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Cette thèse s’intéresse à la déformabilité des renforts à bases de fibres de lin lors de leur mise en forme, au cours du procédé RTM (Resin Tranfer Molding), notamment lorsque les formes considérées sont complexes. La compréhension des défauts et mécanismes de déformations de ces renforts est alors nécessaire. S’appuyant sur un banc d’essai d’emboutissage spécifique, une caractérisation globale (défauts de mise en forme) et locale (déformations des mèches par méthode optique) des préformes a été réalisée, pour différents paramètres procédés (pressions serre-flan et orientation du renfort) et matériaux (architecture). De cette étude, un défaut spécifique lors de la mise en forme a été mis en évidence : le bouclage, sous la forme de flambement hors plan des mèches. Afin de contribuer à sa compréhension, peu décrite dans la littérature, un banc de caractérisation, indépendamment du procédé, a été conçu pour reproduire le phénomène dans le plan et identifier les différents mécanismes à l’origine de ce défaut. Une méthode interférométrique pour quantifier ce phénomène est proposée et une étude paramétrique est réalisée (tensions appliquées, angle de courbure, orientation, architecture du renfort). Au sein du renfort, le comportement des mèches présente de fortes non-linéarités en tension. Un modèle macroscopique par éléments finis est proposé afin de mettre en avant l’importance de ces non-linéarités sur les résultats numérique issus de l’opération de formage. Une étude de sensibilité sous différentes conditions procédés de ces non-linéarités est également apportée. / This study concerns the manufacturing process of composite material from woven flax reinforcement and specifically the preforming stage of the RTM (Resin Transfer Molding) process, with complex geometries. During the process several deformation modes take place and several defects may appear and it is therefore important to understand the mechanisms controlling their appearance. A specific sheet forming bench has been used to characterise the formed shapes at the macroscopic scale (global defects) as well as at the mesoscopic scale (tow strains). Various process parameters (blank holder pressures and reinforcement orientation) and the local tensile strains were measured using an optical method. From the observed defects, the tow buckling, out of plane bending of tows, was particularly investigated as this one is not very much described in the litterature. An experimental setup independent of the forming process was designed to specifically study this defect and to quantify the key parameters controlling its appearance. An interferometric method was proposed to measure the size of the buckles with accuracy and a parametric study (applied tensions, bending angles, orientation and architecture of the reinforcement) has been completed. Within the reinforcement, the tensile behaviour of tows presents strong non-linearities. A finite elements model at the macroscopic scale is proposed to highlight the impact of these non-linearities on the forming modeling results. A sensitivity study under several process conditions has been realized.

Este trabalho visa estudar o fluxo de um fluido em um meio poroso (fibroso) durante o processo de Moldagem por Transferência de Resina (RTM) utilizando e comparando dois softwares comerciais: o ANSYS CFX, software de simulação numérica CFD não-dedicado a RTM, e o PAM-RTM, software de simulação numérica dedicado a esta aplicação. Foram utilizados dados experimentais, empregando uma pré-forma de tecido (0/90) de fibra de vidro e que foi impregnada por um óleo vegetal em injeção radial de RTM. Diversos experimentos foram realizados variando-se a pressão de injeção e o teor volumétrico de fibras a fim de observar o efeito no comportamento do fluxo. Com estes dados, alimentou-se o ANSYS CFX e o PAM-RTM utilizando equações dos meios porosos conhecidas, e foram feitas análises numéricas de todos os casos experimentais. Resultados de permeabilidade, viscosidade do fluido, tempo de preenchimento do molde, campo de pressão, variação da fração volumétrica das fases presentes e vetor velocidade de fluxo são apresentados e analisados. Concluiu-se que há uma sólida relação entre o experimental e o simulado (erros inferiores a 10%), o software PAM-RTM possui menor erro do que o ANSYS CFX quando comparados aos resultados experimentais, mas este último apresenta maior versatilidade de análises. / This work aims to study the flow of fluid through a porous (fibrous) media that occurs during Resin Transfer Molding (RTM) of composite materials and to compare it with the numerical results obtained with two commercial simulation software, ANSYS CFX, a general-use CFD package, and PAM-RTM, which is dedicated to RTM modeling. Experimental data were produced using a glass-fiber cloth (0/90) perform, which was impregnated with a vegetable oil in an RTM radial infiltration. Several experiments were performed varying injection pressure and fiber volume content in order to observe their effect on the flow behavior. These data were input into ANSYS CFX and PAM-RTM using known porous media equations and they were used to model all experiments. Results of permeability, fluid viscosity, mold filling time, pressure field, variation of volume fraction of the phases and the flow velocity vector are presented and analyzed. An excellent correlation between experimental and simulated results was found (errors less than 10%), and PAM-RTM yielded smaller error than ANSYS CFX, but the latter allows greater flexibility.

Made available in DSpace on 2016-12-08T17:19:17Z (GMT). No. of bitstreams: 1 Tarcisio Sanson Sene.pdf: 3938998 bytes, checksum: 4f0f85a51934cd08bc44991295bfcef1 (MD5) Previous issue date: 2012-06-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Interesting changes in mechanical and electrical conductivity properties of polymeric matrixes are provided by dispersing carbon nanotubes, obtaining a nanocomposite. Current researches showed an effect of assisted dispersion of carbon nanotubes (CNT) by montmorilonite clay in an epoxy matrix, in a way that increments of clay provided better dispersion of CNT in the matrix, increasing the nanocomposite electrical conductivity when the same fraction of CNT was kept. This work intended to assess the effect of the simultaneous dispersion of a montmorillonite clay and CNT on a diglycidyl ether of bisphenol-A (DGEBA) epoxy matrix. Further, the assisted dispersion of CNT was assessed by two different montmorillonite clays: as natural (MMT-Na) and an organoclay (MMT-30B). The nanocomposites were fabricated by in situ polymerization method, using high energy sonication as the dispersion method, without the aid of solvents in the medium. The nanocomposites were molded by casting or by resin transfer molding (RTM), adding 27% v/v of glass-fibers in the latter molding method, obtaining a hybrid micro/nanocomposite. The glass transition temperature (Tg) of the nanocomposites was increased until 10ºC for the samples containing MMT-30B clay, however it practically did not change with the dispersion of MMT-Na clay, when compared to the Tg of the neat epoxy matrix. In the other hand, the simultaneous dispersion of CNT with each one of the clays provided two different Tg behaviors, with the same 10ºC increasing in Tg when the CNT were added with MMT-30B, and a lower increase of 3ºC in the Tg when the MMT-Na and CNT were added, also comparing to the neat sample. The casted samples did not show a significant change in the flexural modulus, though the flexural strength was reduced in the samples containing any of the clays, being this reduction proportional to the agglomerated feature of the nanocomposite. Regarding to the CNT percolation threshold in the epoxy matrix, it was verified to be between 0,04 and 0,10% v/v of CNT. The simultaneous dispersion of CNT with the clays just produced distinct dielectric behaviors when the fraction of CNT was higher than the percolation threshold. Both clays affected the continuity of the CNT percolated network, considering the clay fraction used. The simultaneous adding of MMT-30B clay with CNT was the condition that most reduced the conductivity of the samples, among those containing the same CNT fraction. The MMT-Na clay did not reduce the number of percolated ways of CNT as the MMT-30B, and, above a critical frequency of electrical current, the simultaneous dispersion of MMT-Na and CNT exhibited higher conductivity than the sample containing just the same CNT fraction, suggesting that more polarizable interfaces are being produced at this condition. Regarding to the hybrid micro/nanocomposites produced by RTM, there is a suspect that the low fraction of nanoparticles did not favor the increasing in the flexural modulus of the hybrid composite. The high viscosity of the samples containing any one of the clays caused low impregnation in the glass-fibers, obtaining regions of the composite without fibers dispersed. The MMT-Na clay was filtered though the porous medium during the resin infusion, probably due to its hydrophilic nature, showing lower compatibility with the epoxy matrix. / Nanotubos de carbono dispersos em matrizes poliméricas podem proporcionar interessantes alterações em propriedades mecânicas e de condutividade elétrica no material nanocompósito resultante. Trabalhos atuais demonstram um possível efeito de dispersão de nanotubos de carbono (NTC) assistida pela dispersão simultânea com argila montmorilonita natural em uma matriz epoxídica, de modo que incrementos de argila proporcionariam melhor dispersão dos NTC na matriz, elevando a condutividade elétrica quando mantido constante o teor de NTC. Este trabalho intencionou avaliar o efeito da dispersão simultânea de argila montmorilonita e NTC nas propriedades mecânicas, térmicas e dielétricas de uma matriz de epóxi do diglicidil éter do bisfenol-A (DGEBA). Ainda, foi avaliado o efeito de dispersão de NTC assistido por duas diferentes argilas montmorilonita: natural (MMT-Na) e uma organoargila (MMT-30B). Os nanocompósitos foram fabricados pelo método de polimerização in situ, utilizando sonicação de alta energia como fonte de dispersão e sem a utilização de solventes. Os nanocompósitos foram moldados por casting e por moldagem por transferência de resina (RTM resin transfer molding), neste último método sendo utilizados 27% v/v de fibras-de-vidro, obtendo-se um híbrido micro/nanocompósito. A temperatura de transição vítrea (Tg) dos nanocompósitos foi elevada em até 10ºC para os nanocompósitos contendo argila MMT-30B, porém praticamente não se alterou com a dispersão argila MMT-Na, quando comparado com a Tg da matriz sem as nanopartículas. Já a dispersão simultânea de NTC com cada uma das duas argilas promoveu diferentes alterações na Tg, não alterando em relação à Tg do nanocompósito que possuía somente argila MMT-30B e elevando a Tg da amostra que possuía argila MMT-Na em 3ºC em relação à amostra pura. As amostras preparadas por casting não apresentaram significante alteração de módulo de elasticidade, porém, quando presente alguma das argilas na composição da amostra, a resistência à flexão foi reduzida proporcionalmente ao caráter aglomerado das nanopartículas. Com relação ao limiar de percolação de NTC, foi verificado estar situado entre teores 0,04 e 0,10% v/v. A dispersão simultânea de cada argila com NTC somente gerou comportamentos distintos de condutividade quando utilizado teor de NTC acima da ocorrência de percolação. Nos teores utilizados, ambas as argilas afetaram a continuidade da rede percolada de NTC, porém a argila MMT-30B foi a que mais reduziu a condutividade em freqüências abaixo de 100 Hz. A argila MMT-Na já não reduziu o número de caminhos percolados de NTC como no caso da argila MMT-30B, e acima de determinada frequência de corrente elétrica, a dispersão simultânea de argila MMT-Na com NTC exibe maior condutividade do que a amostra contendo somente o mesmo teor de NTC, sugerindo que estão sendo geradas interfaces mais polarizáveis quando dispersos simultaneamente a argila MMT-Na e NTC. Em relação aos híbridos micro/nanocompósitos produzidos por RTM, suspeita-se que o baixo teor de nanopartículas não favoreceu o aumento de módulo de elasticidade do material híbrido. A alta viscosidade das amostras que possuíam alguma argila em sua composição gerou baixa impregnação de fibras e formação de regiões sem fibras-de-vidro no volume do compósito. A argila MMT-Na foi filtrada pelo meio poroso durante a infusão, provavelmente devido à sua natureza hidrofílica, possuindo menor compatibilidade com a matriz epoxídica.

Made available in DSpace on 2014-12-17T14:08:57Z (GMT). No. of bitstreams: 1 IgoPL_DISSERT.pdf: 1338632 bytes, checksum: 5c21a0cb714155a0e215d803dca007ce (MD5) Previous issue date: 2014-06-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / With the growth of energy consumption worldwide, conventional reservoirs, the reservoirs called "easy exploration and production" are not meeting the global energy demand. This has led many researchers to develop projects that will address these needs, companies in the oil sector has invested in techniques that helping in locating and drilling wells. One of the techniques employed in oil exploration process is the reverse time migration (RTM), in English, Reverse Time Migration, which is a method of seismic imaging that produces excellent image of the subsurface. It is algorithm based in calculation on the wave equation. RTM is considered one of the most advanced seismic imaging techniques. The economic value of the oil reserves that require RTM to be localized is very high, this means that the development of these algorithms becomes a competitive differentiator for companies seismic processing. But, it requires great computational power, that it still somehow harms its practical success. The objective of this work is to explore the implementation of this algorithm in unconventional architectures, specifically GPUs using the CUDA by making an analysis of the difficulties in developing the same, as well as the performance of the algorithm in the sequential and parallel version / Com o crescimento do consumo energ?tico em todo o mundo, os reservat?rios convencionais, chamados de reservat?rios de f?cil explora??o e produ??o n?o est?o atendendo a demanda energ?tica mundial. Isso tem levado muitos pesquisadores a desenvolver trabalhos que venham sanar essas car?ncias. Empresas do setor petrol?fero tem investido em t?cnicas que ajudem na localiza??o e perfura??o de po?os. Uma das t?cnicas empregadas no processo de explora??o de petr?leo ? a Migra??o Reversa no Tempo (RTM), do ingl?s, Reverse Time Migration, que ? um m?todo de imageamento s?smico que produz excelente imagem de subsuperf?cie. ? um algoritmo baseado no c?lculo da equa??o de onda. A RTM ? considerada uma das t?cnicas mais avan?adas de imageamento s?smico. O valor econ?mico das reservas de petr?leo que requerem RTM para ser localizada ? muito alto, isso significa que o desenvolvimento desses algoritmos torna-se um diferencial competitivo para as empresas de processamento s?smico. No entanto, o mesmo requer grande poder computacional que, de alguma forma, ainda prejudica o seu sucesso pr?tico. Assim, o objetivo deste trabalho ? explorar a implementa??o desse algoritmo em arquiteturas n?o convencionais, especificamente as GPUs, utilizando a plataforma CUDA, fazendo uma an?lise das dificuldades no desenvolvimento do mesmo, bem como a performance do algoritmo na vers?o sequencial e paralela

Este trabalho visa estudar o fluxo de um fluido em um meio poroso (fibroso) durante o processo de Moldagem por Transferência de Resina (RTM) utilizando e comparando dois softwares comerciais: o ANSYS CFX, software de simulação numérica CFD não-dedicado a RTM, e o PAM-RTM, software de simulação numérica dedicado a esta aplicação. Foram utilizados dados experimentais, empregando uma pré-forma de tecido (0/90) de fibra de vidro e que foi impregnada por um óleo vegetal em injeção radial de RTM. Diversos experimentos foram realizados variando-se a pressão de injeção e o teor volumétrico de fibras a fim de observar o efeito no comportamento do fluxo. Com estes dados, alimentou-se o ANSYS CFX e o PAM-RTM utilizando equações dos meios porosos conhecidas, e foram feitas análises numéricas de todos os casos experimentais. Resultados de permeabilidade, viscosidade do fluido, tempo de preenchimento do molde, campo de pressão, variação da fração volumétrica das fases presentes e vetor velocidade de fluxo são apresentados e analisados. Concluiu-se que há uma sólida relação entre o experimental e o simulado (erros inferiores a 10%), o software PAM-RTM possui menor erro do que o ANSYS CFX quando comparados aos resultados experimentais, mas este último apresenta maior versatilidade de análises. / This work aims to study the flow of fluid through a porous (fibrous) media that occurs during Resin Transfer Molding (RTM) of composite materials and to compare it with the numerical results obtained with two commercial simulation software, ANSYS CFX, a general-use CFD package, and PAM-RTM, which is dedicated to RTM modeling. Experimental data were produced using a glass-fiber cloth (0/90) perform, which was impregnated with a vegetable oil in an RTM radial infiltration. Several experiments were performed varying injection pressure and fiber volume content in order to observe their effect on the flow behavior. These data were input into ANSYS CFX and PAM-RTM using known porous media equations and they were used to model all experiments. Results of permeability, fluid viscosity, mold filling time, pressure field, variation of volume fraction of the phases and the flow velocity vector are presented and analyzed. An excellent correlation between experimental and simulated results was found (errors less than 10%), and PAM-RTM yielded smaller error than ANSYS CFX, but the latter allows greater flexibility.

Este trabalho visa estudar o fluxo de um fluido em um meio poroso (fibroso) durante o processo de Moldagem por Transferência de Resina (RTM) utilizando e comparando dois softwares comerciais: o ANSYS CFX, software de simulação numérica CFD não-dedicado a RTM, e o PAM-RTM, software de simulação numérica dedicado a esta aplicação. Foram utilizados dados experimentais, empregando uma pré-forma de tecido (0/90) de fibra de vidro e que foi impregnada por um óleo vegetal em injeção radial de RTM. Diversos experimentos foram realizados variando-se a pressão de injeção e o teor volumétrico de fibras a fim de observar o efeito no comportamento do fluxo. Com estes dados, alimentou-se o ANSYS CFX e o PAM-RTM utilizando equações dos meios porosos conhecidas, e foram feitas análises numéricas de todos os casos experimentais. Resultados de permeabilidade, viscosidade do fluido, tempo de preenchimento do molde, campo de pressão, variação da fração volumétrica das fases presentes e vetor velocidade de fluxo são apresentados e analisados. Concluiu-se que há uma sólida relação entre o experimental e o simulado (erros inferiores a 10%), o software PAM-RTM possui menor erro do que o ANSYS CFX quando comparados aos resultados experimentais, mas este último apresenta maior versatilidade de análises. / This work aims to study the flow of fluid through a porous (fibrous) media that occurs during Resin Transfer Molding (RTM) of composite materials and to compare it with the numerical results obtained with two commercial simulation software, ANSYS CFX, a general-use CFD package, and PAM-RTM, which is dedicated to RTM modeling. Experimental data were produced using a glass-fiber cloth (0/90) perform, which was impregnated with a vegetable oil in an RTM radial infiltration. Several experiments were performed varying injection pressure and fiber volume content in order to observe their effect on the flow behavior. These data were input into ANSYS CFX and PAM-RTM using known porous media equations and they were used to model all experiments. Results of permeability, fluid viscosity, mold filling time, pressure field, variation of volume fraction of the phases and the flow velocity vector are presented and analyzed. An excellent correlation between experimental and simulated results was found (errors less than 10%), and PAM-RTM yielded smaller error than ANSYS CFX, but the latter allows greater flexibility.

ALes travaux présentés sont une contribution à l’élaboration de composites à matrices thermoplastiques (TP) par un procédé de type Liquid Composite Molding non réactif pour l’industrie automobile. La thèse a été effectuée dans le cadre du projet ANR TAPAS (ThermoplAstic Process for Automotive composite Structure) et s’est focalisée sur la mise en œuvre de plaques composites en renfort continu injectées avec des matrices polyamides 6,6 (PA 6,6) de hautes fluidités par Resin Transfer Molding. Le premier objectif est porté sur l’optimisation des cadences d’injection à travers l’étude de la perméabilité de préformes unidirectionnelles (UD) en fibres de verre et à hauts modules mécaniques. L’architecture de ces UD a ainsi été modifiée de manière à faciliter les écoulements. La perméabilité des différents tissus a pu être évaluée par un couplage entre des mesures expérimentales et une modélisation analytique basée sur un raisonnement à deux échelles de pores : l’écoulement intra et inter-torons. Le deuxième objectif sur lequel les travaux de thèse se sont concentrés s’est reposé sur la maitrise de l’état d’imprégnation par le bais d’une étude complète sur les phénomènes qui se déroulent à l’interface entre la fibre et la matrice à haute température. Plusieurs viscosités et formulations du PA 6,6 ainsi qu’un traitement appliqué sur le verre ont pu être caractérisés et discutés en termes de mouillabilité et d’adhésion. Enfin, la dernière partie du manuscrit présente les résultats obtenus sur les plaques mises en œuvre par RTM-TP en injection in-plane. Les conditions optimales de fonctionnement ainsi que les aspects de saturation, de santé matière et des propriétés mécaniques sont ensuite présentés et discutés. / The present work is a contribution to the thermoplastic composites manufacturing by a non-reactive Liquid Composite Molding process for the automotive industry. The thesis was carried out by the « ANR TAPAS » project (Thermoplastic Process for Automotive Composite Structure) and was focused on the elaboration of continious-fiber reinforced composites plates injected with a high-fluidity polyamide 6,6 (PA 6,6) by the Resin Transfer Molding process. The first goal was focused on increasing injection rates through the study of the in-plane permeability of unidirectional (UD) glass fiber fabrics with high mechanical modulus (HM). Experiments and modelling results showed that the permeability of these UD has been enhanced by modifying specific structural parameters of their architecture. The analytical model developped and used is based on a flow distribution according two differents scales of porosity : in and inter-yarns. The second part of the work was focused on the understanding of phenomenas that take place at the interface created between glass fiber and the matrix during the impregnation step. The wettability and adhesion of molten PA 6,6 dropped on a glass substrate is studied at different processing temperature. The last part introduce the thermoplastic composite plates elaborated by RTM-TP process. The optimum operating conditions as well as preforms saturation and mechanical properties are also studied and discussed.

Les transducteurs ultrasonores font l'objet de nombreux développements en contrôle non-destructif (CND) industriel. Utilisé ponctuellement et périodiquement, le CND ultrasonore permet d'établir des diagnostics sur la santé des matériaux. La caractérisation ultrasonore en temps réel constitue un outil de surveillance de l'évolution des propriétés physiques lors de la fabrication des matériaux composites. Dans ce contexte, des études sont menées au LOMC pour optimiser le procédé de fabrication des matériaux composites par RTM (Resin Transfer Molding) afin d’améliorer la qualité du produit. Ce travail de thèse consiste à développer des méthodes ultrasonores pour le suivi des propriétés viscoélastiques d’un composite pendant la phase de production. Les propriétés viscoélastiques sont étudiées à l’aide de modèles théoriques, de simulations numériques et de résultats expérimentaux. Des études de calibration ont été menées afin d’étudier les facteurs d’influence sur le suivi de propriétés ultrasonores lors de la mise en oeuvre d’un procédé RTM. Le suivi des paramètres viscoélastiques de résines époxy est effectué dans un premier temps à basse température au cours d'une polymérisation isotherme et d’une post-cuisson. Ensuite, une approche basée sur la méthode de caractérisation en émission/transmission a été développée afin d’étudier le comportement à haute température. La modélisation de la réponse électroacoustique par série de Debye (DSM) a été effectuée en se basant sur des approches analytiques. L’utilisation des transducteurs multiéléments permet la localisation et le dimensionnement de défauts lors du déplacement de fibres de carbone dans une résine liquide, entre des moules. / The developments based on ultrasonic transducers are nowadays numerous in the industrial non-destructive testing (NDT). Used punctually and periodically, the ultrasonic NDT is used for health diagnostics of materials. Ultrasonic characterization in real time allows a physical properties monitoring during the manufacturing of composite materials. In this context, studies are conducted in LOMC in view to optimize the manufacturing process of composite materials using RTM (Resin Transfer Molding) in order to improve the product quality. This work consists to develop ultrasonic methods for the monitoring of viscoelastic properties during the production phase of composites. The viscoelastic properties are studied using theoretical models, numerical simulations and experimental measurements. Calibration studies were carried out to study the influencing factors on the monitoring of ultrasonic properties during the RTM process. The monitoring of viscoelastic parameters of epoxy resins is performed in a first time at low temperature during an isothermal polymerization and a post-curing. Then, an approach based on the transmission mode characterization was developed to study high-temperature behavior. Based on analytical approaches, the electroacoustic response was simulated by Debye series method (DSM). The use of phased array transducers was investigated for the location and sizing of defects during the movement of the carbon fiber in a liquid resin between the molds.

It is important to track how a requirement changes throughout the software lifecycle. Each requirement should be validated during and at the end of each phase of the software lifecycle. It is common to build traceability matrices to demonstrate that requirements are satisfied by the design. Traceability matrices are needed in various tasks in the software development process. Unfortunately, developers and designers do not always build traceability matrices or maintain traceability matrices to the proper level of detail. Therefore, traceability matrices are often built after-the-fact. The generation of traceability matrices is a time consuming, error prone, and mundane process. Most of the times, the traceability matrices are built manually. Consider the case where an analyst is tasked to trace a high level requirement document to a lower level requirement specification. The analyst may have to look through M x N elements, where M and N are the number of high and low level requirements, respectively. There are not many tools available to assist the analysts in tracing unstructured textual artifacts and the very few tools that are available require enormous pre-processing. The prime objective of this work was to dynamically generate traceability links for unstructured textual artifacts using information retrieval (IR) methods. Given a user query and a document collection, IR methods identify all the documents that match the query. A closer observation of the requirements tracing process reveals the fact that it can be stated as a recursive IR problem. The main goals of this work were to solve the requirements traceability problem using IR methods and to improve the accuracy of the traceability links generated while best utilizing the analysts time. This work looked into adopting different IR methods and using user feedback to improve the traceability links generated. It also applied wrinkles such as filtering to the original IR methods. It also analyzed using a voting mechanism to select the traceability links identified by different IR methods. Finally, the IR methods were evaluated using six datasets. The results showed that automating requirements tracing process using IR methods helped save analysts time and generate good quality traceability matrices.