tripurari M.Tech ITGGU

1. Z-Pinning
Presented by
Tripurari
Roll no.-(16701313)
Under the supervision of
Dr. Rajesh Kumar Bhushan
M.TECH. 3rd SEMESTER SEMINAR
Session 2017-18
Department of Mechanical Engineering
School of Engineering and Technology
Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh, India
(A Central University)

2. Contents
Introduction of Z-pinning
Process of Z-pinning
Materials of Z-pin
Effect on Mechanical properties of composite structure
Advantages of Z-pinning
Disadvantages of Z-pinning
Applications
References

3. Introduction
• Z-pinning is a technique to insert reinforcing fibers (also called Z-pins
or Z-fibers) along the Z-Direction of continuous fiber reinforced
plastic.
• Z-pins can be made of metal or pre-cured unidirectional composite
fibers.
• It is designed for use within pre-preg technology, there is extensive
experimental evidence that Z-pinning dramatically improves the
resistance of the composite structure to delamination.

6. Process of Z-Pinning
• The Z-Fibers, hereafter referred to as Z-pins, are inserted orthogonally
to the plane of the composite plies during the manufacturing process,
before the resin matrix is cured, effectively pinning the individual
layers together.
• Several ways of inserting Z-pins have been developed to date. One
method involves the use of an ultrasonic hammer that forces the Z-
pins through the uncured preform while inducing high frequency
vibrations to them.
• The vibrating chamfered tip of the Z-pins locally heats up and softens
the resin allowing the Z-fiber to penetrate the preform with minimal
disruption of the long fibers.

7. Figure: z-fiber perform

11. Figure: Fully automated Z-Fiber insertion robot

12. Materials of Z-pins
• polyacrylonitrile (PAN)- or pitch-based carbon fiber
• HiNicalon
• Quartz
• glass
• Nextel fibers
• These are the most common types, but other, more exotic, materials
have been handled.

13. Effect on Mechanical properties of composite
structure
Sl
N
o
Mechanical Test
Unpinned
Strength
in MPa
Z-pinned
Strength
in MPa
%
Reduction/
Increase in
strength
1
Longitudinal Tensile strength
(0°)
1853.2 1277.3 -31.1%
2
Longitudinal Compression
strength (0°)
858.1 586.5 -31.7%
3
Un-notched Tensile strength
of QI Laminate
661.4 403.1 -39.1%
4
Un-notched Compression
strength of QI Laminate
458.6 353.8 -22.9%
5
Notched Tensile strength of
QI Laminate
370.7 340.0 -8.3%
6
Notched Compression
strength of QI Laminate
280.8 359.2 27.9%

14. Advantages
• Increases delamination resistance.
• Increases post-impact toughness.
• Increases joint strength of composites.
• load bearing capability was significantly increased due to slow
progressive delamination growth.
• Improvement in total fatigue life due to Z-pins as crack propagation
was arrested by Z-pins.
• Stitching, weaving and tufting are generally applicable only to dry
fabric preforms whereas Z-pinning technique is amenable for
application on an uncured prepreg laminate.

15. Disadvantages
• A general trend of reduction in strength for in-plane properties was
noticed due to Z-pinning which was attributed to fiber kink, local
damage to fibers at Z-pin area and resin rich areas.
• Decreases stiffness of composite structure.

17. Applications
• Aerospace: Replace multiple metal fasteners used on composite duct
and aircraft fuselage structure.
• Military aircraft
• Marine Engineering
• Automotives
• Civil Construction

18. References
1. Manjunath D.M., Development of Z-Pinning Technique for
Laminated Composites, CSIR-National Aerospace Laboratories,
Bangalore 560017, 2016
2. http:www.aztex-z-fiber.com
3. http:www.wikkipediaz-pinning
4. Paul Chang, The mechanical properties and failure mechanisms of
Z-pinned composites, Ph D Thesis, School of aerospace RMIT
University, 2006
5. Tze Min Koh, Improving the Mechanical properties of Aerospace
carbon fiber-epoxy Joints by Z-pinning, PhD Thesis, School of
Aerospace, Mechanical and Manufacturing Engineering, RMIT
University, 2012