Analysis and Testing of Mixed-Mode Interlaminar Fracture Behavior of Glass-Cloth∕Epoxy Laminates at Cryogenic Temperatures

2005 ◽  
Vol 127 (4) ◽  
pp. 468-475 ◽  
Author(s):  
Yasuhide Shindo ◽  
Daiki Shinohe ◽  
Susumu Kumagai ◽  
Katsumi Horiguchi
Keyword(s):  
Mixed Mode ◽  
Element Model ◽  
Liquid Nitrogen Temperature ◽  
Bending Test ◽  
Effect Of Temperature ◽  
Mode I ◽  
Mode Ii ◽  
Glass Cloth ◽  
Interlaminar Fracture ◽  
Delamination Crack

This paper presents results from an analytical and experimental study of the effect of temperature and mixed-mode ratio on the interlaminar fracture toughness in glass-cloth∕epoxy laminates. Mode I, mode II, and mixed-mode tests were conducted by the double-cantilever beam, end-notched flexure, and mixed-mode bending test methods at room temperature, liquid nitrogen temperature (77 K), and liquid helium temperature (4 K). A finite element model was used to perform the delamination crack analysis. Mode I, mode II, and mixed-mode energy release rates at the onset of delamination crack propagation were computed using the virtual crack closure technique. The fracture surfaces were examined by scanning electron microscopy to correlate with the interlaminar fracture properties.

scholarly journals Mixed-Mode Interlaminar Fracture Toughness of Glass and Carbon Fibre Powder Epoxy Composites—For Design of Wind and Tidal Turbine Blades

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2103
Author(s):  
Christophe Floreani ◽  
Colin Robert ◽  
Parvez Alam ◽  
Peter Davies ◽  
Conchúr M. Ó. Brádaigh
Keyword(s):  
Fracture Toughness ◽  
Carbon Fibre ◽  
Composite Structures ◽  
Mixed Mode ◽  
Epoxy Composites ◽  
Mode I ◽  
Mode Ii ◽  
Pure Mode ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture

Powder epoxy composites have several advantages for the processing of large composite structures, including low exotherm, viscosity and material cost, as well as the ability to carry out separate melting and curing operations. This work studies the mode I and mixed-mode toughness, as well as the in-plane mechanical properties of unidirectional stitched glass and carbon fibre reinforced powder epoxy composites. The interlaminar fracture toughness is studied in pure mode I by performing Double Cantilever Beam tests and at 25% mode II, 50% mode II and 75% mode II by performing Mixed Mode Bending testing according to the ASTM D5528-13 test standard. The tensile and compressive properties are comparable to that of standard epoxy composites but both the mode I and mixed-mode toughness are shown to be significantly higher than that of other epoxy composites, even when comparing to toughened epoxies. The mixed-mode critical strain energy release rate as a function of the delamination mode ratio is also provided. This paper highlights the potential for powder epoxy composites in the manufacturing of structures where there is a risk of delamination.

Influence of Temperature on Interlaminar Fracture Toughness of a Carbon Fiber-Epoxy Composite Material

2016 ◽  
Vol 1135 ◽  
pp. 35-51 ◽  
Author(s):  
Rita de Cássia Mendonça Sales ◽  
Bianca Lis Rossi Dias Endo ◽  
Maurício Vicente Donadon
Keyword(s):  
Fracture Toughness ◽  
Mixed Mode ◽  
Mechanical Resistance ◽  
Mode I ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Delamination Resistance ◽  
Different Temperatures ◽  
Influence Of Temperature On

Composite materials have been increasingly used in the aerospace industry for the manufacturing of structures, because of the associated properties of low weight and high mechanical resistance. On the other hand, they have low delamination resistance. This paper presents the results of an experimental study performed to obtain the values of interlaminar fracture toughness (G) of a laminate under three different temperatures, using 0º carbon-epoxy prepreg fabric plies and manufactured via Hand lay up cured in autoclave (HLUP). Double Cantilever Beam (DCB) tests were performed to evaluate mode I toughness, Four Point Bend End Notched Flexure (4ENF) for mode II and Mixed Mode Bending (MMB) for mixed mode I / mode II at -54°C, 25°C and 80°C. The data were collected and analyzed using a routine developed in Matlab®. Finally, the relation between GI and GII through the failure envelope and the temperature influence on the interlaminar fracture toughness was assessed.

scholarly journals A Constitutive Model for Through-Thickness Reinforcement Bridging a Delamination Crack

1999 ◽  
Vol 8 (5) ◽  
pp. 096369359900800 ◽  
Author(s):  
Brian N. Cox
Keyword(s):  
Mixed Mode ◽  
Displacement Vector ◽  
Mode I ◽  
Mode Ii ◽  
Crack Model ◽  
Delamination Crack ◽  
Constituent Material ◽  
Vector Mode ◽  
The Relationship ◽  
Bridging Law

Prior detailed microscopic observations have revealed the essential mechanisms of damage in through-thickness reinforcing tows when a delamination crack passes. As expected, the damage sequence depends quite strongly on whether the crack is loaded in Mode I or Mode II and, if loading is mixed mode, the order of loading. Here, micromechanical models are presented that show how geometry and constituent material properties affect the deformation and displacement of a bridging tow. From these models, the effective bridging law for a bridged crack model of the delamination can be derived. An analytical model is presented that predicts the relationship between the crack displacement vector (mode I and Mode II displacements) and the bridging traction vector that acts on the fracture surfaces. Criteria for rupture or pullout of the bridging tow are incorporated, leading to predictions of the ultimate strength of the bridging ligaments in mixed mode conditions. Given the traction law, which may be a material property, the fracture behaviour of a part can be predicted.

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