@article{HildebrandHechtBliedtneretal.,
  author    = {Hildebrand, J{\"o}rg and Hecht, Kerstin and Bliedtner, Jens and M{\"u}ller, Hartmut},
  title     = {Laser Beam Polishing of Quartz Glass Surfaces},
  series = {Physics Procedia},
  journal   = {Physics Procedia},
  doi       = {10.1016/j.phpro.2011.03.056},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170418-31366},
  pages     = {452 -- 461},
  abstract  = {The laser beam is a small, flexible and fast polishing tool. With laser radiation it is possible to finish many outlines or geometries on quartz glass surfaces in the shortest possible time. It's a fact that the temperature developing while polishing determines the reachable surface smoothing and, as a negative result, causes material tensions. To find out which parameters are important for the laser polishing process and the surface roughness respectively and to estimate material tensions, temperature simulations and extensive polishing experiments took place. During these experiments starting and machining parameters were changed and temperatures were measured contact-free.},
  subject      = {Laser},
  language  = {en}
}
@article{HildebrandHechtBliedtneretal.,
  author    = {Hildebrand, J{\"o}rg and Hecht, Kerstin and Bliedtner, Jens and M{\"u}ller, Hartmut},
  title     = {Advanced Analysis of Laser Beam Polishing of Quartz Glass Surfaces},
  series = {Physics Procedia},
  journal   = {Physics Procedia},
  doi       = {10.1016/j.phpro.2012.10.039},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170418-31372},
  pages     = {277 -- 285},
  abstract  = {The laser beam is a small, flexible and fast polishing tool. With laser radiation it is possible to finish many outlines or geometries on quartz glass surfaces in the shortest possible time. It's a fact that the temperature developing while polishing determines the reachable surface smoothing and, as a negative result, causes material tensions. To find out which parameters are important for the laser polishing process and the surface roughness respectively and to estimate material tensions, temperature simulations and extensive polishing experiments took place. During these experiments starting and machining parameters were changed and temperatures were measured contact-free. The accuracy of thermal and mechanical simulation was improved in the case of advanced FE-analysis.},
  subject      = {Laser},
  language  = {en}
}
@phdthesis{Thumser2009,
  author    = {Thumser, Rayk},
  title     = {Simulation des Rissfortschritts in autofrettierten und nicht autofrettierten Bohrungsverschneidungen auf der Grundlage der linear-elastischen Bruchmechanik},
  isbn      = {978-3-86068-389-7},
  doi       = {10.25643/bauhaus-universitaet.1389},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20090609-14729},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2009},
  abstract  = {Die betriebsfeste Auslegung von Hochdruckbauteilen ist technisch-wirtschaftlich notwendig. In dieser Arbeit werden die wissenschaftlichen Grundlagen daf{\"u}r erarbeitet. Die technische Entwicklung der Hochdruckbauteile f{\"u}hrt insbesondere bei Dieselmotoren zu stetig steigenden Dr{\"u}cken und damit zu einer wachsenden Herausforderung bei der Festigkeitsauslegung. Bei Hochdruckbauteilen sind die M{\"o}glichkeiten der Schwingfestigkeitssteigerung, z. B. durch Wanddickenvergr{\"o}ßerung oder durch den Einsatz h{\"o}herfester Werkstoffe, begrenzt. Eine breite industrielle Anwendung findet derzeit die Autofrettage. Bei diesem Verfahren erzeugt eine einmalige statische {\"U}berlast tief in das Bauteil reichende Druckeigenspannungsfelder, die zu einer erheblichen Schwingfestigkeitssteigerung, insbesondere in der Rissfortschrittsphase, f{\"u}hren. Zuverl{\"a}ssige Lebensdauervorhersageverfahren f{\"u}r diese Phase existieren derzeit nicht. Sie werden in der vorliegenden Arbeit entwickelt und anhand experimenteller Ergebnisse verifiziert. F{\"u}r das Berechnungsverfahren fand ein ingenieurm{\"a}ßiger Ansatz Verwendung. Darin sollten zwar alle relevanten Effekte abgebildet werden, jedoch Komplexit{\"a}t und Modellierungsaufwand so gering wie m{\"o}glich gehalten werden. Die gew{\"a}hlten Berechnungsmodule sind nach erfolgter Analyse der Literatur entnommen. Sie umfassen die Berechnung der Autofrettageeigenspannungen, der Spannungsintensit{\"a}t, des Riss{\"o}ffnungs- und Rissschließverhalten und des Rissfortschrittes. Das Modul Eigenspannungsberechnung f{\"u}r die Autofrettage basiert auf der Superposition von Autofrettagebe- und -entlastung und erm{\"o}glicht die notwendige Ber{\"u}cksichtung des Bauschinger-Effektes. Spannungsintensit{\"a}ten werden mit einer 3D-Gewichtsfunktion f{\"u}r einen ebenen Riss unter Mode I Beanspruchung ermittelt, weil aufgrund der Symmetrie der meisten Hochdruckbauteile das stabile Langrisswachstum ausschließlich unter Mode I Beanspruchung stattfindet. Die Riss{\"o}ffnungs- und -schließeffekte werden {\"u}ber N{\"a}herungsformeln abgebildet. In der Anwendung dieser N{\"a}herungsformeln hat sich die Riss{\"o}ffnungsbeziehung nach Ibrahim et. al. durch den Vergleich mit von rechnerischen mit experimentellen Lebensdaueren als am Besten geeignet erwiesen. Bei dem untersuchten Werkstoff 42CrMo4 spielen die Reihenfolgeeffekte eine untergeordnete Bedeutung und werden deshlab nicht modelliert. F{\"u}r die Rissfortschrittsbeziehung konnte auf die Formulierung der Paris-Erdogan Beziehung f{\"u}r effektive Schwingweiten zur{\"u}ckgegriffen werden. Die gew{\"a}hlten Berechnungsmodule sind nach erfolgter Analyse der Literatur entnommen, aber in dieser Zusammenstellung ein neuer Ansatz. Da die Einzelmodule nur in geringem Umfang zu verifizieren sind, kann das Berechnungsverfahren nur in seiner Gesamtheit durch den Vergleich von experimentellen zu vorhergesagten Lebensdauern und Dauerfestigkeiten {\"u}berpr{\"u}ft werden. In verschiedenen Sensitivit{\"a}tsanalysen konnten f{\"u}r die Berechnungsparameter Riss{\"o}ffnungsbeziehung, Anfangsrissl{\"a}nge, Bruchz{\"a}higkeit, Rissfortschrittsgleichung und Schwellwert der Spannungsintensit{\"a}t der Einfluss auf die berechnete Rissfortschrittslebensdauer und -dauerfestigkeit aufgezeigt werden. So hat der Schwellwert der Spannungsintensit{\"a}t einen geringen Einfluss auf die Vorhersage der Rissstillstandsdauerfestigkeit autofrettierter Kreuzbohrungen, weil der Riss{\"o}ffnungsdruck sehr nahe am Maximaldruck ist. Eine andere Sensitivit{\"a}tsanalyse zeigt beispielsweise, dass sich die l{\"a}ngsten Rissfortschrittslebensdauern bei Verwendung der Riss{\"o}ffnungsbeziehung nach Ibrahim et. al. ergeben, weil diese Beziehung die gr{\"o}ßten Riss{\"o}ffnungsdr{\"u}cke vorhersagt. F{\"u}r die Verifikation des Berechnungsverfahrens sind Innendruckschwellversuche an insgesamt 14 Versuchsreihen mit Kreuzbohrungen durchgef{\"u}hrt worden. Die allgemeine Anwendbarkeit des Berechnungsverfahrens konnte durch die Anwendung auf Kreuzbohrungen aus den Forschungsvorhaben Autofrettage I-III, auf Railst{\"u}cke und auf Hochdruckverteilerleisten nachgewiesen werden. Auch hier st{\"u}tzt sich die Verifikation auf umfangreiche experimentelle Ergebnisse. Die statistische Auswertung des Verh{\"a}ltnisses der vorhergesagten zu experimentellen Lebensdauern und Schwingfestigkeiten aller untersuchten Bohrungsverschneidungen zeigt eine gute mittlere Vorhersageg{\"u}te bei geringer Streuung. Damit ist die Leistungsf{\"a}higkeit der vorgestellten Lebensdauervorhersagemethode nachgewiesen.},
  subject      = {Bruchmechanik},
  language  = {de}
}
@inproceedings{OPUS4-1470,
  title     = {SYSWELD Forum 2011},
  editor    = {Hildebrand, J{\"o}rg},
  doi       = {10.25643/bauhaus-universitaet.1470},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111213-15694},
  year      = {2011},
  abstract  = {Am 25. und 26. Oktober 2011 trafen sich an der Bauhaus-Universit{\"a}t Weimar 70 nationale und internationale Fachleute aus Forschung und Praxis, um sich im Rahmen des vierten SYSWELD Forums {\"u}ber aktuelle Entwicklungen der numerischen Simulation auf dem Gebiet der W{\"a}rmebehandlung und des Schweißens auszutauschen. Die numerische Simulation im Bereich des Schweißens und der W{\"a}rmebehandlung hat sich in den letzten Jahren beachtlich weiterentwickelt und bietet ein zukunftsweisendes und innovatives Arbeitsfeld f{\"u}r Ingenieure.},
  subject      = {Schweißen},
  language  = {de}
}
@misc{Kurukuri2005,
  type      = {Master Thesis},
  author    = {Kurukuri, Srihari},
  title     = {Homogenization of Damaged Concrete Mesostructures using Representative Volume Elements - Implementation and Application to SLang},
  doi       = {10.25643/bauhaus-universitaet.667},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-6670},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2005},
  abstract  = {This master thesis explores an important and under-researched topic on the so-called bridging of length scales (from >meso< to >macro<), with the concept of homogenization in which the careful characterization of mechanical response requires that the developed material model >bridge< the representations of events that occur at two different scales. The underlying objective here is to efficiently incorporate material length scales in the classical continuum plasticity/damage theories through the concept of homogenization theory. The present thesis is devoted to computational modeling of heterogeneous materials, primarily to matrix-inclusion type of materials. Considerations are focused predominantly on the elastic and damage behavior as a response to quasistatic mechanical loading. Mainly this thesis focuses to elaborate a sound numerical homogenization model which accounts for the prediction of overall properties with the application of different types of boundary conditions namely: periodic, homogeneous and mixed type of boundary conditions over two-dimensional periodic and non-periodic RVEs and three-dimensional non-periodic RVEs. Identification of the governing mechanisms and assessing their effect on the material behavior leads one step further. Bringing together this knowledge with service requirements allows for functional oriented materials design. First, this thesis gives attention on providing the theoretical basic mechanisms involved in homogenization techniques and a survey will be made on existing analytical methods available in literature. Second, the proposed frameworks are implemented in the well known finite element software programs ANSYS and SLang. Simple and efficient algorithms in FORTRAN are developed for automated microstructure generation using RSA algorithm in order to perform a systematic numerical testing of microstructures of composites. Algorithms are developed to generate constraint equations in periodic boundary conditions and different displacements applied spatially over the boundaries of the RVE in homogeneous boundary conditions. Finally, nonlinear simulations are performed at mesolevel, by considering continuum scalar damage behavior of matrix material with the linear elastic behavior of aggregates with the assumption of rigid bond between constituents.},
  subject      = {Schadensmechanik},
  language  = {en}
}
@phdthesis{Sorge2006,
  author    = {Sorge, Hans-Christian},
  title     = {Technische Zustandsbewertung metallischer Wasserversorgungsleitungen als Beitrag zur Rehabilitationsplanung},
  doi       = {10.25643/bauhaus-universitaet.813},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20070516-8681},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2006},
  abstract  = {Die Instandhaltung der st{\"a}dtischen Trinkwassernetze ist Aufgabenschwerpunkt der Wasserversorgungsunternehmen bzw. Netzbetreiber. Dazu notwendige Rehabilitationsplanungen st{\"u}tzen sich zurzeit weitgehend auf die Trendprognose von Schadensraten und die Erfahrungen der Mitarbeiter. Der Einfluss wesentlicher Kenngr{\"o}ßen wie Werkstoffeigenschaften oder die Resttragf{\"a}higkeit des Rohres bleiben hierbei gr{\"o}ßtenteils unber{\"u}cksichtigt. {\"U}ber materialtechnische Untersuchungen werden die notwendigen Kenngr{\"o}ßen ermittelt, die eine zuverl{\"a}ssige Bewertung des technischen Zustands des Rohrstrangs erm{\"o}glichen. So lassen sich die Prognose der technischen Nutzungsdauer und Rehabilitationsplanungen auf eine solide Basis stellen. In dieser Dissertationsschrift wird hierzu ein Untersuchungs- und Bewertungsalgorithmus mit integrierten Prognoseverfahren erarbeitet.},
  subject      = {Instandhaltungsplanung},
  language  = {de}
}
@misc{Schrader2005,
  type      = {Master Thesis},
  author    = {Schrader, Kai},
  title     = {Algorithmische Umsetzung eines elasto-plastischen Kontakt-Materialgesetzes zur Abbildung der Rissfl{\"a}chen-Degradation bei koh{\"a}siven Rissen},
  doi       = {10.25643/bauhaus-universitaet.619},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-6195},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2005},
  abstract  = {Entwicklung eines Algorithmus f{\"u}r ein nichtlineares Materialgesetz f{\"u}r die vollautomatische Rissentwicklungssimulation unter Verwendung der am Institut f{\"u}r Strukturmechanik entwickelten netzfreien Verfahren. In Anlehnung an die Kontinuumsplastizit{\"a}t wird unter Verwendung einer arbeitsbasierten Formulierung mit Kombination der Mode I und Mode IIa Bruchenergien f{\"u}r sensitive Strukturen und eines nicht-assoziierten Fließgesetzes werden die Rissweggr{\"o}ßen (Riss{\"o}ffnungsweite und Rissgleitungen) iterativ ermittelt. Dadurch ist es m{\"o}glich, den Dilatanzeffekt sowie die verzahnte Kontaktfl{\"a}che und die daraus resultierenden erh{\"o}hten Schubwiderst{\"a}nde abzubilden. Umsetzung mit Hilfe des sehr effizienten impliziten Closest Point Projection Iterationsverfahren auf Basis einer 3-D Kontaktformulierung (Kontakt-Elemente). 2-D Implementation in die Forschungssoftware SLang des Instituts f{\"u}r Strukturmechanik der Bauhaus-Universit{\"a}t Weimar. Verifikation der Modellcharakteristik mit signifikanten Belastungszust{\"a}nden. Zwei Anwendungsbeispiele zur Rissfortschrittsberechnung sind unter Verwendung des umgesetzten Materialgesetzes zum Einsatz gekommen. Untersuchungen hinsichtlich der Materialparameter wurden vorgenommen.},
  subject      = {Dilatanz},
  language  = {de}
}
@phdthesis{Luther2010,
  author    = {Luther, Torsten},
  title     = {Adaptation of atomistic and continuum methods for multiscale simulation of quasi-brittle intergranular damage},
  doi       = {10.25643/bauhaus-universitaet.1436},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20101101-15245},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2010},
  abstract  = {The numerical simulation of damage using phenomenological models on the macroscale was state of the art for many decades. However, such models are not able to capture the complex nature of damage, which simultaneously proceeds on multiple length scales. Furthermore, these phenomenological models usually contain damage parameters, which are physically not interpretable. Consequently, a reasonable experimental determination of these parameters is often impossible. In the last twenty years, the ongoing advance in computational capacities provided new opportunities for more and more detailed studies of the microstructural damage behavior. Today, multiphase models with several million degrees of freedom enable for the numerical simulation of micro-damage phenomena in naturally heterogeneous materials. Therewith, the application of multiscale concepts for the numerical investigation of the complex nature of damage can be realized. The presented thesis contributes to a hierarchical multiscale strategy for the simulation of brittle intergranular damage in polycrystalline materials, for example aluminum. The numerical investigation of physical damage phenomena on an atomistic microscale and the integration of these physically based information into damage models on the continuum meso- and macroscale is intended. Therefore, numerical methods for the damage analysis on the micro- and mesoscale including the scale transfer are presented and the transition to the macroscale is discussed. The investigation of brittle intergranular damage on the microscale is realized by the application of the nonlocal Quasicontinuum method, which fully describes the material behavior by atomistic potential functions, but reduces the number of atomic degrees of freedom by introducing kinematic couplings. Since this promising method is applied only by a limited group of researchers for special problems, necessary improvements have been realized in an own parallelized implementation of the 3D nonlocal Quasicontinuum method. The aim of this implementation was to develop and combine robust and efficient algorithms for a general use of the Quasicontinuum method, and therewith to allow for the atomistic damage analysis in arbitrary grain boundary configurations. The implementation is applied in analyses of brittle intergranular damage in ideal and nonideal grain boundary models of FCC aluminum, considering arbitrary misorientations. From the microscale simulations traction separation laws are derived, which describe grain boundary decohesion on the mesoscale. Traction separation laws are part of cohesive zone models to simulate the brittle interface decohesion in heterogeneous polycrystal structures. 2D and 3D mesoscale models are presented, which are able to reproduce crack initiation and propagation along cohesive interfaces in polycrystals. An improved Voronoi algorithm is developed in 2D to generate polycrystal material structures based on arbitrary distribution functions of grain size. The new model is more flexible in representing realistic grain size distributions. Further improvements of the 2D model are realized by the implementation and application of an orthotropic material model with Hill plasticity criterion to grains. The 2D and 3D polycrystal models are applied to analyze crack initiation and propagation in statically loaded samples of aluminum on the mesoscale without the necessity of initial damage definition.},
  subject      = {Mechanik},
  language  = {en}
}
@phdthesis{Budarapu,
  author    = {Budarapu, Pattabhi Ramaiah},
  title     = {Adaptive multiscale methods for fracture},
  doi       = {10.25643/bauhaus-universitaet.2391},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20150507-23918},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {One major research focus in the Material Science and Engineering Community in the past decade has been to obtain a more fundamental understanding on the phenomenon 'material failure'. Such an understanding is critical for engineers and scientists developing new materials with higher strength and toughness, developing robust designs against failure, or for those concerned with an accurate estimate of a component's design life. Defects like cracks and dislocations evolve at nano scales and influence the macroscopic properties such as strength, toughness and ductility of a material. In engineering applications, the global response of the system is often governed by the behaviour at the smaller length scales. Hence, the sub-scale behaviour must be computed accurately for good predictions of the full scale behaviour. Molecular Dynamics (MD) simulations promise to reveal the fundamental mechanics of material failure by modeling the atom to atom interactions. Since the atomistic dimensions are of the order of Angstroms ( A), approximately 85 billion atoms are required to model a 1 micro- m^3 volume of Copper. Therefore, pure atomistic models are prohibitively expensive with everyday engineering computations involving macroscopic cracks and shear bands, which are much larger than the atomistic length and time scales. To reduce the computational effort, multiscale methods are required, which are able to couple a continuum description of the structure with an atomistic description. In such paradigms, cracks and dislocations are explicitly modeled at the atomistic scale, whilst a self-consistent continuum model elsewhere. Many multiscale methods for fracture are developed for "fictitious" materials based on "simple" potentials such as the Lennard-Jones potential. Moreover, multiscale methods for evolving cracks are rare. Efficient methods to coarse grain the fine scale defects are missing. However, the existing multiscale methods for fracture do not adaptively adjust the fine scale domain as the crack propagates. Most methods, therefore only "enlarge" the fine scale domain and therefore drastically increase computational cost. Adaptive adjustment requires the fine scale domain to be refined and coarsened. One of the major difficulties in multiscale methods for fracture is to up-scale fracture related material information from the fine scale to the coarse scale, in particular for complex crack problems. Most of the existing approaches therefore were applied to examples with comparatively few macroscopic cracks. Key contributions The bridging scale method is enhanced using the phantom node method so that cracks can be modeled at the coarse scale. To ensure self-consistency in the bulk, a virtual atom cluster is devised providing the response of the intact material at the coarse scale. A molecular statics model is employed in the fine scale where crack propagation is modeled by naturally breaking the bonds. The fine scale and coarse scale models are coupled by enforcing the displacement boundary conditions on the ghost atoms. An energy criterion is used to detect the crack tip location. Adaptive refinement and coarsening schemes are developed and implemented during the crack propagation. The results were observed to be in excellent agreement with the pure atomistic simulations. The developed multiscale method is one of the first adaptive multiscale method for fracture. A robust and simple three dimensional coarse graining technique to convert a given atomistic region into an equivalent coarse region, in the context of multiscale fracture has been developed. The developed method is the first of its kind. The developed coarse graining technique can be applied to identify and upscale the defects like: cracks, dislocations and shear bands. The current method has been applied to estimate the equivalent coarse scale models of several complex fracture patterns arrived from the pure atomistic simulations. The upscaled fracture pattern agree well with the actual fracture pattern. The error in the potential energy of the pure atomistic and the coarse grained model was observed to be acceptable. A first novel meshless adaptive multiscale method for fracture has been developed. The phantom node method is replaced by a meshless differential reproducing kernel particle method. The differential reproducing kernel particle method is comparatively more expensive but allows for a more "natural" coupling between the two scales due to the meshless interpolation functions. The higher order continuity is also beneficial. The centro symmetry parameter is used to detect the crack tip location. The developed multiscale method is employed to study the complex crack propagation. Results based on the meshless adaptive multiscale method were observed to be in excellent agreement with the pure atomistic simulations. The developed multiscale methods are applied to study the fracture in practical materials like Graphene and Graphene on Silicon surface. The bond stretching and the bond reorientation were observed to be the net mechanisms of the crack growth in Graphene. The influence of time step on the crack propagation was studied using two different time steps. Pure atomistic simulations of fracture in Graphene on Silicon surface are presented. Details of the three dimensional multiscale method to study the fracture in Graphene on Silicon surface are discussed.},
  subject      = {Material},
  language  = {en}
}
@phdthesis{Hamdia,
  author    = {Hamdia, Khader},
  title     = {On the fracture toughness of polymeric nanocomposites: Comprehensive stochastic and numerical studies},
  doi       = {10.25643/bauhaus-universitaet.3765},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180712-37652},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {Polymeric nanocomposites (PNCs) are considered for numerous nanotechnology such as: nano-biotechnology, nano-systems, nanoelectronics, and nano-structured materials. Commonly , they are formed by polymer (epoxy) matrix reinforced with a nanosized filler. The addition of rigid nanofillers to the epoxy matrix has offered great improvements in the fracture toughness without sacrificing other important thermo-mechanical properties. The physics of the fracture in PNCs is rather complicated and is influenced by different parameters. The presence of uncertainty in the predicted output is expected as a result of stochastic variance in the factors affecting the fracture mechanism. Consequently, evaluating the improved fracture toughness in PNCs is a challenging problem. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) have been employed to predict the fracture energy of polymer/particle nanocomposites. The ANN and ANFIS models were constructed, trained, and tested based on a collection of 115 experimental datasets gathered from the literature. The performance evaluation indices of the developed ANN and ANFIS showed relatively small error, with high coefficients of determination (R2), and low root mean square error and mean absolute percentage error. In the framework for uncertainty quantification of PNCs, a sensitivity analysis (SA) has been conducted to examine the influence of uncertain input parameters on the fracture toughness of polymer/clay nanocomposites (PNCs). The phase-field approach is employed to predict the macroscopic properties of the composite considering six uncertain input parameters. The efficiency, robustness, and repeatability are compared and evaluated comprehensively for five different SA methods. The Bayesian method is applied to develop a methodology in order to evaluate the performance of different analytical models used in predicting the fracture toughness of polymeric particles nanocomposites. The developed method have considered the model and parameters uncertainties based on different reference data (experimental measurements) gained from the literature. Three analytical models differing in theory and assumptions were examined. The coefficients of variation of the model predictions to the measurements are calculated using the approximated optimal parameter sets. Then, the model selection probability is obtained with respect to the different reference data. Stochastic finite element modeling is implemented to predict the fracture toughness of polymer/particle nanocomposites. For this purpose, 2D finite element model containing an epoxy matrix and rigid nanoparticles surrounded by an interphase zone is generated. The crack propagation is simulated by the cohesive segments method and phantom nodes. Considering the uncertainties in the input parameters, a polynomial chaos expansion (PCE) surrogate model is construed followed by a sensitivity analysis.},
  subject      = {Bruch},
  language  = {en}
}
@misc{Korkmaz2008,
  type      = {Master Thesis},
  author    = {Korkmaz, Sinan},
  title     = {Extension of the Uniform Material Law for High Strength Steels},
  doi       = {10.25643/bauhaus-universitaet.1387},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20090602-14718},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2008},
  abstract  = {Uniform Material Law (UML) is a handy and user-friendly method since only the tensile strength data of the material is needed for estimation of the strain-life curve, in contrast to other methods, such as four-point correlation method, universal slopes method, Mitchell's method, modified universal slopes method, which also require the data of the reduction in area or the fracture ductility of the material. On the other hand, the error level of UML estimations can be still decreased by refining the method. The objective of this thesis is putting forward a more refined method by extending conventional UML. Furthermore, a life prediction computation is carried out with the proposed extended UML and the results are compared to that of the conventional method. The results have proven that the maximum error is dropped down to 0.59\% from 38\% with the proposed extended UML method.},
  subject      = {Materialerm{\"u}dung},
  language  = {en}
}