COMPUTATIONAL MODELING OF A MULTI-LAYERED PIEZO-COMPOSITE BEAM MADE UP OF MFC

The Variational Asymptotic Method (VAM) is used for modeling a coupled non-linear electromechanical problem finding applications in aircrafts and Micro Aerial Vehicle (MAV) development. VAM coupled with geometrically exact kinematics forms a powerful tool for analyzing a complex nonlinear phenomena as shown previously by many in the literature 3 - 7] for various challenging problems like modeling of an initially twisted helicopter rotor blades, matrix crack propagation in a composite, modeling of hyper elastic plates and various multi-physics problems. The problem consists of design and analysis of a piezocomposite laminate applied with electrical voltage(s) which can induce direct and planar distributed shear stresses and strains in the structure. The deformations are large and conventional beam theories are inappropriate for the analysis. The behavior of an elastic body is completely understood by its energy. This energy must be integrated over the cross-sectional area to obtain the 1-D behavior as is typical in a beam analysis. VAM can be used efficiently to approximate 3-D strain energy as closely as possible. To perform this simplification, VAM makes use of thickness to width, width to length, width multiplied by initial twist and strain as small parameters embedded in the problem definition and provides a way to approach the exact solution asymptotically. In this work, above mentioned electromechanical problem is modeled using VAM which breaks down the 3-D elasticity problem into two parts, namely a 2-D non-linear cross-sectional analysis and a 1-D non-linear analysis, along the reference curve. The recovery relations obtained as a by-product in the cross-sectional analysis earlier are used to obtain 3-D stresses, displacements and velocity contours. The piezo-composite laminate which is chosen for an initial phase of computational modeling is made up of commercially available Macro Fiber Composites (MFCs) stacked together in an arbitrary lay-up and applied with electrical voltages for actuation. The expressions of sectional forces and moments as obtained from cross-sectional analysis in closed-form show the electro-mechanical coupling and relative contribution of electric field in individual layers of the piezo-composite laminate. The spatial and temporal constitutive law as obtained from the cross-sectional analysis are substituted into 1-D fully intrinsic, geometrically exact equilibrium equations of motion and 1-D intrinsic kinematical equations to solve for all 1-D generalized variables as function of time and an along the reference curve co-ordinate, x(1).

无人机编队飞行技术的研究现状与展望

无人机编队飞行是无人机及其应用技术发展研究的新热点。在分析无人机编队飞行特点的基础上,阐述了无人机编队飞行原理与方法的研究现状,并展望了其今后的主要应用前景。

分布式多无人机编队飞行的阵形保持策略

设计了一种仅采用相对位置偏差状态进行多无人机编队阵形保持的分布式保持策略.首先,分析多无人机编队的特点及其阵形保持问题,提出其阵形保持策略的要求,然后设计一种采用局部阵形状态制定的阵形保持策略.该保持策略从非一致性的冗余状态中进行简洁的处理,判断阵形的保持状态,采取相应的保持机制.最后,应用于几个多无人机编队飞行的例子,仿真结果验证了该保持策略的可行性.

Aportaciones metodológicas a la gestión y explotación de nubes de puntos procedentes de escáneres tridimensionales, aplicados a la documentación geométrica del patrimonio. El caso de la Portada de los Hierros de la Catedral de Valencia

Presentado en: IX Congreso Internacional de Rehabilitación del Patrimonio Arquitectónico y Edificación (Sevilla, España, 9-12 julio 2008)

Methodological keys for the acquisition and long-term use of photographic collections representing elements of Heritage

Contributed to: Fusion of Cultures. XXXVIII Annual Conference on Computer Applications and Quantitative Methods in Archaeology – CAA2010 (Granada, Spain, Apr 6-9, 2010)

[A_Laguardia_SanJuan] Levantamiento fotogramétrico de la portada Sur o “de los abuelos” de la iglesia de San Juan de Laguardia (Álava)

[ES] La documentación contenida en este registro ha servido de base para los siguientes documentos:

[R_Clavijo_SanPrudencio] Intensive Program ERASMUS: TOPCART. Geometric Documentation of the Heritage (report of activities 2010-2011)

[EN] Data contained in this record come from the following accademic activity (from which it is possible to locate additional records related with the Monastery):

[A_Elvillar_Hechicera] Documentación geométrica del dolmen de la Chabola de la Hechicera (Elvillar, Álava)

[ES] Tumba megalítica compuesta por 17 losas de gran tamaño, incluida la tapa. La estructura ocupa un espacio de 10 x 4 metros en planta, unos 4 metros de altura en la cámara. Conserva restos del túmulo que forma aproximadamente un círculo de unos 10 metros de radio.

Documentación y representación de paramentos verticales en riesgo de colapso. Aplicación en el Monasterio de San Prudencio (Clavijo, La Rioja)

[ES] Los datos de este registro provienen de la una actividad académica que también aparece descrita en el repositorio y desde donde se puede acceder a otros trabajos relacionados con el Monasterio:

Metodología fotogramétrica para la cuantificación de las alteraciones en paramentos pétreos patrimoniales. Aplicación a la iglesia de San Juan de Laguardia

[ES] Este proyecto fin de carrera está realacionado con el siguiente proyecto de documentación de un elemento patrimonial:

Broughton Archipelago Clam Terrace Survey : final report

During a 1995 aerial video survey of the coastline of Johnstone Strait, an unusual shoreline feature was noted and termed “clam terraces” (inset) because of the terrace-type morphology and the apparent association with high clam productivity on the sandflats. Typical alongshore lengths of the terrace ridges are 20-50m, and across-shore widths are typically 20-40m. An area with an especially high density of clam terraces was noted in the Broughton Archipelago, between Broughton and Gilford Islands of southeastern Queen Charlotte Strait. Clam terraces in this area were inventoried from the aerial video imagery to quantify their distribution. The terraces accounted for over 14 km of shoreline and 365 clam terraces were documented. A three-day field survey by a coastal geomorphologist, archeologist and marine biologist was conducted to document the features and determine their origin. Nine clam terraces were surveyed. The field observations confirmed that: the ridges are comprised of boulder/cobblesized material, ridge crests are typically in the range of 1-1.5m above chart datum, sandflats are comprised almost entirely of shell fragments (barnacles and clams) and sandflats have very high shellfish production. There are an abundance of shell middens in the area (over 175) suggesting that the shellfish associated with the terraces were an important food source of aboriginal peoples. The origin of the ridges is unknown; they appear to be a relict feature in that they are not actively being modified by present-day processes. The ridges may be a relict sea-ice feature, although the mechanics of ridge formation is uncertain. Sand accumulates behind the ridge because the supply rate of the shell fragments exceeds the dispersal rate in these low energy environments. The high density areas of clam terraces correspond to high density areas of shell middens, and it is probable that the clam terraces were subjected to some degree of modification by aboriginal shellfish gatherers over the thousands of years of occupation in the region. (Document contains 39 pages)

Geometric documentation and reconstruction of the church of the Monastery of San Prudencio (La Rioja, Spain)

[EN] Data contained in this record come from the following accademic activity (from which it is possible to locate additional records related with the Monastery):

[A_Vitoria_SantaMaria] Documentación geométrica de las excavaciones de la Catedral de Santa María (Vitoria-Gasteiz). Mayo 2000-Junio 2003

[ES] Información sobre este proyecto ha servido de base a los siguientes artículos:

[R_SanMillan_Yuso] Documentación geométrica de las excavaciones arqueológicas realizadas en el Monasterio de Yuso (San Millán de la Cogolla, La Rioja)

[ES] El seguimiento arqueológico se realiza sobre las capillas del la nave Norte de la iglesia más la capilla “de las reliquias”, en total 9 capillas de unos 10 x 10 metros cada una. Los elementos a documentar son las unidades estratigráficas exhumadas que, en gran medida corresponden a enterramientos (fosas y los propios esqueletos).

[G_Oñati_Arantzazu] Documentación fotográfica del Apostolado y la Piedad del exterior del Monasterio de Arantzazu (Oñati, Gipuzkoa)

[ES] Conjunto de figuras en piedra de gran porte (unos 4 metros de altura cada una), lo componen 14 figuras en la zona baja del apostolado y un conjunto de 2 personajes más formando la Piedad en la parte superior. Se trata de formas esquemáticas de perfil redondeado que corresponden artísticamente a una de las corrientes más destacadas del siglo XX.