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http://hdl.handle.net/10985/6560
A torsion test for the study of the large deformation recovery of shape memory polymers
DIANI, Julie; FREDY, Carole; GILORMINI, Pierre; MERCKEL, Yannick; REGNIER, Gilles; ROUSSEAU, Ingrid
A torsion device was designed and built for testing the shape fixity and shape recovery of shape memory polymers at large deformation. A simple thermal chamber was used to regulate the thermal environment during testing and a CCD camera was used for recording the deformation. Such a torsion testing system provided a quantitative estimate of the kinematics and kinetics of shape recovery for samples submitted to large deformations at moderate strains that are more likely expected in actual shape memory applications. In addition, such measurements are complementary to those obtained from large strain uniaxial tension tests usually run for during traditional shape memory effect characterization. As a result, the torsional shape memory testing device and testing method described is expected to contribute building complementary data for the thermomechanical modeling of shape memory polymers.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10985/65602011-01-01T00:00:00ZDIANI, JulieFREDY, CaroleGILORMINI, PierreMERCKEL, YannickREGNIER, GillesROUSSEAU, IngridA torsion device was designed and built for testing the shape fixity and shape recovery of shape memory polymers at large deformation. A simple thermal chamber was used to regulate the thermal environment during testing and a CCD camera was used for recording the deformation. Such a torsion testing system provided a quantitative estimate of the kinematics and kinetics of shape recovery for samples submitted to large deformations at moderate strains that are more likely expected in actual shape memory applications. In addition, such measurements are complementary to those obtained from large strain uniaxial tension tests usually run for during traditional shape memory effect characterization. As a result, the torsional shape memory testing device and testing method described is expected to contribute building complementary data for the thermomechanical modeling of shape memory polymers.On modeling shape memory polymers as elastic two-phase composite materials
http://hdl.handle.net/10985/6558
On modeling shape memory polymers as elastic two-phase composite materials
GILORMINI, Pierre; DIANI, Julie
A model has been proposed recently, which describes the experimentally observed mechanical behavior of some shape memory polymers. It considers a purely thermoelastic behavior, without strain rate effects, and assumes essentially that the polymer can be considered as a two-phase composite, with glassy and rubbery phases having volume fractions that depend on temperature only. Since a uniform stress hypothesis was used in the original formulation, with an inconsistency when thermal expansion was considered, this model is revisited here by taking advantage of the many results that have been established in the theory of composite materials. It is shown, especially, that a uniform strain hypothesis is more appropriate than assuming a uniform stress.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10985/65582012-01-01T00:00:00ZGILORMINI, PierreDIANI, JulieA model has been proposed recently, which describes the experimentally observed mechanical behavior of some shape memory polymers. It considers a purely thermoelastic behavior, without strain rate effects, and assumes essentially that the polymer can be considered as a two-phase composite, with glassy and rubbery phases having volume fractions that depend on temperature only. Since a uniform stress hypothesis was used in the original formulation, with an inconsistency when thermal expansion was considered, this model is revisited here by taking advantage of the many results that have been established in the theory of composite materials. It is shown, especially, that a uniform strain hypothesis is more appropriate than assuming a uniform stress.Experimental study and numerical simulation of the vertical bounce of a polymer ball over a wide temperature range
http://hdl.handle.net/10985/7694
Experimental study and numerical simulation of the vertical bounce of a polymer ball over a wide temperature range
DIANI, Julie; GILORMINI, Pierre; AGBOBADA, Gerry
The dependence to temperature of the rebound of a solid polymer ball on a rigid slab is investigated. An acrylate polymer ball is brought to a wide range of temperatures, covering its glass to rubbery transition, and let fall on a granite slab while the coe cient of restitution, duration of contact, and force history are measured experimentally. The ball fabrication is controlled in the lab, allowing the mechanical characterization of the material by classic dynamic mechanical analysis (DMA). Finite element simulations of the rebound at various temperatures are run, consider- ing the material as viscoelatic and as satisfying a WLF equation for its time-temperature superposition property. A comparison between the experiments and the simulations shows the strong link between viscoelasticity and time-temperature superposition properties of the material and the bounce characteristics of the ball.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/76942014-01-01T00:00:00ZDIANI, JulieGILORMINI, PierreAGBOBADA, GerryThe dependence to temperature of the rebound of a solid polymer ball on a rigid slab is investigated. An acrylate polymer ball is brought to a wide range of temperatures, covering its glass to rubbery transition, and let fall on a granite slab while the coe cient of restitution, duration of contact, and force history are measured experimentally. The ball fabrication is controlled in the lab, allowing the mechanical characterization of the material by classic dynamic mechanical analysis (DMA). Finite element simulations of the rebound at various temperatures are run, consider- ing the material as viscoelatic and as satisfying a WLF equation for its time-temperature superposition property. A comparison between the experiments and the simulations shows the strong link between viscoelasticity and time-temperature superposition properties of the material and the bounce characteristics of the ball.Molecular mobility with respect to accessible volume in Monte Carlo lattice model for polymers
http://hdl.handle.net/10985/11439
Molecular mobility with respect to accessible volume in Monte Carlo lattice model for polymers
DIANI, Julie; GILORMINI, Pierre
A three-dimensional cubic Monte Carlo lattice model is considered to test the impact of volume on the molecularmobility of amorphous polymers. Assuming classic polymer chain dynamics, the concept of locked volume limiting the accessible volume around the polymer chains is introduced. The polymer mobility is assessed by its ability to explore the entire lattice thanks to reptation motions. When recording the polymer mobility with respect to the lattice accessible volume, a sharp mobility transition is observed as witnessed during glass transition. The model ability to reproduce known actual trends in terms of glass transition with respect to material parameters, is also tested.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/114392017-01-01T00:00:00ZDIANI, JulieGILORMINI, PierreA three-dimensional cubic Monte Carlo lattice model is considered to test the impact of volume on the molecularmobility of amorphous polymers. Assuming classic polymer chain dynamics, the concept of locked volume limiting the accessible volume around the polymer chains is introduced. The polymer mobility is assessed by its ability to explore the entire lattice thanks to reptation motions. When recording the polymer mobility with respect to the lattice accessible volume, a sharp mobility transition is observed as witnessed during glass transition. The model ability to reproduce known actual trends in terms of glass transition with respect to material parameters, is also tested.On necessary precautions when measuring solid polymer linear viscoelasticity with dynamic analysis in torsion
http://hdl.handle.net/10985/12466
On necessary precautions when measuring solid polymer linear viscoelasticity with dynamic analysis in torsion
DIANI, Julie; GILORMINI, Pierre
Solid polymer linear viscoelasticity in shear is often characterized by applying torsion and using the Saint-Venant solution when rectangular prismatic specimens are considered. It is shown that experimental dynamic torsion tests can show a dependency of the storage modulus and damping factor on the dimensions of the rectangular prismatic specimen when linear temperature ramps are applied. While the discrepancy of damping factor is explained by temperature heterogeneities and can be corrected easily by applying temperature steps, the inconsistency of storage modulus is due to an invalid application of the Saint-Venant solution. Finite element simulations allowed definition of the sample dimensions for which the Saint-Venant solution provides a good approximation, and a coefficient is given to correct the results obtained with commercial rheometers when other sample dimensions are used.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/124662017-01-01T00:00:00ZDIANI, JulieGILORMINI, PierreSolid polymer linear viscoelasticity in shear is often characterized by applying torsion and using the Saint-Venant solution when rectangular prismatic specimens are considered. It is shown that experimental dynamic torsion tests can show a dependency of the storage modulus and damping factor on the dimensions of the rectangular prismatic specimen when linear temperature ramps are applied. While the discrepancy of damping factor is explained by temperature heterogeneities and can be corrected easily by applying temperature steps, the inconsistency of storage modulus is due to an invalid application of the Saint-Venant solution. Finite element simulations allowed definition of the sample dimensions for which the Saint-Venant solution provides a good approximation, and a coefficient is given to correct the results obtained with commercial rheometers when other sample dimensions are used.Volume changes in a filled elastomer studied via digital image correlation
http://hdl.handle.net/10985/6521
Volume changes in a filled elastomer studied via digital image correlation
DE CREVOISIER, Jordan; BESNARD, Gilles; MERCKEL, Yannick; ZHANG, Huan; CAILLARD, Julien; VION-LOISEL, Fabien; BERGHEZAN, Daniel; CRETON, Costantino; DIANI, Julie; BRIEU, Mathias; HILD, François; ROUX, Stéphane
Volumetric strains in a filled SBR specimen subjected to cyclic uniaxial tension with increasing extensions are studied. Digital image correlation is used to follow the kinematics of two orthogonal free faces. A volume expansion is observed past a critical elongation, which can be interpreted as the onset of cavitation. Under unloading, the volume returns to its original value and remains constant upon reloading. Increasing the elongation to higher values than the previous cycle leads again to a volumetric expansion.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10985/65212012-01-01T00:00:00ZDE CREVOISIER, JordanBESNARD, GillesMERCKEL, YannickZHANG, HuanCAILLARD, JulienVION-LOISEL, FabienBERGHEZAN, DanielCRETON, CostantinoDIANI, JulieBRIEU, MathiasHILD, FrançoisROUX, StéphaneVolumetric strains in a filled SBR specimen subjected to cyclic uniaxial tension with increasing extensions are studied. Digital image correlation is used to follow the kinematics of two orthogonal free faces. A volume expansion is observed past a critical elongation, which can be interpreted as the onset of cavitation. Under unloading, the volume returns to its original value and remains constant upon reloading. Increasing the elongation to higher values than the previous cycle leads again to a volumetric expansion.A numerical study of the influence of polydispersity on the behaviour until break of a reinforced hyperelastic material with a cohesive interface
http://hdl.handle.net/10985/9629
A numerical study of the influence of polydispersity on the behaviour until break of a reinforced hyperelastic material with a cohesive interface
TOULEMONDE, Paul-Aymé; DIANI, Julie; GILORMINI, Pierre; DESGARDIN, Nancy
Solid propellants manufacturers commonly monitor the granulometries of the explosive fllers they introduce in the material to pack high fller volume fraction and thus obtain satisfactory energetic performance. However, to our knowledge, the effect of a mix of small and large particles in the micrometric size range in flled elastomers has not yet been fully understood. This work aims at producing a better understanding of the underlying mechanisms that take place in a bidisperse flled elastomer composite under uniaxial loading by using finite element simulations. An original process for creating bidisperse microstructures is proposed and analyzed. The key role of the fller/matrix interface is emphasized through the use of a cohesive zone model. Plane- strain simulations in uniaxial tension of such cells with different fractions of large and small particles are performed.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/96292015-01-01T00:00:00ZTOULEMONDE, Paul-AyméDIANI, JulieGILORMINI, PierreDESGARDIN, NancySolid propellants manufacturers commonly monitor the granulometries of the explosive fllers they introduce in the material to pack high fller volume fraction and thus obtain satisfactory energetic performance. However, to our knowledge, the effect of a mix of small and large particles in the micrometric size range in flled elastomers has not yet been fully understood. This work aims at producing a better understanding of the underlying mechanisms that take place in a bidisperse flled elastomer composite under uniaxial loading by using finite element simulations. An original process for creating bidisperse microstructures is proposed and analyzed. The key role of the fller/matrix interface is emphasized through the use of a cohesive zone model. Plane- strain simulations in uniaxial tension of such cells with different fractions of large and small particles are performed.Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network
http://hdl.handle.net/10985/9223
Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network
DIANI, Julie; GILORMINI, Pierre; ARRIETA, Juan Sebastian
The time-temperature superposition property of an amorphous polymer acrylate network is characterized at infinitesimal strain by standard dynamic mechanical analysis tests. Comparison of the shift factors determined in uniaxial tension and in torsion shows that both tests provide equivalent time-temperature superposition properties. More interestingly, finite strain uniaxial tension tests run until break at constant strain rate show that the acrylate network exhibits the same time-temperature superposition property at finite strain as at infinitesimal strain. Such original experimental evidence provides new insight for finite strain constitutive modelling of polymer amorphous networks.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/92232015-01-01T00:00:00ZDIANI, JulieGILORMINI, PierreARRIETA, Juan SebastianThe time-temperature superposition property of an amorphous polymer acrylate network is characterized at infinitesimal strain by standard dynamic mechanical analysis tests. Comparison of the shift factors determined in uniaxial tension and in torsion shows that both tests provide equivalent time-temperature superposition properties. More interestingly, finite strain uniaxial tension tests run until break at constant strain rate show that the acrylate network exhibits the same time-temperature superposition property at finite strain as at infinitesimal strain. Such original experimental evidence provides new insight for finite strain constitutive modelling of polymer amorphous networks.Some features of the PPR cohesive-zone model combined with a linear unloading/reloading relationship
http://hdl.handle.net/10985/11537
Some features of the PPR cohesive-zone model combined with a linear unloading/reloading relationship
GILORMINI, Pierre; DIANI, Julie
A loading/unloading/reloading process is applied to a cohesive zone where the model proposed by Park, Paulino and Roesler in 2009 is combined with a linear unloading/reloading relationship. The applied loading and unloading use the same mixed mode and reloading is in mode I. When the amplitude of preloading is varied, several features are evidenced: jumps of the dissipated energy, reversibility maintained after a traction peak, nonlinear traction variations during unloading, increasing traction during unloading, finite traction after a fracture criterion has been fulfilled, different traction values at the beginning of unloading and when dissipative reloading begins. Moreover, the results depend strongly on the path followed during unloading. Simple modifications of the model allow none of these questionable features to appear.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/115372017-01-01T00:00:00ZGILORMINI, PierreDIANI, JulieA loading/unloading/reloading process is applied to a cohesive zone where the model proposed by Park, Paulino and Roesler in 2009 is combined with a linear unloading/reloading relationship. The applied loading and unloading use the same mixed mode and reloading is in mode I. When the amplitude of preloading is varied, several features are evidenced: jumps of the dissipated energy, reversibility maintained after a traction peak, nonlinear traction variations during unloading, increasing traction during unloading, finite traction after a fracture criterion has been fulfilled, different traction values at the beginning of unloading and when dissipative reloading begins. Moreover, the results depend strongly on the path followed during unloading. Simple modifications of the model allow none of these questionable features to appear.Experimental and modelling studies of the shape memory properties of amorphous polymer network composites
http://hdl.handle.net/10985/8458
Experimental and modelling studies of the shape memory properties of amorphous polymer network composites
ARRIETA, Juan Sebastian; DIANI, Julie; GILORMINI, Pierre
Shape memory polymer composites (SMPCs) have become an important leverage to improve the development of shape memory polymers (SMPs) applications. An amorphous SMP matrix has been filled with different types of reinforcements in this study. An experimental set of results is presented and then compared to 3D finite element simulations. Thermomechanical shape memory cycles were performed in uniaxial tension. The fillers effect was studied in stress-free and constrained-strain recoveries. Experimental observations indicate complete shape recovery and put in evidence the increased sensitivity of constrained length stress recoveries to the heating ramp on the tested composites. The simulations reproduced a simplified periodic reinforced composite and use a model for the matrix material that has been previously tested on regular SMPs. The latter combines viscoelasticity at finite strain and time-temperature superposition. The simulations permit to represent the recovery properties of a reinforced SMP easily.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/84582014-01-01T00:00:00ZARRIETA, Juan SebastianDIANI, JulieGILORMINI, PierreShape memory polymer composites (SMPCs) have become an important leverage to improve the development of shape memory polymers (SMPs) applications. An amorphous SMP matrix has been filled with different types of reinforcements in this study. An experimental set of results is presented and then compared to 3D finite element simulations. Thermomechanical shape memory cycles were performed in uniaxial tension. The fillers effect was studied in stress-free and constrained-strain recoveries. Experimental observations indicate complete shape recovery and put in evidence the increased sensitivity of constrained length stress recoveries to the heating ramp on the tested composites. The simulations reproduced a simplified periodic reinforced composite and use a model for the matrix material that has been previously tested on regular SMPs. The latter combines viscoelasticity at finite strain and time-temperature superposition. The simulations permit to represent the recovery properties of a reinforced SMP easily.