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An eight-legged vibration isolation platform (ELVIP) with dual-pyramid-shape (DPS) struts is proposed in this paper to achieve six-degree-of-freedom vibration isolation. The DPS strut has higher static stiffness and lower dynamic stiffness than the equivalent linear strut due to geometric nonlinearity, and therefore the ELVIP with DPS struts possesses high-static–low-dynamic-stiffness characteristic...
A comprehensive dynamic study on a distributed parameter model of a straight uniform rotating shaft is developed, aimed at presenting some clarifications and corrections to published results, together with novel contributions. The model includes the effects of transverse shear, rotatory inertia and gyroscopic moments with additional combined end thrust and twisting moment. The equations of motion...
A particular hydro-elastic model is considered to examine a radiation problem involving an immersed sphere in an infinitely extended ice-covered sea, where the lower surface is enveloped by a flexible base surface. Both the flexible base surface and floating ice-plate are modelled as thin elastic plates with different configurations and are based on the Euler–Bernoulli beam equation. The appearance...
This paper deals with nonlinear mechanics of an elevator brake system subjected to uncertainties. A deterministic model that relates the braking force with uncertain parameters is deduced from mechanical equilibrium conditions. In order to take into account parameters variabilities, a parametric probabilistic approach is employed. In this stochastic formalism, the uncertain parameters are modeled...
Simple formulas for calculating equivalent von Mises stress and von Mises effective plastic strain in an elastic–plastic ordinary peridynamic analysis are proposed. The equivalent von Mises stress is calculated by equating the deviatoric part of strain energy obtained from classical continuum mechanics and peridynamics. The effective plastic strain is proposed so that it reduced to uniaxial plastic...
This paper is devoted to investigate the nonlinear dynamic characteristics of lattice sandwich composite panels resting on Winkler–Pasternak elastic foundations under simultaneous aerodynamic and thermal loads in supersonic airflow. The first-order shear deformation and von Kármán large deflection theories are applied in the structural modeling. The supersonic piston theory is used to model the aerodynamic...
The article deals with materials with a constraint on the stress, which must belong to a closed and convex subset of the space of the second order tensors, called stress range. With particular reference to the case of polyhedral stress ranges, the nonlinear elastic constitutive model and the elastoplastic one are compared to each other and a new “mixed model” is proposed. The latter may be appropriate...
A theoretical and experimental study has been undertaken, under ESA contract, by a team including GMV, the University of Bologna and EADS-Astrium, to assess the feasibility of an entry descent and landing (EDL) vehicle based on unpowered rotary decelerator. A deployable rotor with telescopic blades is considered, aimed at replacing all the standard deceleration devices for a descent module (parachutes,...
The issue of gear noise is fairly common in power transmission systems. This noise largely stems from the gear pairs vibration triggered by transmission error excitation. This is mainly caused by tooth profile errors, misalignment and tooth deflections. This research endeavors to examine nonlinear spiral bevel gears vibration with the innovative method of tooth surface modification. To design spiral...
Wear between balls and races has significant effects on the dynamic characteristics of bearing, which is the main reason to cause bearing failure. Some existing contact stiffness models were established to study the dynamic characteristics of bearing. However, the wear of bearing has been rarely investigated due to the complexities of contact load and wear mechanism. This paper presents a new dynamic...
This paper focuses on the interaction of low Reynolds number (Re) flows and thin shell type deformable structures in the context of flexible body locomotion and addresses the coupled field problem through a numerical solution framework. The thin structure is discretized by enhanced three-node finite elements and coupled with boundary element based treatment of Stokes flow in a monolithic manner. The...
Compressor behaviour analysis in critical working conditions, such as incipient surge, represents a significant aspect in the turbomachinery research field. Turbines connected with large-size volumes present critical issues related to surge prevention especially during transient operations. Investigations based on acoustic and vibrational measurements appear to provide an interesting diagnostic and...
The pin-ended, slender, Euler strut has been used as the archetypal buckling problem for many years (Euler in Additamentum I de curvis elasticis, methodus inveniendi lineas curvas maximi minimivi proprietate gaudentes, Bousquet, Lausanne, 1744). Even though it is not conventionally imperfection-sensitive (i.e., in which the magnitude of the buckling load is compromised by the presence of imperfections),...
The present work deals with temporal electro-aerodynamics instability properties of an inviscid confined planar jet in a zero gravity environment and the existence of electric field. The considered system is composed of a horizontal liquid sheet surrounded by two identical moving layers of fluid. The electric field acts uniformly normal to the interfaces. The governing equations with the boundary...
This study addresses the linear and nonlinear resonance of the film flow on an inclined slippery topography plate in the frame of long-wave theory. The influence of the surface tension is taken into account. The fluid flow is assumed to be steady, and confined to the limit of a small amplitude of the wall corrugation. The influence of the slip condition is the main factor in the study. The effects...
This paper presents the numerical and experimental study on mixing enhancement in a novel electro-osmotic micro-mixer in the presence of AC and DC electric fields. PDMS is used for the fabrication of the microchip and gold nanoparticles are employed to make the electrodes. It is demonstrated that the generation of vortices due to electro-osmotic force enhances the mixing quality considerably. The...
A model has been proposed to estimate the average number of fragments produced by ductile fracture of a rapidly expanding ring with arbitrary cross-section. The model uses a minimum number of constants characterizing the material properties of the ring. We assume that material of the ring is incompressible with the density ρ and its mechanical behavior obeys the ideal rigid-plastic model with yield...
Pneumatic Artificial Muscles (PAMs) also called braided pneumatic actuators were invented by Mckibben to help the Polio patients. When the internal bladder is pressurized the actuator gets shorter which can produce a tensile force. PAMs are widely used in bio robotic as well as industrial, medical and rehabilitation robotic applications due to their salient advantages such as high power to weight...
In the mechanical tribology research, reasonable and effective improvement of lubrication performance for friction pairs of sleeve bearings is one of the hot topics, surface micro texture processing technology has gradually become an important way to improve the lubrication performance of friction pairs. Taking the friction pair model of infinite wide bearing as the research object, the Reynolds equation...
A flow mixing nozzle can produce satisfactory atomization for heavy oil. However, the study of the internal flow pattern of this nozzle, along with the spray morphology and its transformation, is currently limited to a low flow rate for the two-phase inlet. A flow mixing nozzle with a moderate inlet flow rate and various nozzle structures (H/D) was experimentally studied using a self-designed flow...
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