Compressional mode softening and Euler buckling patterns in mesoscopic beams

We examine submerged nonlinear tubular columns with slenderness ratios between 40 and 160 and ratios of diameter to thickness between 20 and 50. We demonstrate that the column’s Euler buckling load can be increased nearly 30 percent by a volume preserving taper of only a few degrees. We determine the effect of hydrostatic pressure and self-weight on such conical columns and offer some preliminary remarks on the role played by model imperfections.

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Effects of plies orientations and initial geometric imperfections on buckling strength of a composite stiffened panel

MATEC Web of Conferences ◽

10.1051/matecconf/201819100008 ◽

2018 ◽

Vol 191 ◽

pp. 00008

Author(s):

Ikram Feddal ◽

Abdellatif Khamlichi ◽

Koutaiba Ameziane

Keyword(s):

Stiffened Panel ◽

Buckling Mode ◽

Element Analysis ◽

Geometric Imperfections ◽

Stiffened Panels ◽

Specific Strength ◽

Euler Buckling ◽

Buckling Behavior ◽

Composite Stiffened Panel ◽

Strength And Stiffness

The use of composite stiffened panels is common in several activities such as aerospace, marine and civil engineering. The biggest advantage of the composite materials is their high specific strength and stiffness ratios, coupled with weight reduction compared to conventional materials. However, any structural system may reach its limit and buckle under extreme circumstances by a progressive local failure of components. Moreover, stiffened panels are usually assembled from elementary parts. This affects the geometric as well as the material properties resulting in a considerable sensitivity to buckling phenomenon. In this work, the buckling behavior of a composite stiffened panel made from carbon Epoxy Prepregs is studied by using the finite element analysis under Abaqus software package. Different plies orientations sets were considered. The initial distributed geometric imperfections were modeled by means of the first Euler buckling mode. The nonlinear Riks method of analysis provided by Abaqus was applied. This method enables to predict more consistently unstable geometrically nonlinear induced collapse of a structure by detecting potential limit points during the loading history. It was found that plies orientations of the composite and the presence of geometric imperfections have huge influence on the strength resistance.

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Silicon Pillars as Resonators in an Acoustical Metamaterial

Volume 13: Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2014-37914 ◽

2014 ◽

Author(s):

Bernard Bonello ◽

Rémi Marchal ◽

Rayisa Moiseyenko ◽

Yan Pennec ◽

Bahram Djafari-Rouhani ◽

...

Keyword(s):

Thin Plate ◽

Lamb Waves ◽

Mass Density ◽

Resonant Mode ◽

Ultrasonic Technique ◽

Frequency Range ◽

Negative Mass ◽

Laser Ultrasonic ◽

Compressional Mode ◽

Bending Modes

We have investigated the propagation of Lamb waves in structures made of either an isolated resonant pillar or a set of pillars arranged in a line on a thin plate. The resonators as well as the plate are made of silicon. FEM computations show that two bending modes and one compressional mode are unambiguously identified in the frequency range of interest (0–10 MHz). We used a laser ultrasonic technique to map both the amplitude and the phase of the normal displacements on top of the pillars and at the surface of the sample. When the frequency is tuned to a resonant mode, either compressional or bending, the pillars vibrate 180° out-of-phase with respect to the Lamb waves, resulting in a negative modulus or negative mass density respectively.

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Polar mode softening and elastic anomaly temperatures of partially deuterated KDP

Journal of Physics C Solid State Physics ◽

10.1088/0022-3719/11/23/011 ◽

1978 ◽

Vol 11 (23) ◽

pp. 4643-4649

Author(s):

G K Roy ◽

B K Chakrabarti

Keyword(s):

Polar Mode ◽

Mode Softening

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Elasticity, shear-mode softening and high-pressure polymorphism of wüstite (Fe1-xO)

Journal of Geophysical Research Atmospheres ◽

10.1029/jb095ib13p21671 ◽

1990 ◽

Vol 95 (B13) ◽

pp. 21671 ◽

Cited By ~ 78

Author(s):

Ian Jackson ◽

S. K. Khanna ◽

A. Revcolevschi ◽

J. Berthon

Keyword(s):

High Pressure ◽

Shear Mode ◽

Mode Softening

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The Friction Effect on Buckling Behavior of Cellular Structures Under Axial Load

International Journal of Applied Mechanics ◽

10.1142/s1758825118500138 ◽

2018 ◽

Vol 10 (02) ◽

pp. 1850013 ◽

Cited By ~ 9

Author(s):

Jianying Hu ◽

Yu Zhou ◽

Zishun Liu

Keyword(s):

Nonlinear Response ◽

Structural Response ◽

Cellular Structures ◽

Future Perspectives ◽

Euler Buckling ◽

Simple Theoretical Model ◽

Buckling Behavior ◽

Elastic Instabilities ◽

Switching Mode ◽

Periodic Materials

When soft cellular structures are compressed axially beyond critical limits, elastic instabilities induce buckling behavior. Although the nonlinear response of periodic materials with different shape voids has been widely investigated, the effect of the friction on the structural response has not yet been explored. In this paper, we develop a simple theoretical model for the buckling of holey column with holes. Meanwhile, we also numerically and experimentally explore the effect of friction on the buckling behavior of the cellular structures. We find out that friction could prevent conventional, global Euler buckling for holey column, which tends to choose the pattern switching mode, and our study also provides future perspectives for mechanics of buckling or optimal design for the cellular structures.

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