Prediction of Onset of Mode I Delamination Growth under a Tensile Spectrum Load | Chapter 07 | New Advances in Materials Science and Engineering Vol. 2
In this investigation, the onset of
mode I delamination growth under a standard aircraft spectrum load sequence,
mini-FALSTAFF truncated to contain only tension-tension fatigue cycles is
predicted. The study was carried out on a standard Double Cantilever Beam (DCB)
test specimen of Uni Directional (UD) layup Carbon Fiber Composite (CFC)
IMA/M21. Finite element modeling and analysis was carried out using ABAQUS
standard to determine Strain Energy Release Rate (SERR) by Virtual Crack
Closure Technique (VCCT). Both two dimensional (2D) and three dimensional (3D) models
were studied. Using the FE analysis results, an empirical equation was derived
for SERR (G) and load (P) relationship. Further, the load cycles in the
spectrum sequence were rain flow counted to separate individual cycles. For
each of the counted cycle, the SERR was obtained and corresponding N onset
for that cycle was estimated from the Constant Onset Life Diagram (COLD) of the
material. Linear damage accumulation law was used to predict the number of
spectrum load blocks required for onset of mode I delamination growth. The
prediction was carried out for various reference loads (P ref) and
the corresponding reference SERR (G ref) of the spectrum sequence.
Predicted results show that decreasing the reference stress increases the mode
I delamination onset life under spectrum loads.
Author(s) Details
J. Raju
Structural Technologies
Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India.
Manjusha S. Duragkar
Department of Metallurgical
and Materials Engineering, Visveswaraya National Institute of Technology,
Nagpur 400016, India.
N. Jagannathan
Structural Technologies
Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India.
C. M. Manjunatha
Structural Technologies
Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India.
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