TY - GEN A1 - Fabry, Cagtay A1 - Hirthammer, Volker A1 - Scherer, Martin K. T1 - weldx - welding data exchange format N2 - Scientific welding data covers a wide range of physical domains and timescales and are measured using various different sensors. Complex and highly specialized experimental setups at different welding institutes complicate the exchange of welding research data further. The WelDX research project aims to foster the exchange of scientific data inside the welding community by developing and establishing a new open source file format suitable for the documentation of experimental welding data and upholding associated quality standards. In addition to fostering scientific collaboration inside the national and international welding community an associated advisory committee will be established to oversee the future development of the file format. The proposed file format will be developed with regard to current needs of the community regarding interoperability, data quality and performance and will be published under an appropriate open source license. By using the file format objectivity, comparability and reproducibility across different experimental setups can be improved. KW - Welding KW - Research data management KW - Open science KW - Open Data KW - WelDX PY - 2021 U6 - https://doi.org/10.5281/zenodo.6563282 PB - Zenodo CY - Geneva AN - OPUS4-55226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Jörg F. A1 - Kindrachuk, Vitaliy A1 - Hirthammer, Volker A1 - Titscher, Thomas A1 - Pohl, Christoph T1 - The importance of multiphysics and multiscale modelling of concrete to understand its complex macroscopic properties N2 - Concrete is a complex material. Its properties evolve over time, especially at early age, and are dependent on environmental conditions, i.e. temperature and moisture conditions, as well as the composition of the material. This leads to a variety of macroscopic phenomena such as hydration/solidification/hardening, creep and shrinkage, thermal strains, damage and inelastic deformations. Most of these phenomena are characterized by specific set of model assumptions and often an additive decomposition of strains into elastic, plastic, shrinkage and creep components is performed. Each of these phenomena are investigated separately and a number of respective independent models have been designed. The interactions are then accounted for by adding appropriate correction factors or additional models for the particular interaction. This paper discusses the importance of reconsider even in the experimental phase the model assumptions required to generalize the experimental data into models used in design codes. It is especially underlined that the complex macroscopic behaviour of concrete is strongly influenced by its multiscale and multiphyscis nature and two examples (shrinkage and fatigue) of interacting phenomena are discussed. T2 - International RILEM Conference on Materials, Systems and Structures in Civil Engineering CY - Lyngby, Denmark DA - 22.08.2016 KW - Concrete KW - Multiscale KW - Multiphysics PY - 2016 VL - 1 SP - 115 EP - 124 PB - International RILEM Conference on Materials, Systems and Structures in Civil Engineering, Conference segment on COST TU1404 AN - OPUS4-38651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fabry, Cagtay A1 - Pittner, Andreas A1 - Hirthammer, Volker A1 - Rethmeier, Michael T1 - Recommendations for an Open Science approach to welding process research data N2 - The increasing adoption of Open Science principles has been a prevalent topic in the welding science community over the last years. Providing access to welding knowledge in the form of complex and complete datasets in addition to peer-reviewed publications can be identified as an important step to promote knowledge exchange and cooperation. There exist previous efforts on building data models specifically for fusion welding applications; however, a common agreed upon implementation that is used by the community is still lacking. One proven approach in other domains has been the use of an openly accessible and agreed upon file and data format used for archiving and sharing domain knowledge in the form of experimental data. Going into a similar direction, the welding community faces particular practical, technical, and also ideological challenges that are discussed in this paper. Collaboratively building upon previous work with modern tools and platforms, the authors motivate, propose, and outline the use of a common file format specifically tailored to the needs of the welding research community as a complement to other already established Open Science practices. Successfully establishing a culture of openly accessible research data has the potential to significantly stimulate progress in welding research. KW - Welding KW - Research data management KW - Open science KW - Digitalization KW - Weldx KW - Open source PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-529332 SN - 1878-6669 SN - 0043-2288 SP - 1 EP - 9 PB - Springer CY - Heidelberg AN - OPUS4-52933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pittner, Andreas A1 - Fabry, Cagtay A1 - Hirthammer, Volker A1 - Rethmeier, Michael T1 - Open Science in der Schweißtechnik N2 - Darstellung der aktuellen Situation sowie des Potenzials von Forschungsdatenmanagement und OpenScience in der Schweißtechnik. T2 - WelDX - Open Science Seminar CY - BAM Berlin, Germany DA - 04.03.2020 KW - Digitalisierung KW - Schweißtechnik KW - OpenScience KW - Forschungsdatenmanagement PY - 2020 UR - https://www.bam.de/Content/DE/Veranstaltungen/2020/2020-03-09-weldx-open-science-seminar.html AN - OPUS4-51857 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hirthammer, Volker A1 - Unger, Jörg F. A1 - Ozbolt, J. T1 - Modeling the interactions of creep, shrinkage and damage in a multiphysics simulation of concrete N2 - The time dependent, mechanical behavior of concrete is affected by multiple phenomena like creep, shrinkage and damage propagation. The interactions of these processes are supposed to have significant influence on the materials response to external loading. For example it can be observed that the compressive strength of concrete rises with lowering the moisture content [Dahms, 1968]. Most of the constitutive models for finite element methods are designed with just a single phenomena in mind. In multiphysics simulations it is quiet common to use a linear superposition, i.e. additive decomposition of the total strain into elastic shrinkage, creep or thermal strains. In this paper, the interactions of creep, shrinkage and damage models are investigated, in particular for cases where the assumption of linear superposition is questionable. A gradient enhanced damage model proposed by [Peerlings et al., 1996] is employed. Creep is modeled as a Kelvin chain as described in [Jirásek and Bažant, 2001]. Shrinkage is simulated by using two different approaches. The first model simulates shrinkage as an additional moisture dependent strain component. In the second model, shrinkage is simulated as a moisture dependent pore pressure applied to the solid bulk. The impact of model interactions will be discussed with a focus on simulating the influence of the moisture content on the macroscopic strength. The model is validated by comparison to experimental data. T2 - 6th European Conference on Computational Mechanics (ECCM 6) CY - Glasgow, UK DA - 11.06.2018 KW - Concrete KW - Damage KW - FEM KW - Multiphysics Problems KW - Shrinkage PY - 2018 AN - OPUS4-45692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hirthammer, Volker A1 - Unger, Jörg F. A1 - Ozbolt, J. ED - von Scheven, M. ED - Keip, M.-A. ED - Karajan, N. T1 - Mesoscale influence on the macroscopic material behavior of concrete N2 - The heterogeneous mesostructure of concreted causes local stress concentrations. Stress dependent phenomena like damage and creep as well as their interactions are effected by those stress concentrations. Therefore a material model’s macroscopic behavior will differ whether the mesoscale structure is considered or not. The differences between the mesoscale approach and an homogeneous approach will be presented. The results are discussed with focus on the true materials behavior. T2 - 7th GACM Colloquium on Computational Mechanics for Young Scientists from Academia and Industry CY - Stuttgart, Germany DA - 11.10.2017 KW - Mesoscale KW - Material behavior KW - Macroscopic PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-436611 VL - 7 SP - MS13, 414 EP - 417 PB - Institute for Structural Mechanics, University of Stuttgart CY - Stuttgart AN - OPUS4-43661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas A1 - Hirthammer, Volker A1 - Unger, Jörg F. ED - Meschke, G. ED - Pichler, B. ED - Rots, J.G. T1 - A continuum damage model for the simulation of concrete under cyclic loading N2 - Lifetime aspects including fatigue failure of concrete structures were traditionally only of minor importance. Because of the growing interest in maxing out the capacities of concrete, its fatigue failure under compression has become an issue. A variety of interacting phenomena such as e.g. loss of prestress, degradation due to chemical reactions or creep and shrinkage influence the fatigue resistance. Failure due to cyclic loads is generally not instantaneous, but characterized by a steady damage accumulation. Therefore, a reliable numerical model to predict the performance of concrete over its lifetime is required, which accurately captures order effects and full three-dimensional stress states. Many constitutive models for concrete are currently available, which are applicable for specific loading regimes, different time scales and different resolution scales. However, a key limitation of those models is that they generally do not address issues related to fatigue on a structural level. Very few models can be found in the literature that reproduce deterioration of concrete under repeated loading-unloading cycles. This is due to the computational effort necessary to explicitly resolve every cycle which exceeds the currently available computational resources. The limitation can only be overcome by the application of multiscale methods in time. The objective of the paper is the development of numerical methods for the simulation of concrete under fatigue loading using temporal multiscale methods. First, a continuum damage model for concrete is developed with a focus on fatigue under compressive stresses [1]. This includes the possibility to model stress redistributions and capture size effects. In contrast to cycle based approaches, where damage is accumulated based on the number of full stress cycles, a strain based approach is developed that can capture cyclic degradation under variable loading cycles including different amplitudes and loading frequencies. The model is designed to represent failure under static loading as a particular case of fatigue failure after a single loading cycle. As a consequence, most of the material parameters can be deduced from static tests. Only a limit set of additional constitutive parameters is required to accurately describe the evolution under fatigue loading. Another advantage of the proposed model is the possibility to directly incorporate other multi-physics effects such as creep and shrinkage or thermal loading on the constitutive level. Second, a multiscale approach in time is presented to enable structural computations of fatigue failure with a reduced computational effort. The damage rate within the short time scale corresponding to a single cycle is computed based on a Fourier based approach [2]. This evolution equation is then solved on the long time scale using different implicit and explicit time integration schemes. Their performance and some limitations for specific loading regimes is discussed. Finally, the developed methods will be validated and compared to experimental data. [1] Vitaliy Kindrachuk, Marc Thiele, Jörg F. Unger. Constitutive modeling of creep-fatigue interaction for normal strength concrete under compression, International Journal of Fatigue, 78:81-94, 2015 [2] Vitaliy Kindrachuk, Jörg F. Unger. A Fourier transformation-based temporal integration scheme for viscoplastic solids subjected to fatigue deterioration, International Journal of Fatigue, 100:215-228, 2017 T2 - Conference on Computational Modelling of concrete and concrete structures (EURO_C 2018') CY - Bad Hofgastein, Austria DA - 26.02.2018 KW - Fatigue KW - Concrete KW - Damage PY - 2018 SN - 978-1-138-74117-1 U6 - https://doi.org/10.1201/9781315182964-19 SP - 155 EP - 164 PB - CRC Press, Taylor & Francis Group CY - Boca Raton, Lodon, New York, Leiden AN - OPUS4-47999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -