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Dynamic characterization of satellite assembly for responsive space applications
Mascarenas, David,Macknelly, David,Mullins, Josh,Wiest, Heather,Park, Gyuhae IOP Pub 2013 Measurement Science and Technology Vol.24 No.7
<P>The rapid deployment of satellites for responsive space surveillance applications is hindered by the need to flight-qualify their components and the resulting mechanical assembly. Conventional methods for qualification testing of satellite components are costly and time consuming. Furthermore, full-scale vehicles must be subjected to simulated launch loads during testing, and this harsh testing environment increases the risk of damage to satellite components during qualification. This work focuses on replacing this potentially destructive testing procedure with a non-destructive structural health monitoring (SHM)-based technique while maintaining the same level of confidence in the testing procedure's ability to qualify the satellite for flight. We focus on assessing the performance of SHM techniques to replace the high-cost qualification procedure and to localize faults introduced by improper assembly. The goal of this work is to create a dual-use system that can both assist in the process of qualifying the satellite for launch, as well as provide continuous structural integrity monitoring during manufacture, transport, launch and deployment. SHM techniques were applied on a small-scale structure representative of a responsive satellite. The test structure consisted of an extruded aluminum space-frame covered with aluminum shear plates assembled using bolted joints. Multiple piezoelectric transducers were bonded to the test structure and acted as combined actuators and sensors. Piezoelectric active-sensing based techniques, including measurements of low-frequency global frequency response functions and high-frequency wave propagation techniques, were employed. Using these methods in conjunction with finite element modeling, the dynamic properties of the test structure were established and areas of potential damage could be identified and localized. A procedure for guiding the effective placement of the sensors and actuators is also outlined.</P>
무인기 날개 변형 센싱을 위한 파일롯 팔 착용형 무선 햅틱 인터페이스 개발
이정률,김형철,강래형,박찬익,David L. Mascarenas,Charles R. Farrar 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.4
무인기는 지상에서 파일롯에 의해 비행 제어되는 데, 파일롯이 날개의 변형을 실시간으로 인지 하는 기술이 필요하며 일체형구조건전성모니터링에 의해 날개의 변형을 파일롯에게 전달되는 연구가 체계투입을 목표로 진행 중에 있다. 그러한 기체 변형 정보는 지상 파일롯의 시각을 통해 모니터링되는데, 본 논문에서는 시각이 아닌 촉각을 이용하여 파일롯이 보는 것이 아니라 느끼게 해주는 인터페이스(“Fly-by-Feel”)를 제안한다. 4 개의 광섬유브래그격자 변형률 센서가 날개시편에 설치되고 획득된 변형률은 베르누이-오일러 빔 모델 기반 변형률 및 변위 모드 형상에 입력된다. 획득된 날개 변형정보는 지상 파일롯의 팔에 착용할 수 있는 인터페이스에 설치된 다수의 진동햅틱모터를 가진하기 위해 무선으로 전달된다. When the flight of an unmanned air vehicle is controlled by a ground pilot, wing deformation monitoring technology is required. Therefore, integrated structural health monitoring technology is being developed to transfer such information to the pilot in real time for real world application. In general, the information is monitored by the vision of the ground pilot. In this paper, we propose an interface for “fly-by-feel” using not vision but haptic for the transfer of the wing deformation information. Four integrated fiber Bragg grating sensors were installed in a wing specimen to measure dynamic strains and the measured strains were input to displacement and strain mode shapes based on Bernoulli-Eulerbeam equation. The wing deformation information was wirelessly transferred to actuate vibro-haptic motors installed in a pilot arm-wearable haptic interface.
박재형,김정태,홍동수,David Mascarenas,Jerome Peter Lynch 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.6
This study presents the design of autonomous smart sensor nodes for damage monitoring of tendons and girders in prestressed concrete (PSC) bridges. To achieve the objective, the following approaches are implemented. Firstly, acceleration-based and impedance-based smart sensor nodes are designed for global and local structural health monitoring (SHM). Secondly, global and local SHM methods which are suitable for damage monitoring of tendons and girders in PSC bridges are selected to alarm damage occurrence, to locate damage and to estimate severity of damage. Thirdly, an autonomous SHM scheme is designed for PSC bridges by implementing the selected SHM methods. Operation logics of the SHM methods are programmed based on the concept of the decentralized sensor network. Finally, the performance of the proposed system is experimentally evaluated for a lab-scaled PSC girder model for which a set of damage scenarios are experimentally monitored by the developed smart sensor nodes.
Relative baseline features for impedance-based structural health monitoring
Jung, Hwee Kwon,Jo, HyeJin,Park, Gyuhae,Mascarenas, David L,Farrar, Charles R SAGE Publications 2014 Journal of intelligent material systems and struct Vol.25 No.18
<P>Various experimental studies have demonstrated that an impedance-based method is an effective means of structural damage detection. Using the self-sensing and active-sensing capabilities of piezoelectric materials, the electromechanical impedance response can be monitored to provide a qualitative indication of the overall health of a structure. In this article, two new signal processing tools for the impedance method are described in order to improve the damage detection capability and to reduce the amount of data to process for structural health assessment. The first approach is to instantaneously correlate the impedance data between different sensor sets, as opposed to be correlated to pre-stored baseline data. Another approach is to use the pre-defined parameter of impedance data to establish a generalized baseline for bolted joint monitoring. These approaches could reduce the number of data sets and could be efficiently used for low-power impedance devices. The proposed signal processing techniques are applied to several experimental structures, and the efficiency in damage detection is demonstrated.</P>
Park, Jae-Hyung,Kim, Jeong-Tae,Hong, Dong-Soo,Mascarenas, David,Lynch, Jerome Peter Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.5
This study presents the design of autonomous smart sensor nodes for damage monitoring of tendons and girders in prestressed concrete (PSC) bridges. To achieve the objective, the following approaches are implemented. Firstly, acceleration-based and impedance-based smart sensor nodes are designed for global and local structural health monitoring (SHM). Secondly, global and local SHM methods which are suitable for damage monitoring of tendons and girders in PSC bridges are selected to alarm damage occurrence, to locate damage and to estimate severity of damage. Thirdly, an autonomous SHM scheme is designed for PSC bridges by implementing the selected SHM methods. Operation logics of the SHM methods are programmed based on the concept of the decentralized sensor network. Finally, the performance of the proposed system is experimentally evaluated for a lab-scaled PSC girder model for which a set of damage scenarios are experimentally monitored by the developed smart sensor nodes.