Laminated composites have important applications in modern aeronautical structures due to their extraordinary mechanical and environmental behaviour. Nevertheless, aircraft composite structures are highly vulnerable to impact damage, either by low-velocity sources during maintenance or high-velocity sources during in-flight events. Even barely visible impact damage induced by low-velocity loading, substantially reduces the residual mechanical performance and the safe-service life of the composites structures. Despite the extensive research already carried out, impact damage of laminated composite structures is still not well understood and it is an area of on-going research. Numerical modelling is considered as the most efficient tool as compared to the expensive and time-consuming experimental testing. In this paper, a finite element model based on explicit dynamics formulations is adopted. Hashin criterion is applied to predict the intra-laminar damage initiation and evolution. The numerical analysis is performed using the ABAQUS ® programme. The employed modelling approach is validated using numerical results found in the literature and the presented results show an acceptable correlation to the available literature data. It is demonstrated that the presented model is able to capture force-time response as well as damage evolution map for a range of impact energies.
''This paper aims to analyze the behavior of experimentally tested unreinforced masonry walls subjected to in-plane loading. Monotonic load analyses are conducted using FEM and AEM modeling approaches. The models presented here are based on the assumption of both unit and mortar joints modeled as solid elements, which behave nonlinearly. Therefore, the damages occur along the mortar and brick in the analyses. The FEM analysis is carried out by using LS-DYNA, and the AEM analysis is carried out by using ELS (Extreme Loading for Structures). Experimental studies of a masonry wall in-plane loading conditions are used for verification against numerical models. Analysis of the tests performed on masonry shear walls by Raijmakers and Vermeltfoort within the CUR project is carried out. The presented analyses methods can be applied to other unit and mortar compositions. Computational results from this study provide a monotonic load-deformation curve, which then is compared to the envelope of the horizontal load-deformation curves that are experimentally obtained. The agreement of each method with the experimental results, in terms of strength, stiffness and ductility, as well as the predicted damage mechanisms, are discussed.''
With summaries in Dutch, Esperanto and English. DOI: 10.4233/uuid:d7132920-346e-47c6-b754-00dc5672b437 "The subject of this study is deformation analysis of the earth's surface (or part of it) and spatial objects on, above or below it. Such analyses are needed in many domains of society. Geodetic deformation analysis uses various types of geodetic measurements to substantiate statements about changes in geometric positions.Professional practice, e.g. in the Netherlands, regularly applies methods for geodetic deformation analysis that have shortcomings, e.g. because the methods apply substandard analysis models or defective testing methods. These shortcomings hamper communication about the results of deformation analyses with the various parties involved. To improve communication solid analysis models and a common language have to be used, which requires standardisation.Operational demands for geodetic deformation analysis are the reason to formulate in this study seven characteristic elements that a solid analysis model needs to possess. Such a model can handle time series of several epochs. It analyses only size and form, not position and orientation of the reference system; and datum points may be under influence of deformation. The geodetic and physical models are combined in one adjustment model. Full use is made of available stochastic information. Statistical testing and computation of minimal detectable deformations is incorporated. Solution methods can handle rank deficient matrices (both model matrix and cofactor matrix). And, finally, a search for the best hypothesis/model is implemented. Because a geodetic deformation analysis model with all seven elements does not exist, this study develops such a model.For effective standardisation geodetic deformation analysis models need: practical key performance indicators; a clear procedure for using the model; and the possibility to graphically visualise the estimated deformations."
Stringent nitrogen oxide (NOx) regulations are crucial for minimizing environmental harm and enhancing public health. The Selective Non-Catalytic Reduction (SNCR) technique is an effective after-treatment method for reducing NOx emissions in combustion systems. By injecting a reagent, typically ammonia or urea, into the flue gas within a specified temperature window, SNCR facilitates the chemical reaction that converts NOx into harmless nitrogen and water. The optimal temperature range for this reaction is critical for maximizing efficiency and effectiveness. The primary advantage of the SNCR technique is its lower installation and operating costs in comparison to other after-treatment methods. The partners involved in this proposal are highly interested in implementing the SNCR method to reduce NOx emissions from heavy-duty engines. This proposal aims to develop a numerical model to evaluate the NOx reduction potential in heavy-duty engine applications using the SNCR method. The model will enable the analysis of key parameters, including the injection site temperature and the reagent-to-NOx concentration ratio, to determine their impact on NOx reduction.
