Nanofillers’ Effects on Fracture Energy in Composite Aerospace Structures

2019 ◽  
Vol 827 ◽  
pp. 43-48
Author(s):  
Andrea Sellitto ◽  
Aniello Riccio ◽  
A. Russo ◽  
Antonio Garofano ◽  
Mauro Zarrelli
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Composite Laminates ◽  
Compressive Loading ◽  
Compressive Load ◽  
Numerical Procedure ◽  
Delamination Growth ◽  
Different Types ◽  
Research Programmes ◽  
Consequent Reduction

Composite materials damage behaviour is, nowadays, extensively investigated in the frame of aerospace research programmes. Among the several failure mechanisms which can affect composites, delamination can be considered as the most critical one, especially when combined to compressive loading conditions. In this context, nanofillers can represent an effective way to increase the composites fracture toughness with a consequent reduction of the delamination onset and evolution. Hence, in this paper, the toughening effect of the nanofillers on the delamination growth in composite material panels, subject to compressive load, has been numerically studied. A validated robust numerical procedure for the prediction of the delamination growth in composite materials panel, named SMXB and based on the VCCT-Fail release approach, has been used to perform numerical analyses by considering two different types of nanofillers. Reference material, without nanofillers insertion, has been used as benchmark in order to assess the capability of nanofillers to enhance the fracture toughness in composite laminates.

Effect of Cryogenic Temperature on the Fracture Toughness of Graphite/Epoxy Composites

2005 ◽  
Vol 128 (2) ◽  
pp. 151-157 ◽  
Author(s):  
S. G. Kalarikkal ◽  
B. V. Sankar ◽  
P. G. Ifju
Keyword(s):  
Fracture Toughness ◽  
Composite Laminates ◽  
Cryogenic Temperature ◽  
Liquid Nitrogen Temperature ◽  
Woven Composites ◽  
Cryogenic Temperatures ◽  
Textile Composite ◽  
Different Types ◽  
Cryogenic Conditions ◽  
Displacement Diagram

The research presented in this paper is an effort to better understand the interlaminar fracture behavior of graphite/epoxy composite laminates in cryogenic conditions. Double cantilever beam tests were performed on different types of specimens, at room and cryogenic temperatures, and the fracture toughness was calculated from their load-displacement diagram. Additionally, the fracture toughness of some plain-weave textile composite specimens and specimens treated with nanoparticles (38nmAl2O3) were also measured. It was observed that all specimens, with the exception of woven composites, showed deterioration in fracture toughness at the liquid nitrogen temperature. Nanoparticle treated specimens showed an improvement in fracture toughness, both at room and cryogenic temperatures compared to the control specimens. The woven composite specimens showed an increase in fracture toughness at cryogenic temperature. The results indicate that woven fiber composites may have potential in lightweight cryogenic storage systems.

Strain rate effects on the intralaminar fracture toughness of composite laminates subjected to compressive load

2018 ◽  
Vol 186 ◽  
pp. 94-105 ◽  
Author(s):  
Bruno Martins Leite ◽  
Luiz Fernando Martins Leite ◽  
Vitor Luiz Reis ◽  
Maurício Vicente Donadon ◽  
Nubia Nale Alves da Silveira
Keyword(s):  
Fracture Toughness ◽  
Strain Rate ◽  
Composite Laminates ◽  
Compressive Load ◽  
Strain Rate Effects ◽  
Rate Effects

scholarly journals Experimental and Numerical Investigation of Octagonal Partially Encased Composite Columns Subject to Axial and Torsion Moment Loading

2017 ◽  
Vol 3 (10) ◽  
pp. 939 ◽  
Author(s):  
Mehdi Ebadi Jamkhaneh ◽  
Mohammad Ali Kafi
Keyword(s):  
Numerical Study ◽  
Compressive Loading ◽  
Compressive Load ◽  
Thickness Ratio ◽  
Composite Columns ◽  
Deformation Curves ◽  
Concrete Confinement ◽  
Different Types ◽  
Analytical Phase ◽  
Partially Encased Composite Columns

This paper includes experimental and numerical study of the octagonal partially encased composite (PEC) columns specimens under axial and torsion loading. The major difference between them was the concrete reinforcement details. The parameters investigated in the experimental and numerical study were the type of reinforcement details, the failure mode, width-to-thickness ratio of flange, transverse links spacing and diameter. The results were presented as load-deformation curves. Numerical model was validated using finite element method and the results indicated acceptable accuracy with tests results in the form of capacity and ductility. In the analytical phase, the experimental results in the compressive loading were compared with those obtained from CSA S16-14 and EN 1994-1-1 equations. Also, the new concrete confinement factor in proportion to the web width to thickness ratio was presented to octagonal PEC columns under pure compressive load. Furthermore, different types of retrofit of cross-shaped steel column including concrete encasement, use of stiffener plates and transverse links were investigated in this research. Results revealed that concrete confinement and use of transverse links had respectively the most and the least effect on increasing torsional capacity of the specimens.

Local Delamination Growth in Layered Systems Under Compressive Load

1993 ◽  
Vol 60 (4) ◽  
pp. 895-902 ◽  
Author(s):  
E. Madenci ◽  
R. A. Westmann
Keyword(s):  
Mixed Boundary ◽  
Compressive Loading ◽  
Compressive Load ◽  
Necessary Condition ◽  
Layered Systems ◽  
Infinite Layer ◽  
Delamination Growth ◽  
Mathematical Techniques ◽  
The Stability

This paper addresses the problem of delamination growth prior to its buckling using mathematical techniques appropriate for mixed boundary value problems. The formulation presented herein does not require buckling as a necessary condition for delamination growth. By employing the stability equations of elasticity theory, solutions to the problem of an infinite layer with a slightly imperfect circular delamination subjected to axisymmetric and uniaxial in-plane compressive loading are presented. This approach permits the determination of the stress intensity factors under specified initial imperfections for applied compressive stress.

scholarly journals Fracture Toughness Analysis of Delamineted Composites under Variable Temperatures

2020 ◽  
Vol 22 (1) ◽  
pp. 171-178
Author(s):  
Meryem El Moufari ◽  
Larbi El Bakkali
Keyword(s):  
Fracture Toughness ◽  
Mechanical Loading ◽  
Composite Laminates ◽  
Failure Modes ◽  
Effect Of Temperature ◽  
Element Simulation ◽  
Different Types ◽  
Epoxy Material ◽  
Mode Energy ◽  
Safe Working

AbstractThe main goal of the present paper is to approach the modeling of one of the most important and critical failure modes for composite laminates which is known as interlaminar delamination in the aeronautical structures. The analytical model is based on a fracture mechanics approach; it’s used to estimate the total mixed mode energy release rate for composite laminates. A finite element simulation has been achieved in combination with the virtual crack closure technique (VCCT) to analyze the effect of temperature on the interlaminar fracture toughness growth of a delaminated carbon/epoxy material, namely IM7/8552 subjected to mechanical loading at variable temperatures. The developed model may serve as the basis for treating different types of thermal and mechanical loading, different stacking sequences and thickness of lamina in order to build safe working conditions for composite laminates.

scholarly journals Experimental Investigation of Delamination Growth in Composite Laminates under a Compressive Load

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
A. Riccio ◽  
R. Cristiano ◽  
G. Mezzacapo ◽  
M. Zarrelli ◽  
C. Toscano
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Composite Laminates ◽  
Compressive Load ◽  
Composite Plates ◽  
Mechanical Tests ◽  
Initial Position ◽  
Image Correlation ◽  
Indirect Measurements ◽  
Delamination Growth

This paper focuses on the use of no-contact experimental techniques for monitoring the interlaminar damage evolution in composite laminates. Indeed, Infrared Thermography and Digital Image Correlation are adopted to investigate, in composite plates with artificial delamination, the influence of the delamination initial position on the delamination growth. The paper also investigates the feasibility of using a no-contact experimental technique for the measurement of displacement and strain during mechanical tests, such as the Digital Image Correlation, to evaluate, by means of indirect measurements, the delamination growth as a function of the applied load.

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