Validation of the computational fluid–structure interaction simulation at real-scale tests of a flexible 29 m umbrella in natural wind flow

The sensitivity of membrane structures to wind loads due to their flexibility and small inertial masses raises the question of their behavior under natural wind conditions. Particularly transient wind loads could lead to dynamic amplification of the structural response. The assessment of the dynamic response of membrane structures is complex due to their special load carrying behavior, their material properties, and their distinct structural interaction with flow induced effects. Computationally intensive fluid–structure interaction simulation could overcome simplifications and limitations of existing approaches, especially small scale wind tunnel tests, and allow the assessment of all relevant structural and fluid phenomena. This paper outlines a virtual design methodology for lightweight flexible membrane structures under the impact of fluctuating wind loads and provides results on the unique validation of the method at real-scale tests of a highly flexible 29 m umbrella

Coupling the Discrete Element Method with the Finite Element Method to Simulate Rockfall Impact Experiments

To numerically simulate rockfall impact on flexible protection structures two different numerical methods are coupled within the open-source multi-physics code KRATOS. The impacting object is modeled with the help of a cluster of spherical discrete elements and its movement and contact forces are simulated using the Discrete Element Method (DEM). To realize a partitioned coupling simulation the contact forces are subsequently transferred to the light-weight protection structure which is analyzed and simulated using the Finite Element Method (FEM). To allow a stable simulation even in the case of large contact forces and/or large time steps a strong coupling GaussSeidel algorithm is presented. Subsequently the applicability of the method is shown by calculating experiments and finally the inclusion of digital terrain data is demonstrated

Spin dependent scattering of a domain-wall of controlled size

Magnetoresistance measurements in the CPP geometry have been performed on single electrodeposited Co nanowires exchange biased on one side by a sputtered amorphous GdCo layer. This geometry allows the stabilization of a single domain wall in the Co wire, the thickness of which can be controlled by an external magnetic field. Comparing magnetization, resistivity, and magnetoresistance studies of single Co nanowires, of GdCo layers, and of the coupled system, gives evidence for an additional contribution to the magnetoresistance when the domain wall is compressed by a magnetic field. This contribution is interpreted as the spin dependent scattering within the domain wall when the wall thickness becomes smaller than the spin diffusion length.Comment: 9 pages, 13 figure

PREFACE

Self-organization plays a key architectural role for the future Internet. Self-organization will enhance flexibility and evolvability of organically growing, large-scale distributed systems, e.g., of large-scale pervasive computing systems such as wireless sensor networks. These statements could be proved by the technical program of the IWSOS 2006. Sixteen high-quality papers were selected by a thorough review process out of more than 70 submissions from 21 different countries. The technical program of the IWSOS 2006 was particularly covering application-oriented topics like: the dynamics of structured and unstructured overlays; self-organization in grids, peer-to-peer networks, wireless environments, and autonomic computing; and the application of self-organization for enhancing network management and routing. The program of the IWSOS 2006 has been supplemented, besides the social events and tutorials, by a poster session on the role of “Self-Organization in European Next Generation Internet ” and also by a Technical Discussion on “Performance Modeling of Self-Organizing Systems”. The two parts of the technical report on hand is used to make the contributions to the poster sessio

Contribution to the Fluid-Structure Interaction Analysis of Ultra-Lightweight Structures using an Embedded Approach

International audienceDesigning large ultra-lightweight structures within a fluid flow, such as inflatable hangars in an atmospheric environment, requires an analysis of the naturally occurring fluid-structure interaction (FSI). To this end multidisciplinary simulation techniques may be used. The latter, though, have to be capable of dealing with complex shapes and large deformations as well as challenging phenomena like wrinkling or folding of the structure. To overcome such problems the method of embedded domains may be used. In this work we discuss a new solution procedure for FSI analyses based on the method of embedded domains. In doing so, we are in particular answering the questions: How to track the interface in the embedded approach, how does the subsequent solution procedure look like and how does both compare to the well-known Arbitrary-Lagrangian-Eulerian (ALE) approach? In this context a level set technique as well as different mapping and mesh-updating strategies are developed and evaluated. Furthermore the solution procedure of a completely embedded FSI analysis is established and tested using different small- and large-scale examples. All results are finally compared to results from an ALE approach. It is shown that the embedded approach offers a powerful and robust alternative in terms of the FSI analysis of ultra-lightweight structures with complex shapes and large deformations. With regard to the solution accuracy, however, clear restrictions are elaborated

Contribution to the fluid-structure interaction analysis of ultra-lightweight structures using an embedded approach

Designing large ultra-lightweight structures within a fluid flow, such as inflatable hangars in an atmospheric environment, requires an analysis of the naturally occurring fluid-structure interaction (FSI). To this end multidisciplinary simulation techniques may be used. The latter, though, have to be capable of dealing with complex shapes and large deformations as well as challenging phenomena like wrinkling or folding of the structure. To overcome such problems the method of embedded domains may be used. In this work we discuss a new solution procedure for FSI analyses based on the method of embedded domains. In doing so, we are in particular answering the questions: How to track the interface in the embedded approach, how does the subsequent solution procedure look like and how does both compare to the well-known Arbitrary Lagrangian-Eulerian (ALE) approach? In this context a level set technique as well as different mapping and mesh-updating strategies are developed and evaluated. Furthermore the solution procedure of a completely embedded FSI analysis is established and tested using different small- and large-scale examples. All results are finally compared to results from an ALE approach. It is shown that the embedded approach offers a powerful and robust alternative in terms of the FSI analysis of ultra-lightweight structures with complex shapes and large deformations. With regard to the solution accuracy, however, clear restrictions are elaborated

Technology transfer from laboratory to industry for fabrication of large superconducting coil joints

The future magnetic thermonuclear fusion reactors will use superconducting magnets. The development during the last decade of the cable-in-conduit conductor (CICC) allows the transport of high current intensities. The construction of the winding pac