Modeling the Behavior of Crystallizable Shape Memory Polymers Subject to Inhomogeneous Deformations

2010 ◽  
Author(s):  
Mahesh Khanolkar ◽  
Jaskirat Sodhi ◽  
I. Joga Rao
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Research Work ◽  
Shape Memory Polymers ◽  
Inhomogeneous Deformation ◽  
The Past ◽  
Constant Shear ◽  
Multiple Natural Configurations ◽  
Constant Moment

The constitutive model for the mechanics of crystallizable shape memory polymers (CSMP) has been developed in the past [1, 2]. The model was developed using the theory of multiple natural configurations and has been successful in addressing a diverse class of problems. In this research work, the efficacy of the developed CSMP model is tested by applying it to the torsion of a cylinder, which is an inhomogeneous deformation. The crystallization of the cylinder is studied under two different conditions i.e. crystallization under constant shear and crystallization under constant moment.

Inhomogeneous Deformation Examples and Applications of Light Activated Shape Memory Polymers

2012 ◽  
Author(s):  
Jaskirat S. Sodhi ◽  
Swapnil Moon ◽  
I. Joga Rao
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Boundary Value Problems ◽  
Boundary Value ◽  
Aerospace Industry ◽  
Shape Memory Polymers ◽  
Inhomogeneous Deformation ◽  
The Past ◽  
Innovative Materials ◽  
Biomedical Industry

Light Activated Shape Memory Polymers (LASMP) are recently developed innovative materials defined by their capacity to store a deformed (temporary) shape and recover an original (parent) shape. This change in shape and the return to original shape is achieved by exposing the polymer to light at different wavelengths. These unique properties have led to the use of LASMP’s in a wide variety of applications. These SMP’s have a great potential in the biomedical industry as well as the aerospace industry. In the past, the authors have introduced a constitutive model to model the mechanics of these LASMP [1] and used it to solve a few cases of boundary value problems of interest. In this paper, the developed model is used to solve some other inhomogeneous deformation boundary value problems.

Application of a Constitutive Modeling for Light Activated Shape Memory Polymer to Circular Shear

2012 ◽  
Author(s):  
Fangda Cui ◽  
I. J. Rao
Keyword(s):  
Shape Memory ◽  
Constitutive Modeling ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Polymer Chains ◽  
Covalent Bonds ◽  
The Past ◽  
Original Shape ◽  
Multiple Natural Configurations ◽  
New Type

Shape memory polymers (SMP’s) are polymers that have the ability to retain a temporary shape, which can revert back to the original shape on exposure to specific triggers such as increase in temperature or exposure to light at specific wavelengths. A new type of shape memory polymer, light activated shape memory polymers (LASMP’s) have been developed in the past few years. In these polymers the temporary shapes are fixed by exposure to light at a specific wavelength. Exposure to light at this wavelength causes the photosensitive molecules, which are grafted on to the polymer chains, to form covalent bonds. These covalent bonds are responsible for the temporary shape and act as crosslinks. On exposure to light at a different wavelength these bonds are cleaved and the material can revert back to its original shape. A constitutive model of LASMP’s which based on the notion of multiple natural configurations has been developed (see Sodhi and Rao[1]). In this work we use this model to analyze the mechanical behavior of LASMP’s under a specific boundary value problem, namely, the problem of circular shear. We use this model problem to study the behavior of the LASMP’s when a temporary configuration is formed by exposing the polymer to light. In addition we show that these materials are able to undergo complex cycles of deformation due to the flexibility with which these temporary configurations can be formed and removed by exposure to light.

Light Activated Shape Memory Polymers: Some Inhomogeneous Deformation Examples

2011 ◽  
Author(s):  
Jaskirat S. Sodhi ◽  
I. Joga Rao
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Uv Light ◽  
Large Family ◽  
Shape Memory Polymers ◽  
Space Structures ◽  
Inhomogeneous Deformation ◽  
Mems Devices ◽  
Multiple Natural Configurations ◽  
Specific Frequency

Shape memory polymers (SMP’s) belong to a large family of shape memory materials, which are defined by their capacity to store a deformed (temporary) shape and recover an original (parent) shape. SMP’s have the ability to change size and shape when activated through a suitable trigger. This trigger, which can be heating the polymer or exposing it to light of a specific frequency, is responsible for the new temporary shape. Return to the original shape can be achieved by a suitable reverse trigger. Light Activated Shape Memory Polymers (LASMP) are recently developed smart materials which are synthesized with special photosensitive molecules. These molecules when exposed to Ultraviolet (UV) light at specific wavelengths, form covalent crosslinks that are responsible for providing LASMP with their temporary shape. Light activation removes temperature constraints faced by thermoresponsive SMP for medical applications and also brings the added advantage of remote activation. Thus LASMP find use in a variety of applications ranging from MEMS devices to widespread usage for biomedical devices such as intravenous needles and stents. Furthermore, the aerospace industry has found use for these materials for applications ranging from easily deployable space structures to morphing wing aircraft. The authors have introduced a constitutive model to model the mechanics of these LASMP [1]. The modeling is done using a framework based on the theory of multiple natural configurations. A few homogenous and inhomogeneous examples were solved in [1], but with tacit understanding that the intensity of light and hence the extent of reaction is homogenous throughout the polymer sample. In this paper we use the developed model to solve the cases of inhomogeneous deformation with inhomogeneous exposure to light.

Modeling the Circular Shear in Light Activated Shape Memory Polymers With Three Networks

2013 ◽  
Author(s):  
Fangda Cui ◽  
I. J. Rao
Keyword(s):  
Shape Memory ◽  
Deformation Process ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Polymer Chains ◽  
Covalent Bonds ◽  
The Past ◽  
Original Shape ◽  
Multiple Natural Configurations ◽  
New Type

Shape memory polymers (SMP’s) are polymers that have the ability to retain a temporary shape, which can revert back to the original shape on exposure to specific triggers such as increase in temperature or exposure to light at specific wavelengths. A new type of shape memory polymer, light activated shape memory polymers (LASMP’s) have been developed in the past few years. In these polymers the temporary shapes are fixed by exposure to light at a specific wavelength. Exposure to light at this wavelength causes the photosensitive molecules, which are grafted on to the polymer chains, to form covalent bonds. These covalent bonds are responsible for the temporary shape and act as crosslinks. On exposure to light at a different wavelength these bonds are cleaved and the material can revert back to its original shape. A constitutive model of LASMP’s which based on the notion of multiple natural configurations has been developed (see Sodhi and Rao [1]). It has been applied to model the circular shear of light activated shape memory polymer with two networks. In this work we use this model to analyze the mechanical behavior of LASMP’s with three different networks undergoing a circular shear deformation cycle. This involves study of the behavior of the LASMP’s when two temporary configurations are formed by exposing the polymer to light at different time during the deformation process. In addition, we show that these materials are able to undergo complex cycles of deformation due to the flexibility with which these temporary configurations can be formed and removed by exposure to light.

Three-dimensional constitutive model for shape-memory polymers considering temperature-rate dependent behavior

2021 ◽  
Vol 30 (3) ◽  
pp. 035030
Author(s):  
Jinsu Kim ◽  
Seung-Yeol Jeon ◽  
Seokbin Hong ◽  
Yongsan An ◽  
Haedong Park ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Temperature Rate

A large deformation framework for shape memory polymers: Constitutive modeling and finite element implementation

2012 ◽  
Vol 24 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Mostafa Baghani ◽  
Reza Naghdabadi ◽  
Jamal Arghavani
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Shape Memory ◽  
Finite Deformation ◽  
Deformation Gradient ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Shape Memory Polymers ◽  
Small Strain ◽  
Internal Variables

Shape memory polymers commonly experience both finite deformations and arbitrary thermomechanical loading conditions in engineering applications. This motivates the development of three-dimensional constitutive models within the finite deformation regime. In the present study, based on the principles of continuum thermodynamics with internal variables, a three-dimensional finite deformation phenomenological constitutive model is proposed taking its basis from the recent model in the small strain regime proposed by Baghani et al. (2012). In the constitutive model derivation, a multiplicative decomposition of the deformation gradient into elastic and inelastic stored parts (in each phase) is adopted. Moreover, employing the mixture rule, the Green–Lagrange strain tensor is related to the rubbery and glassy parts. In the constitutive model, the evolution laws for internal variables are derived during both cooling and heating thermomechanical loadings. Furthermore, we present the time-discrete form of the proposed constitutive model in the implicit form. Using the finite element method, we solve several boundary value problems, that is, tension and compression of bars and a three-dimensional beam made of shape memory polymers, and investigate the model capabilities as well as its numerical counterpart. The model is validated by comparing the predicted results with experimental data reported in the literature that shows a good agreement.

Constitutive model for photo-mechanical behaviors of photo-induced shape memory polymers

2009 ◽  
Author(s):  
Kevin N. Long ◽  
Timothy F. Scott ◽  
H. Jerry Qi ◽  
Martin L. Dunn ◽  
Christopher N. Bowman
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Shape Memory Polymers ◽  
Mechanical Behaviors
Sign in / Sign up

Export Citation Format

Share Document