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Peer Reviewed
See detailNumerical Modeling of Flow-Driven Piezoelectric Energy Harvesting Devices
Ravi, Srivathsan UL; Zilian, Andreas UL

in Ibrahimbegovic, Adnan (Ed.) Computational Methods for Solids and Fluids (2016)

The present work proposes uniform and simultaneous computational analysis of smart, low power energy harvesting devices targeting flow-induced vibrations in order to enable reliable sensitivity ... [more ▼]

The present work proposes uniform and simultaneous computational analysis of smart, low power energy harvesting devices targeting flow-induced vibrations in order to enable reliable sensitivity, robustness and efficiency studies of the associated nonlinear system involving fluid, structure, piezo-ceramics and electric circuit. The article introduces a monolithic approach that provides simultaneous modeling and analysis of the coupled energy harvester, which involves surface-coupled fluid-structure interaction, volume-coupled piezoelectric mechanics and a controlling energy harvesting circuit for applications in energy harvesting. A space-time finite element approximation is used for the numerical solution of the governing equations of the flow-driven piezoelectric energy harvesting device. This method enables modeling of different types of structures (plate, shells) with varying cross sections and material compositions, and different types of simple and advanced harvesting circuits. [less ▲]

Detailed reference viewed: 214 (22 UL)
Peer Reviewed
See detailNumerical modelling of electrified particle layer formation on the surface of filtration fabric.
Peters, Bernhard UL; Dzuigys, A.

in Environmental Engineering (2001), 4

Detailed reference viewed: 48 (0 UL)
Full Text
See detailNumerical Modelling of Piezoelectric Energy Harvesting Devices
Ravi, Srivathsan UL; Zilian, Andreas UL

in 2nd ECCOMAS Young Investigators Conference (YIC 2013) (2013)

This paper introduces a monolithic approach that provides simultaneous solution to the coupled system which involves volume-coupled piezoelectric mechanics and a controlling energy harvesting circuit for ... [more ▼]

This paper introduces a monolithic approach that provides simultaneous solution to the coupled system which involves volume-coupled piezoelectric mechanics and a controlling energy harvesting circuit for applications in energy harvesting. The weak form of the governing equations is discretized by space-time nite element method based on mixed velocity-stress/ rate of potential-dielectric displacement setting. The results will be compared to the simple cases with closed-form solution available from literature. [less ▲]

Detailed reference viewed: 118 (17 UL)
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See detailNumerical Modelling of Piezoelectric Energy Harvesting Devices
Ravi, Srivathsan UL; Zilian, Andreas UL

Scientific Conference (2013)

This paper introduces a monolithic approach that provides simultaneous modeling and analysis of the coupled energy harvester, which involves surface-coupled fluid-structure interaction, volume-coupled ... [more ▼]

This paper introduces a monolithic approach that provides simultaneous modeling and analysis of the coupled energy harvester, which involves surface-coupled fluid-structure interaction, volume-coupled piezoelectric mechanics and a controlling energy harvesting circuit for applications in energy harvesting. The weak form of the governing equations is discretized by the space-time finite element method based on a mixed velocity-stress/rate form of the potential-dielectric displacement framework. The results will be compared to the simple cases with closed-form solution available from literature. [less ▲]

Detailed reference viewed: 148 (16 UL)
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Peer Reviewed
See detailNumerical Modelling of Tension Piles
Van Baars, Stefan UL; Van Niekerk, W.J.

in Beyond 200 in Computational Geotechnics (1999)

For determinations of the ultimate tension capacity of a piled foundation, often use is made of empirical relations between soil strength and skin friction. The disadvantage of these (analytical) methods ... [more ▼]

For determinations of the ultimate tension capacity of a piled foundation, often use is made of empirical relations between soil strength and skin friction. The disadvantage of these (analytical) methods is that they are in general not very accurate for most soil conditions. Therefore a numerical method for determination of the ultimate bearing capacity is presented here. Results were successively compared with actual test results which were measured during pile tests. It was found that the numerical model assessed the actual pile bearing capacity more closely than analytical models based on empirical calculation rules. Therefore lower factors of safety can be accepted. The behaviour of the (virtual) interface between pile and soil significantly influences the behaviourof the pile. [less ▲]

Detailed reference viewed: 155 (0 UL)
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Peer Reviewed
See detailNumerical modelling of visco-plastic soft soils
Van Baars, Stefan UL

in 11th Baltic Sea Geotechnical Conference on Geotechnics in Maritime Engineering (2008, September)

In many cases geotechnical calculations are made with linear or non-linear elastoplastic soil models. The most common case in which these types of soil models are not sophisticated enough is during the ... [more ▼]

In many cases geotechnical calculations are made with linear or non-linear elastoplastic soil models. The most common case in which these types of soil models are not sophisticated enough is during the modelling of creep of soft soils. Most constitutive soil models modelling creep are based on volumic strain reduction over time. In this paper the creep is modelled through shear stress reduction (the viscous behaviour). The key point of viscous modelling is that this type of stress reduction (Mohr-circle squeezing) also takes place below the Coulomb failure line. In other words, viscosity is a sort of slow and rate-depending plasticity without reaching the Coulomb criterion; therefore also the word visco-plasticity can be used. This paper shows that visco-plastic modelling of soft soils will produce more realistic results and shows how this visco-plastic modelling works. [less ▲]

Detailed reference viewed: 62 (0 UL)
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See detailNumerical parametric study on minimum degree of shear connection in steel-concrete composite beams
Romero Guzman, Alfredo UL

Bachelor/master dissertation (2019)

In steel-concrete composite beams, the mechanical shear connectors are used to provide the shear transfer at the steel-concrete interface by connecting the concrete slab and the steel beam. Eurocode 4 (EN ... [more ▼]

In steel-concrete composite beams, the mechanical shear connectors are used to provide the shear transfer at the steel-concrete interface by connecting the concrete slab and the steel beam. Eurocode 4 (EN 1994-1-1), provides the design rules to achieve an adequate degree of shear connection. In recent years, revised rules have been proposed for the new generation of Eurocodes and research has been done to assess their suitability. The aim of this study is to complement previous studies and to evaluate the revised rules for minimum degree of shear connection of propped composite beams with ductile shear connectors and symmetric cross sections. First, a simple and comprehensive numerical model of a simply supported composite beam was developed in the finite element software ABAQUS and validated against previous numerical studies. Then, a parametric study was performed to evaluate the proposed rules on solid composite beams and composite beams with profiled steel sheeting for four span lengths (i.e. Lₑ= 6, 9, 12, and 15 m). For each span length, ten distinct configurations were analysed and each configuration was evaluated for five different degrees of shear connection (i.e. η= 0.20, 0.40, 0.60, 0.80, and 1.0). Thus, more than 200 simulations were completed in this parametric study. The results were post-processed and the suitability of the proposed rules was assessed in terms of end slip and midspan deflection at ULS and SLS respectively. The design rules led to adequate results in terms of midspan deflection. However, in some cases the end slip at ULS exceeded the 6 mm upper bound given in EN 1994-1-1 for ductile shear connectors. In order to properly identify and limit the end slip of the unsafe cases, the data from previous studies focusing on long span beams (i.e. 15m<Lₑ≤25m) was gathered with the results of the present study. Based on the assessment of the results, additional limitations to the revised rules were provided for the unsafe configurations. In these cases, the load level shall be limited by a reduction factor βₓ varying between 0.85 and 1, as a function of the plastic neutral axis depth to the overall height ratio (i.e. xₚₗ/h) and the composite to steel beam plastic bending resistance ratio (i.e. Mpl,Rd/Mpl,a,Rd). The effectiveness of this condition was re-evaluated and the results showed that more than 90% of the cases exhibited a maximum allowable end slip lower than 6 mm. Finally, a design proposal that accounts for the reduction factor βₓ was developed. [less ▲]

Detailed reference viewed: 164 (37 UL)
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Peer Reviewed
See detailNumerical prediction of the bulk density of granular particles of di erent geometries
Peters, Bernhard UL; Samiei, Kasra UL; Berhe, Girma UL

in KONA Powder and Particle Journal (2013)

Detailed reference viewed: 125 (4 UL)
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See detailNumerical prediction of the rheological properties of fresh self-compacting concrete
Huang, Haiqin UL; Zilian, Andreas UL

Scientific Conference (2017, July 14)

Self-Compacting Concrete (SCC) is a high-performance construction material that can simplify classical handling on concrete construction by avoiding the need for additional vibrational compaction ... [more ▼]

Self-Compacting Concrete (SCC) is a high-performance construction material that can simplify classical handling on concrete construction by avoiding the need for additional vibrational compaction. Challenges in the use of SCC lie in ensuring optimal operation of the material in terms of properly filled castings in presence of complex reinforcement arrangements, reduction of entrained gas bubbles and limitation of aggregate separation. A major factor influencing the aforementioned aspects is the rheological properties of SCC mixtures under varying conditions (e.g. content composition, mechanical impact, temperature, moisture). This contribution aims at unified constitutive modelling of SCC in the setting stage. Concrete setting describes the transition from fluid-like fresh concrete, which -in presence of time- dependent transport-reaction processes- develops a porous cementitious structure, to hardened concrete showing solid-like behaviour. The constitutive model is implemented using the open-source finite element framework FENICS and applied to a number of benchmark problems. [less ▲]

Detailed reference viewed: 161 (25 UL)
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See detailA Numerical Scheme for Multisignal Weight Constrained Conditioned Portfolio Optimisation Problems
Boissaux, Marc; Schiltz, Jang UL

E-print/Working paper (2013)

Detailed reference viewed: 44 (2 UL)
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See detailNumerical simulation and Identification of the Failure Criterion for Structural Silicone
Staudt, Yves UL; Odenbreit, Christoph UL; Schneider, Jens

Speeches/Talks (2016)

In civil engineering, silicone sealants are widely used in structural sealant glazing applications as an adhesively bonded connection between the glass panels and the building substructure. The current ... [more ▼]

In civil engineering, silicone sealants are widely used in structural sealant glazing applications as an adhesively bonded connection between the glass panels and the building substructure. The current design concept does not take into account the actual stress state and the actual failure mechanism. Therefore, no information about the exact failure probability can be given. Alternative approaches, such as the Finite Element Analysis, also have major disadvantages due to the presence of singularities. Therefore, a method from Finite Fracture Mechanics, calibrated with experimental investigations on bulk material, is applied on silicone sealants, focusing on the shear failure mechanism. The procedure is validated using small scale tests such as simple shear and torsion tests. [less ▲]

Detailed reference viewed: 83 (4 UL)
Peer Reviewed
See detailNumerical Simulation of a Diesel Particulate Filter during Loading and Regeneration
Peters, Bernhard UL

in ASME Internal Combustion Engine Division (2003)

Detailed reference viewed: 139 (1 UL)
Peer Reviewed
See detailNumerical simulation of a motion of non-sherical granular material using object-orientated techniques.
Peters, Bernhard UL; Dzuigys, A.

in Computer Methods in Applied Mechanics and Engineering (2002), 191

Detailed reference viewed: 65 (6 UL)
See detailNumerical simulation of energy harvesting devices driven by fluid-structure interaction
Zilian, Andreas UL; Ravi, Srivathsan UL

Scientific Conference (2015, June)

A specific class of piezo-electric energy harvesting devices for renewable energy resources is investigated. The key idea is to invert the traditional intention of engineers to avoid flow-induced ... [more ▼]

A specific class of piezo-electric energy harvesting devices for renewable energy resources is investigated. The key idea is to invert the traditional intention of engineers to avoid flow-induced excitation of structures such, that flow-induced vibrations can successfully be controlled and utilised in order to provide independent power supply to small-scale electrical devices. Possible application are e.g. micro electro-mechanical systems, monitoring sensors at remote locations or even in-vivo medical devices with the advantage of increased independence on local energy storage and reduced maintenance effort. This energy converter technology involves transient boundary-coupled fluid-structure interaction, volume-coupled piezo-electric-mechanics as well as a controlling electric circuit simultaneously. In order to understand the phenomenology and to increase robustness and performance of such devices, a mathematical and numerical model of the transient strongly-coupled non-linear multi-physics system is developed for systematic computational analyses. On basis of numerical investigations of the overall system optimal designs of the flow-induced vibrating piezo-electric energy harvester shall be identified with respect to electric power supply under varying exterior conditions. Vortex-induced excitations of a cantilever piezo-electric plate are exemplarily considered for studies on robustness and efficiency. [less ▲]

Detailed reference viewed: 205 (15 UL)
See detailNumerical simulation of high impedance T-match antennas for terahertz photomixers
Juul, Lars UL; Mikulics, Martin; Marso, Michel UL et al

in Proc. SPIE 9585, Terahertz Emitters, Receivers, and Applications VI, 95850K (August 31, 2015); (2015, August)

Detailed reference viewed: 125 (2 UL)
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See detailNumerical simulation of load flux and crack initiation in reinforced concrete columns with anchor plates and headed shear studs.
Fromknecht, Stephan UL; Odenbreit, Christoph UL

Scientific Conference (2006)

A typical constructional solution for the connection between steel and concrete load bearing elements in highrise- as well as multi-storey-buildings is the anchor plate in steel. A research project deals ... [more ▼]

A typical constructional solution for the connection between steel and concrete load bearing elements in highrise- as well as multi-storey-buildings is the anchor plate in steel. A research project deals with the numerical simulation of the load flux between anchor plate, headed shear studs and concrete. Most existing solutions in narrow constructions are dissatisfying in the point of using and analyzing the reinforcement effects. For crack propagation detailed concrete elements with 3d-nonlinear material properties are used. This includes tension and compression capabilities to simulate crack initiation and local failure behavior of the concrete. To cover structural nonlinearities the contact between steel and concrete is considered. The results in form of load flux and crack pattern are validated by comparisons to test results. The numerical simulation will help in optimizing the ratio and position of the reinforcement. [less ▲]

Detailed reference viewed: 34 (5 UL)
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Peer Reviewed
See detailNumerical simulation of the load bearing behaviour of concrete dowels in slim-floor construction – CoSFB
Braun, Matthias Volker UL; Obiala, Renata UL; Odenbreit, Christoph UL

in Eurosteel 2017 (2017, September 13)

In this paper the current status of an ongoing research on composite slim-floor beams (SFB) with concrete dowels (CoSFB) is presented, Fig. 1. Using commercial software ABAQUS [1], a 3D solid model with ... [more ▼]

In this paper the current status of an ongoing research on composite slim-floor beams (SFB) with concrete dowels (CoSFB) is presented, Fig. 1. Using commercial software ABAQUS [1], a 3D solid model with non-linear material laws has been developed to simulate the load bearing behaviour of concrete dowels numerically. The model was validated by the results of experimental investigations, which have proven a high stiffness of the concrete dowels under service loads and their ductile behaviour in reaching the load bearing resistance [2], [3]. Further, in comparison to traditional shear studs, the thickness of the concrete cover above the upper flange of composite SFB with concrete dowels can be reduced to a minimum, which leads to an optimized floor thickness and overall to a more economic construction. Main parameters defining the FE model, which influence the load bearing capacity, the behaviour and failure of the shear connection were identified and described in this paper. Available results and analysis from the parametric study are described. Wide range of results obtained from the numerical study will be used to derive an analytical model to allow predicting the load bearing resistance of the system. [less ▲]

Detailed reference viewed: 59 (7 UL)