close

Вход

Забыли?

вход по аккаунту

код для вставкиСкачать
Simulation of Twisted Fiber Laminates
Dept of Mechanical & Industrial Engineering, TAMUK
Graduate Student: Madhuri Lingala
Faculty Mentor: Dr. Larry D Peel, P.E.
Abstract
The current work explores extreme Poisson’s ratio twisted fiber
laminates. Fiber reinforced elastomer (FRE) composites show promise
for use in tires, morphing wings, vibration dampers, impact resistance,
solid-state actuators, inflatable aerospace structures, and various biomechanical applications. These are made possible because of their
high impact strength, vibration damping ability, large elastic
deformations, and tailorable nonlinear characteristics.
Recently, FRE laminates have been fabricated that exhibit extreme
(high and negative) Poisson’s ratios. The current research includes
developing finite element models of twisted fiber laminates, which will
be investigated using linear and non-linear finite element analysis and
verifying the simulations through fabricated specimens, if possible.
Research Objectives
•Develop linear and non-linear FEA models of twisted fiber-reinforced
elastomer laminates that:
a) Exhibit Stress Stiffening,
b) Exhibit High Poisson’s ratios, or
c) Exhibit Negative Poisson’s ratios.
•Fabricate specimens of each type, and conduct experiments.
•Verify the simulations by comparing experimental and simulated
results.
It has been observed that uni-axial fiber-reinforced elastomer
laminates, where the fibers are twisted, exhibit an effective increase in
axial stiffness, and may have high Poisson’s Ratios. Negative Poisson’s
ratios may be produced if the fibers have a double helical path.
Advantages
•High impact strength
•Vibration damping
•Tailaroble non-linear properties
•Good in plane stiffness
Drawbacks
•High viscosity
•Short cure times
•Difficulty in testing
•Non-linear properties
Previous work on Fiber Reinforced Elastomers (FRE)
Research areas of Peel on Fiber reinforced elastomers:
• Fabrication of FRE specimens
•Tensile response of FRE laminates
•Nonlinear modeling
•Comparison of predicted and experimental data
•Fabrication of morphing wing
Spiral fiberglass fibers/
RP6410 resin with matrix
Poisson’s Ratio =.5
Spiral fiberglass fibers /
RP6410 resin with matrix
Poisson’s Ratio = .35
Concerns with FEA of twisted fibers
Previous Work with Twisted Fiber-Reinforced Elastomers
Background - Fiber Reinforced Elastomers
Finite Element Analysis
•Fabrication and testing of twisted cotton / rubber specimens
•Finite element analysis of twisted cotton laminates
•Comparison of FE analysis and experimental results
•FE analysis of twisted fiber bundles and Gr/elastomer
Comparison of FEA and Twisted Cotton / Elastomer Test Results
Material @25
o
twist
Matrix PR
% E Increase
Axial stiffness (psi)
Cotton Fiber – Test
Cotton/RP6410 - Test
Cotton/Silastic S-test
dna
0.499
0.499
0.00%
127.7 %
74.5 %
47,000
107,000
82,000
Cotton Fiber - FEA
Cotton /RP6410 - FEA
Cotton/RP6410 - FEA
dna
0.499
0.350
0.00 %
138.7 %
72.1 %
10,523
25,122
18,105
Fiberglass- FEA
Fiberglass/RP6410 FEA
Fiberglass/RP6410 FEA
Fiberglass/Epoxy - FEA
Fiberglass/Epoxy – FEA
dna
0.499
0.350
0.300
0.499
0.00 %
46 %
6.1 %
198.7 %
266.7 %
1,254,956
1,831,929
1,331,287
3,748,148
4,602,469
•Fibers merge into one another
contact elements / formulation)
•Spacing of strands
•Mesh size
•High number of elements
(need
Non-Linear analysis required when:
•Contact elements needed
•Nonlinear material properties
•Large and nonlinear displacements
•Large geometry changes
•Trying to gain better understanding of physical phenomenon
Intermediate Conclusions and Planned Work
FEA results indicate that an increase in axial stiffness is
possible, but better analysis is needed.
Poisson’s ratio of twisted fiber laminates:
We will ensure that fibers do not merge into each other
(through contact formulations).
We will assess laminate
Poisson’s ratios of single and double twisted fiber laminates
using nonlinear FEA, and we plan to simulate several
applications.
We intend to fabricate twisted fiber bundle
specimens using better impregnation methods than before and
would try to overcome gripping issues that were faced to test
the specimens due to low stiffness values of the fibers. Results
from FEA will be verified through tests.
•Single twist fibers- Possible High Poisson ratio
•Double twisted fibers- Possible Negative Poisson’s ratio
Acknowledgement
•Increase in effective axial stiffness is noticed
•Increased stiffness is function of elastomer stiffness, non-linearity
I wish to express my sincere gratitude to my mentor, Dr. Larry
Peel for his valuable suggestions, guidance and encouragement
at every point. This work is based on Dr. Peel’s in-depth research
in the field of FREs.
1/--страниц
Пожаловаться на содержимое документа