Micromechanics of Longitudinal Mechanical Properties for Active Fiber Composites With Embedded Metal-Core Piezoelectric Fibers

Aerospace ◽  
2005 ◽  
Author(s):  
Mehrdad N. Ghasemi Nejhad ◽  
Davood Askari
Keyword(s):  
Mechanical Properties ◽  
Fiber Composite ◽  
Transversely Isotropic ◽  
Fiber Composites ◽  
Core Material ◽  
Metal Core ◽  
Element Analysis ◽  
Active Fiber ◽  
Active Fiber Composites ◽  
Piezoelectric Fiber

An analytical micromechanics approach is presented to model the effective longitudinal mechanical properties of Metal-Core Piezoelectric Fibers (MPF). The model assumes general orthotropic material properties for the piezoelectric as well as the core material. Next, the general orthotropic solution is reduced to transversely isotropic for the piezoelectric fiber and isotropic for the metal-core. This MPF system is also modeled using finite element analysis (FEA) and the results from the analytical solution and FEA are compared for verification purpose. Next, the Metal-Core Piezoelectric Fiber (MPF) is embedded inside a metal or a polymer and the resulting longitudinal mechanical properties of these Active Fiber Composite (AFC) systems are given analytically.

Analytical Solutions for Effective Axial Mechanical Properties of a Three-Phase Active Fiber Composite Model

2007 ◽  
Author(s):  
Davood Askari ◽  
Mehrdad N. Ghasemi Nejhad
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Analytical Solutions ◽  
Fiber Composite ◽  
Fiber Composites ◽  
Orthotropic Materials ◽  
Exact Analytical Solutions ◽  
Active Fiber ◽  
Three Phase ◽  
Active Fiber Composites

Active fiber composites are among the many other components used in intelligent and smart composite structures which undergo mechanical deformation upon the application of external loads or electric fields. This work presents an analytical approach for derivations of exact solutions for the effective axial mechanical properties of active fiber composites with circular cross-sections, and while the properties of the constituent materials are considered to be generally orthotropic. First, exact analytical solutions of the effective longitudinal Young’s modulus and Poisson’s ratio are obtained for a three-phase composite cylindrical model composed of orthotropic materials. Next, Finite element analysis, as an alternative approach, is performed to numerically determine the effective axial properties of an identical three-phase composite cylinder. Finally, effective material properties obtained from analytical and finite element methods are compared to verify the derived analytical solutions. Excellent agreements are achieved between the results obtained from both techniques validating the exact analytical solutions.

A Comparative Finite Element Analysis of Residual Stresses in Active Fiber Composites With Embedded Metal-Core Piezoelectric Fibers and Macro Fiber Composites

Aerospace ◽  
2005 ◽  
Author(s):  
Davood Askari ◽  
Hiroshi Asanuma ◽  
Mehrdad N. Ghasemi-Nejhad
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Fiber Composites ◽  
Stress And Strain ◽  
Metal Core ◽  
Element Analysis ◽  
Active Fiber ◽  
Active Fiber Composites

Residual stresses are basically developed due to intrinsic and extrinsic strains that form during the processing of composite materials. The extrinsic strains can be determined using Coefficient of Thermal Expansion (CTE), material properties, geometry of the structure, and processing conditions. Finite Element Method (FEM) as an efficient alternative technique for stress and strain analysis of the micromechanical systems and structures, has been employed to numerically investigate the residual stresses developed in Metal-Core Piezoelectric Fibers (MPF) and Active Fiber Composites (AFC) (or Macro Fiber Composites (MFC)), during the processing. Here in this work, ANSYS Finite Element Analysis (FEA) software is used to develop three different 3-dimensional models for MPF and MFC structures and then each model is solved for strain and stress results. Next, the stress and strain components of these models are studied throughout the structures to identify the magnitude and type of the stresses and strains within the constituent materials and then compared.

Mechanical Performance Analysis of Axially Loaded Active Fiber Composites

Aerospace ◽  
2006 ◽  
Author(s):  
Davood Askari ◽  
Mehrdad N. Ghasemi Nejhad
Keyword(s):  
Exact Solutions ◽  
Cross Sections ◽  
Mechanical Performance ◽  
Fiber Composites ◽  
Sensors And Actuators ◽  
Element Analysis ◽  
Active Fiber ◽  
Axially Loaded ◽  
The Individual ◽  
Active Fiber Composites

Active fiber composites (AFCs) or macro fiber composites (MFCs) are often subjected to external loads and mechanical deformations. Furthermore, demands from industry for sensors and actuators with higher quality and better performance for specific applications have lead the researchers to design piezoelectric systems with optimal configurations to enhance the performance of such actuators and sensors. Therefore, it is important to investigate the mechanical performance of the individual AFCs/MFCs that exist in different geometrical configurations with alternative constituent materials. Here in this work, analytical exact solutions for effective mechanical properties of AFCs/MFCs are derived and then used to obtain the analytical exact solutions for displacements, strains and stresses induced in axially loaded AFCs/MFCs, which is the most common loading condition, i.e., tension/compression, that exist for such structures. In our study, constituent materials are considered orthotropic and two different geometries, i.e., AFCs/MFCs with circular and rectangular cross-sections, are investigated. For the given material properties, the displacement, strain, and stress results, corresponding to an axially applied external load are obtained in the domain of each constituent for both AFC/MFC geometrical configurations. To verify the analytical exact solution, 3-dimensional finite element analysis is performed and then the results obtained from both techniques are compared where excellent agreement was achieved.

Analytical Modeling for Mechanical Responses of an Axially Loaded Three-Phase Active Fiber Composite

2007 ◽  
Author(s):  
Davood Askari ◽  
Mehrdad N. Ghasemi-Nejhad
Keyword(s):  
Structural Control ◽  
Structural Integrity ◽  
Fiber Composite ◽  
Fiber Composites ◽  
Sensors And Actuators ◽  
Element Analysis ◽  
Mechanical Responses ◽  
Active Fiber ◽  
Structural Applications ◽  
Axially Loaded

Structural integrity and stability are among the key requirements for any mechanical component used in structural applications when subjected to external or internal loads. For example, Active Fiber Composites (AFCs) or micro fiber composites (MFCs) used as sensors and actuator for vibration damping, structural control, and health monitoring in intelligent structures can be subjected to both external and internal loading. Furthermore, demands from industry for better performing sensors and actuators for the use in adaptive structures have led the researchers to investigate and design AFC/MFC systems with optimal configurations to enhance their performances. Therefore, it is essential to understand and be able to predict the mechanical behaviour of the individual AFCs/MFCs that exist in different geometrical configurations composed of various constituent materials. In this work, an analytical approach based on elasticity equations is introduced to derive exact solutions for mechanical responses (i.e., displacements, strains, and stresses) of an axially loaded threephase composite cylinder, representing an individual AFC/MFC tube. Materials of the constituents are considered to be orthotropic for no loss of generality. To validate the exact analytical solutions, finite element analysis is performed and then the results obtained from both techniques are compared where excellent agreements are achieved.

Analytical Solutions for Effective Axial Mechanical Properties of Active Fiber Composites

Aerospace ◽  
2006 ◽  
Author(s):  
Davood Askari ◽  
Mehrdad N. Ghasemi Nejhad
Keyword(s):  
Mechanical Properties ◽  
Exact Solutions ◽  
Cross Sections ◽  
Analytical Solutions ◽  
Fiber Composites ◽  
Orthotropic Materials ◽  
Young’S Moduli ◽  
Active Fiber ◽  
Active Fiber Composites ◽  
Effective Mechanical Properties

This work presents analytical solutions for the effective axial mechanical properties of the active fiber composites with different geometries, e.g., circular and rectangular cross-sections, and while the properties of the constituent materials are considered to be generally orthotropic. Analytical exact solutions of the effective longitudinal Young's moduli and major Poisson's ratios are obtained for two different geometries of a 2-phase composite model composed of orthotropic materials. Finite element analyses (FEAs) are also performed to verify the obtained analytical exact solutions. Excellent agreements are achieved between the results obtained from both techniques. Finally, the effective mechanical properties calculated from analytical solutions for the modeled geometrical configurations are compared.

Fabrication and Process Characterization of Piezoelectric Nano Fiber Composites

2006 ◽  
Author(s):  
Yong Shi ◽  
Xiangyi Zhang ◽  
Shiyou Xu ◽  
Sang-Gook Kim
Keyword(s):  
Structural Integrity ◽  
Large Diameter ◽  
Fiber Composites ◽  
Electrospinning Process ◽  
Polymer Materials ◽  
Micro Fabrication ◽  
Active Fiber ◽  
Nano Fiber ◽  
Active Fiber Composites ◽  
Piezoelectric Fiber

This paper studies the fabrication of nano piezoelectric fiber composites using an integrated nano/micro process. Previously, piezoelectric composites or Active Fiber Composites (AFCs) use large diameter piezo fibers (120 to 400 μm), which have limited their applications. Nano piezoelectric fiber composites provide much superior structural integrity and also enable the design and fabrication of nano active structures. In this paper, micro fabrication method was combined with electrospinning process to form the nano active fiber composites (Nano AFCs). Two polymer materials PDMS and Epon828 epoxy were studied as candidates for the matrix materials because of their compatibility with micro fabrication. Clamped-clamped Nano AFC beams were micro fabricated over a trench on a silicon substrate. The beams were studied with SEM and Atomic Force Microscope (AFM). More effort is needed to improve the uniformity of the nano fiber distribution and the process influence of the piezoelectric properties of the nano AFCs.

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