The effect of stitch distribution on Mode I delamination toughness of stitched laminated composites – experimental results and FEA simulation

2007 ◽  
Vol 67 (6) ◽  
pp. 1058-1072 ◽  
Author(s):  
M WOOD ◽  
X SUN ◽  
L TONG ◽  
A KATZOS ◽  
A RISPLER ◽  
...  
Keyword(s):  
Laminated Composites ◽  
Experimental Results ◽  
Mode I ◽  
Delamination Toughness ◽  
Fea Simulation ◽  
Mode I Delamination

Effect of Reinforcing Tabs on the Mode I Delamination Toughness of Stitched CFRPs

1998 ◽  
Vol 32 (22) ◽  
pp. 2016-2041 ◽  
Author(s):  
Lalit K. Jain ◽  
Kimberley A. Dransfield ◽  
Yiu-Wing Mai
Keyword(s):  
Mode I ◽  
Delamination Toughness ◽  
Mode I Delamination

A Study on the Fracture Characteristics of Plasma-Treated Graphite/Epoxy Laminated Composites

2006 ◽  
Vol 321-323 ◽  
pp. 869-872 ◽  
Author(s):  
M.H. Kim ◽  
Kyong Yop Rhee ◽  
Young Nam Paik ◽  
S.H. Ryu
Keyword(s):  
Contact Angle ◽  
Double Cantilever Beam ◽  
Treatment Time ◽  
Laminated Composites ◽  
Mode I ◽  
Fracture Characteristics ◽  
Delamination Fracture ◽  
Delamination Resistance ◽  
Fracture Tests ◽  
Mode I Delamination

For a present study, the surfaces of graphite/epoxy prepregs were modified using plasma treatment to improve the delamination resistance behavior of graphite/epoxy laminated composites. The optimal treatment time was determined by measuring the change of contact angle with treatment time. Unidirectional DCB (double cantilever beam) specimens were used in the mode I delamination fracture tests. The delamination resistance curve of regular (untreated) specimen was compared with that of plasma-treated specimen in order to determine the effect of prepreg treatment on the resistance behavior. It was found that contact angle was changed from ~64° to ~47° depending on the treatment time. The contact angle was a minimum for a 30 min treatment time. It was also found that delamination resistance behavior of graphite/epoxy composites was improved about 20%.

Experimental and Numerical Study on the Mode I Delamination Toughness of Z-Pinned Composite Laminates

2009 ◽  
Vol 417-418 ◽  
pp. 185-188 ◽  
Author(s):  
Xi Tao Zheng ◽  
Lin Hu Gou ◽  
Shu Yun Han ◽  
Fan Yang
Keyword(s):  
Composite Laminates ◽  
Numerical Study ◽  
Crack Opening ◽  
Mode I ◽  
Fe Model ◽  
Cantilever Beams ◽  
Critical Crack ◽  
Delamination Toughness ◽  
Double Cantilever Beams ◽  
Mode I Delamination

An experimental investigation was performed on mode I delamination of z-pinned double-cantilever-beams (DCB) and associate z-pin bridging mechanisms. Tests were performed with ten types of samples: (1) big-pin reinforced DCB (double-cantilever-beams) with three areal densities D=2.01%, 5.15%, 8.04%, respectively; (2) median-pin reinforced DCB with three areal densities D=0.85%, 2.17%, 3.40%; (3) small-pin reinforced DCB with three areal densities D=0.25%, 0.63%, 0.90% and (4) without pin reinforced DCB specimens. Delamination tests samples were prepared from unidirectional continuous carbon fibre/epoxy prepreg (T300/TDE86), made into 3 mm thick unidirectional laminates with and without a block of Z-pins in the crack path. Fracture testing was carried out under Mode I (standard DCB test). Experiments have shown that increases in debond resistance and ultimate strength depend on the material, size, density, location of the pins and the mechanisms of pin deformation. A finite element (FE) model is developed to investigate mode I delamination toughness of z-pin reinforced composite laminates. The z-pin pullout process is simulated by the deformation of a set of non-linear springs. A critical crack opening displacement (COD) criterion is used to simulate crack growth in a DCB made of z-pinned laminates. The toughness of the structure is quantified by the energy release rate, which is calculated using the contour integral method. The FE model is verified for both unpinned and z-pinned laminates. Predicted loading forces from FE analysis are compared to available test data. Good agreement is achieved. The numerical results indicate that z-pins can greatly increase the mode I delamination toughness of the composite laminates.

A Spring Foundation Model for Mode I Failure of Laminated Composites Based on an Energy Criterion

1994 ◽  
Vol 116 (4) ◽  
pp. 512-516 ◽  
Author(s):  
Seung J. Song ◽  
Anthony M. Waas
Keyword(s):  
Laminated Composites ◽  
Current Model ◽  
Crack Opening ◽  
Energy Criterion ◽  
Experimental Results ◽  
Mode I ◽  
Beam Specimen ◽  
Opening Displacement ◽  
Wide Range ◽  
Crack Problems

A mechanical model which can predict mode I delamination failure of laminated composites has been developed. A beam on a nonlinear spring foundation was used to model experimental results obtained from DCB type fracture specimens. The entire thickness of the beam specimen was used as a spring length, and a nonuniform strain distribution throughout the spring length was utilized, based on the 2-D asymptotic solution of the stress field near a crack tip. The failure condition of the spring foundation is based on an energy criterion. Mode I fracture tests were performed to verify the current model using two types of laminated composite DCB specimens. The current model reproduced the experimental results of pulling force versus crack opening displacement curves very closely for a wide range of resin layer thickness of the specimens. The current model has a potential capability of being extended to solve 2-D crack problems, where the evolution of an arbitrary shape of 2-D crack geometry will be predicted as a part of the solution of the current model.

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