An incremental-onset model for fatigue delamination propagation in composite laminates

2020 ◽  
Vol 200 ◽  
pp. 108394
Author(s):  
Man Zhu ◽  
Larissa Gorbatikh ◽  
Stepan V. Lomov
Keyword(s):  
Composite Laminates ◽  
Delamination Propagation

Progressive Fracture Evaluation in Composite Materials by Acoustic Emission Technique

2011 ◽  
Vol 465 ◽  
pp. 535-538 ◽  
Author(s):  
Milad Hajikhani ◽  
Amir Refahi Oskouei ◽  
Mehdi Ahmadi Najaf Abadi ◽  
Amir Sharifi ◽  
Mohammad Heidari
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Structural Design ◽  
Composite Laminates ◽  
Damage Tolerance ◽  
Acoustic Emission Technique ◽  
Out Of Plane ◽  
Progressive Fracture ◽  
Laminar Fracture ◽  
Delamination Propagation

Glass/polyester and glass/epoxy laminated composites widely used in structures and have very near properties. These composite laminates have poor inter-laminar fracture resistance and suffer extensive damage by delamination cracking when subjected to out of plane loading and hence are vulnerable to delamination. The presence of delamination in the composite material may reduce the overall stiffness. Structural design and nondestructive test techniques have evolved as increased emphasis has been placed on the durability and damage tolerance of these materials. There are several methods used to investigate damages of composite materials. Acoustic emission is one of these. In this work the effect of delamination propagation on acoustic emission (AE) events in glass/polyester and glass/epoxy composites is obtained also Fracture surface examinations were conducted using a scanning electron microscope (SEM) and results in these two common composites compared. Consequently, revealed that the AE technique is a practicable and effective tool for identifying and separating kinds of cracks in these composites.

scholarly journals Influence of interface ply orientation on delamination growth in composite laminates

2021 ◽  
pp. 002199832110316
Author(s):  
A Raimondo ◽  
I Urcelay Oca ◽  
C Bisagni
Keyword(s):  
Fracture Toughness ◽  
Composite Laminates ◽  
Double Cantilever Beam ◽  
Numerical Approach ◽  
Field Variable ◽  
Numerical Analyses ◽  
Structural Components ◽  
Closure Technique ◽  
Ply Orientation ◽  
Delamination Propagation

The standard experimental procedures for determining the interlaminar fracture toughness are designed for delamination propagation in unidirectional specimens. However, in aerospace structural components, delamination usually occurs between plies at different orientations resulting in different damage mechanisms which can increase the value of the fracture toughness as the delamination propagates. Generally, numerical analyses employ the value measured at the delamination onset, leading to conservative results since the increase resistance of the delamination is neglected. In this paper, the fracture toughness and the R-curves of carbon/epoxy IM7/8552 are experimentally evaluated in coupons with delamination positioned at 0°/0° and 45°/−45° interfaces using Double Cantilever Beam (DCB) and Mixed-Mode Bending (MMB) tests. A simplified numerical approach based on the Virtual Crack Closure Technique (VCCT) is developed to simulate variable fracture toughness with the delamination length within a Finite Element code using a predefined field variable. The results of the numerical analyses compared with the experimental data in terms of load-displacement curves demonstrate the effectiveness of the proposed technique in simulating the increase resistance in delamination positioned between plies at 45°/−45° interface.

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