceramic, (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (hereafter (1-x)BZT-xBCT), was investigated for functional device applications. Lead-free piezoelectric materials with high piezoelectric charge coefficients and voltage coefficients are indispensable for functional industrial applications. Piezoelectric ceramic specimens tend to shrink in size during the sintering process without melting. This study focused on this phenomenon as a unique characteristic of piezoelectric ceramic materials, and derived the materials’ activation energies from this phenomenon, employing the Arrhenius relationship. Then the estimated activation energy was employed to determine the relationship between the piezoelectric properties and crystalline properties, while varying sintering temperature and chemical stoichiometric composition. Piezoelectric properties can change depending on the sintering temperature and process conditions. Crystalline properties and piezoelectric properties can be influenced by the sintering temperature and holding times. In this research, sintering temperature dependent structural and dielectric properties were investigated. (1-x)BZT-xBCT ceramics showed the highest piezoelectric coefficient of 470 pC/N. Sintering temperature dependent shrinkage rate and activation energy were estimated and calculated for the various sintering processes. In this research, two different activation energies for the shrinkage process were estimated.

Design of piezoelectric energy harvesting structures using ceramic and polymer materials

P. Mangaiyarkarasi,P. Lakshmi,V. Sasrika 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4

Piezoelectric sensors are designed in this work to power implantable medical devices (IMDs). A prosthetic hand is used as the IMD in this study. E, Π, and T piezoelectric structures are designed using five ceramic (PZT-5H, PZT-4D, BaTiO 3 , ZnO, and GaAs) and five polymer (Hytrel 3078, polyetherimide [ULTEM 2100], polyoxymethylene [POM], polyvinylenedifluoride [PVDF, Kynar 710], and Elvax 260) materials. Further analysis is carried out using square and rectangular-shape proof masses under different load conditions. This study aims to determine the maximum power that can be used from the piezoelectric harvester to supply energy to a medical device, such as the prosthetic hand. Structure and material analyses showed that the maximum power generated by the E structure using ceramic material (PZT-5H) with rectangular-shape proof mass ensures the efficient powering of the IMD. The simulation is carried out using COMSOL Multiphysics 5.3a software.

Effect of O-ring Deformation on Saturated Load Pressure of the Small Piezoelectric-Hydraulic Pump Brake System

NGUYEN ANH PHUC,황재혁,배재성 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.1

This paper examines the effect of deformation of the O-ring on maximum pressure in the load side of the small piezoelectric-hydraulic pump brake system. In the previous study, the small piezoelectric-hydraulic pump braking system used for small- and medium-sized unmanned aerial vehicles was developed. To operate the brake system, load pressure must be formed. The magnitude of the load pressure is determined by the pressure in the chamber and the adapted check valve type. Therefore, a study of the parameters affecting the chamber pressure is necessary to improve the load side pressure. The volume change of the O-ring seal has a complicated effect on the maximum pressure in the chamber of the piezoelectric-hydraulic pump. Accordingly, this study analyzed the effect of the O-ring on chamber pressure, considering the changing volume of the O-ring seal with nonlinear property material. The deformation of the O-ring made of nitrile-butadiene rubber was investigated using the finite-element method. In addition, the optimal radius of the piston was determined to obtain the maximum chamber pressure. The obtained maximum pressure and optimal radius are verified by comparison with the pressurization experiment using the developed small piezoelectric-hydraulic pump brake system.

Buckling delamination of the PZT/Metal/PZT sandwich circular plate-disc with penny-shaped interface cracks

Fazile I. Cafarova,Surkay D. Akbarov,Nazmiye Yahnioglu 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.2

The axisymmetric buckling delamination of the Piezoelectric/Metal/Piezoelectric (PZT/Metal/PZT) sandwich circular plate with interface penny-shaped cracks is investigated. The case is considered where open-circuit conditions with respect to the electrical displacement on the upper and lower surfaces, and short-circuit conditions with respect to the electrical potential on the lateral surface of the face layers are satisfied. It is assumed that the edge surfaces of the cracks have an infinitesimal rotationally symmetric initial imperfection and the development of this imperfection with rotationally symmetric compressive forces acting on the lateral surface of the plate is studied by employing the exact geometrically non-linear field equations and relations of electro-elasticity for piezoelectric materials. The sought values are presented in the power series form with respect to the small parameter which characterizes the degree of the initial imperfection. The zeroth and first approximations are used for investigation of stability loss and buckling delamination problems. It is established that the equations and relations related to the first approximation coincide with the corresponding ones of the three-dimensional linearized theory of stability of electro-elasticity for piezoelectric materials. The quantities related to the zeroth approximation are determined analytically, however the quantities related to the first approximation are determined numerically by employing Finite Element Method (FEM). Numerical results on the critical radial stresses acting in the layers of the plate are presented and discussed. In particular, it is established that the piezoelectricity of the face layer material causes an increase (a decrease) in the values of the critical compressive stress acting in the face (core) layer.

Control of free vibration with piezoelectric materials: Finite element modeling based on Timoshenko beam theory

Song, Myung-Kwan,Noh, Hyuk-Chun,Kim, Sun-Hoon,Han, In-Seon Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.5

In this study, a new smart beam finite element is proposed for the finite element modeling of beam-type smart structures that are equipped with bonded plate-type piezoelectric sensors and actuators. Constitutive equations for the direct piezoelectric effect and converse piezoelectric effect of piezoelectric materials are considered in the formulation. By using a variational principle, the equations of motion for the smart beam finite element are derived. The proposed 2-node beam finite element is an isoparametric element based on Timoshenko beam theory. The proposed smart beam finite element is applied to the free vibration control adopting a constant gain feedback scheme. The electrical force vector, which is obtained in deriving an equation of motion, is the control force equivalent to that in existing literature. Validity of the proposed element is shown through comparing the analytical results of the verification examples with those of other previous researchers. With the use of smart beam finite elements, simulation of free vibration control is demonstrated by sensing the voltage of the piezoelectric sensors and by applying the voltages to the piezoelectric actuators.

Analytical evaluation and experimental validation of energy harvesting using low frequency band of piezoelectric bimorph actuator

Kaushik Mishra,Subrata K. Panda,Vikash Kumar,Hukum Chand Dewangan 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.3

The present article reports the feasibility of the electrical energy generation from ambient low-frequency vibration using a piezoelectric material mounted on a bimorph cantilever beam actuator. A corresponding higher-order analytical model is developed using MATLAB in conjunction with finite element method under low-frequency with both damped and undamped conditions. An alternate model is also developed to check the material and dimensional viability of both piezoelectric materials (mainly focussed to PVDF and PZT) and the base material. Also, Genetic Algorithm is implemented to find the optimum dimensions which can produce the higher values of voltage at low-frequency frequencies (≤ 100 Hz). The delamination constraints are employed to avoid inter-laminar stresses and to increase the fracture toughness. The delamination has been done using a Teflon sheet sandwiched in between base plates and the piezo material is stuck to the base plate using adhesives. The analytical model is tested for both homogenous and isotropic material characteristics of the base material and extended to investigate the effect of the different geometrical parameters (base plate dimensions, piezo layer dimensions and placement, delamination thickness and placement, excitation frequency) on the model responses of the bimorph cantilever beam. It has been observed that when the base material characteristics are homogenous, the efficiency of the model remains higher when compared to the condition when it is of isotropic material. The necessary convergence behaviour of the current numerical model has been established and checked for the accuracy by comparing with available published results. Finally, using the results obtained from the model, a prototype is fabricated for the experimental validation via a suitable circuit considering Glass fibre and Aluminium as the bimorph material.

Engineered Domain Configuration and Piezoelectric Energy Harvesting in 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 Single Crystals

Hyun-Cheol Song,강종윤,윤석진,정대용 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.3

The performance of cantilever piezoelectric energy harvesters using three types of piezoelectric materi-als, relaxor ferroelectric 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) single crystals oriented along the <110> and <001> directions, and a PZT-based ceramic, were investigated. The <110> and <001> ori-ented PMN–PT single crystals, which have a rhombohedral phase and spontaneous polarization along the <111> direction, presented electromechanical coupling factor k31’s of 0.78 and 0.42, respectively. The cantilever-type energy harvester operated by 31 resonance mode generated a larger output power of 1.07mW for the <110> oriented PMN-PT single crystal compared to those of the other materials. The effective electromechanical coupling factor of the piezoelectric energy harvester with the <110> ori-ented crystal also reached 0.25, not achievable with the other piezoelectric materials. These results dem-onstrate that the domain engineering of the piezoelectric single crystals can provide higher design flexibility for a tiny energy harvester.