EXPERIMENTAL INVESTIGATION OF THE MICROSCOPIC DAMAGE DEVELOPMENT AT MODE I FATIGUE DELAMINATION TIPS IN CARBON/EPOXY LAMINATES

2016 ◽  
Vol 78 (11) ◽  
Author(s):  
Rafiullah Khan ◽  
Rene Alderliesten ◽  
Saeed Badshah ◽  
M. A. Khattak ◽  
M. S. Khan ◽  
...  
Keyword(s):  
Double Cantilever Beam ◽  
Growth Direction ◽  
Fatigue Tests ◽  
Mode I ◽  
Damage Development ◽  
Delamination Growth ◽  
Fibre Bridging ◽  
Micro Cracks ◽  
Microscopic Damage ◽  
Mode I Delamination

This paper investigates the damage development ahead of mode I delamination tips in carbon /epoxy laminates using scanning electron microscope (SEM). Two techniques were adopted for the investigation; the first technique consisted of the application of stepwise load increments on DCB (double cantilever beam) specimens inside the SEM, while images were recorded until delamination onset. For the second technique, the DCB specimens were fatigue tested under different combinations of monotonic and cyclic loading. After the fatigue tests, the specimens were kept open in the microscope by insertion of steel wedges allowing the inspection of the delamination tips. The investigation revealed that multiple micro-cracks are formed parallel to the delamination growth direction ahead of the tip that coalesces. Micro-cracks that were formed 2 or 3 plies away from the delamination plane were observed to cause fibre bridging. 

Use of an elasto-plastic model and strain measurements of embedded fibre Bragg grating sensors to detect Mode I delamination crack propagation in woven cloth (0/90) composite materials

2017 ◽  
Vol 17 (2) ◽  
pp. 363-378 ◽  
Author(s):  
Ayad Arab Kakei ◽  
Mainul Islam ◽  
Jinsong Leng ◽  
Jayantha A Epaarachchi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Front ◽  
Double Cantilever Beam ◽  
Bragg Grating ◽  
Mode I ◽  
Fibre Bragg Grating ◽  
Element Analysis ◽  
Plastic Model ◽  
Mode I Delamination

Mode I fracture analysis being employed to study delamination damage in fibre-reinforced composite structures under in-plane and out-of-plane load applications. However, due to the significantly low yield strength of the matrix material and the infinitesimal thickness of the interface matrix layer, the actual delamination process can be assumed as a partially plastic process (elasto-plastic). A simple elasto-plastic model based on the strain field in the vicinity of the crack front was developed for Mode I crack propagation. In this study, a double cantilever beam experiment has been performed to study the proposed process using a 0/90-glass woven cloth sample. A fibre Bragg grating sensor has embedded closer to the delamination to measure the strain at the vicinity of the crack front. Strain energy release rate was calculated according to ASTM D5528. The model predictions were comparable with the calculated values according to ASTM D5528. Subsequently, a finite element analysis on Abaqus was performed using ‘Cohesive Elements’ to study the proposed elasto-plastic behaviour. The finite element analysis results have shown a very good correlation with double cantilever beam experimental results, and therefore, it can be concluded that Mode I delamination process of an fibre-reinforced polymer composite can be monitored successfully using an integral approach of fibre Bragg grating sensors measurements and the prediction of a newly proposed elasto-plastic model for Mode I delamination process.

scholarly journals Mode I fatigue delamination growth with fibre bridging in multidirectional composite laminates

2018 ◽  
Vol 189 ◽  
pp. 221-231 ◽  
Author(s):  
Liaojun Yao ◽  
Yi Sun ◽  
Licheng Guo ◽  
Xiuqi Lyu ◽  
Meiying Zhao ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Mode I ◽  
Delamination Growth ◽  
Fibre Bridging

scholarly journals Fibre bridging effect on the Paris relation for mode I fatigue delamination growth in composites with consideration of interface configuration

2017 ◽  
Vol 159 ◽  
pp. 471-478 ◽  
Author(s):  
Liaojun Yao ◽  
Yi Sun ◽  
R.C. Alderliesten ◽  
R. Benedictus ◽  
Meiying Zhao
Keyword(s):  
Mode I ◽  
Delamination Growth ◽  
Fibre Bridging

scholarly journals Interlaminar Fatigue Crack Propagation in Mode I of Carbon Fiber/PEEK Composites

1993 ◽  
Vol 2 (1) ◽  
pp. 096369359300200
Author(s):  
G C Christopoulos ◽  
S A Paipetis
Keyword(s):  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Double Cantilever Beam ◽  
Cyclic Strain ◽  
Strain Energy Release ◽  
Mode I ◽  
Interlaminar Fracture Toughness ◽  
Fatigue Cycle ◽  
Delamination Growth ◽  
Thermoplastic Matrix

A study of the mode I interlaminar fracture toughness of a unidirectional carbon fibre reinforced thermoplastic matrix composite has been made using Double Cantilever Beam, DCB, specimens. Delamination growth per fatigue cycle, da/dN, was related with the maximum applied cyclic strain energy release rate, GIMAX, using a power law.

Multiscale finite element analysis of mode I delamination growth in a fabric composite

2015 ◽  
Vol 133 ◽  
pp. 157-165 ◽  
Author(s):  
Tadayoshi Yamanaka ◽  
Hossein Ghiasi ◽  
Mohammad Heidari-Rarani ◽  
Larry Lessard ◽  
Victor Feret ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mode I ◽  
Element Analysis ◽  
Delamination Growth ◽  
Fabric Composite ◽  
Multiscale Finite Element ◽  
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%.

Sign in / Sign up

Export Citation Format

Share Document