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Sensor Concept Based on Piezoelectric PVDF Films for the Structural Health Monitoring of Fatigue Crack Growth
(2011)
A new sensor concept for monitoring fatigue crack growth in technical structures is presented. It allows the in-situ determination of the position of the crack tip as well as the fracture mechanical quantities. The required data are obtained from a piezoelectric polymer film, which is attached to the surface of the monitored structure. The stress intensity factors and the crack tip position are calculated from electrical potentials obtained from a sensor array by solving the non-linear inverse problem.
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Crack path predictions and experiments in plane structures considering anisotropic properties and material interfaces
(2015-09-28)
In many engineering applications special requirements are directed to a material's fracture behavior and the prediction of crack paths. Especially if the material exhibits anisotropic elastic properties or fracture toughnesses, e.g. in textured or composite materials, the simulation of crack paths is challenging. Here, the
application of path independent interaction integrals (I-integrals), J-, L- and M-integrals is beneficial for an accurate crack tip loading analysis.
Numerical tools for the calculation of loading ...
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Das gute Recht auf Bildung
(2019)
Deutschland hat sich mit der Inkraftsetzung der UN-Behindertenrechtskonvention (BRK) als deutschem Recht ab dem 26. März 2009 unter anderem dazu verpflichtet, ein Bildungssystem zu verwirklichen, an dem Menschen mit Behinderung vollständig und gleichberechtigt teilhaben können. Darin ausdrücklich inbegriffen sind Angebote für Erwachsenenbildung und lebenslanges Lernen. „Die Vertragsstaaten stellen sicher, dass Menschen mit Behinderungen ohne Diskriminierung und gleichberechtigt mit anderen Zugang zu allgemeiner ...
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Coupled atomistic-continuum simulation of the mechanical properties of single-layered graphene sheets
(2019-11-18)
The purpose of this work is the multiscale modeling of a single-layered graphene sheet. The model is divided into three parts. One is an atomistic domain which is simulated with the atomic-scale finite element method (AFEM). Another is a continuum domain. In this domain, the mechanical properties are investigated by using a finite element based on a nonlocal continuum shell model with a high order strain gradient. To be exact, it is a 4-node 60-generalized degree of freedom (DOF) Mindlin–Reissner finite shell element ...
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Wahrnehmungspsychologie und Landschaft
(2010-09-30)
Landschaft ist ein Wahrnehmungsphänomen und als solches kulturwissenschaftlich rekonstruiert worden. Dieser Rekonstruktion zufolge ist es eine an Gemälden gewonnene Anschauungsform, die auf das Land außerhalb von Gemälden übertragen worden ist, das wie ein Bild betrachtet wird. Dieser Erkenntnis widerspricht die Wahrnehmungspsychologie, genauer die Evolutionspsychologie, dahin gehend, dass die Landschaftswahrnehmung schon in der frühen Menschheitsentwicklung erworben wurde. Denn die heutigen landschaftlichen Präferenzen ...
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Increasing energy efficiency of milk product batch sterilisation
(2018-09-07)
The food industry is a large energy consumer and most heat demands in food processing are low-temperature. The aim of this study is to develop and simulate innovative retrofits or redesigns that unlock the heat recovery potential of industrial batch sterilisation processes. The case study focuses on the whey cream process, although the method and results apply to similar batch sterilisation processes. The initial situation is compared to energy efficient designs based on “Energy Storage” and “Rescheduling”. Using a ...
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Weak and strong bi-material interfaces and their influence on propagating cracks in plane elastic structures
(2017-09-06)
The developing crack paths in heterogeneous structures are the result of the inhomogeneous state of stress. The latter stems from e.g. voids or inclusions in an elastic matrix, which are bonded either by strong or weak interfaces. Besides the stiffness of an inclusion, the kind of interface has a decisive influence on the state of stress and therefore on propagating cracks. It is experimentally proven that cracks tend to grow towards regions with lower stiffness (Tilbrook et al., 2006; Judt et al., 2015), therefore ...
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Crack Paths at Multiple-crack Systems in Anisotropic Simulation and Experiment
(2014-06-27)
This paper is targeted on numerical methods for accurate crack tip loading analysis and crack path prediction. Those are based on finite element calculations of the boundary value problem. Applying path-independent integrals to curved cracks in order to accurately calculate the J-integral, energy release rate (ERR) or stress intensity factors (SIF) is still not state of the art. Contours which are not confined to the crack tip require special analytical preparation and numerical treatment to supply results which are ...
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Governing Through Resilience? Exploring Flood Protection in Dresden, Germany
(2014-06-04)
The paper argues for a governmentality perspective on risk-management politics and resilience-related governance. This perspective pays ample attention to conflicts and discursive ‘battles’ in which different truths and normative assessments, including specific rationalities, subjectivities and technologies of governing compete against. Up to now, the literature on governmentality and resilience has mainly been based on empirical research in the UK. This research highlights the growing importance of neoliberal forms ...
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Boxwood Borer Heterobostrychus brunneus (Coleoptera: Bostrichidae) Infesting Dried Cassava: A Current Record from Southern Ethiopia
(2017-01-27)
Insect specimens of adult beetles and larvae of 7–9 and 9–10 mm length, respectively were collected from infested dry cassava at two locations from multiple stores in southern Ethiopia. The specimens were identified as Heterobostrychus brunneus (Murray, 1867) commonly known as boxwood borer and auger beetle. The study presents a current record of H. brunneus in Ethiopia, particularly in the context of infesting food products. Additionally, a wide geographical distribution of the pest was reviewed and presented in ...