Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM)
http://hdl.handle.net/10985/191
2024-03-28T15:02:32ZIn vitro study of drug release from various loaded polyurethane samples and subjected to different non-pulsed flow rates
http://hdl.handle.net/10985/18479
In vitro study of drug release from various loaded polyurethane samples and subjected to different non-pulsed flow rates
ABBASNEZHAD, Navideh; SHIRINBAYAN, Mohammadali; BAKIR, Farid; TCHARKHTCHI, Abbas
Drug-eluting implants with a polymeric matrix are currently widely used and the interest of modeling their behavior is increasing. This article aims to present preliminary results of an in vitro under steady flow, study the behavior of drug-loaded polyurethane samples used as drug delivery matrices. Polyisocyanate and polyol synthesis supplied the polyurethane studied in this work. A molding and heat at 50 °C for about 30 min make it possible to prepare films from these components. The prepared samples are placed in the impermeable Plexiglas tube and they are in contact with the medium (distilled water). Tests have been performed without flow and three other cases with steady flow, at a temperature of 37 °C. The substance active incorporated in these films, as the drug, for carrying out the release tests is the C20H24C12N2O3. This drug supplied in granular form is composed of a mixture in the following proportions, 15 mg of diclofenac epolamine and 50 mg of diclofenac-sodium. Four sample variants were carefully prepared: pure-PU and PU loaded in a mass ratio of 10, 20 or 30%. Weighing, DSC, FT-IR, and DMTA are the methods used to analyze the samples. In addition, SEM micrographs are used to explore qualitatively the microstructure during the release tests. The kinetics in vitro of the drug release and water absorption by the polyurethane films are discussed in detail. The results show that these two quantities depend on the initial drug loading and the flow rate value, as a function of the in vitro incubation time.
2020-01-01T00:00:00ZABBASNEZHAD, NavidehSHIRINBAYAN, MohammadaliBAKIR, FaridTCHARKHTCHI, AbbasDrug-eluting implants with a polymeric matrix are currently widely used and the interest of modeling their behavior is increasing. This article aims to present preliminary results of an in vitro under steady flow, study the behavior of drug-loaded polyurethane samples used as drug delivery matrices. Polyisocyanate and polyol synthesis supplied the polyurethane studied in this work. A molding and heat at 50 °C for about 30 min make it possible to prepare films from these components. The prepared samples are placed in the impermeable Plexiglas tube and they are in contact with the medium (distilled water). Tests have been performed without flow and three other cases with steady flow, at a temperature of 37 °C. The substance active incorporated in these films, as the drug, for carrying out the release tests is the C20H24C12N2O3. This drug supplied in granular form is composed of a mixture in the following proportions, 15 mg of diclofenac epolamine and 50 mg of diclofenac-sodium. Four sample variants were carefully prepared: pure-PU and PU loaded in a mass ratio of 10, 20 or 30%. Weighing, DSC, FT-IR, and DMTA are the methods used to analyze the samples. In addition, SEM micrographs are used to explore qualitatively the microstructure during the release tests. The kinetics in vitro of the drug release and water absorption by the polyurethane films are discussed in detail. The results show that these two quantities depend on the initial drug loading and the flow rate value, as a function of the in vitro incubation time.An overview of filtration efficiency through the masks: Mechanisms of the aerosols penetration
http://hdl.handle.net/10985/19215
An overview of filtration efficiency through the masks: Mechanisms of the aerosols penetration
ABBASNEZHAD, Navideh; ZARBINI SEYDANI, Mohammad; ZIRAK, Nader; FARZANEH, Sedigheh; SHIRINBAYAN, Mohammadali; TCHARKHTCHI, Abbas
The masks have always been mentioned as an effective tool against environmental threats. They are considered as protective equipment to preserve the respiratory system against the non-desirable air droplets and aerosols such as the viral or pollution particles. The aerosols can be pollution existence in the air, or the infectious airborne viruses initiated from the sneezing, coughing of the infected people. The filtration efficiency of the different masks against these aerosols are not the same, as the particles have different sizes, shapes, and properties. Therefore, the challenge is to fabricate the filtration masks with higher efficiency to decrease the penetration percentage at the nastiest conditions. To achieve this concept, knowledge about the mechanisms of the penetration of the aerosols through the masks at different effective environmental conditions is necessary. In this paper, the literature about the different kinds of face masks and respiratory masks, common cases of their application, and the advantages and disadvantages of them in this regard have been reviewed. Moreover, the related mechanisms of the penetration of the aerosols through the masks are discussed. The environmental conditions affecting the penetration as well as the quality of the fabrication are studied. Finally, special attention was given to the numerical simulation related to the different existing mechanisms.
2021-01-01T00:00:00ZABBASNEZHAD, NavidehZARBINI SEYDANI, MohammadZIRAK, NaderFARZANEH, SedighehSHIRINBAYAN, MohammadaliTCHARKHTCHI, AbbasThe masks have always been mentioned as an effective tool against environmental threats. They are considered as protective equipment to preserve the respiratory system against the non-desirable air droplets and aerosols such as the viral or pollution particles. The aerosols can be pollution existence in the air, or the infectious airborne viruses initiated from the sneezing, coughing of the infected people. The filtration efficiency of the different masks against these aerosols are not the same, as the particles have different sizes, shapes, and properties. Therefore, the challenge is to fabricate the filtration masks with higher efficiency to decrease the penetration percentage at the nastiest conditions. To achieve this concept, knowledge about the mechanisms of the penetration of the aerosols through the masks at different effective environmental conditions is necessary. In this paper, the literature about the different kinds of face masks and respiratory masks, common cases of their application, and the advantages and disadvantages of them in this regard have been reviewed. Moreover, the related mechanisms of the penetration of the aerosols through the masks are discussed. The environmental conditions affecting the penetration as well as the quality of the fabrication are studied. Finally, special attention was given to the numerical simulation related to the different existing mechanisms.Viscoelastic Behavior of Drug-Loaded Polyurethane
http://hdl.handle.net/10985/20795
Viscoelastic Behavior of Drug-Loaded Polyurethane
ABBASNEZHAD, Navideh; SHIRINBAYAN, Mohammadali; CHABI, Fatiha; CHAMPMARTIN, Stephane; BAKIR, Farid; TCHARKHTCHI, Abbas
Drug-eluting stents are desirable platforms for local medicine delivery. However, the incorporation of drugs into polymers can influence the mechanical and physicochemical properties of said matrix, which is a topic that is still poorly understood. In fact, this is more noticeable since the apposition is most often accompanied by mechanical stresses on the polymer coating, which can induce therapeutic failure that can result in death. It is therefore necessary to better understand their behavior by examining their properties in conditions such as those in living beings. We studied polyurethane drug carriers made in-house. Diclofenac epolamine was chosen as a model hydrophilic medicine. We used thermal measurements (DMTA) and tensile tests. The aim was to establish the influence of the loading and release of the drug on the physicochemical properties of this polymer in the presence of a stagnant or circulating fluid medium, phosphate-buffered saline (PBS). For the two PU/drug loadings studied, the effect of the initial drug load was more marked. The free volume fraction and the number of pores in the samples increased with the increasing percent of the drug and with release time. The kinetic profiles were accelerated with the loading ratio and with the presence of flow. Young′s modulus and ultimate stress were not significantly influenced by the release time. A relevant relationship between the tensile properties and the viscoelastic behavior of the samples was developed. Our results have implications for optimizing the performance of drug coatings for stents.
2021-01-01T00:00:00ZABBASNEZHAD, NavidehSHIRINBAYAN, MohammadaliCHABI, FatihaCHAMPMARTIN, StephaneBAKIR, FaridTCHARKHTCHI, AbbasDrug-eluting stents are desirable platforms for local medicine delivery. However, the incorporation of drugs into polymers can influence the mechanical and physicochemical properties of said matrix, which is a topic that is still poorly understood. In fact, this is more noticeable since the apposition is most often accompanied by mechanical stresses on the polymer coating, which can induce therapeutic failure that can result in death. It is therefore necessary to better understand their behavior by examining their properties in conditions such as those in living beings. We studied polyurethane drug carriers made in-house. Diclofenac epolamine was chosen as a model hydrophilic medicine. We used thermal measurements (DMTA) and tensile tests. The aim was to establish the influence of the loading and release of the drug on the physicochemical properties of this polymer in the presence of a stagnant or circulating fluid medium, phosphate-buffered saline (PBS). For the two PU/drug loadings studied, the effect of the initial drug load was more marked. The free volume fraction and the number of pores in the samples increased with the increasing percent of the drug and with release time. The kinetic profiles were accelerated with the loading ratio and with the presence of flow. Young′s modulus and ultimate stress were not significantly influenced by the release time. A relevant relationship between the tensile properties and the viscoelastic behavior of the samples was developed. Our results have implications for optimizing the performance of drug coatings for stents.On the importance of physical and mechanical properties of PLGA films during drug release
http://hdl.handle.net/10985/20155
On the importance of physical and mechanical properties of PLGA films during drug release
ABBASNEZHAD, Navideh; ZIRAK, Nader; SHIRINBAYAN, Mohammadali; BAKIR, Farid; TCHARKHTCHI, Abbas
Physical and mechanical properties of the drug-incorporated polymer play a significant role in the release behavior from the drug carriers. Understanding the relative extent of variation in the physical and mechanical properties of the polymer makes it possible to improve the design of polymer carriers to obtain better release profile and increase drug stability. Drug delivery from PLGA loaded with various percentages of diclofenac sodium (DS: 0, 5%, and 10%) at different flow rates of 0 and 7.5 ml/s (flow rate of the healthy internal carotid artery) in phosphate buffered saline (PBS) for different release intervals has been studied. In this research, the change of some physical properties such as free volume fraction, glass transition temperature (Tg) and mechanical properties before and during PLGA release have been investigated. In-vitro release tests have been performed in the PBS medium at the temperature of 37 °C. The results showed that during drug release, Youngs’ modulus and ultimate stress were increased while elongation at break was decreased for different drug loaded films and flow rates. In addition, the zero order kinetic model was found to best fit all the release-profiles obtained.
2021-01-01T00:00:00ZABBASNEZHAD, NavidehZIRAK, NaderSHIRINBAYAN, MohammadaliBAKIR, FaridTCHARKHTCHI, AbbasPhysical and mechanical properties of the drug-incorporated polymer play a significant role in the release behavior from the drug carriers. Understanding the relative extent of variation in the physical and mechanical properties of the polymer makes it possible to improve the design of polymer carriers to obtain better release profile and increase drug stability. Drug delivery from PLGA loaded with various percentages of diclofenac sodium (DS: 0, 5%, and 10%) at different flow rates of 0 and 7.5 ml/s (flow rate of the healthy internal carotid artery) in phosphate buffered saline (PBS) for different release intervals has been studied. In this research, the change of some physical properties such as free volume fraction, glass transition temperature (Tg) and mechanical properties before and during PLGA release have been investigated. In-vitro release tests have been performed in the PBS medium at the temperature of 37 °C. The results showed that during drug release, Youngs’ modulus and ultimate stress were increased while elongation at break was decreased for different drug loaded films and flow rates. In addition, the zero order kinetic model was found to best fit all the release-profiles obtained.Influence of loading conditions on the overall mechanical behavior of polyether-ether-ketone (PEEK)
http://hdl.handle.net/10985/13276
Influence of loading conditions on the overall mechanical behavior of polyether-ether-ketone (PEEK)
ABBASNEZHAD, Navideh; KHAVANDI, Alireza; ARABI, Hossein; SHIRINBAYAN, Mohammadali; TCHARKHTCHI, Abbas; FITOUSSI, Joseph
Testing methods have been developed to compare the mechanical responses and failure behavior of polyether-ether-keton (PEEK) thermoplastic polymer; under quasi-static, high strain rate tensile tests and fatigue loading. Tensile tests were performed with the strain rates varying from 0.0003 s−1 to 60 s−1 and at different temperatures to compare the flow characteristics of the samples undergone various testing conditions. Fatigue tests at different amplitudes and frequencies were also performed to evaluate the temperature rise during cyclic loading and its effect on the fracture behavior. Results show that dynamic tension, in comparison with quasi-static behavior, causes brittle fracture; whereas under fatigue test at high frequencies and loading amplitudes the material behaves not only a more ductile behavior but also it clearly shows the influences of induced self-heating in the modulus and mechanical properties of the PEEK were significant. So the major aim of this article is to discuss about the induced temperature and its effect on the fracture surface. Thermal fatigue has a very significant role in increasing temperature and reducing fatigue life; from there it is necessary to know the conditions at which thermal fatigue happens and also the amount of energy which is consumed. Obtained equation from the experimental results and calculations can estimate the energy dissipation in the fatigue tests which is as a function of cycle and frequency.
2018-01-01T00:00:00ZABBASNEZHAD, NavidehKHAVANDI, AlirezaARABI, HosseinSHIRINBAYAN, MohammadaliTCHARKHTCHI, AbbasFITOUSSI, JosephTesting methods have been developed to compare the mechanical responses and failure behavior of polyether-ether-keton (PEEK) thermoplastic polymer; under quasi-static, high strain rate tensile tests and fatigue loading. Tensile tests were performed with the strain rates varying from 0.0003 s−1 to 60 s−1 and at different temperatures to compare the flow characteristics of the samples undergone various testing conditions. Fatigue tests at different amplitudes and frequencies were also performed to evaluate the temperature rise during cyclic loading and its effect on the fracture behavior. Results show that dynamic tension, in comparison with quasi-static behavior, causes brittle fracture; whereas under fatigue test at high frequencies and loading amplitudes the material behaves not only a more ductile behavior but also it clearly shows the influences of induced self-heating in the modulus and mechanical properties of the PEEK were significant. So the major aim of this article is to discuss about the induced temperature and its effect on the fracture surface. Thermal fatigue has a very significant role in increasing temperature and reducing fatigue life; from there it is necessary to know the conditions at which thermal fatigue happens and also the amount of energy which is consumed. Obtained equation from the experimental results and calculations can estimate the energy dissipation in the fatigue tests which is as a function of cycle and frequency.Development of a Model Based on Physical Mechanisms for the Explanation of Drug Release: Application to Diclofenac Release from Polyurethane Films
http://hdl.handle.net/10985/20316
Development of a Model Based on Physical Mechanisms for the Explanation of Drug Release: Application to Diclofenac Release from Polyurethane Films
ABBASNEZHAD, Navideh; KEBDANI, Mohamed; SHIRINBAYAN, Mohammadali; CHAMPMARTIN, Stéphane; KOUIDRI, SMAINE; BAKIR, Farid; TCHARKHTCHI, Abbas
In this study, we present a method for prediction of the drug-release profile based on the physical mechanisms that can intervene in drug release from a drug-carrier. The application presented here incorporates the effects of drug concentration and Reynolds number defining the circulating flow in the testing vein. The experimental data used relate to the release of diclofenac from samples of non-degradable polyurethane subjected to static and continuous flow. This case includes simultaneously three mechanisms: burst-release, diffusion and osmotic pressure, identified beforehand here as being able to contribute to the drug liberation. For this purpose, authors coded the Sequential Quadratic Programming Algorithm to solve the problem of non-linear optimization. The experimental data used to develop the mathematical model obtained from release studies carried out in water solution at 37 °C, for three concentrations of diclofenac and two water flow rates. We discuss the contribution of mechanisms and kinetics by considering two aforementioned parameters and, following that, we obtain the specific-model and compare the calculated results with the experimental results for the reserved cases. The results showed that drug percentage mostly affect the burst release, however flow rate has affected the osmotic release. In addition, release kinetics of all the mechanisms have increased by increasing the values of two considered parameters.
2021-01-01T00:00:00ZABBASNEZHAD, NavidehKEBDANI, MohamedSHIRINBAYAN, MohammadaliCHAMPMARTIN, StéphaneKOUIDRI, SMAINEBAKIR, FaridTCHARKHTCHI, AbbasIn this study, we present a method for prediction of the drug-release profile based on the physical mechanisms that can intervene in drug release from a drug-carrier. The application presented here incorporates the effects of drug concentration and Reynolds number defining the circulating flow in the testing vein. The experimental data used relate to the release of diclofenac from samples of non-degradable polyurethane subjected to static and continuous flow. This case includes simultaneously three mechanisms: burst-release, diffusion and osmotic pressure, identified beforehand here as being able to contribute to the drug liberation. For this purpose, authors coded the Sequential Quadratic Programming Algorithm to solve the problem of non-linear optimization. The experimental data used to develop the mathematical model obtained from release studies carried out in water solution at 37 °C, for three concentrations of diclofenac and two water flow rates. We discuss the contribution of mechanisms and kinetics by considering two aforementioned parameters and, following that, we obtain the specific-model and compare the calculated results with the experimental results for the reserved cases. The results showed that drug percentage mostly affect the burst release, however flow rate has affected the osmotic release. In addition, release kinetics of all the mechanisms have increased by increasing the values of two considered parameters.Controlled release from polyurethane films: Drug release mechanisms
http://hdl.handle.net/10985/19932
Controlled release from polyurethane films: Drug release mechanisms
ABBASNEZHAD, Navideh; ZIRAK, Nader; SHIRINBAYAN, Mohammadali; KOUIDRI, SMAINE; SALAHINEJAD, Erfan; BAKIR, Farid; TCHARKHTCHI, Abbas
In this study, polyurethane-films loaded with diclofenac were used to analyze the drug release kinetics and mechanisms. For this purpose, the experimental procedures were developed under static and dynamic conditions with different initial drug loads of 10, 20, and 30%. In the dynamic condition, to better simulate the biological flow, drug release measurements were investigated at flow rates of 7.5 and 23.5 ml/s. These values indicate the flow rate of the internal carotid artery (ICA) for a normal state of a body and for a person during the exercise, respectively. The experimental data were analyzed and adjusted by Higuchi, Korsmeyer–Peppas, First-order, zero-order, and Peppas–Sahlin models in order to understand the mechanisms contributed. Finally, drug release mechanisms were specified by investigating the model correlation coefficients. Experimental results showed that increasing the flow rate and initial drug loads enhance drug liberation. In addition, the rate of release is more influenced by the drug dosage in the static state. The analysis revealed that diffusion, burst, and osmotic pressure are the principal mechanisms contributed. Moreover, Fickian type was the dominant mechanism at all duration of release. However, it was discovered using Peppas–Sahlin model that the contribution of the diffusion mechanism decreases with increasing flow rate and initial dosage. Furthermore, the tests at different drug dosages showed that the number of stages in medication release profile is independent of the flow rate and the medicine percentage. One can conclude that the drug release kinetic in static state is more influenced by drug dosage compared with dynamic state.
2021-01-01T00:00:00ZABBASNEZHAD, NavidehZIRAK, NaderSHIRINBAYAN, MohammadaliKOUIDRI, SMAINESALAHINEJAD, ErfanBAKIR, FaridTCHARKHTCHI, AbbasIn this study, polyurethane-films loaded with diclofenac were used to analyze the drug release kinetics and mechanisms. For this purpose, the experimental procedures were developed under static and dynamic conditions with different initial drug loads of 10, 20, and 30%. In the dynamic condition, to better simulate the biological flow, drug release measurements were investigated at flow rates of 7.5 and 23.5 ml/s. These values indicate the flow rate of the internal carotid artery (ICA) for a normal state of a body and for a person during the exercise, respectively. The experimental data were analyzed and adjusted by Higuchi, Korsmeyer–Peppas, First-order, zero-order, and Peppas–Sahlin models in order to understand the mechanisms contributed. Finally, drug release mechanisms were specified by investigating the model correlation coefficients. Experimental results showed that increasing the flow rate and initial drug loads enhance drug liberation. In addition, the rate of release is more influenced by the drug dosage in the static state. The analysis revealed that diffusion, burst, and osmotic pressure are the principal mechanisms contributed. Moreover, Fickian type was the dominant mechanism at all duration of release. However, it was discovered using Peppas–Sahlin model that the contribution of the diffusion mechanism decreases with increasing flow rate and initial dosage. Furthermore, the tests at different drug dosages showed that the number of stages in medication release profile is independent of the flow rate and the medicine percentage. One can conclude that the drug release kinetic in static state is more influenced by drug dosage compared with dynamic state.Some New Concepts of Shape Memory Effect of Polymers
http://hdl.handle.net/10985/7985
Some New Concepts of Shape Memory Effect of Polymers
ABDALLAH-ELHIRTSI, Sofiane; EBRAHIMI, Kambiz; SHIRINBAYAN, Mohammadali; FARZANEH, Sedigheh; TCHARKHTCHI, Abbas; FITOUSSI, Joseph
In this study some new concepts regarding certain aspects related to shape memory polymers are presented. A blend of polylactic acid (PLA) (80%) and polybutylene succinate (PBS) (20%) was prepared first by extrusion, then by injection molding to obtain the samples. Tensile, stress-relaxation and recovery tests were performed on these samples at 70 °C. The results indicated that the blend can only regain 24% of its initial shape. It was shown that, this partial shape memory effect could be improved by successive cycles of shape memory tests. After a fourth cycle, the blend is able to regain 82% of its shape. These original results indicated that a polymer without (or with partial) shape memory effect may be transformed into a shape memory polymer without any chemical modification. In this work, we have also shown the relationship between shape memory and property memory effect. Mono and multi-frequency DMA (dynamic mechanical analyzer) tests on virgin and 100% recovered samples of polyurethane (PU) revealed that the polymer at the end of the shape memory tests regains 100% of its initial form without regaining some of its physical properties like glass transition temperature, tensile modulus, heat expansion coefficient and free volume fraction. Shape memory (with and without stress-relaxation) tests were performed on the samples in order to show the role of residual stresses during recovery tests. On the basis of the results we have tried to show the origin of the driving force responsible for shape memory effect.
2014-01-01T00:00:00ZABDALLAH-ELHIRTSI, SofianeEBRAHIMI, KambizSHIRINBAYAN, MohammadaliFARZANEH, SedighehTCHARKHTCHI, AbbasFITOUSSI, JosephIn this study some new concepts regarding certain aspects related to shape memory polymers are presented. A blend of polylactic acid (PLA) (80%) and polybutylene succinate (PBS) (20%) was prepared first by extrusion, then by injection molding to obtain the samples. Tensile, stress-relaxation and recovery tests were performed on these samples at 70 °C. The results indicated that the blend can only regain 24% of its initial shape. It was shown that, this partial shape memory effect could be improved by successive cycles of shape memory tests. After a fourth cycle, the blend is able to regain 82% of its shape. These original results indicated that a polymer without (or with partial) shape memory effect may be transformed into a shape memory polymer without any chemical modification. In this work, we have also shown the relationship between shape memory and property memory effect. Mono and multi-frequency DMA (dynamic mechanical analyzer) tests on virgin and 100% recovered samples of polyurethane (PU) revealed that the polymer at the end of the shape memory tests regains 100% of its initial form without regaining some of its physical properties like glass transition temperature, tensile modulus, heat expansion coefficient and free volume fraction. Shape memory (with and without stress-relaxation) tests were performed on the samples in order to show the role of residual stresses during recovery tests. On the basis of the results we have tried to show the origin of the driving force responsible for shape memory effect.Study of partial shape memory effect of polymers by multicycle tests
http://hdl.handle.net/10985/10180
Study of partial shape memory effect of polymers by multicycle tests
ABDALLAH-ELHIRTSI, Sofiane; RASHMI, Baralu-Jagannatha; PRASHANTHA, Kalappa; FARZANEH, Sedigheh; LACRAMPE, Marie-France; KRAWCZAK, Patricia; TCHARKHTCHI, Abbas; FITOUSSI, Joseph
In this work, an experimental investigation on a partial shape memory polymer (PSMP) which is transformed into shape memory material is presented. Multicycle shape memory tests are performed on thermoplastic polyurethane (TPU) at 70°C. At the end of each cycle, the capacity of the shape memory material increases. At the end of the first cycle, the recovery rate of TPU is only 67%; this partial shape memory effect (PSME) has been improved by successive cycles of shape memory tests. After the fourth cycle, it becomes nearly 100% shape memory material. The results of the fifth and sixth cycles confirm this modification. These original results indicate that a polymer with partial shape memory may be transformed into an SMP without any chemical modification. This increase of SME could be related to the creation of residual stresses during the tensile tests. The residual stresses are the origin of the driving force responsible for SME.
2015-01-01T00:00:00ZABDALLAH-ELHIRTSI, SofianeRASHMI, Baralu-JagannathaPRASHANTHA, KalappaFARZANEH, SedighehLACRAMPE, Marie-FranceKRAWCZAK, PatriciaTCHARKHTCHI, AbbasFITOUSSI, JosephIn this work, an experimental investigation on a partial shape memory polymer (PSMP) which is transformed into shape memory material is presented. Multicycle shape memory tests are performed on thermoplastic polyurethane (TPU) at 70°C. At the end of each cycle, the capacity of the shape memory material increases. At the end of the first cycle, the recovery rate of TPU is only 67%; this partial shape memory effect (PSME) has been improved by successive cycles of shape memory tests. After the fourth cycle, it becomes nearly 100% shape memory material. The results of the fifth and sixth cycles confirm this modification. These original results indicate that a polymer with partial shape memory may be transformed into an SMP without any chemical modification. This increase of SME could be related to the creation of residual stresses during the tensile tests. The residual stresses are the origin of the driving force responsible for SME.Development of a New Hydraulic Ankle for HYDROïD Humanoid Robot
http://hdl.handle.net/10985/13816
Development of a New Hydraulic Ankle for HYDROïD Humanoid Robot
ABDELLATIF, A; ZWEIR, Yahya; OUEZDOU, F.B; HILDEBRANDT, Arne-Christoph; ALFAYAD, S; MECHBAL, Nazih
For humanoid robots, design of the ankle mechanism is still open research problem since high torque is required while compact structures have to be maintained. This paper investigates an enhanced design of 3 degree-of-freedom hydraulic hybrid ankle mechanism. The design is based on (US9327785) Alfayad et al. (2011). Using a hybrid kinematic structure with hydraulic actuation, allows us to reach a slender humanoid ankle shape while enabling the high torque performances required for stable walking. Performances analysis of the first version ankle mechanism designed for HYDROïD humanoid robot showed some limits mainly induced by seal friction and pistons misalignment. In this paper, the influence of the friction parameters is explored. A virtual model is developed to evaluate the performances of a new flexion/extension and adduction/abduction pistons arrangement. Then, a control algorithm is simulated and implemented, as an example, to the flexion/extension motion of the new ankle mechanism. Finally, an experimental validation for the performances of the new proposed hydraulic ankle is conducted using the built hardware prototype, the results show significant improvement
2018-01-01T00:00:00ZABDELLATIF, AZWEIR, YahyaOUEZDOU, F.BHILDEBRANDT, Arne-ChristophALFAYAD, SMECHBAL, NazihFor humanoid robots, design of the ankle mechanism is still open research problem since high torque is required while compact structures have to be maintained. This paper investigates an enhanced design of 3 degree-of-freedom hydraulic hybrid ankle mechanism. The design is based on (US9327785) Alfayad et al. (2011). Using a hybrid kinematic structure with hydraulic actuation, allows us to reach a slender humanoid ankle shape while enabling the high torque performances required for stable walking. Performances analysis of the first version ankle mechanism designed for HYDROïD humanoid robot showed some limits mainly induced by seal friction and pistons misalignment. In this paper, the influence of the friction parameters is explored. A virtual model is developed to evaluate the performances of a new flexion/extension and adduction/abduction pistons arrangement. Then, a control algorithm is simulated and implemented, as an example, to the flexion/extension motion of the new ankle mechanism. Finally, an experimental validation for the performances of the new proposed hydraulic ankle is conducted using the built hardware prototype, the results show significant improvement