Numerical Analyses of Bearing Capacity of Deep-Embedded Large-Diameter Cylindrical Structure on Soft Ground Against Lateral Loads

Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotmpic soft ground. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in the passive zone or two wedges in both active and passive zones near the mudline, depending on the separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge, and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method by virtue of the general-purpose FEM software ABAQUS, in which the soil is assumed to obey tie Hill＇s criterion of yield. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. For the K0-consolidated ground of clays typically with anisotropic undrained strength property, it is indicated through a parametric study that limit analysis without consideration of anisotropy of soil overestimates the lateral ultimate bearing capacity of a deeply-embedded cylindrical structure in soft ground in a certain condition.

Numerical Simulation of Large Diameter Cylindrical Structure Slamming

The water entry of large diameter cylindrical structure is studied by applying numerical simulation method. The processes of different diameter cyhndrical structures impacting water with various constant velocities are calculated numerically. Thereafter, analyzed are the distribution of slamming pressure on structure during slamming course and the influence of slamming velocity and cylindrical diameter on slamming process. Furthermore, presented herein is an equation being used to forecast the peak slamming force on a large diameter cylindrical structure.

Dynamic Wave Pressures on Deeply Embedded Large Cylindrical Structures due to Random Waves

The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil and structure. In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves, and accordingly to offer valuable findings for engineering, the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different embedment depths in response to two wave spectra.The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain. By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder, experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory, and detailed comparisons were also carried out between the single and continuous cylinders. Some new findings and the corresponding analysis are reported in present paper. The investigation on continuous cylinders will be used in particular for reference in engineering applications because information is scarce on studying such kind of problem both analytically and experimentally.

INVESTIGATION ON INSTABLE STANDARD OF EMBEDDED CYLINDRICAL STRUCTURE

The control value of the deflection of the embedded cylindrical structure, which is the maximum deflection allowed for stability of the cylinder, is a vital quantity of stability calculation. The deflection and the soil pressure on the embedded cylinder were investigated by model experiment. When the inclined angle of cylinder is less than or equal to 0.25°, the effective anti-overturning ratio increases gradually and reaches the maximum. When the inclined angle of cylinder is more than 0.25°, the effective anti-overturning ratio decreases gradually. The control value of instability of the cylindrical structure approximates 0.2°. and the bearing stress at the back edge of the cylinder is equal to zero.

A new local resonance metamaterial for flat and cylindrical structures depended on elastic chiral spiral beams

In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to control low-frequency vibrations,making them difficult to apply in real-world engineering scenarios.To address this limitation,we propose a homogeneous locally resonance metamaterial with tunable low-frequency bandgaps.This design overcomes the challenges associated with conventional local resonators,which are often large and heavy,making them impractical for engineering applications.By integrating resonator structures composed of elastic chiral spiral beams and mass blocks onto the supporting structure,we achieve lowfrequency vibration control within limited spaces,broadband absorption with gradient parameter units,and vibration control under different curvatures.The effectiveness of the proposed design is validated through comparative computational methods,dispersion curve calculations,frequency response simulations,and experimental tests.This study proposes a novel LRM structure with a full bandgap from 96.9 to 124 Hz.The transmittance is negative in most of the band gap range,which has been verified through numerical and experimental results.This approach effectively meets the complex low-frequency vibration control requirements of various curved structures in engineering applications,providing a viable solution for low-frequency vibration control of structures such as flat and cylindrical shells.

EXPERIMENTAL RESEARCH ON RADIATION FROM DOUBLE CYLINDRICAL STRUCTURES

An experiment on radiation from double cylindrical structures was held in an open-air pond. Radiation responses from one-point harmonic force driven model and two-point stochastic forces driven model were measured. Numerical results show a good agreement with the experimental results. Possible errors are analyzed.

Elastic Buckling of Bionic Cylindrical Shells Based on Bamboo

High load-bearing efficiency is one of the advantages of biological structures after the evolution of billions of years. Biomimicking from nature may offer the potential for lightweight design. In the viewpoint ofrnechanics properties, the culm of bamboo comprises of two types of cells and the number of the vascular bundles takes a gradient of distribution. A three-point bending test was carried out to measure the elastic modulus. Results show that the elastic modulus of bamboo decreases gradually from the periphery towards the centre. Based on the structural characteristics of bamboo, a bionic cylindrical structure was designed to mimic the gradient distribution of vascular bundles and parenchyma cells. The buckling resistance of the bionic structure was compared with that of a traditional shell of equal mass under axial pressure by finite element simulations. Results show that the load-bearing capacity of bionic shell is increased by 124.8%. The buckling mode of bionic structure is global buckling while that of the conventional shell is local buckling.

Pullout of the Cylindrical Helicoidal Fiber

The multi-layer cylindrical helicoidal fiber structure(MCHFS)exists widely in biological materials such as bone and wood at the microscale.MCHFSs typically function as reinforcing elements to enhance the toughness of materials.In this study,we establish a shear lag-based pullout model of the cylindrical helicoidal fiber(CHF)for investigating interlayer stress transfer and debonding behaviors,with implications regarding the underlying toughening mechanism of MCHFS.Based on the shear lag assumptions,analytical solutions for the stress and displacement fields of the MCHFS during the pullout are derived by considering the CHF as a cylindrically monoclinic material and verified through the 3D finite element simulation.It is found that the helical winding of CHF results in both axial and hoop interlayer shear stresses.Both the helical winding angle and the elastic moduli of the fiber and matrix have significant influences on interlayer stress transfer.This work reveals a new interlayer stress transfer mechanism in the MCHFS existing widely in biological materials.

Sound Insulation Performance of Pyramidal Truss Core Cylindrical Sandwich Structure

Recently,cylindrical structures have been exploited in various fields due to their excellent mechanical properties.With the increase in the application of cylindrical shell structures,researchers are paying more and more attention to its acoustic performance and sound insulation applications.By inserting the pyramidal truss lattice into the cylindrical shell structure,a cylindrical sandwich structure is obtained and the sound insulation performance of the structure is investigated.The space-harmonic expansion method and the principle of virtual work are employed to establish a theoretical model for the acoustic analysis of cylindrical sandwich structures.The vibro-acoustic coupling is taken into account by imposing the velocity continuity condition at the fluid-solid interface.The sound transmission loss(STL)performance of the structure is examined by establishing both theoretical and finite element models.Subsequently,the influence of various parameters on sound transmission loss is researched and analyzed.

Safety-enhanced Polymer Electrolytes with High Ambient-temperature Lithium-ion Conductivity Based on ABA Triblock Copolymers

Liquid electrolytes used in lithium-ion batteries suffer from leakage,flammability,and lithium dendrites,making polymer electrolyte a potential alternative.Herein,a series of ABA triblock copolymers(ABA-x)containing a mesogen-jacketed liquid crystalline polymer(MJLCP)with a polynorbornene backbone as segment A and a second polynorbornene-based polymer having poly(ethylene oxide)(PEO)side chains as segment B were synthesized through tandem ring-opening metathesis polymerizations.The block copolymers can self-assemble into ordered morphologies at 200℃.After doping of lithium salts and ionic liquid(IL),ABA-x self-assembles into cylindrical structures.The MJLCP segments with a high glass transition temperature and a stable liquid crystalline phase serve as physical crosslinking points,which significantly improve the mechanical performance of the polymer electrolytes.The ionic conductivity of ABA-x/lithium salt/IL is as high as 10-3 S·cm-1 at ambient temperature owing to the high IL uptake and the continuous phase of conducting PEO domains.The relationship between ionic conductivity and temperature fits the Vogel-Tamman-Fulcher(VTF)equation.In addition,the electrolyte films are flame retardant owing to the addition of IL.The polymer electrolytes with good safety and high ambient-temperature ionic conductivity developed in this work are potentially useful in solid lithium-ion batteries.