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C andidato: Professor Adrián Cisilino
Instituição de Origem:
e Mar del Plata y CONICET de Materiales ‐ INTEMA
Universidad Nacional dInstituto de Ciencia y Tecnología
a Av. Juan B. Justo 4302 (7600) Mar del Plata, Argentinemail: [email protected]
Professor Solicitante: Ignacio Iturrioz Curriculum Vitae: (//http://lattes.cnpq.br/2887483998607584). Instituição de origem do Professor Solicitante e instituição onde o Professor Visitante realizará suas atividades: Programa de Pós‐graduação em Engenharia Mecânica da Universidade Federal de Rio Grande do Sul (PROMEC/UFRGS).
Project Tit
tle: Mechanics of Micro Fracture in Polycrystalline Brittle Materials Abstract: Brittle failure in polycrystalline materials usually occurs due to the presence of deleterious features at the grain boundaries. The state of the art is the ability to predict and evaluate the performance of materials using multiscale analysis; this is the synergistic integration of different computational, analytical, and experimental techniques to the development of systemic models that consider the global behavior of materials by integrating representation and information across multiple scales. Within this framework, it is proposed in this project to develop a high‐performance Boundary Element Model (BEM) computational tool for the three‐dimensional modeling and homogenization of the damage‐mechanics behavior of brittle materials at micro structural level. The activities are planed to complement and enhance the research activities on the fracture mechanics of heterogeneous materials under progress at the GMAp/UFRGS. A key point of the work plan is complementation with the experimental and theoretical studies that GMAp does in collaboration with research centers in Italy. It is expected that the project will produce novel knowledge in the fields of computational mechanics and the mechanics of materials and highly trained human resources. ey words: fragile fracture, microcracking, damage, boundary elements, high performace omputing, acoustic emission. Kc Título do Projeto: Mecânica da Microfratura em Materiais Frágeis com Estrutura Policristalina Resumo: A falha frágil em materiais policristalinos, usualmente, acontece devido à presença de características prejudiciais nos contornos dos grãos. O estado da arte sobre a habilidade de predizer e avaliar o desempenho de materiais, utilizando análise multiescala é a integração sinérgica de diferentes técnicas, experimentais, computacionais e analíticas, para o desenvolvimento de modelos sistêmicos que considerem o comportamento global de materiais, através de sua representação integrada e transferência de informação nas múltiplas escalas. Dentro deste contexto, é proposto, neste projeto, desenvolver uma ferramenta computacional de alta performance, utilizando o Método dos Elementos de Contorno (BEM), para simular modelos tridimensionais e homogeneização do dano em Materiais Frágeis a escala micro estrutural. As atividades são planejadas para complementar a pesquisa em andamento
relacionada com a Mecânica da Fratura em Materiais Heterogêneos no GMAp/UFRGS. O ponto chave da proposta é que a complementação do trabalho seja desenvolvida com os estudos teóricos e experimentais que o GMAp realiza com centros de pesquisa na Itália. Espera‐se que o projeto produza novo conhecimento na área de mecânica computacional, mecânica dos materiais e formação de recursos humanos.
alavra Chave : Fratura Frágil, micro fissuração, dano, elementos de contorno, computação de lto desempenho, emissão acústica.
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1. INTRODUCTION AND MOTIVATION Efficient and safe engineering products are fundamental for the modern society. A countless number of products ranging from house furnishings to space satellites, and from orthopedic prostheses to plane engines are masterpieces of design, which combine the latest advances in engineering and materials science. In this sense the developing of new materials will tend to follow population growth and have strong environmental influences, therefore there is an increasing need for conservation of both materials and energy resources. Also increased throughput in manufacturing processes will involve increased energy consumption, materials waste, water waste and pollution. This “broad‐brush” scenario indicates that we need to
lexploit materials up to their property imits safely for greater economy of usage and improved ecology. It is widely recognized that relevant macroscopic properties of materials, like stiffness and strength, are governed by damage processes that occur at one to several scales below the level of observation. Engineering materials are in general heterogeneous at a certain scale. Textile composites, concrete, ceramic composites, and classic metallic materials are heterogeneous at the micro and grain scale. Brittle failure in polycrystalline materials usually occurs due to the presence of deleterious features at the grain boundaries, such as relatively coarse impurity particles and preferential segregation of embrittling elements, as appears in the majority of engineering metallic alloys (ferrous, non‐ferrous) and ceramics (Crocker et al, 2005; Krupp, 2005; Farkas et al, 2000; Lynch et al, 2002; Rice, 2000). Moreover, grain boundaries exhibit increased surface free energy, which makes them more susceptible to aggressive environmental conditions and phenomena such as stress‐corrosion cracking, see for example Kamaya (2004) and McMahon (2001). It is well known that the propagation and coalescence of these defects leads, eventually, to the complete (macroscopic) failure of the material (Scutti and McBrine, 2002). However, from a modeling perspective, the transition from the micro to the macro‐scale is still not fully understood. Continuum damage mechanics aims to fill that gap. From the pioneering work due to Kachanov (1958), continuum damage mechanics, in its simplest form, introduces an isotropic scalar multiplier that reduces the initial elastic stiffness of the material over a specific region of the macro‐continuum, in order to describe the local loss of the material integrity due to the effect of micro cracks. Eventually, a macro crack is subsequently introduced if the damaged region cannot sustain more load (Lemaitre, 1996). Although effective to deal with the initiation of macro cracks, continuum damage mechanics does not provide sufficient details about the actual initiation and behavior of cracks at micro‐scale. The state of the art is the ability to predict and evaluate the performance of materials from direct micro/nano mechanical simulations. In this sense, the multiscale analysis is the theoretical foundation that entails the integrated and synergistic use of different
computational, analytical, and experimental techniques to the development of systemic models that consider the global behavior of materials by integrating representation and information across multiple scales. Thus, no constitutive law is required at scales where the mechanical behavior is unknown, since it can be defined at smaller scales where the behavior is known. The integration of the material representation and information across the different scales is achieved via homogenization methods, like those proposed by Ghosh et al (1996), Terada et al (2000) and Kouznetsova et al, (2002 and 2004) among many others. To date, the finite element method (FEM) is the most popular approach for multiscale modeling. The initiation, propagation, branching and arresting of multiple cracks in the microstructure are modeled using the cohesive surfaces approach. Among the cohesive failure models, the linear law proposed by Ortiz and coworkers (Camacho and Ortiz, 1996; Ortiz and Pandolfi, 1999) for mixed mode failure initiation and propagation, and the potential‐based laws proposed by Tvergaard (1990) and Xu and Needleman (1996) are the most popular. Examples on the application of the cohesive FEM are the works of Espinosa and Zavattieri (2003a y 2003b) and Zhai et al. (2004) who studied the dynamic fragmentation of ceramics, Wei and Anand (2004) who investigated the grain boundary sliding and separation in nanocrystalline metals, Clayton (2005) who modeled dynamic plasticity and spall fracture of polycrystalline alloys, Kamaya (2004) who studied stress corrosion cracking while Kim et al. (1996) and Sukumar et al. (2003) who investigated the competition and transition between intergranular and transgranular fracture. An alternative numerical method to the FEM is the boundary element method (BEM). Thanks to the advances achieved in the last several years, BEM become a powerful numerical technique for the simulation of challenging engineering problems (Andjelić et al, 2007). BEM offers excellent features in reduction in the dimensionality of the discretization, modeling of problem with open boundaries and high precision in the representation of discontinuities. In particular, BEM provide a powerful tool for solving a wide range of fracture problems (Aliabadi, 1997). In the special case of modeling the microstructure of a polycrystalline material at the grain‐micro level only the grain boundaries are modeled, thus reducing the size of the problem substantially. Moreover, in the BEM the field unknowns are directly the displacements and the surface tractions (Aliabadi, 2002), thus providing a direct way to implement cohesive laws to model damage. Examples about the application of BEM to the modeling of microstructures at grain‐micro level are the works by Sfantos and Aliabadi (2007a and 2007b). In contrast to the aforementioned advantages, the BEM has some serious practical limitations when leading to large problems, mostly related to the full populated, often ill‐conditioned matrices. But new numerical developments like Fast Multipole BEM (Liu and Nishimura, 2006), Adaptive Cross Approximation Hierarchical BEM (Benedetti at al, 2008) and Domain‐Decomposition Techniques bridge these limitations; promoting BEM to a high‐level computational tool. Based on the above background, this proposal focuses in developing of a state‐of‐the‐art fast EM modeling tool for the modeling of the damage‐mechanics of brittle materials at micro tructural level. Bs 2. OBJECTIVES General
To develop a high‐performance BEM‐based framework for the three‐dimensional modeling and homogenization of the damage‐mechanics of brittle materials at micro structural level.
The framework should be general and versatile enough in order to be able to deal with a wide range of material behaviors such as isotropic and anisotropic elasticity, thermoelasticity, piezoelectricity and magneto‐electro‐elasticity; and their associated damage mechanisms.
Specific
To develop a three‐dimensional high‐performance BEM‐based tool for the modeling and homogenization of fragile fracture mechanics at grain‐micro level.
To produce novel knowledge in the fields of computational mechanics and the mechanics of materials.
To produce highly trained human resources in the fields of computational and material mechanics.
To enhance the scope and products of the research activities at the Grupo de Mecânica Aplicada (GMAp) of the UFRGS, by providing complementary capabilities and knowledge to its area of expertise.
To further develop and strength the cooperation links between the UFRGS and the UNMdP in the fields of scientific research and training of high‐level human resources.
3. BACKGROUND OF THE VISITING RESEARCHER Professor Cisilino possesses and extensive and fruitful research background in the fields of fracture mechanics and damage modeling. In particular, he has made contributions on the application of BEM to a variety of fracture problems: elastic (Cisilino et al, 1998a; Cisilino and Ortiz, 2005a), elastoplastic (Cisilino et al, 1998b), thermoelastic (Balrderrama et al, 2006 and 2008), crack‐fiber debonding in composite materials (Cisilino and Ortiz, 2005b; Ortiz and Cisilino, 2005), fatigue crack propagation (Cisilino y Aliabadi, 1997, 1999, 2004, 2010) and delamination in composites (Larrosa et al, 2011a y 2011b). Many of hese works are the results of international collaboration with researchers from Imperial College (UK), the Univesity of Seville (Spain) and the Universidad Central de Venezuela. Besides, using the FEM, Prof. Cisilino has worked on the modelling of fracture of polymer welded (Fasce et al, 2007) and adhesive (Sturiale et al, 2007) joints, delamination defects in pipelines (Fazzini et al, 2005), impact fracture specimens (Niglia et al, 2002), assessing the essential work of fracture in polymer specimens (Luna et al, 2003) and microstructural damage in ductile cast iron (Ortiz et al, 2001a and 2001b; Basso et al, 2009). Figure 1 illustrates examples of the FEM and BEM models developed for this last case. Other works on the field of numerical fracture mechanics are those on crack closure using the weight function methods (López Montenegro el at, 1996, 2006 and 2008).
(a)
(b)
Figure 1: (a) Left: detail of the finite element discretization of the dual‐phase austempered ductile iron (ADI) microscructure. Right: the resultant crack progation path (Basso et al, 2009); (b) Boundary
r icrocraks element model of the fatigue p opagation of m in ADI in the near‐threshold regime (Ortiz et al, 2001b)
Professor Cisilino, has also experience in the field of high‐performance BEM. He is actually using Fast Multipole BEM to model diffusion problems in microheterogeneous materials (Dondero et al, 2011a and 2011b) and developing Hirachical BEM formulations as part of his participation in the project PIRSES‐GA2009_246977 “Numerical Simulation in Technical Sciences” sponsored by the European Union (http://portal.tugraz.at/portal/page/portal/TU_Graz/Einrichtungen/Institute/i2020/numsim) .
4. RESULTS OF PREVIOUS COOPERATION ACTIVITES AND IMPACT OF THE PROJECT ON THE HOST INSTITUTION
The project proposed here is intended to further strength the scientific and academic cooperation between the UFRGS and the UNMdP. Professors Cisilino and Iturrioz have a rich collaboration record, which started in 2002. Collaborative activities include the execution of two joint research projects, CAPES/SECYT BR/PA02‐EXII/007 Numerical Modeling of the Damage Mechanics in Composite Materials” (2003‐2004) and PROSUL 040/2006 “Microstructural Optimization of Polymer Composite Materials Reinforced with Rubber Particles” during the period 2006‐2008) (information about these projects is available in http://www‐gmap.mecanica.ufrgs.br/~ignacio/ ); the joint supervision of two PhD thesis at
the UFRGS, Ruben G. Batista in 2007 (http://hdl.handle.net/10183/12149) and Gilson Soares in 2010, (http://hdl.handle.net/10183/30141) and the exchange of postgraduate students and professors to develop research and teaching activities, including the participation in postgraduate examination activities. Among the student exchange activities, it is worth mention that F. Buroni from the UNMdP obtained a MSc degree at the UFRGS in 2009 (http://hdl.handle.net/10183/8702). The cooperation between the UFRGS and the UNMdP have been mainly focused on modeling of fracture problems using the Discrete Element Method (DEM), the field of expertise of Prof. Iturrioz. The product of this research reflects in the two aforementioned PhD theses, and in 19 research papers, co‐authored by researchers from the UFRGS and the UNMdP, which have been published in journals and conference proceedings. Among them, the most relevant to this proposal are those by Barrios D’Ambra et al (2007) and Kosteski at al (2011). A product of this work is given in Figure 2, which illustrates a model developed to assess the microcracking of nodular cast iron.
Figure 2: Macroscopic stress vs strain response of nodular cast iron showing the evolution of the
idamage at the microstructural level computed us ng DEM (Kosteski at al, 2011). The fracture mechanics of heterogeneous materials, like ceramics, composite of ceramic matrices, concrete and rocks is a core research activity at GMAp. In particular, the research activity of Prof Iturrioz focuses in the development of a real‐time procedure for the detection and monitoring of crack damage in structures made of quasi‐brittle heterogeneous materials. To this end, he uses experimental data from acoustic emission tests, which is analyzed using Statistical Discrete Damage (SDD) tools within the framework of the so‐called Computational Mechanics of Discontinua (Munjiza, 2009). The theoretical models are numerically solved using the Discrete Element Method (DEM). Recent results for this research are in the works Kosteki at al (2011,2012), Miguel et al (2010), Riera et al (2011). As part of this research, Prof Iturrioz has established a strong research collaboration links with Prof Alberto Carpintieri from the
Politécnico de Torino (http://areeweb.polito.it/ricerca/fracmechlab/finalita.htm), where he spent a year working as postdoctoral researcher during 2011, and with Prof Antonio Rinaldi from Materials Division of ENEA Italy (http://www.enea.it/it) who will visit the UFRGS in 2013 (the workplan for the visit of Prof Rinaldi to the UFRGS are available in http://chasqueweb.ufrgs.br/~ignacio.iturrioz/Proposta%20PV_rinaldi.pdf). The project presented in this proposal is planed to complement and enhance the scope and products of research at the GMAp. The continuum mechanics approach proposed here to study the microcracking of brittle materials will complement the non‐continuous approach used by GMAp. The combination of both approaches will provide a powerful analysis means to understand the underlying physical phenomena to the mechanics of fracture nucleation and propagation. Besides the results from complementary methods will also serve for the verification and validation of theoretical models and numerical simulations. In addition to Prof Iturrioz, it is also proposed that other professors from the PROMEC will contribute to the project. These are: Prof. Rogério José Marczak: his area of actuation are integral methods in continuum media, including non linear phenomena and optimization. It is of special interest for the project his expertise in the development of fundamental solutions to anisotropic materials. His CV is available at http://lattes.cnpq.br/5773989861369461.
Prof. Jun Sérgio Ono Fonseca: his area of specialization is structural optimization and homogenization methods. His expertize will be most valuable to develop the numerical methods for the homogenization of the mechanical behavior of the damaged microstructures. His CV is available at http://lattes.cnpq.br/1645630141306804.
Prof. Rodrigo Rossi: he works in the numerical modeling of plasticity and mechanics of damage using finite element and meshless methods. He has also experience in the field of homogenization. It is planned to collaborate with Prof. Rossi in aspects related to the intergranular damage modeling and the homogenization of the damaged microstructures. His CV is available at http://lattes.cnpq.br/6564425041995316.
Prof. Jakson Manfredini Vassoler:his areas of expertise are DIC techniques, constitutive models and material characterization. It is planned to collaborate with Prof. Vassoler in the experimental aspects of the project. His CV is available at http://lattes.cnpq.br/4585428395415027
In addition with the UFRGS, there are researchers from two other Brazilian universities that have demonstrated interest to collaborate with project:
Prof. Wang Chong from the Universidade Federal do Pampa and ad‐hoc advisor of the PROMEC/UFRGS program. His research activity focuses on numerical modeling of fracture problems and the mechanical response of composite materials. His CV is available athttp://lattes.cnpq.br/3721096641255364. Also at the Universidade Federal do Pampa are Dr Luis Kosteski and Dr Vicente Vendramini Puiglia, who obtained their PhD from the PROMEC/UFRGS. under the supervision of Dr. Iturrioz. Dr Kosteski has already collaborated with Prof Cisilino when being at the UFRGS.
5. MATERIALS AND METHODS Fast Boundary Element Method based on Adaptive Cross Approximation Hierarchical Matrices BEM (HBEM)
Fast Boundary Element Methods allow for the reduction of the memory requirements and computational complexity of the solution process. Nowadays, the Fast Multipole BEM (FMBEM) and the ACA H‐BEM are the most popular and best‐developed methods. Both methods are based on the approximation of the contributions of the so‐called “far field”. The FMBEM uses series expansion of the fundamental solutions (Liu and Nishimura, 2006), whereas the H‐BEM is of pure algebraic nature and approximates the system matrix using low‐rank blocks (Börm et al, 2003). Both methods achieve reductions in memory usage and CPU time from 50% to 75% for large problems (say more than 10.000 d.o.f.), see for example Bruneer et al (2010), Benedetti at al (2008) and Kolk et al (2005). However, both methods present pros and cons in terms of performance when compared to each other, and in most cases, the selection of the best method is problem dependent. Professor Cisilino has experience with both, FMBEM and ACA H‐BEM. Bearing in mind the general objective of the project and based on the experience from Prof. Cisilino, the ACA H‐BEM is s hwil
elected for this work. The main characteristics of the ACA H‐BEM from whic this project l benefit are:
Being of pure algebraic nature, it can be easily adapted for the solution of different behaviors. This allows for the reutilization of existent computer problems and material
codes. It is easy to parallelize.
The high‐performance BEM to be implemented in this project will have the following characteristics:
Boundary integral representation of the linear behavior for the single grains of the polycrystalline microstructure, expressed in terms of the intergranular fields, namely displacements and tractions. This representation will lead to a three‐dimensional multi‐region boundary formulation, which will be solved using the ACA H‐BEM. The development and implementation of this formulation will result in original work, since, to the author’s
u H Mknowledge, no previous work has been reported abo t the application of the ACA ‐BE to multi‐region problems.
Modular design in order to be easily adapted to general material behaviors. The first implementations will deal with anisotropic elastic regions, but the code will be ready to incorporate more complex material behaviors like piezoelectricity and magneto‐electro‐elasticity. For the first implementations, there will be used well‐known classic fundamental solutions like that due to Schlar (1944) for anisotropic elasticity. In a second stage, more recent developments, like those due to Buroni and Saez (2009) and Buroni (2012) for anisotropic elasticity and magneto‐electro‐elasticity, will be employed. The implementation of the new fundamental solutions will result in original contributions to the field of computational mechanics.
Modeling of the intergranular microcracking evolution using non‐linear frictional contact in combination with a cohesive law. This approach will allow not only to model crack damage initiation and propagation, but also to account for internal friction of the material, which becomes important in cases of compressive localized pressures over cracked surfaces. The microcrack propagation will be modeled using the cohesive‐zone model approach proposed by Espinosa and Zavattieri (2003a y 2003b) and Ortiz and Pandolfi (1999), which has been effectively implemented using BEM by Sfantos and Aliabadi (2007a) for two‐dimensional problems. This approach has shown robust and capable to deal with the initiation and propagation of multiple cracks. In this project, it will be extended to three‐dimensional problems. This will result in original contributions to the fields of computational mechanics
and the modeling of material damage. At the same time, it is worth to mention that, the results and experience gained from the previous collaborative work by professors Iturrioz and Cisilino in the field of damage modeling using DEM (see Kosteski at al, 2011) will be most valuable for the development of this part of the project.
Homogenization Analysis Homogenization analysis will be used to compute the macroscopic material behavior from the results of the models at the micro structural level:
In a first stage, the homogenization analysis will be applied to damage‐free microstructures. This will allow the computation of the overall elastic behavior of the materials, which will be validated by comparing with Digital Image Correlation (DIC) strain measurements. The homogenization will be performed using the asymptotic method with periodic boundary conditions due to Hollister and Kikuchi (1992). The starting point for this task will be the programs implemented at the INTEMA‐UNMdP for the homogenization of the elastic response of trabecular bone (see Ibarra Pino et al, 2011), which will be adapted post process data resulting from BEM models.
In a second stage, the homogenization analysis will be extended to account for the effects of micro cracking. Based in the revision of bibliography done so far, two approaches have been identified as the most promising ones for this task: asymptotic‐type methods (similar to that mentioned in the previous paragraph), and methods based on the thermodynamics of cracked bodies, which use of the free energy to bridge the cracked microstructure to the damaged macroscopic continua. Thermodynamics‐based methods are reported to be computationally cheaper than their asymptotic counterparts and they can be easily adapted to different damage models to describe the material behavior in the macro scale, like one‐parameter, two‐parameter and fully‐tensional models (see for example Rent et al, 2011). Further research and review of the published work will be done in order to identify the best approach. In this sense, it will be important that the selected approach is suitable for its
the t himplementation within BEM framework. It is expec ed that he completion of t is task will lead to the production of original procedures and results.
Homogenization analysis will be done using computer generated representative volume elements (RVE) embodying the relevant statistical features of the actual material, such as number of vertices, edges and faces per grain, grain size distribution, grain shape and crystallographic orientation. Models will be automatically generated using Voronoi tesselation from sets of randomly distributed seed points. This approach possesses statistical features that make it topologically close to real ceramic and metallic microstructures, as it has been reported by Fritzen et al (2009) and Quey et al (2011) among many others. The size of the RVEs will be determined by statistical analyses on samples of increasing size. This approach has been already used by the workgroup, see Dondero et al (2011) and Kostesky at al (2011). Software and Hardware The starting point for the implementation of the H‐BEM will be the code developed by Prof. Cisilino as part of his activities in the project PIRSES‐GA2009_246977 “Numerical Simulation in Technical Sciences”. Although that is a relatively simple code for the solution two‐dimensional potential problems, it contains all the features of a general implementation. In particular, a valuable part of the implementation is the library for the Arithmetic of Hierarchical Matrices. The code is implemented using Matlab, bearing in mind two benefits:
Matlab is easier to learn than other programing languages. The experience shows that, even students with no background on scientific computing, get familiar with Matlab very fast. By shortening the learning time, it is much easier to find students to get involved into the project.
The performance of the code can be easily improved by means of Graphics Processing Unit (GPU) accelerated hardware.
Following the strategy mentioned in the previous paragraphs, the H‐BEM and the complementary software to be developed as part of this project will be implemented in Matlab. The programs will be coded to run in parallel on multi‐core shared‐memory Linux workstations with GPU‐accelerated hardware. An indicative description of this hardware can be found in http://www.nvidia.com/object/tesla‐matlab‐accelerations.html. Experimental work As it has been mentioned before, the project activities will be coordinated with the ongoing research activities at GMAp. A key point in this sense will be the utilization of the experiment database available from the acoustic emission tests performed at the GMAp and by Prof. Rinaldi at the ENEA. This database, together with experiments that will be specially designed for the present project, will be used to retrieve data for the model preparation and validation. In this sense, it will be of special benefit to the project the future incorporation to the GMAp laboratory of equipment to perform strain measurements using Digital Image Correlation (DIC). The DIC will be most helpful for the characterization of materials with anisotropic behavior. At the same time, it is also planned to use the facilities at the INTEMA‐UNMdP (http://www.intema.gob.ar), the home institution of Prof. Cisilino, to complement the
are o ial interexperimental work at GMAP. Two devices f spec est for this project: the micro‐ Triboindenter Hysitron TI900 with Micro Range Nano Probe (http://www.hysitron.com/products/ti‐series/ti‐900‐triboindenter) for the characterization of the material properties at the grain level , and X’pert PANalytical X‐Ray Difractometer http://www.panalytical.com/index.cfm?pid=321 for the measuring of residual stresses.
6. GOALS AND PRODUCTS
Goal Performance indicator
To produce novel knowledge in the fields of computational mechanics and the mechanics of materials.
Publication of papers in scientific journals and scientific conferences. Papers will be produced based on the novel kno dfiel
wle ge the project will contribute to the following ds:
f a The ormulation nd application of H‐BEM to multiregion problems.
The formulation and implementation of a three‐dimensional fast BEM to model intergranular microcracking.
Homogenization analysis for the characterization of the macroscopic mechanical response of neat and damaged materials.
To produce highly trained The supervision by Prof. Cisilino of 2 or 3 postgraduate
human resources students at the UFRGS who will develop their theses (doctoral or magister) as part of the project activities.
The teaching activities of Prof. Cisilino at the UFRGS. It is planned that he will collaborate teaching special topics in the courses Fracture Mechanics and Micromechanics of the Programa de Pós‐Graduação em Engenharia Mecânica (PROMEC). Besides, and based on
d t othe deman , there could be organized shor courses n specific areas of expertise of Prof Cisilino.
To promote the scientific and academic collaboration with others centers in Brazil and the INTEMA‐Universidad Nacional de Mar del Plata in Argentina.
The visits of the Brazilian postgraduate students to INTEMA in order to do experimental work and to develop their research activities under the supervision from Prof. Cisilino.
New collaboration links with researchers at the Universidade do Estado de Santa Caterina in Joinville and the Universidade Federal do Pampa.
7. ACTIVITIES Year 1
Year 2
Year 3
1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6
Single region 3D HBEM x x x
Multi region 3D HBEM x x x x x
Automatic mesh generation x x x x x
Intergranular cracking x x x x x x
Homogenization of crack‐free
microstructures x x x x x
Homogenization of cracked
microstructures x x x x x x x x
8. FACILITIES AT THE UNIVERSIDADE FEDERAL DE RIO GRANDE DO SUL The project will be developed at the Programa de Pós‐graduação em Engenharia Mecânica (PROMEC, http://www.mecanica.ufrgs.br/promec). Since its creation in 1976, PROMEC has awarded 364 magister and 148 doctoral degrees. The program rank is 6 in the CAPES rank (being the maximum grade 7). Thirty‐six doctors form the faculty of the PROMEC. At present, there number of students is 178; 119 are in the magister programs and 59 in the doctoral one. In particular, Grupo de Mecânica Aplicada (GMAp, http://www‐gmap.mecanica.ufrgs.br). The group has a computer laboratory with the equipment necessary for the development of the project and experimental facilities and equipment for the mechanical testing of materials and
structures. Of particular interest for this project are the Digital Image Correlation (DIC) and Acoustic Emission (EA). The funding applied for in this project will be used to strengthen the computer capabilities of the GMAp. 9. REFERENCES Aliabadi MH. (1997) A new generation of boundary element methods in fracture mechanics. International Journal of Fracture; 86:91–125. Aliabadi MH. (2002) The Boundary Element Method, Applications in Solids and Structures, vol. 2. Wiley, London. Andjelić, Z., Smajić, J., & Conry, M. (2007). BEM‐Based Simulations in Engineering Design. Lecture Notes in Applied and Computational Mechanics (pp. 281–352). Springer.
R hBalderrama , Cisilino AP, Martinez, M. (2006) Analysis of t ree‐dimensional thermoelastic fracture problems. Journal of Applied Mechanics; 73:959–969. Balderrama R, Cisilino AP, Martinez M. (2008) Boundary element analysis of three‐dimensional mixed‐mode thermoelastic crack problems using the interaction and energy domain integrals. International Journal for Numerical Methods in Engineering, 74:294–320. Barrios D’Ambra R, Iturrioz I, Coceres H, Kosteski L, Tech T, Cisilino AP. (2007). Cálculo del factor de intensidad de tensiones utilizando el metodo de los elementos discretos. Revista SulAmericana de Engenharia Estrutural; 4(2): 7–20. Basso A, Martinez R, Cisilino AP, Sikora J. (2009) Experimental and numerical assessment of fracture
r atoughness of dual‐phase austempe ed ductile iron. Fatigue and Fracture of Engineering M terials & Structures; 33:1–11.
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