fracture in composite materials

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‫ءاتونى زبر الحديدحتى إذا ساوى بين‬ ‫الصدفين قال انفخوا حتى إذا جعله نارا‬ ‫فما‬ ‫عليه قطرا‬ ‫أفرغ‬ ‫ءاتونى‬ ‫قال‬ ‫*‬ ‫اسطاعوا أن يظهروه وما استطاعوا له‬ ‫نقبا‬ ‫صدق ا العظيم‬

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‫سورة الكهف ‪ ،‬الية ‪96‬و‪97‬‬

‫‪02/04/13‬‬

‫‪Hossam Sallam‬‬

Fatigue and Fracture Behavior of Composites by .Hossam Sallam, Ph.D ,Materials Engineering Department Zagazig University Hossam Sallam

02/04/13

Objective The goal of this review article is to present a sound background regarding the development of the understanding of the fracture processes and fatigue damage in composite materials and show how they act as a foundation for current models. This presentation shows the importance of matrix, reinforcement, and reinforcement/matrix interface in fatigue and fracture behavior of composite materials.

Composites exhibit an unusual combination of brittle .and ductile phenomena Hossam Sallam

02/04/13

out line Introduction Continuous Fiber-Reinforced Composites Short Fiber-Reinforced Composites Particulate-Reinforced Composites Summary

Hossam Sallam

02/04/13

COMPOSITE MATERIALS C L A S S IF IC A T IO N OF C O M P O S IT E M A T E R IA L S w rt R E IN F O R C E M E N T F O R M S F IB E R

PO LY M ER S M ETA LS

D IS C O N T IN U O U S

C E R A M IC S

C O N T IN U O U S

P A R T IC L E L A M IN A T E

Hossam Sallam

w rt T Y P E O F M A T R IX

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Introduction to Fracture Mechanics (Linear Elastic Fracture Mechanics (LEFM SIF, K* plain strain fracture Toughness, KIc*

(Elastic-Plastic Fracture Mechanics (EPFM J-integral* (Crack Tip Opening Displacement (CTOD*

Crack tip Deformation* Hossam Sallam

02/04/13

Introduction to Fatigue of Materials Wohler’s S-N Curve, 1871 S

N

Hossam Sallam

ris a P

w La

∆Kth

,

63 9 1

Kc

da/dN

da/dN

da/dN-∆ K curve

∆K 02/04/13

Elber,1970

∆Keff

out line Introduction Continuous Fiber-Reinforced Composites Short Fiber-Reinforced Composites Particulate-Reinforced Composites Summary

Hossam Sallam

02/04/13

Continuous Fiber-Reinforced Composites Fiber Bridging Shear lag Models

•

Fiber Bridging

Crack Front Debonding

Fiber Pull-out

Fiber Pressure model • Matrix Crack Wake Debonding/Sliding

Hossam Sallam

The various mechanisms that accompany mode I matrix crack propagation in unidirectional composites 02/04/13

out line Introduction Continuous Fiber-Reinforced Composites Short Fiber-Reinforced Composites Particulate-Reinforced Composites Summary

Hossam Sallam

02/04/13

1

Short Fiber-Reinforced Composites Fiber Reinforced Concrete

Microcrack

Stress

Microfiber

P

PC Large Fiber

P

Crack

Strain

Illustration of different sizes fibers on crack Hossam Sallam 02/04/13 bridging

1

out line Introduction Continuous Fiber-Reinforced Composites Short Fiber-Reinforced Composites Particulate-Reinforced Composites Summary

Hossam Sallam

02/04/13

1

Particulate-Reinforced Composites Ductile Particle in Brittle Matrix (a )

(b)

•

( c)

The stages of crack propagation Hossam Sallam

02/04/13

1

Brittle Particle in Ductile Matrix

a)

High strength matrix)

& Coarse particles

&b) Strong interface) High modulus of particles

c) Weak interface)

Possible particle-crack tip interactions in fatigue crack growth Hossam Sallam

02/04/13

1

out line Introduction Continuous Fiber-Reinforced Composites Short Fiber-Reinforced Composites Particulate-Reinforced Composites Summary

Hossam Sallam

02/04/13

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Summary

Crack-Tip Shielding Mechanisms b) Zone Shielding)

a) Crack Deflection)

microcrack toughening-

c) Contact Shielding) Wedging •

Bridging •

corrosion-induced crack closureroughness-induced crack closure-

d) Combined Zone and Contact Shielding) plasticity-induced crack closure-

Hossam Sallam

02/04/13

1

‫الحمد لله رب‬ ‫العالمين‬ ‫وشكر َا‬

‫‪1‬‬

‫‪02/04/13‬‬

‫‪Hossam Sallam‬‬