Finite Element Analysis of Linear Thermal Expansion Coefficients of Unidirectional Cracked Composites

2001 ◽  
Vol 35 (19) ◽  
pp. 1762-1776 ◽  
Author(s):  
R. Islam ◽  
S. G. Sjölind ◽  
A. Pramila
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

scholarly journals Organizing Cells Within Non-Periodic Microarchitectured Materials That Achieve Graded Thermal Expansions

2015 ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Lucas A. Shaw ◽  
Todd H. Weisgraber ◽  
George R. Farquar ◽  
Christopher D. Harvey ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Large Lattice ◽  
Unit Cells ◽  
Expansion Coefficients ◽  
Bulk Behavior

The aim of this paper is to introduce an approach for optimally organizing a variety of different unit cell designs within a large lattice such that the bulk behavior of the lattice exhibits a desired Young’s modulus with a graded change in thermal expansion over its geometry. This lattice, called a graded microarchitectured material, can be sandwiched between two other materials with different thermal expansion coefficients to accommodate their different expansions or contractions caused by changing temperature while achieving a desired uniform stiffness. First, this paper provides the theory necessary to calculate the thermal expansion and Young’s modulus of large multi-material lattices that consist of periodic (i.e., repeating) unit cells of the same design. Then it introduces the theory for calculating the graded thermal expansions of a large multimaterial lattice that consists of non-periodic unit cells of different designs. An approach is then provided for optimally designing and organizing different unit cells within a lattice such that both of its ends achieve the same thermal expansion as the two materials between which the lattice is sandwiched. A MATLAB tool is used to generate images of the undeformed and deformed lattices to verify their behavior and various examples are provided as case studies. The theory provided is also verified and validated using finite element analysis and experimentation.

Linear Thermomechanical Microactuators

1999 ◽  
Author(s):  
Rebecca Cragun ◽  
Larry L. Howell
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Cross Sections ◽  
Variable Cross ◽  
Element Analysis ◽  
Thermal Actuators ◽  
Output Force ◽  
Analysis Models ◽  
High Output

Abstract Thermomechanical in-plane microactuators (TIMs) have been designed, modeled, fabricated, and tested. TIMs offer an alternative to arrays of smaller thermal actuators to obtain high output forces. The design is easily modified to obtain the desired output force or deflection for specific applications. The operational principle is based on the symmetrical thermal expansion of variable cross sections of the surface micromachined microdevice. Sixteen configurations of TIMs were fabricated of polysilicon. Finite element analysis models were used to predict the deflection and output force for the actuators. Experimental results were also recorded for all sixteen configurations, including deflections and output forces up to 20 micron and 35 dyne.

scholarly journals Temperature-dependent structural behaviour of samarium cobalt oxide

2017 ◽  
Vol 32 (S2) ◽  
pp. S38-S42
Author(s):  
Matthew R. Rowles ◽  
Cheng-Cheng Wang ◽  
Kongfa Chen ◽  
Na Li ◽  
Shuai He ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Cobalt Oxide ◽  
Sol Gel ◽  
Linear Thermal Expansion ◽  
Rietveld Analysis ◽  
Structural Behaviour ◽  
Temperature Dependent ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Sol Gel Synthesis

The crystal structure and thermal expansion of the perovskite samarium cobalt oxide (SmCoO3) have been determined over the temperature range 295–1245 K by Rietveld analysis of X-ray powder diffraction data. Polycrystalline samples were prepared by a sol–gel synthesis route followed by high-temperature calcination in air. SmCoO3 is orthorhombic (Pnma) at all temperatures and is isostructural with GdFeO3. The structure was refined as a distortion mode of a parent $ Pm{\bar 3}m $ structure. The thermal expansion was found to be non-linear and anisotropic, with maximum average linear thermal expansion coefficients of 34.0(3) × 10−6, 24.05(17) × 10−6, and 24.10(18) × 10−6 K−1 along the a-, b-, and c-axes, respectively, between 814 and 875 K.

Measurement of thermal expansion coefficient of substrate GGG and its epitaxial layer YIG

1999 ◽  
Vol 14 (1) ◽  
pp. 2-4 ◽  
Author(s):  
Rui-sheng Liang ◽  
Feng-chao Liu
Keyword(s):  
Thin Film ◽  
Thermal Expansion ◽  
Single Crystal ◽  
Thermal Expansion Coefficient ◽  
Epitaxial Layer ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
New Method ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

A new method is used in measuring the linear thermal expansion coefficients in composite consisting of a substrate Gd3Ga2Ga3O12 (GGG) and its epitaxial layer Y3Fe2Fe3O12 (YIG) within the temperature range 13.88 °C–32.50 °C. The results show that the thermal expansion coefficient of GGG in composite is larger than that of the GGG in single crystal; the thermal expansion coefficient of thick film YIG is also larger than that of thin film. The results also show that the thermal expansion coefficient of a composite consisting of film and its substrate can be measured by using a new method.

Thermal compensation using the hybrid metrology approach compared to traditional scaling

2017 ◽  
Vol 232 (13) ◽  
pp. 2364-2374
Author(s):  
David Ross-Pinnock ◽  
Glen Mullineux
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Temperature Measurement ◽  
Large Scale ◽  
Element Analysis ◽  
Linear Temperature ◽  
Temperature Distributions ◽  
Finite Element Analysis Simulation ◽  
Uniform Scaling

Control of temperature in large-scale manufacturing environments is not always practical or economical, introducing thermal effects including variation in ambient refractive index and thermal expansion. Thermal expansion is one of the largest contributors to measurement uncertainty; however, temperature distributions are not widely measured. Uncertainties can also be introduced in scaling to standard temperature. For more complex temperature distributions with non-linear temperature gradients, uniform scaling is unrealistic. Deformations have been measured photogrammetrically in two thermally challenging scenarios with localised heating. Extended temperature measurement has been tested with finite element analysis to assess a compensation methodology for coordinate measurement. This has been compared to commonly used uniform scaling and has outperformed this with a highly simplified finite element analysis simulation in scaling a number of coordinates at once. This work highlighted the need for focus on reproducible temperature measurement for dimensional measurement in non-standard environments.

Development of an Engineering Model for Predicting the Transverse Coefficients of Thermal Expansion of Unidirectional Fiber Reinforced Composites

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Chensong Dong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Engineering Model ◽  
Element Analysis ◽  
Unidirectional Composites ◽  
Representative Unit Cell

The coefficients of thermal expansion (CTEs) of fiber reinforced composites play an important role in the design and analysis of composite structures. Since the thermal expansion coefficients of polymer matrix materials are typically much higher than those of fibers, and the fiber often exhibits anisotropic thermal and mechanical properties, the stress induced in the composite due to temperature change is very complex. Large discrepancies exist among the analytical models for the transverse CTE of unidirectional composites. Hence, it is problematic when choosing a suitable model. With the development of computer technologies, finite element analysis (FEA) proved its effectiveness in calculating the effective CTE of composites. In this study, the transverse CTEs of unidirectional carbon fiber composites were calculated by finite element analysis using a representative unit cell. The analytical micromechanical models from literature were compared against the FEA data. It shows that Hashin’s concentric cylinder model is the best. However, it is inconvenient for practical applications due to the amount of computation. In this study, based on the FEA data, an engineering model for predicting the transverse CTE of unidirectional composites was developed by regression analysis. This model was validated against the FEA and experimental data. It shows that the developed model provides a simple and accurate approach to calculate the transverse CTE of unidirectional composites.

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