R. Costa¹, J. Alfaiate²

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 11-18, 2006, DOI:10.3970/sdhm.2006.002.011

Abstract In this paper a numerical simulation is performed on the behaviour of reinforced concrete beams, submitted to initial damage, subsequently strengthened with external steel plates bonded with epoxy. Modelling these structures requires the characterization of the behaviour of different materials as well as the connection between them. Fracture is modelled within the scope of a discrete crack approach, using a formulation in which strong discontinuities are embedded in the finite elements. In this approach, the displacement field is truly discontinuous and the jumps are non-homogeneous within each parent element [Alfaiate, Wells and Sluys (2000)]. More >

Han Li¹, Tianding Chen^{2, *}, Hualiang Teng³, Yingtao Jiang⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.2, pp. 253-274, 2019, DOI:10.31614/cmes.2019.05807

Abstract In any classical value-based reinforcement learning method, an agent, despite of its continuous interactions with the environment, is yet unable to quickly generate a complete and independent description of the entire environment, leaving the learning method to struggle with a difficult dilemma of choosing between the two tasks, namely exploration and exploitation. This problem becomes more pronounced when the agent has to deal with a dynamic environment, of which the configuration and/or parameters are constantly changing. In this paper, this problem is approached by first mapping a reinforcement learning scheme to a directed graph, and the set that contains all… More >

Smitha Gopinath^1,2, J. Rajasankar¹, Nagesh R.Iyer¹, A.Rama Chandra Murthy¹

CMC-Computers, Materials & Continua, Vol.33, No.1, pp. 87-110, 2013, DOI:10.3970/cmc.2013.033.087

Abstract An integrated model is proposed to describe tension stiffening in reinforced concrete (RC) flexural members that are undergoing uniform corrosion of reinforcement. The tension stiffening model is taken as base to incorporate the effects of reinforcement corrosion. The model is developed in two steps. In the first step, tension stiffening of concrete is modelled using an exponential stress-strain curve defined as function of a decay parameter. Modular ratio and reinforcement ratio are considered in the definition of the decay parameter. In the second step, the effects of uniform corrosion of reinforcement are integrated with the tension stiffening model. For this,… More >

Yongzheng Ma, Hong Zheng

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.1, pp. 7-8, 2011, DOI:10.3970/icces.2011.019.007

Abstract The traditional Discontinuous Deformation Analysis (DDA) method, like other Discrete Element Methods, is created to model the discrete block system. The extended DDA method based on meshless interpolations means utilizing meshless interpolations, usually the Moving Least-Squares interpolations, to present block displacement field. In the new extensions here, the effects of earthquake, excavation and bolt reinforcement on the assemblages of large blocks are modeled: for modeling earthquake, the initial acceleration value from earthquake at certain DDA time step can be interpolated from the earthquake acceleration vs. time curve; the modeling of excavation is by reversing in-situ stresses at excavation internal boundaries… More >

Nina Graupner^1,*, Koranat Narkpiban^2,5, Thiprada Poonsawat³, Porntip Tooptompong⁴, Jörg Müssig¹

Journal of Renewable Materials, Vol.7, No.8, pp. 693-711, 2019, DOI:10.32604/jrm.2019.06785

Abstract Toddy palm fruit have an apparent density below 0.8 g/cm³ and offer an interesting lightweight construction potential in polylactide (PLA) composites reinforced with 37 mass-% fibres. Single fibre bundles show similar mechanical properties compared with coir: tensile strength of 240 MPa, Young´s modulus of 3.8 GPa and an elongation at break of 31%. However, density and diameter (~ 50 μm) of fruit fibre bundles are significantly lower. The compression moulded composites have a density of 0.9 g/cm³ and achieved an unnotched Charpy impact strength of 12 kJ/m², a tensile strength of 25 MPa, Young’s modulus of 1.9 GPa and an… More >

Sofía Collazo-Bigliardi^1,*, Rodrigo Ortega-Toro², Amparo Chiralt Boix¹

Journal of Renewable Materials, Vol.6, No.6, pp. 599-610, 2018, DOI:10.32604/JRM.2018.00127

Abstract Cellulosic fibres from coffee (CF) and rice (RF) husks have been obtained applying chemical treatments and characterized as to their microstructure and thermal behaviour. These materials have been incorporated into glycerol plasticised thermoplastic starch (TPS) films obtained by melt blending and compression moulding at 1 wt%, 5 wt% and 10 wt%. Microstructure, thermal behaviour and optical, tensile and barrier properties of the composites were analysed. Both kinds of micro-fibres improve the film stiffness while reduced the film stretchability. However, CF better maintained the film ductility at 1 and 5 wt%. A network of fine oriented fibres was observed on the… More >

Alexandre S. Botta¹, Wilson S. Venturini²

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 15-28, 2005, DOI:10.3970/cmes.2005.008.015

Abstract In this work a regularized boundary-finite element combination is proposed to analyse 2D elastostatic solids reinforced by fibres. The boundary element is adopted to model the matrix behaviour, while finite elements model the embedded fibres. The debonding effects caused by the adherence loss between the two materials are also considered. A three-degree polynomial is adopted to approach the displacement field along the fibre elements, while linear approximations are used to represent the bonding forces between fibres and the matrix. The non-linear debonding model is governed by a loading function written in terms of the contact forces and the relative displacements.… More >

H.J. Bohm¨ ¹, W. Han^1,2, A. Eckschlager^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 5-20, 2004, DOI:10.3970/cmes.2004.005.005

Abstract Three-dimensional periodic micromechanical models are used for studying the mechanical behavior of discontinuously reinforced ductile matrix composites. The models are based on unit cells that contain a number of randomly positioned and, where applicable, randomly oriented spherical, spheroidal or cylindrical reinforcements. The Finite Element method is used to resolve the microscale stress and strain fields and to predict the homogenized responses under overall uniaxial tensile loading in the elastic and elastoplastic regimes. Periodicity boundary conditions are employed in the analyses.\\ The main emphasis of the contribution is put on studying the microscale stresses in the reinforcements, which are evaluated in… More >

N. A. Sri Aprilia¹, M. S. Nurul Atiqah², Zhari Ismail³, C. Y. Loo², Chaturbhuj K. Saurabh², Rudi Dungani⁴, Abdul Khalil H.P.S^2*

Journal of Renewable Materials, Vol.5, No.5, pp. 380-387, 2017, DOI:10.7569/JRM.2017.634130

Abstract Due to environmental concerns, green composites have become a highly researched material. In the present study, kenaf fiber was used as reinforcement in epoxy-based composite with weight fraction ranges from 0, 5, 10, and 15% (w/w of resin). The ratio of epoxy to hardener was 65:32.5. Prior to incorporation, kenaf bast fiber underwent Soda-AQ pulping followed by total chlorine-free bleaching (OAZP sequence). The obtained pulp was then subjected to supercritical carbon dioxide extraction (SCE) treatment. It was observed that epoxy composite with 10% of fiber loading demonstrated the highest mechanical properties with a tensile strength of 64 MPa, tensile modulus… More >

Nicole Segura Salas¹, Felipe Orozco Gutiérrez³, Luis Daniel Mora Murillo², Yendry Corrales Ureña³, Shakira Johnson¹, José Vega Baudrit³, Rodolfo Jesús González-Paz^3*

Journal of Renewable Materials, Vol.5, No.3-4, pp. 313-322, 2017, DOI:10.7569/JRM.2017.634122

Abstract Vegetable oils are being used for the production of biodegradable polymers, opening new possibilities for the synthesis of greener materials that could compete in national markets with petroleum-based polymers. In this study, castor oil and a catalyst (cobalt[II] naphtenate as promotor and MEKP as initiator) from local stores and styrene in different ratios were used to produce thermostable polymers. The kinetics of the polymerization reaction was followed by infrared spectroscopy. A polymeric material was synthetized which presents good mechanical properties. Therefore, composites were produced using 1 wt% of microcellulose extracted from biomass waste as reinforcement or 1 wt% microsilica to… More >