Computational Investigation of the Effect of Reinforcement Schemes and Angles on the Stress-Strain State and Strength of Composite Cylinders Under Axisymmetric Internal Explosion. Part 3. Results of Calculations for Two-Layer Cylinders with Orthogonal and Combined Reinforcement of the Layers

Strength of Materials - The effect of reinforcement patterns and angles on the stress-strain state and strength of two-layer wound composite cylinders of finite length with orthogonal reinforcement...     

Explosive Deformation and Fracture of Thick-Wall Cylinders

Deformation and fracture behavior of thick-wall cylinders under the action of detonation products was considered. Upon the outflow of the detonation products from the bore filled with explosive, spalling effects in the end of the cylinder and regular vortex structures over its thickness were noted.     

Computational Investigation of the Effect of Reinforcement Schemes and Angles on the Stress-Strain State and Strength of Composite Cylinders Under Axisymmetric Internal Explosion. Part 1. Effect of the Discretization Spacings of the Computational Domain on the Accuracy of Determination of Stress-Strain State and Strength

Strength of Materials - The effect of two-dimensional regular finite-difference mesh spacings on the accuracy of calculation of the dynamic axisymmetric stress-strain state and strength of hollow...     

Buckling Analysis of Cylinders Reinforced with Stiffening Rings and Foam. Numerical and Experimental Investigation

Strength of Materials - In this paper, a new regression formulation for buckling analysis of a cylinder with one, two and three stiffening rings with foam is presented. For this purpose, the...     

Helium and Hydrogen Adsorbed on Spheres and Cylinders

We examine the metastable and unstable regimes of condensation of superfluid helium and parahydrogen on spheres and cylinders at finite temperatures, employing finite range density functionals. The goal is to compare calculations of sizes and spreads of films at the onset of metastability and of instability with the predictions of a simple phenomenological model that contemplates the curvature of the substrate. We have focused on two cases, helium on nanospheres and nanocylinders of different materials, and hydrogen on fullerenes. We are able to locate the onset of metastability and of spinodal instability in the adsorption isotherms of every sample and to extract the width of the condensed fluid. It is shown that the predictions of the so-called simple model agree surprisingly well with the more elaborate calculations.     

Superfluid Helium Between Rotating Cylinders

The isotopic ordering of H2–D2 mixtures adsorbed at low temperature on graphite in the monolayer range is measured by small angle neutron scattering (SANS). We show that below 8 K, solid mixtures exhibit isotopic clustering at large density (monolayer completion) and a tendency towards the formation of ordered compounds for smaller density (near the commensurate structure).     

Magnetophoretic Potential of a Plane‐Ordered System of Ferrocylinders. 2. Rectangular Cylinders

The magnetophoretic properties of a system of equidistant identical rectangular ferromagnetic cylinders located in one plane and exposed to a uniform magnetic field are considered. The analytical solution of the problem on distribution of the magnetic field and the magnetophoretic potential in magnetization of the system to saturation along the packing plane and across it is obtained. The influence of geometric and magnetic parameters on the magnetophoretic properties of the system is investigated.     

Magnetophoretic Potential of a Plane‐Ordered System of Ferrocylinders. I. Circular Cylinders

The magnetophoretic potential of a system of equidistant identical ferrocylinders packed in one plane and exposed to a uniform magnetic field is studied. The influence of the structural step and the direction of magnetization of the structure are investigated.     

高强铝合金圆筒的稳定性

以高强铝合金圆筒为研究对象,研究了其在恒温恒载条件下长期承载后的尺寸稳定性和力学性能稳定性.结果表明:该高强铝合金圆筒在40℃温度下承载0.78σ0～0.92σ0约2×104h以后,其圆度有不同程度的减小,其蠕胀速率与试验载荷之间成指数关系,其环向力学性能与试验前相比,没有显著性差异.     

Micro VS. Macro Reinforcement of Brickwork Masonry

In this paper the effect of different modifications of mortar on the behaviour of brick masonry has been experimentally studied. Two modifications of ordinary cement lime rich mortar were made by introducing polypropylene fibres (micro reinforcement) and by reinforcing mortar bed joints by means of non-metallic meshes (macro reinforcement). Experimental tests were carried on the constituents of the masonry, as well as on masonry specimens consisting of wallettes and panels. Following different methodologies of testing masonry by means of compressive, diagonal and shear tests, the results of the investigation revealed that by reinforcing masonry material both compressive and tensile (shear) strength could be improved. Also from the results of the different test methods, it has been concluded that diagonal tests are not suitable for investigations of reinforced masonry.     

Circumferential Catastrophic Burst Failures of Pressurized Cylinders

Complete circumferential (360°) tearing has been observed at the bottom of body walls in a number of three-piece, steel, cylindrical aerosol containers. This type of failure has not been well documented and analyzed in previous aerosol can failure analysis literature. In one instance, a worker accidentally dropped an aerosol spray paint can, and it instantly burst via catastrophic 360° circumferential failure near the bottom of the body wall. This was a relatively low-pressure, low-temperature, nearly instantaneous fracture. The burst aerosol became a high-velocity rocket and impacted the worker in the face and caused the loss of one eye. Other similar incidents involving this same failure mechanism have occurred with varying degrees of injury. The objective of this study was to determine why the aerosols catastrophically burst in the 360° circumferential manner and, more importantly, to find a remedy and prevent future failures. Test methods were developed to quantitatively control the force and angle of impact that might result from the tapping, hitting, or accidental dropping of an aerosol container. More common failure analysis methods were also used, such as metallography, scanning electron microscopy, energy dispersive spectroscopy, simple bending tests to simulate low-cycle fatigue, and a method to measure internal aerosol pressure as a function of temperature. The most likely root cause for the 360° burst failures was determined to be a combination of pre-existing circumferential flaw or flaws, the anisotropic microstructure of the aerosol body steel and above yield stress that is facilitated by the geometry of the body-to-bottom design when the aerosol is tapped, hit, or accidentally dropped. Experiments show that changing microstructure and/or design significantly reduce the likelihood of this failure mechanism and offer simple, cost-effective remedies.     

Trapping and Near-Trapping by Arrays of Cylinders in Waves

In this paper, some recent developments and new results concerning the trapping of waves by arrays of vertical circular cylinders is presented. In particular, the cases are examined when there is a circular arrangement of cylinders and both finite and infinite periodic linear arrays of identical cylinders. Only for the infinite array is there pure trapping of waves – known as Rayleigh–Bloch or edge waves – which, for particular dominant wavenumbers, reduce to the well-known trapped-mode solutions for a cylinder between two parallel walls having either Neumann or Dirichlet conditions upon them. This latter case is considered separately and some new results are presented. In the circular array and finite linear array the concept of near-trapping is introduced where large resonant motions are found to occur at certain frequencies of the incident wave field. In the case of the finite linear array, these near-trapping frequencies are related to the Rayleigh–Bloch trapped-wave frequencies for the infinite array. Finally, the case when there are two or more lines of cylinders in the linear array is examined.     

两个同心施转圆柱间的Taylor问题

本文推导了在修正双极坐标系下的Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程和讨论了它的基本流的扰动解     

浅谈测压铜柱现状及发展

简介了测压铜柱的工作原理、使用方法及其发展过程,阐明了静标铜柱测量时产生动态误差的原因。介绍了测压铜柱准动态校准的含义及其实现方法,讨论了测压铜柱的高低温修正及脉宽修正的必要性。     

乙醇气体标准物质的气瓶内吸附性试验

以普通铝瓶等四种气瓶为试验对象,分别灌装不同含量的乙醇气体标准物质,对灌装一个月内的吸附平衡情况进行试验研究;再通过饱和预处理,找到不同浓度下,饱和气体的浓度和平衡时间,试验结果表明不同的铝质气瓶在经充分的预处理后,吸附水平整体降至1%以下,有效保证了乙醇气体标准物质的量值准确。     

The Fragmentation of Standard Concrete Cylinders During the Compressive Testing

The paper alternatively discusses the concrete cylinder compressive test. Basically, the fracture is treated as a single comminution process. After compressive testing, the main concrete debris as well as the samples of fine-grained particles, including grain-size distribution and grain shape, are analyzed. The fine-grained samples are distributed according to a R(osin)-R(ammler)-S(perling)-distribution. The distribution parameters depend on the mechanical properties of the concrete. The shpae factor increases as the compressive strength increases. Generally, with an increase in the strength properties, the fracture becomes non-regular due to a ‘homogenization’ of the fracture process. This revised version was published online in August 2006 with corrections to the Cover Date.     

Fabrication and Mechanical Testing of Ultralight Folded Lattice-Core Sandwich Cylinders

In this research, two novel folded lattice-core sandwich cylinders were designed, manufactured, and tested. The lattice core has periodic zigzag corrugations, whose ridges and valleys are directed axially or circumferentially. Free vibration and axial compression experiments were performed to reveal the fundamental frequency, free vibration modes, bearing capacity, and failure mode of the cylinder. A folded lattice core effectively restricts local buckling by reducing the dimension of the local skin periodic cell, and improves the global buckling resistance by enhancing the shear stiffness of the sandwich core. The cylinders fail at the mode of material failure and possess excellent load-carrying capacity. An axially directed folded sandwich cylinder has greater load-carrying capacity, while a circumferentially directed folded sandwich cylinder has higher fundamental frequencies. These two types of folded lattices provide a selection for engineers when designing a sandwich cylinder requiring strength or vibration. This research also presents a feasible way to fabricate a large-dimensional folded structure and promote its engineering application.     

Prediction of Distortion of Cylinders without Phase Transformations

The rule of Ameen whereby steel made cylinders with no phase transformations during quenching approach the spherical shape is contrary to the finding of Berger, who observes an elongation of thin and long work pieces. If the prediction of Ameen is correct, cylinders should decrease in length during heat treatment. This paper describes a first step of broader investigation of strain hardening and distortion of cylinders during gas quenching in a gas nozzle field. To make more general predictions about the distortion of cylinders which show no phase transformations during heat treatment, different dimensions of cylinders (lengths 50 mm, 100 mm and 200 mm, diameters 10 mm up to 100 mm) were investigated by means of numerical and experimental methods. The prediction of dimension and shape changes during gas quenching of steel cylinders has been performed by numerical simulation using the commercial Finite Element Program SYSWELD. The austenitic steel SAE30300 (German grade X8CrNiS18.9) was selected as investigated material; it shows no phase transformations during performed heating and cooling. The investigations show a good agreement between the kinematic strain hardening model and the experimental data, whereas the isotropic model is not in line with the experimental data. If the ratio of length and diameter is greater than 3, the relative changes in length displayed against the Biot number give uniform curves for all investigated geometries and heat transfer coefficients.     

Design and Optimization of Thick-Walled Cylinders with Load Localization Near the End Face

Strength of Materials - The paper presents a procedure for determining the design parameters of multilayer thick-walled structures with a local load on the inner surface portion located near the...