A new visco-plastic damper for seismic protection is introduced. This device combines and enhances many of the proven characteristics of both displacement-dependent and velocity-dependent devices. The device consists of a block of a high-damping viscoelastic material sandwiched between two steel shapes (plates or channels) bent in a certain configuration to amplify the deformations in the device in order to obtain large tensile and compressive strains in the viscoelastic material. Under low levels of vibrations, the device dissipates energy through amplified strains in the viscoelastic material only; however, under moderate to strong levels of vibrations, a new source of energy dissipation is added through the yielding of the steel elements. The inelastic behavior of the steel elements is controlled by the rigidity of the viscoelastic material. In addition to the energy dissipation, the device provides stiffness through the steel elements as well as the viscoelastic material. Moreover, one of the main advantages of the device is that its behavior is fully controlled through different parameters. First, a nonlinear time history analysis was conducted on structures with a preliminary model of the device using SAP2000 program to check the effectiveness of the device on the response of different structures under ground excitations. The device resulted in better improvement in the structural response compared to the existing viscoelastic dampers. A three-dimensional finite element model was developed for the device using the finite element package, ABAQUS. The hyperelastic and viscoelastic behavior of the block of the viscoelastic material were considered. The inelastic behavior of the steel elements was considered as well using the Von Mises yielding criterion. The device was analyzed under different dynamic loadings with different frequencies. Three simplified models were developed using SAP2000 program in order to facilitate the modeling of the device for structural engineers. These models were compared to the detailed finite element model to check their accuracy. The best model was used in the analysis of a multi-story steel frame with the visco-plastic devices under different ground excitations. Two different arrangements of the device were considered. The devices caused significant reduction in the story displacements, base shear and bending moment at column bases. / Ph. D.

This dissertation describes the development and verification of a general purpose computer program, CONSOL97, for analysis of one dimensional consolidation of multi-layered soil profiles. The program uses an elasto-visco-plastic model that can simulate both consolidation and creep in a single consistent analysis. The finite element program uses standard oedometer test data to model stress-strain-time relationships, and the effect of strain rate on preconsolidation stress observed in the laboratory and in the field. Validation of the computer program by simulating standard oedometer tests is described and the applicability of the program in predicting field behavior is examined. The oedometer test simulations indicate good agreement with stress-strain and strain-log time test results during loading. Unloading behavior produces excessive rebound. Well-instrumented field tests at Väsby, Sweden, Skå-Edeby, Sweden and Berthierville, Canada indicate that elasto-visco-plastic CONSOL97 analyses produce better predictions of field behavior than conventional elasto-plastic models. CONSOL97 results were in good agreement for the Väsby and Berthierville test fills but underestimated displacements and pore pressures near the center of the normally consolidated clay layer beneath the Skå-Edeby test fill. / Ph. D.

To model dissipation of energy in vibrating civil structures, existence of viscous damping is commonly assumed primarily for mathematical convenience. In such a classical damper, the damping force is assumed to depend only on the velocity of deformation. Fluid viscous dampers that provide this type of damping have been manufactured to provide supplementary damping in civil and mechanical systems to enhance their performance. Some fluid dampers, however, exhibit stiffening characteristics at higher frequencies of deformation. The force deformation relationship of such dampers can be better represented by the Maxwell model of visco-elasticity. This model consists of a viscous dashpot in series with a spring, the latter element providing the stiffening characteristics. This study is concerned with the optimal utilization of such Maxwell dampers for seismic performance improvement of civil structures. The force deformation relationship of Maxwell dampers is described by a first order differential equation. Earlier studies dealing with these dampers, used an unsymmetric set of equations for combined structure and damper system. The solution of such equations for response analysis or for optimization calculation by a modal analysis approach would require the pair of the left and right eigenvectors. In this study, an auxiliary variable is introduced in the representation of a Maxwell damper to obtain symmetric equations of motion for combined structure and damper system. This eliminates the need for working with two sets of eigenvectors and their derivatives, required for optimal analysis. Since the main objective of installing these dampers is to reduce the structural response in an optimal manner, the optimization problem is defined in terms of the minimization of some response-based performance indices. To calculate the optimal parameters of dampers placed at different location in the structure, Rosen's gradient projection method is employed. For numerical illustration, a 24-story shear building is considered. Numerical results are obtained for seismic input defined by a spectral density function; however, the formulation permits direct utilization of response spectrum-based description of design earthquake. Three different performance indices -- inter story drift-based, floor acceleration-based, and base shear-based performance indices-- have been considered to calculate the numerical results. A computational scheme is presented to calculate the amount of total damping required to achieve a desired level of response reduction. The effect of ignoring the stiffening effect at higher frequencies in the Maxwell model on the optimal performance is evaluated by parametric variation of relaxation time coefficient. It is observed that the models with higher relaxation time parameter show a decreased response reducing damping effect. Thus ignoring the stiffening effect when it is, indeed, present would provide an unconservative estimation of the damping effect. The effect of brace flexibilities on different performance indices is also investigated. It is observed that flexibility in a brace reduces the effectiveness of the damper. / Master of Science

Structural engineering has progressed from design for life safety limit states to performance based engineering, in which energy dissipation systems in structural frameworks assume prime importance. A visco-hyperelastic device is a completely new type of passive energy dissipation system that not only combines the energy dissipation properties of velocity and displacement dependent devices but also provides additional stability to the structure precluding overall collapse. The device consists of a viscoelastic material placed between two steel rings. The energy dissipation in the device is due to a combination of viscoelastic dissipation from rubber and plastic dissipation due to inelastic behavior of the steel elements. The device performs well under various levels of excitation, providing an excellent means of energy dissipation. The device properties are fully controlled through modifiable parameters. An initial study was conducted on motorcycle tires to evaluate the hyperelastic behavior and energy dissipation potential of circular rubber elements, which was preceded by preliminary finite element modeling. The rubber tires provided considerable energy dissipation while displaying a nonlinear stiffening behavior. The proposed device was then developed to provide additional stiffness that was found lacking in rubber tires. Detailed finite element analyses were conducted on the proposed device using the finite element software package ABAQUS, including parametric studies to determine the effect of the various parameters of device performance. This was followed by a nonlinear dynamic response history analysis of a single-story steel frame with and without the device to study the effects of the device in controlling structural response to ground excitations. Static analyses were also done to verify the stabilizing effects of the proposed device. Results from these analyses revealed considerable energy dissipation from the device due to both viscoelastic as well as plastic energy dissipation. Detailed experimental analyses on the proposed device, finite element analyses of the device on multistory structures have been put forth as the areas of future research. It may also be worthwhile to conduct further research, as suggested, in order to evaluate the use of scrap tires which is potentially a very valuable structural engineering material. / Master of Science

Le soufflage des bouteilles en polyéthylène téréphtalate (PET) génère des modifications importantes des propriétés mécaniques du matériau comme le montre l'étude de caractérisation des propriétés hétérogènes et anisotropes réalisée sur le fond pétaloïde, une partie 3D de géométrie complexe de bouteille soufflée présentée en fin de mémoire. L'étude principale présentée dans ce rapport s'inscrit dans le cadre du procédé de soufflage par bi-orientation où le matériau, qui se trouve à des températures légèrement supérieures à la température de transition vitreuse (Tg), est fortement biétiré générant ainsi de grandes modifications de morphologie microstructurale. Pour permettre à terme une simulation numérique du procédé qui prenne en compte ces modifications de propriétés en cours de soufflage, l'objectif de la thèse est de décrire le comportement du PET par un modèle visco hyperélastique original en grandes déformations, d'identifier ce modèle couplé à la thermique à partir des données expérimentales très récentes de tension biaxiale à des conditions de vitesse et de température proches du procédé et enfin d'implanter ce modèle pour la simulation du procédé. En parallèle, les aspects thermiques, qui s'avèrent fondamentaux pour le procédé, sont explorés via une identification des propriétés thermiques réalisée sur la base d'essais de chauffage infrarouge et de mesure de champs par caméra thermique. La proximité de Tg rend les propriétés mécaniques très sensibles aux moindres variations de température aussi est-il particulièrement important de prédire correctement les conditions thermique initiales de la préforme avant soufflage. De plus, la très forte viscosité à ces températures génère une dissipation importante et qui contribue à l'auto échauffement du matériau modifiant les propriétés mécaniques au cours du temps. La formulation de ce problème thermo-mécanique couplé est implémenté et résolu par la méthode des éléments finis pour simuler le gonflage des préformes / The stretch blow moulding process for polyethylene terephthalate (PET) bottles generates important modifications of the mechanical properties of the material as it can be shown in an identification study of the orthotropic and heterogeneous elastic properties in the 3D region of the petaloïd bottom of PET bottles. The main topic of this work deals with the modelling of the complex behaviour of the PET during the process that is managed at a temperature slightly above the glass transition temperature Tg. In this range of temperature and considering the high strain rates involved during the process, large changes in the material morphology can be observed and the goal of this work is to propose a visco hyperelastic model to predict the PET behaviour under these severe conditions: large deformations, high strain rate… An original procedure is proposed to manage the identification of the material properties from the experimental data of recent biaxial elongation tests. On the other hand, effects of temperature are of fundamental importance during the injection stretch blow moulding process of PET bottles. Near Tg small variations of temperature have great influence on physical properties: an accurate prediction of the initial temperature field generated by the infrared heating is proposed. Also, the important viscous dissipation induces self-heating of the material during the process which is necessary to be taken into account during the numerical simulation. The identification of the thermal parameters is achieved by an experimental infrared heating study. The global thermo mechanical model is implemented and numerical simulations are managed using the finite element method to solve the free blowing of PET preforms

Le secteur des transports aéronautiques, navals et terrestres fait de plus en plus appel pour les pièces d'habitacles ou de structure à des composites techniques de type thermoplastique thermostable renforcé par des fibres courtes. Ces matériaux alliant légèreté et résistance présentent l’intérêt majeur d’une meilleure recyclabilité d’une facilité de mise en œuvre et de maintenance que les matrices thermodurcissables dans les composites classiques. Toutefois, le développement de modèles de comportement dans le but de dimensionner des structures reste un véritable challenge. L’objectif de cette thèse concerne la modélisation du comportement de ce type de composite soumis à des chargements monotone et cyclique. Une étude expérimental a permis la détermination du comportement de chacun des constituants du composite. Leur comportement a ensuite été utilisé dans un calcul d'homogénéisation en champs complet basé sur une méthode FFT. Le comportement du composite est ensuite modélisé à l'aide d'un modèle visco-élastique spectral. Finalement, l'évolution des paramètres de ce modèle est étudiée en faisant varier la microstructure du composite (taux de fibre, dispersion d'orientation) afin d'établir un méta-modèle permettant de prédire le comportement du composite rapidement, et efficacement. / Transportation industries uses more and more composite materials each year. These composite materials provide a good alternative to classic materials thanks to their good specific resistances and stiffness. Short fiber composite materials and well suited for automotive applications, thanks to their ability to be used in injection process inducing very short fabrication cycles. But, the modeling of the behavior of these materials remains a challenge to this day. In this PhD work, an experimental characterization of a PEEK / short glass fiber composite has been conducted. A precise study of the PEEK behaior have also been conducted. The PEEK behavior was then used in an full field homogenization method based on FFT to obtain an effective behavior of the composite. A visco-elastic model was then used to model its behavior. Finally, a meta-model is build to accelerate the modeling process by studying the variation of the composite behavior with its microstructure parameters.

Este trabalho teve por objetivo o desempenho de misturas asfálticas densas utilizando um ligante convencional (CAP-20) e o mesmo ligante modificado com polímeros tipo SBS, produzido sob o nome comercial de BETUFLEX B 65/60, através dos ensaios Marshall, fluência por compressão uniaxial estática e dinâmica, resistência à tração por compressão diametral e módulo resiliente pro compressão diametral dinâmica, em misturas compactadas com uma mesma faixa granulométrica e diferentes teores de ligantes. O ensaio Marshall apresentou, para as misturas preparadas com asfalto modificado, valores maiores de estabilidade para a maioria dos teores, apesar de valores elevados de fluência em todos os teores analisados. Os resultados de deformação do ensaio de fluência por compressão uniaxial não distinguiram claramente o efeito da adição de polímeros em misturas asfálticas, ao contrário do observado no ensaio dinâmico, onde as deformações foram consideravelmente menores para a maioria dos teores analisados. Os resultados do ensaio de resistência à tração por compressão diametral mostram um desempenho superior da mistura modificada. O ensaio de módulo resiliente por compressão diametral dinâmica indicou, à temperatura de 25ºC, valores menores para a mistura com asfalto modificado, não sendo notada, entretanto, uma diferenciação de desempenho nas temperaturas de 5ºC e 40ºC. A modelação matemática das curvas de fluência e de recuperação às equações constitutivas de alguns modelos visco-elásticos básicos detectou uma diferenciação entre os valores de alguns elementos constitutivos, tanto do ensaio dinâmico, quanto do estático. / The purpose of this study is to evaluate the performance of asphalt mixes using conventional binder and the same binder modified with SBS polymer (Betuflex B 65/60) based on Marshall test, static and dynamic creep tests, indirect tensile strength test and resilient modulus by indirect tensile test, with the same granulometric composition and different binders contents. In Marshall test, polymer modified asphalt mixes presented better stability performance than conventional asphalt mixes in most of binders contents, despite of the higher flow values obtained for all binders contents. The static creep test results indicated that this test does not clearly distinguish the effect of polymer in asphalt mixes while the results of dynamic creep test indicated the opposite, i. e., polymer modified asphalt mixes deformations are smaller for most of the asphalt binders contents studied. The indirect tensile strength test results showed a better performance of modified asphalt. The results of resilient modulus by indirect tensile test at 25°C showed smaller values for modified asphalt, while the results at 5ºC and 40ºC did not show differences between the asphalt mixes. The mathematics modelling of the creep and recovering curves according to constitutive equations of some basic visco- elastic models showed a difference between the values of some constitutive elements in both cases, dynamic and static tests.

Este trabalho teve por objetivo o desempenho de misturas asfálticas densas utilizando um ligante convencional (CAP-20) e o mesmo ligante modificado com polímeros tipo SBS, produzido sob o nome comercial de BETUFLEX B 65/60, através dos ensaios Marshall, fluência por compressão uniaxial estática e dinâmica, resistência à tração por compressão diametral e módulo resiliente pro compressão diametral dinâmica, em misturas compactadas com uma mesma faixa granulométrica e diferentes teores de ligantes. O ensaio Marshall apresentou, para as misturas preparadas com asfalto modificado, valores maiores de estabilidade para a maioria dos teores, apesar de valores elevados de fluência em todos os teores analisados. Os resultados de deformação do ensaio de fluência por compressão uniaxial não distinguiram claramente o efeito da adição de polímeros em misturas asfálticas, ao contrário do observado no ensaio dinâmico, onde as deformações foram consideravelmente menores para a maioria dos teores analisados. Os resultados do ensaio de resistência à tração por compressão diametral mostram um desempenho superior da mistura modificada. O ensaio de módulo resiliente por compressão diametral dinâmica indicou, à temperatura de 25ºC, valores menores para a mistura com asfalto modificado, não sendo notada, entretanto, uma diferenciação de desempenho nas temperaturas de 5ºC e 40ºC. A modelação matemática das curvas de fluência e de recuperação às equações constitutivas de alguns modelos visco-elásticos básicos detectou uma diferenciação entre os valores de alguns elementos constitutivos, tanto do ensaio dinâmico, quanto do estático. / The purpose of this study is to evaluate the performance of asphalt mixes using conventional binder and the same binder modified with SBS polymer (Betuflex B 65/60) based on Marshall test, static and dynamic creep tests, indirect tensile strength test and resilient modulus by indirect tensile test, with the same granulometric composition and different binders contents. In Marshall test, polymer modified asphalt mixes presented better stability performance than conventional asphalt mixes in most of binders contents, despite of the higher flow values obtained for all binders contents. The static creep test results indicated that this test does not clearly distinguish the effect of polymer in asphalt mixes while the results of dynamic creep test indicated the opposite, i. e., polymer modified asphalt mixes deformations are smaller for most of the asphalt binders contents studied. The indirect tensile strength test results showed a better performance of modified asphalt. The results of resilient modulus by indirect tensile test at 25°C showed smaller values for modified asphalt, while the results at 5ºC and 40ºC did not show differences between the asphalt mixes. The mathematics modelling of the creep and recovering curves according to constitutive equations of some basic visco- elastic models showed a difference between the values of some constitutive elements in both cases, dynamic and static tests.

L’élastographie-IRM du sein (MRE) est une technique d’imagerie fonctionnelle non invasive utilisant les propriétés visco-élastiques des tissus et qui permet comme en élastographie-échographie d’évaluer la rigidité d’une lésion. Il est également possible, à la différence de l’élastographie-échographie, d’évaluer le degré de viscosité d’une lésion, et ainsi grâce à la combinaison élasticité/viscosité, comparée à l’analyse des paramètres IRM classiques comme la morphologie ou la cinétique de rehaussement, d’améliorer la caractérisation lésionnelle. Très peu d’études en élastographie-IRM du sein ont été menées à ce jour, essentiellement du fait d’une problématique instrumentale et de mise à disposition d’une antenne dédiée sein équipé d’un dispositif de génération des ondes de cisaillement dans le sein. Dans un premier temps, nous avons pu établir et optimiser une séquence élasto-IRM du sein sur une série de 10 volontaires saines. Cette séquence basée sur un principe de séquence Spin Echo EPI-MRE 3D, a permis l’acquisition de 50 coupes en 10 minutes sur un sein, compatible avec la pratique clinique en IRM du sein. Une approche multifréquence à 37,5 Hz, 75 Hz et 112,5 Hz a été ensuite testée sur les trois dernières volontaires puis transférées à notre population de patientes. Cette séquence multifréquence permettait la continuité de diffusion des ondes dans le sein. 50 patientes présentant des lésions indéterminées ou suspectes du sein (37 cancers, 13 bénins) ont ensuite été incluses dans ce protocole et examinées par IRM du sein classique avec séquence supplémentaire élasto-IRM. Certaines patientes étaient aussi examinées en élasto-échographie. Les données IRM morphologiques, dynamiques et de visco-élasticité IRM ont été corrélées à l’histologie. Nous avons pu montrer que les paramètres visco-élastiques IRM étaient fortement corrélés avec le score de malignité d’une lésion (Bi-RADS ACR) et avec le caractère différentiel bénin/malin. C’est notamment le paramètre Gd qui représente l’élasticité, qui était plus faible en cas de lésion suspecte BI-RADS 5. Le paramètre Gl était plus élevé dans les lésions malignes par rapport aux lésions bénignes, avec un niveau de viscosité statistiquement supérieur dans les lésions malignes. Le meilleur paramètre semble être le rapport y (Gl/Gd) qui était aussi significativement élevé dans les lésions malignes par comparaison avec les lésions bénignes du sein, et qui a été analysé comme un facteur indépendant. En pratique, l’ajout de la séquence MRE à un examen IRM du sein classique a permis dans notre étude d’améliorer significativement la sensibilité de l’IRM (de 78 à 91 %) sans perte de spécificité, celle-ci étant initialement très bonne dans cette étude. Nous n’avons pas en revanche établi de lien entre la fibrose, la quantification vasculaire ou la nécrose pour expliquer ces phénomènes de visco-élasticité des tumeurs. En conclusion, l’élasto-IRM peut s’avérer utile pour améliorer le diagnostic de lésions du sein en IRM. Une poursuite des travaux avec optimisation de la séquence pour qu’elle puisse permettre l’analyse des deux seins sera nécessaire pour sa diffusion en pratique clinique. Ce travail pourrait idéalement se poursuivre sur une plus grande série de patientes. / MR-elastography (MRE) is a non-invasive functional Imaging technique using tissue mechanical visco-elastic properties to evaluate tissue stifness. MRE is different from elasticity Imaging in ultrasound, as it is possible to evaluate tumour viscosity. Combining viscosity and elasticity may improve MRI accuracy, in comparison with classical morphological and kinetics criteria. Only very few studies are focused on breast MRE, because of low availability of dedicated breast coils with MRE devices. Firstly, we developed and optimized a breast MRE sequence on a population of 10 volunteers. This sequence is based on a Spin Echo EPI-MRE 3D, and it was possible to acquire 50 slices on one breast in 10 minutes, which is applicable in a clinical routine in breast MRI. Secondly, a multi-frequency approach 37,5 Hz, 75 Hz and 112,5 Hz has been evaluated on the last three volunteers, then transferred to our patient’s population. A continous diffusion of waves within the breast was possible with this multifrequency approach sequence. 50 patients presenting undetermined or suspicious breast lesions (37 cancers, 13 benign lesions) were included in this study and examined with a standard breast MRI and MRE sequence. Some patients were also examined with shear-wave ultrasound elastography (ARFI mode, Siemens ®). Morphological, kinetic and visco-elastic MR parameters were correlated to pathology. We demonstrated that MR visco-elastic properties were strongly correlated with Bi-RADS ACR malignancy score of a breast lesion and with malignant and benign status. The best parameter was Gd (dynamic modulus), which corresponded to lesion stiffness. Gd was lower in case of BI-RADS 5 lesions. Gl parameter (Loss modulus) was higher in malignant lesions in comparison with benign lesions, with viscosity level statistically higher in malignant lesions. The best criterion was the ratio y (Gl/Gd), which was significantly higher in malignant lesions in comparison with benign lesions; ratio y was statistically an independent factor. In practice, addition of a MRE sequence to a standard breast MRI improved significantly breast MRI Sensitity (78 to 91 %) without reduction in specificity; Sp was anyway initially high in our study. Nevertheless, we didn’t demonstrate a statistical correlation with fibrosis, vascular grading or necrosis with MRE parameters, to explain visco-elastic properties of breast tumours. In conclusion, MR-elastography may be useful to improve breast MRI accuracy. In future studies, MRE sequence may be optimized to allow a bilateral acquisition on both breasts, which would be useful in clinical practice. Future works could include higher number of patients to confirm our results.

Óleos essenciais, basicamente formados por hidrocarbonetos terpênicos e compostos oxigenados, têm função aromatizante nas indústrias química, farmacêutica e de alimentos. Os compostos terpênicos são instáveis ao calor e sua remoção resulta em um produto mais estável e com maior valor comercial. No processo de desterpenação, a viscosidade é um parâmetro de grande interesse, pois afeta a perda de energia por atrito e os mecanismos de transferência de calor e massa. Devido o grande número de variáveis que podem afetar a viscosidade, como temperatura, pressão e concentração, métodos para estimar esta propriedade apresentam grande importância prática. O objetivo desta dissertação de mestrado foi ajustar o modelo UNIFAC-VISCO aos dados de viscosidade de sistemas similares aos resultantes do processo de desterpenação dos óleos essenciais de bergamota, hortelã e limão por extração líquido-líquido (ELL), a 25 ºC, utilizando etanol hidratado como solvente. O modelo foi programado utilizando a plataforma MATLAB® e a correlação foi realizada utilizando duas abordagens: na primeira, somente foram ajustados parâmetros referentes aos grupos funcionais ainda não descritos na literatura para o UNIFAC-VISCO, resultando em um desvio médio relativo (DMR) igual a 1,70 %; na segunda abordagem, todos os grupos funcionais foram ajustados aos dados experimentais, resultando em um desvio médio relativo (DMR) igual 0,68 %. Os parâmetros UNIFAC-VISCO foram ajustados utilizando um método heurístico o que possibilitou avaliar o desempenho de um método de inteligência computacional. A capacidade preditiva dos parâmetros obtidos foi testada nos sistemas semelhantes aos formados na desterpenação de óleo de eucalipto. Os valores de DMR para estes sistemas foram 3,56 e 1,83%, utilizando os parâmetros obtidos na primeira e na segunda abordagem, respectivamente. Estes resultados mostram que o modelo fornece uma boa estimativa desta propriedade e pode ser uma ferramenta útil para a indústria de alimentos e para o processo de extração, possibilitando a melhoria de processos e permitindo o projeto de equipamentos mais eficientes em escala industrial. / Essential oils, that are primarily composed for terpenoids and oxygenates, have flavoring function in the chemical, pharmaceutical and food industries. Terpenes compounds are unstable to heat and its removal results in a better quality product besides its higher commercial value. In the deterpenation process, the viscosity has a great importance since it affects the loss of energy by friction and the mechanisms of heat and mass transfer. There are a large amount of variables that can affect this parameter such as temperature, pressure and concentration and the use of estimation methods for this property becomes a tool of great practical importance. The aim of this dissertation was to adjust the UNIFAC-VISCO model to the kinematic viscosities of similar systems to those formed after deterpenation process of bergamot, mint and lemon essential oils, by liquid-liquid extraction (LLE) at 25ºC, with aqueous ethanol as solvent. The model was programmed using MATLAB ® platform and the correlation was accomplished using two approaches: in the first one, only parameters related to functional groups with no previous literature references to the UNIFAC-VISCO were adjusted, providing an average relative deviation (ARD) equal to 1.70 %; in the second approach, all functional groups were fitted to the experimental data, which provided an average relative deviation (ARD) equal to 0.68 %. The UNIFAC-VISCO parameters were adjusted by a heuristic method allowing the evaluation of a computational intelligence method performance. The predictive ability of the parameters was evaluated in similar systems to those formed in the deterpenation of eucalyptus essential oil. The ARD values between the experimental and the calculated viscosities were 3.56 and 1.83%, for parameters from first and second approach, respectively. These results show that the model provides a good estimation of this physical property and it can be a good tool for food industry and for extraction process, allowing process improvement and enabling the project of more efficient equipment on industrial scale.