Containment of explosions in cylindrical shells

An experimental and theoretical investigation of the high explosive containment ability of circular cylindrical shells is presented. Approximate expressions for final circumferential strain or radial displacement as a function of cylinder length are developed in terms of elementary functions, based upon an assumed rigid-plastic material relation for the containment vessel. The material relation includes strain hardening and approximate strain-rate sensitivity. The expressions are presented in a form convenient for containment design purposes and are shown to be in reasonable agreement with experimental results for several container materials and radius-to-thickness ratios.     

Experiments on the buckling under internal pressure of thin torispherical ends of cylindrical pressure vessels

Ten cylindrical pressure vessels with torispherical ends, all of the same constant nominal thickness, were tested under internal pressure to observe the buckling behaviour of the toroidal knuckle. All specimens were of constant internal cylinder diameter to thickness ratio of 531·5. The sphere radius was equal to the cylinder diameter and only the torus radius was varied. Buckling was detected by rotating probes at the sphere/torus junction and at the mid-point of the torus. The buckling pressure increased with increasing torus radius and the two specimens with the largest torus radii did not buckle.For all specimens, the change of meridional shape with increase in pressure was measured. For one specimen, strain gauges were used to study the variation of circumferential strain on the inside and outside surface at the sphere/torus junction due to variation in thickness round the circumference.A simple theoretical expression for the buckling pressure, similar to the Rankine formula for a strut, is suggested.     

Stability, bifurcation and chaos of closed flexible cylindrical shells

Complex vibrations of closed cylindrical shells of infinite length and circular cross-section subjected to transversal local load in the frame of the classical non-linear theories are studied. A transition from partial differential equations (PDEs) to ordinary differential equations (ODEs) is carried out using a higher-order Bubnov–Galerkin approach and Fourier representation. On the other hand, the Cauchy problem is solved using the fourth-order Runge–Kutta method.In the first part of this work, static problems of the theory of closed cylindrical shells are studied. Reliability of the obtained results is verified by comparing them with the results taken from literature. The second part is devoted to the analysis of stability, bifurcation and chaos of closed cylindrical shells. In particular, an influence of sign-changeable external pressure and the control parameters such as magnitude of pressure measured by ₀, relative linear shell dimension λ=L/R, frequency ω_p and amplitude q₀ of external transversal load, on the shell's non-linear dynamics is studied.     

The design of ends of cylindrical pressure vessels in glass reinforced plastic

A design procedure for torispherical and semi-ellipsoidal ends of cylindrical chopped strand mat glass-fibre reinforced plastic pressure vessels is presented. The method is applicable where all layers of reinforcement are of the same type. The procedure takes account of the effect of the change of shape of the end due to pressure. The procedure is based on either maximum stress or maximum strain. The criteria used aim to achieve consistency with the BS.4994 method of calculating the design unit loading of laminates and allow for the biaxial stress states which occur in the vessels.     

高精度圆柱套内壁闭合异形曲线槽的检测方法

一种高精度圆柱套内壁闭合曲线槽的检测装置,尤其适用于对高强度、高刚性、高精度的内壁闭合异形曲线槽工作曲面的精密检测,该装置由工件主轴传动系统、床身、深度进给轴传动系统、直线进给轴传动系统、检测装置、数控系统、电感测微仪组成;通过直线进给轴、工件主轴联动,采集电感测微仪的数据并存储到计算机中,实现了圆柱套内壁闭合异形曲线槽工作曲面的精密检测,可满足高强度、高刚性内壁闭合异形曲线槽工作曲面的加工精度要求。     

Adaptation of spherical and cylindrical vessels to variable internal pressure and temperature

The kinematic theorem is applied to solve some problems of shakedown of spherical and cylindrical vessels subjected to variable internal pressure and temperature, taking into account the temperature dependence of the yield stress.     

Analysis of thick-walled cylindrical pressure vessels under the effect of cyclic internal pressure and cyclic temperature

A problem common to the pressure vessels' designer is the evaluation of stresses due to the effect of both cyclic temperature and pressure. This paper presents a complete analysis of stresses within the wall of a cylindrical pressure vessel subjected to cyclic internal pressure and temperature. The time-dependent stress distribution is obtained using a numerical model on the basis of the forward finite difference technique. The influence of the working parameters, such as mean pressure and mean temperature, pressure and temperature amplitudes, diameter ratio, etc. on the effective stress is studied. The relation between the mean stress and stress amplitude is obtained for different working conditions. The relation between the working parameters according to Soderberg criteria is presented. An approximate expression for the relation between the working parameters is introduced in a simple and direct form. The results of the approximate solution are found to fit well with the numerical findings.     

内压作用下斜接管容器塑性极限载荷的数值研究

对三台具有斜接管的圆柱形容器(θ=30°,45°,60°)在内压作用下的塑性变形特征及塑性极限载荷进行了三维非线性有限元数值研究.结果表明:斜接管与筒体截交区纵向截面的锐角侧材料首先进入塑性状态.截交区附近出现明显的塑性变形,纵向截面内发生径向收缩,而横向截面出现明显的径向鼓胀,接管与筒体间的夹角减小.结果同时提供了三台容器的极限载荷值,为该类容器的分析设计提供了依据和参考.     

圆柱滚子轴承的圆柱深孔滚子受力分析

针对铁路客车圆柱滚子轴承的设计和生产工艺，根据圆柱体接触应力有限元计算分析，提出深孔圆柱滚子结构可以消除普通圆柱滚子轴承的接触应力边缘效应问题，提高铁路客车圆柱滚子轴承的疲劳寿命。     

Oscillatory behaviors in initial film boiling: Implications on the triggerability of single droplet vapor explosions

A transient one-dimensional film boiling model was developed to study the film boiling dynamics that would occur when a hot spherical droplet is immersed in cold liquid. The focus of this study was to investigate the effects of noncondensible gas, liquid temperature, droplet temperature, and ambient pressure on film boiling during the initial growth phase. The results indicate that the film generally stablizes with more noncondensible gas present, higher liquid and lower droplet temperature. Small ambient pressurizations cause violent fluctuations of the film pressure while higher ambient pressure suppresses these oscillations. These qualitative behavior of film boiling around hot spherical droplet suggests that the spontaneous triggering of small-scale single droplet vapor explosions is led by the oscillatory characteristics of vapor film in its initial growth phase.     

A method for calculating the lower bound limit pressure for thick shells of revolution with specific reference to cylindrical vessels with torispherical ends

A method is proposed for calculating the lower bound limit pressure for thick shells of revolution under axisymmetric loading conditions. The method, which deals directly with stresses and the material yield criterion, can be applied to shells of any thickness. It is applied here to the problem of evaluating a lower bound to the limit pressure of a thick cylindrical vessel with torispherical ends of constant thickness. The stresses are expressed in terms of an independent set of variables and a non-linear programming method is used in the optimization of the limit pressure. Results are presented for a limited range of geometric parameters.     

A detector for imaging of explosions on a synchrotron radiation beam

Synchrotron radiation (SR) offers a unique chance to study the structure of a substance in fast processes. Since SR is emitted by electron bunches in a storage ring, the SR burst corresponding to a single bunch may be very short. Should a detector capable of detecting SR from a single bunch without mixing signals from different bunches be available, it is possible to obtain information on changes in the state of the material in a sample under investigation with a very high time resolution. A detector for imaging of explosions on an SR beam—DIMEX—has been developed by the Budker Institute of Nuclear Physics (Siberian Division of the Russian Academy of Sciences, Novosibirsk). This detector is a high-pressure ion-ization chamber with a strip readout at a pitch of 0.1 mm. The electron component of primary ionization is collected within 50 ns, which is substantially shorter than the orbital period of a bunch in the VEPP-3 storage ring (250 ns). The DIMEX is filled with a Xe—CO₂ mixture (3: 1) at an absolute pressure of 7 atm. The spatial resolution of the detector is ∼210 μm, and its efficiency for radiation with an energy of 20 keV is ≥50%. The dynamic range of the detector is ∼100, which allows one to measure the signal with an accuracy of ∼1%. In this case, the maximum flux of X-ray photons, at which the DIMEX operates in a linear region, is ∼10¹⁰ photons/(channel s). Today, the detector has been used in experiments aimed at studying evolution of the density in detonation waves and processes of nanoparticle production at the VEPP-3 storage ring by employing the small-angle X-ray scattering technique.     

气力输送系统中柱状粒子运动的研究

根据单粒子的运动理论，研究了圆柱粒子在平行气流中的运动状况。分别推导了圆柱状粒子在平行气流中的水平运动和垂直运动方程，给出了粒子速度与时间和距离的关系，并分析了速度变化和圆柱粒子倾斜角θ的关系，及速度变化与无量纲参数φ=ug／ua之间的关系。     

轴向槽圆柱气体动压轴承的性能研究

采用有限差分法计算轴向槽圆柱气体动压轴承的压力分布,计算轴承的承载能力和偏位角.分析显示,轴向槽位置对轴承性能有较大影响.通过计算结果与相关文献的相应数据进行对比证明,该计算方法的可行性.     

Basing of cylindrical blanks on prisms

The basing of cylindrical blanks on prisms is analyzed. A new approach to selecting bases and basing configurations is proposed.     

管系载荷对设备设计的影响

基于化工过程的生产特点 ,管系载荷引起的设备应力是不可忽视的。本文讨论了管系载荷对设备壳体、接管、法兰和支座的影响     

分布式光纤在全容式低温储罐泄漏检测中的应用

为了提高低温储罐的安全性,降低传统检测方式的成本,采用新技术新方法是一项重要措施。分布式光纤测温系统在效率、精度、成本、安装等方面优点突出,已经在众多行业和场合得到了广泛应用。本文概述了分布式光纤测温系统的基本原理与构成以及在全容式低温储罐上应用的可行性,并对其安装与敷设方式进行了探讨。