Analysis of damage and interlaminar stresses in laminate plates with interacting holes

Abstract Several effects that fiber prestress may have on stress redistribution in the plies of composite laminates and in the phases of individual plies are illustrated. These include improvement of composite damage resistance under tensile mechanical loads, reduction/cancelation of interlaminar stresses at free edges of composite laminate subjected to thermomechanical loading, and stress relaxation in the matrix phase of viscoelastic composite laminates. Specific results are found for quasi-isotropic and cross-ply symmetric S-glass/epoxy and carbon/epoxy AS4/EPON 828 laminates.

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Study of Interlaminar Fracture Properties of Ceramic Matrix Composites at Room and Elevated Temperatures

Volume 6: Ceramics; Controls, Diagnostics and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2017-65168 ◽

2017 ◽

Cited By ~ 2

Author(s):

Rabih Mansour ◽

Yogesh P. Singh ◽

Manigandan Kannan ◽

Gregory N. Morscher ◽

Frank Abdi ◽

...

Keyword(s):

Crack Growth ◽

Cross Sections ◽

Room Temperature ◽

Elevated Temperatures ◽

Ceramic Matrix Composites ◽

In Situ Monitoring ◽

Matrix Composites ◽

Interlaminar Stresses ◽

Fracture Properties ◽

Interlaminar Fracture

Interlaminar fracture properties play an important role in predicting failure of structural components for CMC materials. In engine applications, components are subject to large thermal gradients which induce interlaminar stresses. One of the main challenges in evaluating interlaminar fracture toughness at room and elevated temperatures is the development of an experimental setup that provides ease for testing and allows for in-situ monitoring of the interlaminar crack growth. Therefore, a wedge-loaded DCB testing method is developed. The method utilize electrical resistance to monitor crack growth and was applied to a woven polymer infiltrated pyrolysis (PIP) SiC/SiNC composite. Post-testing inspection was carried out using optical microscopy of polished cross-sections, showing crack morphology. It was found that crack growth rate at room temperature is double the one at 815 °C for initial tests in this composite system. Estimates of Mode I energy release rate suggests flat R-curve behavior at room temperature in comparison to rising R-curve behavior at 815 °C.

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Prediction of Elastic Properties of Honeycomb Core Materials and Analysis of Interlaminar Stress of Honeycomb Sandwich Composite Plate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.306-308.763 ◽

2006 ◽

Vol 306-308 ◽

pp. 763-768

Author(s):

Hyoung Gu Kim ◽

Hoong Soo Yoon ◽

Nak Sam Choi

Keyword(s):

Poisson’S Ratio ◽

Poisson's Ratio ◽

Sandwich Composite ◽

Plate Model ◽

Honeycomb Core ◽

Interlaminar Stresses ◽

Honeycomb Sandwich ◽

Honeycomb Sandwich Composite ◽

Theoretical Results ◽

Core Materials

Theoretical formulas for effective elastic modulus and Poisson's ratio of honeycomb core materials were proposed considering the bending, axial and shear deformations of cell walls. Theoretical results obtained by the formulas showed orthotropic elasticity and large Poisson’s ratio, which were comparable to results by finite element analysis(FEA). Tensile test of honeycomb sandwich composite(HSC) plates was performed for analysis of their deformation behaviors and interlaminar stresses. Equivalent plate model using the theoretical results of honeycomb core layer show that interlaminar shear stress occurring due to large difference of Poisson’s ratio between skin and honeycomb core layers led to the delamination in HSC plate under tensile loading. Load-displacement behavior of HSC specimen simulated by equivalent plate model coincided fairly with that of detailed FEA model similar to experimental results.

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