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A general tangent operator applied to concrete using a multi-surface plasticity model
Ana Beatriz C.G. Silva,Jose Claudio F. Telles,Eduardo M.R. Fairbairn,Fernando Luiz B. Ribeiro 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.2
The present paper aims at developing a method to accommodate multi-surface concrete plasticity from the point of view of a consistency concept applied to general tangent operators. The idea is based on a Taylor series expansion of the actual effective stress at the stress point corresponding to the previous accumulated true stresses plus the current increment values, initially taken to be elastic. The proposed algorithm can be generalized for any multi-surface criteria combination and has been tested here for typical cement-based materials. A few examples of application are presented to demonstrate the effectiveness of the multi-surface technique as used to a combination of Rankine and Drucker-Prager yield criteria.
Modeling refractory concrete lining of fluid catalytic cracking units of oil refineries
Ana B.C.G. Silva,Henrique C.C. Andrade,Eduardo M.R. Fairbairn,Jose C.F. Telles,Fernando L.B. Ribeiro,Romildo D. Toledo-Filho,Jorivaldo Medeiros 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.1
This work presents a numerical modeling procedure to simulate the refractory concrete lining in fluid catalytic cracking units of oil refineries. The model includes the simulation of the anchors that reinforce the contact between the refractory concrete and the steel casing. For this purpose, the constitutive relations of an interface finite element are set to values that represent the homogenized behavior of the anchored interface. The parameters of this constitutive relation can be obtained by experimental tests. The model includes also multi-surface plasticity, in order to represent the behavior of the refractory concrete lining. Since the complexity of real case applications leads to high computational costs, the models presented here were implemented in a high-performance parallelized finite element platform. A case study representing a riser similar to the ones used by the refinery industry demonstrates the potential of the model.
A Proposal for Aluminum Tolerance Selection in White Oat under Hydroponic Conditions
Crestani, Maraisa,Da Silva, Jose Antonio Gonzalez,Tessmann, Elisane Weber,Mezzalira, Itamara,De Oliveira, Antonio Costa,De Carvalho, Fernando Iraja Felix 한국작물학회 2011 Journal of crop science and biotechnology Vol.14 No.1
Single-Stage Double-Buck Topologies with High Power Factor
Vitor Fernao Pires,Jose Fernando Silva 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5
This paper presents two topologies for single-stage single-phase double-buck type PFC converters, designed to operate at high power factor, near sinusoidal input currents and adjustable output voltage. Unlike the known buck type PFC topologies, in which the output voltage is always lower than the maximum input voltage, the proposed converters can operate at output voltages higher than the ac input peak voltage. A reduced number of switches on the main path of the current are another characteristic of the two proposed topologies. To shape the input line currents, a fast and robust controller based on a sliding mode approach is proposed. This active non-linear control strategy, applied to these converters allows high quality input currents. A Proportional Integral (PI) controller is adopted to regulate the output voltage of the converters. This external voltage controller modulates the amplitude of the sinusoidal input current references. The performances of the presented rectifiers are verified with experimental results.
Single-Stage Double-Buck Topologies with High Power Factor
Pires, Vitor Fernao,Silva, Jose Fernando The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5
This paper presents two topologies for single-stage single-phase double-buck type PFC converters, designed to operate at high power factor, near sinusoidal input currents and adjustable output voltage. Unlike the known buck type PFC topologies, in which the output voltage is always lower than the maximum input voltage, the proposed converters can operate at output voltages higher than the ac input peak voltage. A reduced number of switches on the main path of the current are another characteristic of the two proposed topologies. To shape the input line currents, a fast and robust controller based on a sliding mode approach is proposed. This active non-linear control strategy, applied to these converters allows high quality input currents. A Proportional Integral (PI) controller is adopted to regulate the output voltage of the converters. This external voltage controller modulates the amplitude of the sinusoidal input current references. The performances of the presented rectifiers are verified with experimental results.