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Showing papers by "Bauhaus University, Weimar published in 2005"


Journal ArticleDOI
TL;DR: Shape memory alloys (SMAs) as discussed by the authors are metallic materials with great potential to enhance civil engineering structures, such as damping, active vibration control and prestressing or posttensioning of structures with fibres and tendons.
Abstract: Shape memory alloys (SMAs) are metallic materials with great potential to enhance civil engineering structures. They are often referred to as smart materials. A basic description of their highly non-linear material behaviour in terms of shape memory effect, superelasticity, martensite damping and variable stiffness is given in this article. It is followed by a brief introduction to Ni−Ti and Fe−Mn−Si SMAs. Pre-existing and new applications in the fields of damping, active vibration control and prestressing or posttensioning of structures with fibres and tendons are being reviewed with regard to civil engineering. Furthermore, the relatively high costs and the problem of retaining posttensioning forces when using some types of SMAs are named. In this regard is Fe−Mn−Si−Cr discussed as potential low cost SMA. A simple model for calculating the activation times of resistive heated SMA actuators or springs is presented. The results and measured data lead to further constrictions. Finally, new ideas for using SMAs in civil engineering structures are proposed in this article such as an improved concept for the active confinement of concrete members. This article is to introduce civil engineers to the world of shape memory alloys and invite them to contribute to their wider use in civil engineering structures.

439 citations


Proceedings ArticleDOI
23 Oct 2005
TL;DR: A system that allows users to interactively explore complex flow scenarios represented as Sankey diagrams and can be used as a planning tool for the exploration of alternative scenarios by interactively manipulating different parameters in the energy flow network.
Abstract: We present a system that allows users to interactively explore complex flow scenarios represented as Sankey diagrams. Our system provides an overview of the flow graph and allows users to zoom in and explore details on demand. The support for quantitative flow tracing across the flow graph as well as representations at different levels of detail facilitate the understanding of complex flow situations. The energy flow in a city serves as a sample scenario for our system. Different forms of energy are distributed within the city and they are transformed into heat, electricity, or other forms of energy. These processes are visualized and interactively explored. In addition our system can be used as a planning tool for the exploration of alternative scenarios by interactively manipulating different parameters in the energy flow network.

265 citations


Journal ArticleDOI
TL;DR: Smart projectors as mentioned in this paper allow a correct projection onto many arbitrary existing surfaces, such as papered walls or curtained windows, which can generate images much larger than the devices themselves.
Abstract: The popularity of today's flat-panel liquid-crystal and plasma TV displays shows that emerging trends favor large-screen displays. Another display type may soon conquer the entertainment market, however: video projectors have experienced an enormous metamorphosis during the past decade. These devices now offer admirable cost reductions and performance increases, and they can generate images much larger than the devices themselves. The screens on which they project their images, however, require a large area. Smart projectors, on the other hand, allow a correct projection onto many arbitrary existing surfaces, such as papered walls or curtained windows.

164 citations


Journal ArticleDOI
TL;DR: In this article, the phase composition, pore solution composition and strength behavior of the activated blends is reported, and the quantitative phase composition and pore solutions composition of activated blends are analyzed.

121 citations


Journal ArticleDOI
TL;DR: In this article, the authors compared four methods for measuring soil total suction in laboratory: the noncontact filter paper method, the psychrometer technique, the relative humidity (RH) sensor, and the chilled-mirror hygrometer approach.
Abstract: This study assessed four methods for measuring soil total suction in laboratory: the noncontact filter paper method, the psychrometer technique, the relative humidity (RH) sensor, and the chilled-mirror hygrometer technique. Our aim in this study was to compare the four total suction measurement techniques, especially the psychrometer method and the RH sensor, which may be used for field total suction measurements. While field application of the sensors is the eventual concern, no field measurements were performed in the study. Assessment was made using two bentonite–sand mixtures, which can be used as clay liner for landfills. A discussion of factors influencing measurement accuracy is also provided. The chilled-mirror hygrometer technique appears to give the most accurate results, and therefore may be used as a benchmark for assessing the accuracy of the three other methods. For the bentonite–sand mixture used in this study, the total suction measured using the noncontact filter paper technique represents values at a quasi-equilibrium state after redistribution of water in the specimen, instead of the total suction at as-compacted state. The RH sensor provided a faster response than the psychrometer technique. However, the RH sensor exhibited a systematic error in the small suction range.

108 citations


Proceedings ArticleDOI
08 Dec 2005
TL;DR: PhoneGuide -- an enhanced museum guidance system that uses camera-equipped mobile phones and on-device object recognition, realized with single-layer perceptron neuronal networks for simple and light-weight object recognition.
Abstract: We present PhoneGuide -- an enhanced museum guidance system that uses camera-equipped mobile phones and on-device object recognition.Our main technical achievement is a simple and light-weight object recognition approach that is realized with single-layer perceptron neuronal networks. In contrast to related systems which perform computationally intensive image processing tasks on remote servers, our intention is to carry out all computations directly on the phone. This ensures little or even no network traffic and consequently decreases cost for online times. Our laboratory experiments and field surveys have shown that photographed museum exhibits can be recognized with a probability of over 90%.We have evaluated different feature sets to optimize the recognition rate and performance. Our experiments revealed that normalized color features are most effective for our method. Choosing such a feature set allows recognizing an object below one second on up-to-date phones. The amount of data that is required for differentiating 50 objects from multiple perspectives is less than 6KBytes.

105 citations


Proceedings ArticleDOI
31 Jul 2005
TL;DR: The popularity of today's flat-panel liquid-crystal and plasma TV displays shows that emerging trends favor large-screen displays, but another display type may soon conquer the entertainment market: video projectors, which can generate images much larger than the devices themselves.
Abstract: Essentially video projectors enhanced with sensors to gain information about the environment, smart projectors do not require artificial canvases and allow correct projection of images onto many arbitrary existing surfaces, such as papered walls or curtained windows.

103 citations


Proceedings ArticleDOI
31 Jul 2005
TL;DR: This tutorial discusses the Spatial Augmented Reality concept, its advantages and limitations, and presents techniques for projectorbased augmentation of geometrically complex and textured display surfaces, and (along with optical combination) methods for achieving consistent illumination and occlusion effects.
Abstract: This tutorial discusses the Spatial Augmented Reality (SAR) concept, its advantages and limitations. It will present examples of state-of-the-art display configurations, appropriate real-time rendering techniques, details about hardware and software implementations, and current areas of application. Specifically, it will describe techniques for optical combination using single/multiple spatially aligned mirror-beam splitters, image sources, transparent screens and optical holograms. Furthermore, it presents techniques for projector-based augmentation of geometrically complex and textured display surfaces, and (along with optical combination) methods for achieving consistent illumination and occlusion effects. Emerging technologies that have the potential of enhancing future augmented reality displays will be surveyed.

102 citations


Journal ArticleDOI
TL;DR: In this paper, a draft procedure for damage tolerance analysis of railway components is presented and illustrated by a case study on a railway axle, based on the recently developed European flaw assessment procedure SINTAP, the NASGRO/ESACRACK procedure for fatigue crack extension and other documents.

94 citations


Proceedings ArticleDOI
05 Oct 2005
TL;DR: It is shown how view-dependent image-based and geometric warping, radiometric compensation, and multi-focal projection enable a view- dependent stereoscopic visualization on ordinary (geometrically complex, colored and textured) surfaces within everyday environments.
Abstract: We show how view-dependent image-based and geometric warping, radiometric compensation, and multi-focal projection enable a view-dependent stereoscopic visualization on ordinary (geometrically complex, colored and textured) surfaces within everyday environments. Special display configurations for immersive or semi-immersive AR/VR applications that require permanent and artificial projection canvases might become unnecessary. We demonstrate several ad-hoc visualization examples in a real architectural and museum application context.

84 citations


Proceedings ArticleDOI
18 Oct 2005
TL;DR: This work developed a set of interaction techniques that assume that the wrist-worn computer and projector are equipped with position and orientation sensors, in addition to a touch-sensitive built-in screen, and describes the use of a cursor less watch user interface that minimizes the need for the user to look down at the device's built- in screen.
Abstract: One of the major limitations of portable computing devices is the small size of their built-in displays. Fortunately, extremely small projection systems are being developed that can be integrated into devices that are small enough to be body-worn, yet can project a large image onto surfaces in the environment. To explore how a user might interact with this near-horizon technology, we created a functional simulation of a wrist-worn projector. We then developed a set of interaction techniques that assume that the wrist-worn computer and projector are equipped with position and orientation sensors, in addition to a touch-sensitive built-in screen. To complement the techniques that rely on the spatial manipulation of the user's forearm and the device itself, we also describe the use of a cursor less watch user interface that minimizes the need for the user to look down at the device's built-in screen. Finally, we present a sample application that illustrates our interaction techniques.

Journal ArticleDOI
TL;DR: In this paper, a trade-off between rigor and relevance is the overall outcome of this kind of resarch, and the authors show that this effect is a consequence of the inner dynamics of science as a social system.
Abstract: Success factor studies seem to offer a way out of the rigor verses relevance dilemma: Researchers, in their attempts to identify factors that are causes of performance and can be manupulated by managers, apply sophisticated analyses in rigorous ways. As it turns out, however, the findings of performance analyses usually contradict each other, and practitioners are unable to follow and to evaluate the discussions between the researchers that are published in scientific journals. Thus, rather than a correspondence, as implied by performance studies, a trade-off between rigor and relevance is the overall outcome of this kind of resarch. On the basis of sociological concepts, the authors show that this effect is a consequence of the inner dynamics of science as a social system. This means that the potential of performance research to create actionable knowledge is limited.

Journal ArticleDOI
TL;DR: In this article, a new weighting function is presented for meshless shape functions to fulfill these essential conditions with very high accuracy without any additional effort, which gives much more stable results for varying size of the influence radius and for strongly distorted nodal arrangements than existing weighting functions.
Abstract: The Element-free Galerkin Method has become a very popular tool for the simulation of mechanical problems with moving boundaries. The internally applied Moving Least Squares interpolation uses in general Gaussian or cubic weighting functions and has compact support. Due to the approximative character of this interpolation the obtained shape functions do not fulfill the interpolation conditions, which causes additional numerical effort for the application of the boundary conditions. In this paper a new weighting function is presented, which was designed for meshless shape functions to fulfill these essential conditions with very high accuracy without any additional effort. Furthermore this interpolation gives much more stable results for varying size of the influence radius and for strongly distorted nodal arrangements than existing weighting function types.

Journal ArticleDOI
TL;DR: In this article, the authors give insight into some of the principles and possibilities of ultrasonic concrete imaging using Synthetic Aperture Focusing Technique (SAFT) and tomographic reconstruction.
Abstract: Among present non-destructive methods for concrete evaluation, ultrasonic testing uses relatively short wavelengths and therefore has particular potential for detailed assessment of concrete. Methods like SAFT (Synthetic Aperture Focusing Technique) and tomographic reconstruction are able to provide high-resolution images of concrete areas, which can be employed for tasks such as area imaging, duct localization, fault detection, and thickness measurement. This contribution is intended to give insight into some of the principles and possibilities of ultrasonic concrete imaging using SAFT and tomographic reconstruction. It thereby review progress that has been achieved at the author's institute during the last years. For SAFT reconstruction, the processing steps are explained that are necessary to obtain an image that is easy to interpret including the influence of transducers, their coupling, and image noise suppression. Quantitative evaluation of ultrasonic images enables the examination of tendon ducts for voids and the objective assessment of image quality. A field example demonstrates the possibilities of SAFT reconstruction. In a separate section, ultrasonic tomography is shown to have the capability to detect faults such as honeycombing in concrete pillars. Finally, the potential of ultrasonic imaging and remaining steps, necessary to open broad practical application are described.

Journal ArticleDOI
TL;DR: This work presents an approach for using pictorial artwork as information displays and shows how to combine almost any kind of computer-generated visual information directly with the painted content.
Abstract: We present an approach for using pictorial artwork as information displays and show how to combine almost any kind of computer-generated visual information directly with the painted content. We describe a novel technological approach, a mathematical model, a real-time rendering algorithm, and examples of presentation techniques. Our system displays such information while keeping the observers' attention on the original artifact and doesn't require additional screens.

Journal ArticleDOI
TL;DR: In this paper, the authors used a lab-scale fluidized bed gasifier to study the behavior of peach stones and especially its ash during the gasification process and found that fractionation resulted in a deterioration of the ash behavior, increasing the amounts of alkali metals and chlorine included in its ash, while leaching showed a positive effect but to a moderate extent.
Abstract: Peach stones comprise a valuable agroindustrial by-product that is available in many countries of the World and especially in the Mediterranean region. A number of important advantages such as its high energy value, the low ash content in combination with the absence of transportation costs due to the fact that is produced in agro-industries, make peach stones an ideal fuel for energy production via gasification. Gasification tests were performed in a lab-scale fluidized bed gasifier in order to study the behavior of peach stones and especially its ash during the gasification process. Apart from the tests with the initial peach stone samples, gasification tests were performed using peach stones that had been pre-treated using two different methods fractionation and leaching. Pre-treatments used in order to study their effect on the beneficiation of the materials ash and on the avoidance of ash-related problems such as deposition, agglomeration and corrosion during the gasification process. A water-cooled steel tube placed vertical to the flow of the gasification gases was used in order to collect samples of ash deposits that were analyzed using SEM-EDX analysis techniques in order to assess the effect of the pre-treatment techniques on the peach stones ash behavior. The produced results showed that peach stones can be used as gasification feedstock without significant ash problems. Fractionation resulted in a deterioration of the ash behavior of the material, increasing the amounts of alkali metals and chlorine included in its ash, while leaching showed a positive effect but to a moderate extent.

Journal ArticleDOI
TL;DR: In this article, a finite element (FE) model updating technique is applied to estimate the bending stiffness of a gradually damaged prestressed concrete beam, and an iterative sensitivity based algorithm is used for solving this optimization problem.
Abstract: Different methods are proposed in literature using experimental modal information to detect possible damage. In this paper a finite-element (FE) model updating technique is applied. The unknown properties of a FE model are adapted, such that the differences between experimental modal data (modal curvature in combination with eigenfrequencies and mode shapes) and the corresponding analytical predictions are minimized. An iterative sensitivity based algorithm is used for solving this optimization problem. The method is applied to the damage assessment of a gradually damaged prestressed concrete beam. It is assumed, that damage can be characterized by reducing the bending stiffness. The main focus of this paper is to analyze the influence of using modal curvatures. In contrast to eigenfrequencies and mode shapes, modal curvatures are very sensitive to local changes of the bending stiffness nearby the sensor location, but insensitive to local changes far from the measurement location.

Proceedings ArticleDOI
31 Jul 2005
TL;DR: Augmented reality technology has a lot of potential in this respect because it augments real-world environments with computer-generated imagery, but today, most AR systems use see-through head-mounted displays, which share most of the disadvantages of other head-attached display devices.
Abstract: Intuitive access to information in habitual real-world environments is a challenge for information technology. An important question is how can we enhance established and well-functioning everyday environments rather than replace them by virtual environments (VEs)? Augmented reality (AR) technology has a lot of potential in this respect because it augments real-world environments with computer-generated imagery. Today, most AR systems use see-through head-mounted displays, which share most of the disadvantages of other head-attached display devices.

Journal ArticleDOI
TL;DR: The real-time pseudo-dynamic sub-structure (SubPSD) test as discussed by the authors uses sub-stepping instead of iteration to reach equilibrium within each time step.

01 Jan 2005
TL;DR: This paper introduces aparticular form offuzzy-fingerprints—their construction, their interpretation, and their use in the field of information retrieval as well as the way of using them within a similarity search.
Abstract: Thispaper introduces aparticular form offuzzy-fingerprints—their construction, their interpretation, and their use in the field of information retrieval. Though the concept of finger- printing in general is not new, the way of using them within a similarity search as described here is: Instead of computing the similarity between two fingerprints in order to access the similarity between the associated objects, simply the event of a fingerprint collision is used for a similarity assessment. The main impact of this approach is the small number of comparisons necessary to conduct a similarity search.

Journal ArticleDOI
TL;DR: In this article, the authors describe the estimation of permeability functions of Singapore residual soils using the soil-water characteristic curve and saturated coefficient of permutation obtained in the laboratory for a number of residual soils.

Proceedings ArticleDOI
26 Aug 2005
TL;DR: It is proposed that stimuli depicting globally consistent, naturalistic scenes provide observers with a convincing spatial reference frame for the simulated environment which allows them to feel "spatially present" therein and increases the believability of the visual stimuli as a stable "scene" with respect to which visual motion is more likely to be judged as self-motion.
Abstract: The illusion of self-motion induced by moving visual stimuli ("vection") has typically been attributed to low-level, bottom-up perceptual processes. Therefore, past research has focused primarily on examining how physical parameters of the visual stimulus (contrast, number of vertical edges etc.) affect vection. Here, we investigated whether higher-level cognitive and top-down processes - namely global scene consistency and spatial presence - also contribute to the illusion. These factors were indirectly manipulated by presenting either a natural scene (the Tubingen market place) or various scrambled and thus globally inconsistent versions of the same stimulus. Due to the scene scrambling, the stimulus could no longer be perceived as a consistent 3D scene, which was expected to decrease spatial presence and thus impair vection. Twelve naive observers were asked to indicate the onset, intensity, and convincingness of circular vection induced by rotating visual stimuli presented on a curved projection screen (FOV: 54°x45°). Spatial presence was assessed using presence questionnaires. As predicted, scene scrambling impaired both vection and presence ratings for all dependent measures. Neither type nor severity of scrambling, however, showed any clear effect. The data suggest that higher-level information (the interpretation of the globally consistent stimulus as a 3D scene and stable reference frame) dominated over the low-level (bottom-up) information (more contrast edges in the scrambled stimuli, which are known to facilitate vection). Results suggest a direct relation between spatial presence and self-motion perception. We posit that stimuli depicting globally consistent, naturalistic scenes provide observers with a convincing spatial reference frame for the simulated environment which allows them to feel "spatially present" therein. We propose that this, in turn, increases the believability of the visual stimuli as a stable "scene" with respect to which visual motion is more likely to be judged as self-motion. We propose that not only low-level, bottom-up factors, but also higher-level factors such as the meaning of the stimulus are relevant for self-motion perception and should thus receive more attention. This work has important implications for both our understanding of selfmotion perception and motion simulator design and applications.

Proceedings ArticleDOI
12 Mar 2005
TL;DR: 3D UI researchers should approach this problem using some new research approaches, which cluster around the concepts of specificity, flavors, implementation, and emerging technologies, which indicate the promise of these directions for further increasing the understanding of 3D interaction and 3D UI design, and for ensuring the usability of3D UIs in future applications.
Abstract: ! Abstract— Three-dimensional user interfaces (3D UIs) support user tasks in many non-traditional interactive systems such as virtual environments and augmented reality. Although 3D UI researchers have been successful in identifying basic user tasks and interaction metaphors, evaluating the usability of 3D interaction techniques, and improving the usability of many applications, 3D UI research now stands at a crossroads. Very few fundamentally new techniques and metaphors for 3D interaction have been discovered in recent years, yet the usability of 3D UIs in many real-world applications is still not at a desirable level. What directions should 3D UI researchers next explore to improve this situation? In this paper, we make some observations about the history of 3D UIs and the current state-of-the-art. Using this evidence, in addition to our own experience, we argue that 3D UI researchers should approach this problem using some new research approaches, which cluster around the concepts of specificity, flavors, implementation, and emerging technologies. We illustrate and discuss some of these new directions using case studies of research projects undertaken in our group. These explorations indicate the promise of these directions for further increasing our understanding of 3D interaction and 3D UI design, and for ensuring the usability of 3D UIs in future applications.

Book ChapterDOI
01 Jan 2005
TL;DR: In this article, the Soil Water-Characteristic Curves (SWCCs) of Hostun sand were determined by using the suction mode and pressure mode axis translation technique under various vertical net stresses.
Abstract: In this study the behavior of an unsaturated sand is examined. The sand used is Hostun sand from France. The Soil-Water-Characteristic Curves (SWCCs) of loose and dense specimen were determined by using the suction mode and pressure mode axis translation technique under various vertical net stresses. One dimensional compression and rebound behavior was studied for specimens at different initial matric suction values. During these tests the matric suction was maintained constant during loading and unloading processes. To study the wetting induced collapse of the sand, specimens with a known matric suction and water content were prepared and then saturated at several vertical net stresses during loading. The study showed that the SWCC is not significantly influenced by vertical net stress. However there is a influence of initial suction on the compression behavior of the material which is manifested on the stillness moduli, compression index and collapse potential of the sand used in this study. In comparison to these results, results from one dimensional compression and rebound tests, where water content was kept constant, for Quartz sand Weferlingen were added. Results from collapse potential test for Quartz sand Weferlingen are given, too.

Journal ArticleDOI
01 May 2005-Stahlbau
TL;DR: In this article, the effectiveness of post-weld treatment method TIG-dressing and the relatively new method Ultrasonic Impact Treatment (UIT) for the improvement of fatigue strength of welded high strength steels was investigated.
Abstract: Nach dem bisherigen Kenntnisstand haben geschweiste hoherfeste Stahle die gleiche Ermudungsfestigkeit wie geschweiste niedrigfeste Stahle. Um hoherfeste Stahle auch in ermudungsbeanspruchten Konstruktionen effektiv einsetzen zu konnen, bedarf es daher zusatzlicher Anstrengungen, um die Ermudungsfestigkeit zu erhohen, z. B. durch Anwendung von Schweisnahtnachbehandlungsverfahren. Im Stahlbau besteht jedoch bis heute nicht die Moglichkeit, die positiven Effekte einer Schweisnahtnachbehandlung normativ zu berucksichtigen. In dieser Arbeit werden erste Ergebnisse eines laufenden Forschungsprojekts vorgestellt, in dem die Effektivitat des Schweisnahtnachbehandlungsverfahrens WIG-Aufschmelzen und des neuartigen Verfahrens “Ultrasonic Impact Treatment” (UIT) zur Verbesserung der Ermudungsfestigkeit von Schweiskonstruktionen aus hoherfesten Baustahlen untersucht wird. Enhancement of the fatigue strength of welded high strength steels by application of post-weld treatment methods. According to the present state of the art welded high strength steels have the same fatigue strength as welded standard steels. For an effective application of high strength steels in constructions subjected to fatigue are therefore additional efforts necessary in order to improve the fatigue strength, for example by the application of post-weld treatment methods. However up to the present it is not possible to apply the positive effects of these methods in the fatigue design of steel structures. This paper shows first results of a research project, that examines the effectiveness of the post-weld treatment method TIG-dressing and the relatively new method “Ultrasonic Impact Treatment” (UIT) for the improvement of fatigue strength of welded high strength steels.

Journal ArticleDOI
TL;DR: In this article, the authors point out that MEDIA Plus may well have counterproductive outcomes as they are not designed to overcome the structural fragmentation that holds back the industry, and possible corrections to MEDIA's strategy are then outlined.
Abstract: In 2002, the third generation of the EU’s support programme for the European film industry, the MEDIA Plus Programme, was launched. Despite 12 years of integrated efforts, European cinema still does not seem to be able to compete with its American peers. This led us to question the effectiveness and strategy of MEDIA Plus. As we point out in our analysis, the present approach addresses the film industry’s symptoms rather than its problems. We draw the conclusion that the lines of action taken by MEDIA Plus may well have counterproductive outcomes as they are not designed to overcome the structural fragmentation that holds back the industry. Possible corrections to MEDIA’s strategy are then outlined.

Proceedings ArticleDOI
TL;DR: In this article, it is shown that practical constraints of a fundamental nature preclude the application of Bell Inequalities to data from do-able EPR•B experiments and that the violation of these inequalities by data from such experiments is without significance for the questions posed by EPR or Bell.
Abstract: It is shown that practical constraints of a fundamental nature preclude the application of Bell Inequalities to data from do‐able EPR‐B experiments Thus, the violation of these inequalities by data from such experiments is without significance for the questions posed by EPR or Bell Further, other implicit, misguided assumptions in analysis of this issue are discussed and a counterexample to conventional opinion in the form of a local realistic model and simulation of EPR‐B experiments is displayed

Journal ArticleDOI
TL;DR: Analysis of the structural response of the separated sternum using computer-based numerical discretization techniques, such as finite element methods, revealed that for the normal breathing load case the single loop technique is capable of clamping the sternum sufficiently, assuming that the wires are prestressed.

Journal ArticleDOI
TL;DR: In this article, a one-dimensional Radon transform on the group SO(3) was considered and several inversion formulae were derived and compared with the inversion of the spherical Radon Transform on 3 for even functions.
Abstract: We consider a one-dimensional Radon transform on the group SO(3), which is motivated by texture goniometry. In particular, we will derive several inversion formulae and compare them with the inversion of the one-dimensional spherical Radon transform on 3 for even functions. Copyright © 2005 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this article, the Weakest-Link model is used to evaluate the statistic size effect of cyclic loading and static loading on the failure behavior of ferritic steel within the brittle fracture range.
Abstract: The Weakest-Link model is based on defects that are statistically distributed within the material with local stress. The failure at least at one defect causes the failure of the total structure. Based on this model, the so-called statistic size effect can be evaluated in the case of cyclic loading and in the case of static loading the failure behaviour of ferritic steel within the brittle fracture range is highlighted. The application of the Weakest-Link model requires the allocation of the local characteristics - surface and / or volume - to the discrete points of the stress. By using the method “SPIEL” which is independent from the FE code used, the allocation of couples of values -surface and stress and / or volume and stress - by a suitable choice of unit load cases is possible. In consequence of the method “SPIEL” particularities are to be taken into consideration. In the present paper these particularities will be described exemplarily for the FE programs ABAQUS1 and ANSYS2.