scholarly journals Uncertainty Representation of Natural Frequency for Laminated Composite Cylindrical Shells Considering Probabilistic and Interval Variables

2021 ◽  
Vol 11 (4) ◽  
pp. 1883
Author(s):  
Guohai Chen ◽  
Tong Wang ◽  
Congda Lu ◽  
Yuanshan Yang ◽  
Lin Li ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Cylindrical Shells ◽  
Laminated Composite ◽  
Cumulative Distribution ◽  
Probabilistic Uncertainty ◽  
Uncertainty Representation ◽  
Interval Variables ◽  
Moments Method ◽  
Adaptive Kriging ◽  
Composite Cylindrical Shells

Due to manufacturing errors, inaccurate measurement and working conditions changes, there are many uncertainties in laminated composite cylindrical shells, which causes the variation of vibration characteristics, and has an important influence on the overall performance. Therefore, an uncertainty representation methodology of natural frequency for laminated composite cylindrical shells is proposed, which considers probabilistic and interval variables simultaneously. The input interval variables are converted into a probabilistic density function or cumulative distribution function based on a four statistical moments method, and a unified probabilistic uncertainty analysis method is proposed to calculate the uncertainty of natural frequency. An adaptive Kriging surrogate model considering probabilistic uncertainty variables is established to accurately represent the natural frequency of laminated composite cylindrical shells. Finally, the dimensionless natural frequency of three-layer, five-layer and seven-layer laminated composite cylindrical shells with uncertainty input parameters is accurately represented. Compared with the Monte Carlo Simulation results, the mean error and standard deviation error are reduced to less than 0.07% and 4.7%, respectively, and the execution number of calculation function is significantly decreased, which fully proves the effectiveness of the proposed method.

On Crack Growth in Composite Cylindrical Shells

1999 ◽  
Author(s):  
Hayder A. Rasheed ◽  
John L. Tassoulas
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Cylindrical Shells ◽  
Applied Pressure ◽  
Fluid Pressure ◽  
Laminated Composite ◽  
Stable Crack Growth ◽  
Composite Cylindrical Shells

Abstract Interfacial defects, in the form of cracks or layer separation, may occur in composite cylindrical shells during the manufacturing process, transportation or service life. Such defects are expected to affect the integrity of laminated composite structural elements and may reduce their capacity to resist the applied loads. In this article, the growth of pre-existing cracks in moderately thick composite cylinders is studied for the case of externally applied fluid pressure. The cracks considered separate thick layers, which are unlikely to buckle locally prior to the final collapse of the structural component. The potential of growth is assessed by computing the energy release rate. It is found that any initial out-of roundness imperfection introduces a shear force at the crack tip by causing the cross section to ovalize slightly. The energy release rate is found to vary exponentially with the applied pressure, when geometric nonlinearities are considered. The analysis is applied to a carbon/glass-fiber hybrid composite tube and the parameters influencing growth are examined. Crack length, through the thickness location, circumferential location relative to the ovalization orientation and the amount of imperfection are found to control the nature of growth. Unstable as well as stable crack growth and arrest cases are observed for various combinations of these parameters.

scholarly journals Thermo-Mechanical Instability Characteristics of Laminated Composite Cylindrical Shells

2017 ◽  
Vol 214 ◽  
pp. 76-85
Author(s):  
Periyasamy Manikandan ◽  
Sunil Chandrakant Joshi ◽  
Armando Pinter
Keyword(s):  
Cylindrical Shells ◽  
Laminated Composite ◽  
Mechanical Instability ◽  
Composite Cylindrical Shells

Influence of Crack on the Instability of GFRP Composite Cylindrical Shells under Combined Loading

2018 ◽  
Vol 877 ◽  
pp. 453-459
Author(s):  
B. Angelina Catherine ◽  
R.S. Priyadarsini
Keyword(s):  
Structural Integrity ◽  
Cylindrical Shells ◽  
Laminated Composite ◽  
External Pressure ◽  
Industrial Applications ◽  
Combined Loading ◽  
Finite Element Software ◽  
Buckling Behavior ◽  
Thin Walled ◽  
Composite Cylindrical Shells

Buckling is a prominent condition of instability caused to a shell structure as a result of axial loadings. The process of buckling becomes more complex while analyzing thin walled structures like shells. Today such thin walled laminated composite shells are gaining more importance in many defense and industrial applications since they have greater structural efficiency and performance in relation to isotropic structures. Comprehensive understanding of the buckling response of shell structures is necessary to assure the integrity of these shells during their service life. The presence of defects, such as cracks, may severely compromise their buckling behavior and jeopardize the structural integrity. This work aims in conducting numerical analysis of cracked GFRP (Glass fibre-reinforced polymer) composite cylindrical shells under combined loading to study the effect of crack size on the buckling behavior of laminated composite cylindrical shells with different lay-up sequences. The numerical analyses were carried out using the finite element software, ABAQUS in order to predict the buckling behaviour of cracked laminated composite cylinders subject to different combinations of axial compression, torsion, internal pressure and external pressure from the interaction buckling curves.

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