Effect Of Inner Pressure Research Articles

A yield criterion for porous crystalline materials with inner pressure

To theoretically analyze the effects of voids and inner pressure on the nonlinear deformation behavior of porous metallic materials, a yield criterion related to the von Mises stress and hydrostatic stress has been developed based on variational approach. Under different stress triaxial loading conditions, the proposed criterion is applied to analyze the yield surface of porous single crystal with various porosities and inner pressures. It is revealed that the existence of voids and inner pressure significantly reduces the size of yield surface for porous single crystal under high stress triaxial loading, whereas this effect is insignificant in the case of low stress triaxiality. Furthermore, by considering the effect of inner pressure on the effective shear stress of dislocation movement, a modified crystal plastic theory is adopted to evaluate the plastic deformation behavior of porous single crystal with inner pressure. Combining the self-consistent theory, the influence of voids and inner pressure on the yield strength and flow stress of polycrystalline materials have been obtained. Numerical results of proposed criterion can match well with corresponding results of the finite element simulation and experiment, indicating the good accuracy and rationality of the proposed criterion.

Dynamic analysis of an axially moving beam subject to inner pressure using finite element method

A dynamic model of an axially moving flexible beam subject to an inner pressure is present. The coupling principle between a flexible beam and inner pressure is analyzed first, and the potential energy of the inner pressure due to the beam bending is derived using the principle of virtual work. A 1D hollow beam element contain inner pressure is established. The finite element method and Lagrange’s equation are used to derive the motion equations of the axially moving system. The dynamic responses are analyzed by Newmark-β time integration method. Based on the computed dynamic responses, the effects of inner pressure on beam dynamics are discussed. Some interesting phenomenon is observed.

Effect of PyC Thermal Behavior on the Stress of TRISO-Coated Fuel Particles

TRISO coated fuel particle is the most important component in HTR fuel, the silicon carbide (SiC) coating layer is regarded as the pressure vessel to contain the fission products. During reactor operation, the inner pressure resulting from fission products and pyrocarbon (PyC) thermal effect will contribute to the failure of TRISO-coated particles. The higher temperature will result in the increasing of inner pressure and PyC thermal expansion, which will then change the stress of SiC layer. Considering the effects of temperature on inner-pressure expansion and elastic strain into the pressure vessel failure model, thermal effects on the stress of TRISO-coated particles were studied with analytical solution. The results indicated that the effects of inner pressure on the particle stresses were increasingly highlighted at the late stage of irradiation. And the increasing temperature caused a slight effect on PyC elastic modulus while elastic strain is unaffected greatly, either. Therefore, CFP stresses remain unchanged basically.

An experimental study on the leakage process of high pressure CO2from a pipeline transport system

A laboratory scale experimental pipeline system is developed to investigate the leakage behavior of high pressure CO 2 . The 23‐m‐long experimental pipeline could provide an inner pressure varying from 0.1 to 10 MPa and a preset temperature within the range of 0 ∼ 50 °C to ensure a stable initial phase state for the leakage test. Experiments on CO 2 leakage with three initial inner pressures and four different nozzle orifice sizes were conducted using this system. The individual and combined effects of inner pressure and leakage orifice size on the main characteristic flow parameters of the pipeline, the structure of the leakage jet, and the temperature decrease of the plume were investigated. Based on the experimental results, limitations of the previous theoretical formula on mass loss rate were discussed. The maximum temperature decrease along the centerline of the far‐field plume by Joule‐Thomson effect was also studied. The new experimental test facility proves to be valuable in analyzing the hazardous leakage process of CO 2 from pipelines.

Study of the effects of inner pressure and surface tension on the fibre drawing process with the aid of an analytical asymptotic fibre drawing model and the numerical solution of the full N.–St. equations

Micro-structured optical fibres (i.e. fibres that contain holes) have assumed a high profile in recent years and given rise to many novel optical devices. The problem of manufacturing such fibres by heating and then drawing a preform is considered for the case of annular capillaries. A fluid mechanics model suggested in the literature that uses asymptotic analysis based on the small aspect ratio of capillaries has been compared with the full 3D set of the N.–St. equations, for modelling the fabrication of capillaries. The final asymptotic equations, analysed in some asymptotic limits, are solved numerically and then compared with the N.–St. solutions, obtained with a commercial finite elements solver. These asymptotic limits give valuable practical information about the control parameters that influence the drawing process, taking into account the effects of surface tension and inner pressure, since those are of essential importance during drawing. It is shown that the asymptotic method delivers reliable results as long as the inner pressure does not exceed too high values.

Numerical Solution and Experimental Validation of the Drawing Process of Six-Hole Optical Fibers Including the Effects of Inner Pressure and Surface Tension

Microstructured optical fibers (MOFs) achieve their desired performance via a pattern of holes that run trough the whole length of the fiber. The variation of the hole pattern allows the production of a variety of optical effects. However, the cross-sectional hole structure can be different from that designed in the preform, due to the combined effects of surface tension and internal pressure. The present paper focuses on the comparison between experiments and numerical calculation of a six hole-optical fiber taking into account the effects of surface tension and internal hole-pressure, since those are of essential importance during drawing. It is shown that the numerical computations deliver reliable results for practical applications and can be used as a predictive tool for fiber development, as long as the inner pressure or the temperature do not exceed too high values.

Wave propagation in a viscous fluid contained in a prestressed viscoelastic thin tube

In this work a theoretical analysis is presented for the wave propagation in a thin walled prestressed viscoelastic tube filled with a viscous fluid. The fluid is assumed to be incompressible and Newtonian, whereas the tube material is considered to be incompressible, isotropic and viscoelastic. Considering the physiological conditions that the arteries are subjected to, such a tube may be treated to be initially stressed under the effect of inner pressure P i and the axial stretch λ z. Assuming that in the course of blood flow, a small incremental disturbance is added onto this initial field, the governing equations of this incremental motion are obtained for a fluid and viscoelastic tube. A harmonic wave type of solution is sought for these field equations and the dispersion relation is obtained. Some special cases, as well as the general case, are thoroughly discussed and the present formulation is compared with some previous works on the same subject.