Fast buckling load numerical prediction method for imperfect shells under axial compression based on POD and vibration correlation technique

2020 ◽  
Vol 252 ◽  
pp. 112721
Author(s):  
Kuo Tian ◽  
Lei Huang ◽  
Yu Sun ◽  
Kaifan Du ◽  
Peng Hao ◽  
...  
Keyword(s):  
Axial Compression ◽  
Prediction Method ◽  
Numerical Prediction ◽  
Buckling Load ◽  
Correlation Technique

scholarly journals Applicability of the Vibration Correlation Technique for Estimation of the Buckling Load in Axial Compression of Cylindrical Isotropic Shells with and without Circular Cutouts

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Eduards Skukis ◽  
Olgerts Ozolins ◽  
Janis Andersons ◽  
Kaspars Kalnins ◽  
Mariano A. Arbelo
Keyword(s):  
Nondestructive Evaluation ◽  
Failure Mode ◽  
Axial Compression ◽  
Laser Scanner ◽  
Local Buckling ◽  
Bond Line ◽  
Buckling Load ◽  
Reliable Estimate ◽  
Correlation Technique ◽  
Shell Geometry

Applicability of the vibration correlation technique (VCT) for nondestructive evaluation of the axial buckling load is considered. Thin-walled cylindrical shells with and without circular cutouts have been produced by adhesive overlap bonding from a sheet of aluminium alloy. Both mid-surface and bond-line imperfections of initial shell geometry have been characterized by a laser scanner. Vibration response of shells under axial compression has been monitored to experimentally determine the variation of the first eigenfrequency as a function of applied load. It is demonstrated that VCT provides reliable estimate of buckling load when structure has been loaded up to at least 60% of the critical load. This applies to uncut structures where global failure mode is governing collapse of the structure. By contrast, a local buckling in the vicinity of a cutout could not be predicted by VCT means. Nevertheless, it has been demonstrated that certain reinforcement around cutout may enable the global failure mode and corresponding reliability of VCT estimation.

RELIABILITY ASSESSMENT OF AXIALLY COMPRESSED COMPOSITE CYLINDRICAL SHELLS WITH RANDOM IMPERFECTIONS

2011 ◽  
Vol 11 (02) ◽  
pp. 215-236 ◽  
Author(s):  
MATTEO BROGGI ◽  
ADRIANO CALVI ◽  
GERHART I. SCHUËLLER
Keyword(s):  
Mathematical Models ◽  
Axial Compression ◽  
Cylindrical Shells ◽  
Reliability Assessment ◽  
Buckling Analysis ◽  
Buckling Load ◽  
Experimental Results ◽  
Drastic Decrease ◽  
Different Types ◽  
Probability And Statistics

Cylindrical shells under axial compression are susceptible to buckling and hence require the development of enhanced underlying mathematical models in order to accurately predict the buckling load. Imperfections of the geometry of the cylinders may cause a drastic decrease of the buckling load and give rise to the need of advanced techniques in order to consider these imperfections in a buckling analysis. A deterministic buckling analysis is based on the use of the so-called knockdown factors, which specifies the reduction of the buckling load of the perfect shell in order to account for the inherent uncertainties in the geometry. In this paper, it is shown that these knockdown factors are overly conservative and that the fields of probability and statistics provide a mathematical vehicle for realistically modeling the imperfections. Furthermore, the influence of different types of imperfection on the buckling load are examined and validated with experimental results.

Buckling of a Circular Cylindrical Web-Stiffened Sandwich Shell Under Axial Compression

1974 ◽  
Vol 18 (01) ◽  
pp. 55-61
Author(s):  
Vincent Volpe ◽  
Youl-Nan Chen ◽  
Joseph Kempner
Keyword(s):  
Axial Compression ◽  
Large Deflection ◽  
Single Layer ◽  
Subsequent Development ◽  
Buckling Load ◽  
Sandwich Shell ◽  
Cylindrical Sandwich Shell ◽  
Axisymmetric Mode ◽  
Shell Equations ◽  
The Mathematical Model

A stability analysis of an infinitely long web-stiffened, circular cylindrical sandwich shell under uniform axial compression is presented. The formulation begins with the establishment of a set of suitable large-deflection shell equations that forms the basis for the subsequent development of the buckling equations. The mathematical model corresponds to two face layers that are considered as thin shells and a thick core that is capable of resisting both transverse shear and circumferential extension. The associated eigenvalue problem is solved. Results show that the lowest buckling load is associated with the axisymmetric mode and is less than one half the buckling load of an equivalent single-layer shell.

scholarly journals An Equivalent Damping Numerical Prediction Method for the Ring Damper Used in Gears under Axial Vibration

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1469 ◽  
Author(s):  
Shuai Wang ◽  
Xiaolei Wang ◽  
Yanrong Wang ◽  
Hang Ye
Keyword(s):  
Structural Parameters ◽  
Great Influence ◽  
Prediction Method ◽  
Forced Response ◽  
Numerical Prediction ◽  
Axial Stiffness ◽  
Response Analysis ◽  
Axial Vibration ◽  
Equivalent Damping ◽  
Vibration Loads

In aircraft gas turbine engines, gears in the transmission system are typically cyclic in structure and inevitably encounter large dynamic loads, such as meshing excitation, resulting in high vibration loads in resonance. To prevent gear resonance failure, a ring damper is employed to reduce the resonance response. As relative motion between the gear and the ring damper occurs, vibration loads can be reduced by friction energy dissipation. Moreover, the gears in the aircraft engine are thin-walled and their axial stiffness is much smaller than radial stiffness; thus, it is easier for axial vibration to cause resonance failure. This paper proposes an equivalent damping numerical prediction method for a ring damper under axial vibration, which greatly shortens the calculation time and prevents the forced response analysis of nonlinear structures. Via this method, the influence of ring damper structural parameters on friction damping in gears under axial vibration is investigated. The results indicate that the friction coefficient and mass of the ring damper have a great influence on damping performance.

Critical Buckling Load of Triple-Walled Carbon Nanotube Based on Nonlocal Elasticity Theory

2020 ◽  
Vol 62 ◽  
pp. 108-119
Author(s):  
Tayeb Bensattalah ◽  
Ahmed Hamidi ◽  
Khaled Bouakkaz ◽  
Mohamed Zidour ◽  
Tahar Hassaine Daouadji
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Axial Compression ◽  
Buckling Load ◽  
Small Scale ◽  
Beam Model ◽  
Buckling Loads ◽  
Critical Buckling Load ◽  
Nonlocal Continuum Theory ◽  
Walled Carbon Nanotubes

The present paper investigates the nonlocal buckling of Zigzag Triple-walled carbon nanotubes (TWCNTs) under axial compression with both chirality and small scale effects. Based on the nonlocal continuum theory and the Timoshenko beam model, the governing equations are derived and the critical buckling loads under axial compression are obtained. The TWCNTs are considered as three nanotube shells coupled through the van der Waals interaction between them. The results show that the critical buckling load can be overestimated by the local beam model if the small-scale effect is overlooked for long nanotubes. In addition, a significant dependence of the critical buckling loads on the chirality of zigzag carbon nanotube is confirmed, and these are then compared with: A single-walled carbon nanotubes (SWCNTs); and Double-walled carbon nanotubes (DWCNTs). These findings are important in mechanical design considerations and reinforcement of devices that use carbon nanotubes.

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