Deformation of protective flat barriers with access hatches

Based on the model for an ideal rigid-plastic body, a procedure has been developed to analyze dynamic behavior of elliptic hingedly supported or clamped plates containing an absolutely rigid insert of an arbitrary shape. The plate is subjected to a short-time high-intensity dynamic blast load uniformly distributed over the surface. It is shown that the plate can deform through more than one mechanism. Equations for dynamic deformation are derived for each mechanism, and the conditions for their occurrence are analyzed. Examples of numerical solutions for the cases of circular and rectangular rigid inserts are given. __________ Translated from Problemy Prochnosti, No. 1, pp. 22–38, January–February, 2007.     

Interaction of a rotating punch with a half space in the case of partial adhesion in the contact zone

We solve an axisymmetric problem of interaction of a rigid rotating cylinder with an elastic half space. The outer part of the contact zone is subjected to the action of kinematic friction forces and the inner part of this zone is under the action of friction forces of rest. Beyond the punch, the surface of the half space is unloaded. The problem is solved by using the Hankel integral transformation and the method of weighted residuals. We determine the distributions of tangential stresses and displacements on the boundary of the half space and present the plots the internal radius of the sliding zone and the angle of rotation of the punch as functions of the applied moment. Deceased. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 33, No. 2, pp. 55–61, March–April, 1997.     

Computational slosh dynamics: theory and industrial application

 The effect of liquid sloshing upon the performance, control, and acoustics of vehicles is becoming more pronounced with the increasing size of fuel tanks. Especially the fundamental natural frequency and the viscous damping rate are important quantities from an engineering point of view. Theory and industrial application for calculating numerically sloshing effects of viscous liquids within fuel tanks are presented for various container geometries. The numerical treatment uses the volume-of-fluid method for calculating the free surface flows. The efficiency and the error level of the chosen numerical approach are evaluated by academic benchmark tests. The industrial application presented covers a typical contemporary automotive fuel tank and its sloshing problems. Received: 27 May 2002 / Accepted: 6 January 2003 This work has been performed as a part of the automotive slosh research at KAUTEX TEXTRON GmbH & Co. KG, Bonn. In addition, the author expresses his thanks for submitting helpful papers by W. Eidel and H. Bauer, Neubiberg.     

On the resistance to penetration of stiffened plates,Part I – Experiments

The paper deals with hull damage in ships which are subjected to grounding actions. A ship is assumed to settle vertically on a rock. It is further assumed that contact actions are local and restricted to one plate section. The scenario is analyzed by conducting a series of panel indentation experiments. Various configurations of stiffened panels are loaded laterally by a cone shaped indenter until fracture occurs. The specimen dimensions represent a 1:3 scale of the dimensions found in medium sized tankers. Naturally, because damaged hull and cargo tanks may have severe environmental consequences, e.g. as exemplified by high profiled grounding accidents such as the Exxon Valdez grounding which lead to the discharge of nearly 240,000 barrels of oil, focus is on the plastic deformation and fracture resistance of the panel.     

Thermophysical Properties of U–Mo/Al Alloy Dispersion Fuel Meats

Uranium–molybdenum alloy dispersion fuel meats are being studied for utilization as a research reactor fuel. Thermophysical properties of U–Mo/Al dispersion fuel, where U–Mo was dispersed in aluminum in research reactor fuel for the study, were determined by computing the thermal conductivity through measurements of the specific heat capacity and thermal diffusivity. Uranium molybdenum powder was first fabricated and utilized as U–Mo/Al dispersion fuel; the molybdenum-to-uranium ratios were 6, 8, and 10 mass% to produce the initial powder, which was then combined with aluminum (Al 1060). The volume fractions of U–Mo powder to aluminum were 10, 30, 40, and 50 vol.% to fabricate the dispersion fuel. The thermal diffusivity and specific heat capacity were measured by the laser-flash and differential scanning calorimetry (DSC) methods, respectively. Although the thermal diffusivity showed a decreasing trend with the U–Mo volume fraction when the dispersion quantity was insignificant, the trend reversed with a higher dispersion level. The specific heat capacity increases monotonically with temperature; its value is larger for a smaller dispersion level. Additionally, the overall thermal conductivity increases with temperature. Finally, the thermal conductivity decreases with an increase in the amount of U–Mo powder in the dispersion fuel. Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

On the Occurrences of “Frizzle-Type” Surface Defects in a Hot-Rolled Steel Plate

Metallurgical investigations were directed to probe into the genesis of “frizzle” and fissure-type surface defects on 10-mm hot-rolled steel plates meant for application in flat-bed wagons for carrying heavy machinery. The thin hairline fissures on the steel plates were identified as skin laminations associated with long, shallow, and branched cracks, intruding from the plate surfaces to the interior with curved contours, replete with fragmented oxide scale entrapments and debris. The incidence of these superficial defects on the plates was linked to surface damage to the solidifying skin of continuously cast steel slabs, induced by the extensive pitting and cavitation of caster pinch rolls. It is presumed that during hot rolling of the steel slabs, surface blemishes like indentations and folds got rolled over by metal flow, entrapping copious amounts of primary as well as secondary scales underneath the laminated skin. Under the influence of shear forces during rolling, the defects are believed to have ingressed further into the plate interior leading to the formation of long, shallow, and branched cracks with curved contours and entrapped fragmented oxide scales.     

Added mass computations by integral equation methods

This paper presents boundary integral equation procedures for calculating the added mass matrix required to determine hydroelastic vibrational modes of tanks or immersed structures. The liquid is assumed inviscid and incompressible and no surface waves are admitted. Two symmetric variational formulations of the boundary integral equation are derived, including the free surface condition and possible conditions of symmetry. These are approximated by a curved finite element method and numerical results are presented for an axisymmetric tank, immersed cantilever plates and a three-dimensional fuel storage container.     

Formation of a bioactive calcium titanate layer on gum metal by chemical treatment

The so-called gum metal with the composition Ti–36Nb–2Ta–3Zr–0.3O is free from cytotoxic elements and exhibits a low elastic modulus as well as high mechanical strength. In the present study, it was shown that this alloy exhibited a high capacity for apatite formation in a simulated body fluid when subjected to 1 M NaOH treatment, 100 mM CaCl₂ treatment, heat treatment at 700°C, and then hot water treatment. The high apatite formation was attributed to the CaTi₂O₅ which was precipitated on its surface, and found to be maintained even in a humid environment over a long period. The treated surface exhibited high scratch resistance, which is likely to be useful in clinical applications. The surface treatment had little effect on the unique mechanical properties described above. These results show that gum metal subjected to the present surface treatments exhibits a high potential for bone-bonding, which will be useful in orthopedic and dental implants.     

Investigations on gradient a.c. conductivity characteristics of bamboo (Dendrocalamus strictus)

Effect of temperature and frequency variation on a.c. conductivity of bamboo was determined by using a 4274 A Multi-Frequencies LCR meter. Electrical measurements were carried out in the temperature range 24–120°C and in the frequency range 4–100 kHz. It was observed that the a.c. conductivity increased initially and then decreased with increase of temperature and frequencies. The increase of distance from outer surface to the inner surface side increased the a.c. conductivity values and showed the grading in a.c. conductivity behaviour. Two phases of a.c. conductivity behaviour with temperature exist in bamboo. At 10 mm distance a.c. conductivity suddenly increases which is the critical depth from skin for this bamboo. Increase of temperature, at all the frequencies increases the a.c. conductivity initially and then decreases. Downward peaks in a.c. conductivities are observed at all the frequencies due to the presence of moisture in bamboo, which liberated on heating. Sharp peak is observed in case of sample 4, which is inner most strip. Maximum sharp peak is observed at lowest 4 kHz frequency.     

Influence of the addition of hydrogen and of a synthesis gas on the characteristics of the process of combustion of gasoline-air mixtures under conditions typical of internal combustion engines

The influence of the addition of hydrogen and of a synthesis gas on the basic parameters of combustion of gasoline-air fuel mixtures is investigated theoretically. The possibility of feeding gasoline internal combustion engines with lean fuel mixtures with a concentration of 5–10 vol.% hydrogen is shown; this will greatly improve their ecological purity. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 23–28, July–August, 2006.     

Buckling Characteristics of Symmetrically and Antisymmetrically Laminated Composite Plates with Central Cutout

A numerical and experimental study was carried out to determine the effects of anti-symmetric laminate configuration, cutout and length/thickness ratio on the buckling behavior of E/glass-epoxy composite plates. The buckling loads were presented for symmetrically and anti-symmetrically laminated plates subjected to axial compression load. The study included two different laminate configurations ([90/45/−45/0]_as and [90/45/−45/0]_s), two different cutout shapes (circular and semi-circular), two different length/thickness ratios (L/t = 75 and 37.5) and three boundary conditions (clamped–clamped [CC], clamped–pinned [CP] and pinned–pinned [PP]). Firstly, the buckling loads of eight-ply E/glass-epoxy rectangular plates were determined experimentally. Then, the buckling loads of the laminated composites were calculated by ANSYS finite-element computer code. The changing in buckling load of the composites due to the presence of cutout and changing of length/thickness ratio was calculated. Finally, the experimental test results were compared to the buckling loads of plates obtained from the finite element analysis.     

Practical mathematical representation of the flow due to a distribution of sources on a steadily advancing ship hull

A practical mathematical representation of the flow velocity due to a distribution of sources on the mean wetted hull surface and the mean waterline of a ship that steadily advances along a straight path in calm water, of large depth and lateral extent, is presented. A main feature of this flow representation is a simple analytical approximation—valid within the entire flow region—to the local flow component in the expression for the gradient of the Green function associated with the classical Kelvin–Michell linearized free-surface boundary condition. Another notable feature of the flow representation is that the singularity associated with the gradient of the Green function is removed, using a straightforward regularization technique. The flow representation only involves elementary continuous functions (algebraic, exponential and trigonometric) of real arguments. These functions can then be integrated using ordinary Gaussian quadrature rules. Thus, the flow representation is particularly simple and well suited for practical flow calculations. The specific case of a low-order panel method—in which the hull geometry, the source density, and the flow velocity are consistently represented via piecewise linear approximations within flat triangular hull panels or straight waterline segments—is considered.     

Micromechanism of corrosion fracture of the plates of heat exchangers

We have studied the micromechanism of corrosion fracture of heat-transfer plates of a heat exchanger. The operation of heat exchangers under conditions of contamination of the plates with a sediment from water leads to their local corrosion under the sediment. The conditions of operation of the heat exchangers being equal, heat-transfer plates made of AiSi316Ti steel worked 2.36 times as long as those of AiSi304L steel. The corrosion fracture of plates under the sediment began from pitting initiation near nonmetallic inclusions of a certain nature. Afterwards, these pittings built up into corrosion spots by the mechanism of stress corrosion and hydrogen embrittlement. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 1, pp. 110–116, January–February, 2007.     

Influence of melt treatments and turning inserts on cutting force and surface integrity in turning of Al–7Si and Al–7Si–2.5Cu cast alloys

The microstructures, machinability and surface characteristics of Al–7Si and Al–7Si–2.5Cu cast alloys were studied after various melt treatments like grain refinement and modification. Results indicate that combined grain refined and modified Al–7Si–2.5Cu cast alloys have microstructures consisting of uniformly distributed α-Al grains, eutectic Al–silicon and fine CuAl₂ particles in the interdendritic region. These alloys exhibited better machinability and surface characteristics in the cast condition compared with the same alloy subjected to only grain refinement or modification. Performances of the turning inserts (Un-coated, PVD and Polished CVD diamond coated) were evaluated in machining Al–7Si and Al–7Si–2.5Cu cast alloys under dry environment using a lathe. The Polished CVD diamond coated insert outperformed the Un-coated or PVD-coated cutting inserts which suffered from sizeable edge buildup leading to higher cutting force and poor surface finish. The Polished CVD diamond coated insert shows a very small steady wear without flaking of the diamond film during cutting. This paper attempts to investigate the influence of grain refinement, modification and combined action of both on the microstrutural changes in the Al–7Si and Al–7Si–2.5Cu cast alloys and their machinability and surface finish when different turning inserts used.     

Behavior of a fuel oil droplet on a hot surface

Combustion of a fuel oil droplet on a hot oblique surface, whose temperature varies between 350 and 700° C, has been studied experimentally. The influence of the heat conductivity of the wall and its roughness, as well as of the droplet-surface contact angle on the fuel combustion time has been determined. The data on the change in the droplet mass in the process of combustion are presented and chromatographic analysis of the fuel has been performed __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 11–19, January–February, 2006.     

Method of perturbations of the shape of the boundary in fracture mechanics. Part 1: Notches

We analyze exact and approximate methods used for the determination of the stress-strain state of plates bent according to Kirchhoff and isotropic plates weakened by sharp defects subjected to two-dimensional tension-compression. For a computational scheme to describe the actual stress-strain state more adequately, it is necessary to take into account the variation of anisotropic and orthotropic properties of the material of a plate across its thickness. This can be realized by finding approximate solutions of the problem by the method of perturbations of the shape of the boundary. We propose a modified approach based on the use of complex-valued functions adapted to the possibilities of contemporary computers. This method allows one to construct approximate solutions meaningful for fracture mechanics for the case of sharp holes and perfectly rigid inclusions under plane and antiplane loads within the framework of refined sixth-order theories of bent plates. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 33, No. 3, pp. 7–18, May–June, 1997.     

舰船双层底液舱水下爆炸作用下动态响应

用AUTODYN有限元程序研究水下非接触及接触爆炸作用下舰船双层底液舱内底的载荷特性。分别分析非接触及接触爆炸作用下,舰船双层底液舱半载与满载时内底的冲击载荷种类,探讨爆距及装载状态的不同对内底爆炸载荷特性的影响。研究表明,液舱满载时,透射冲击波是威胁内板的主要载荷形式;药包非接触、液舱半载时,液舱内部飞溅载荷是威胁内板的主要载荷形式;药包接触、液舱半载时,高速水层抨击是威胁内板的主要载荷形式,据此,总结得出舰船在服役过程中双层底液舱应采取的装载状态。     

共聚型网状聚氨酯抑爆材料的应用

目的评价共聚型网状聚氨酯抑爆材料的使用性能和抑爆功能。方法介绍共聚型网状聚氨酯抑爆材料的抑爆机理,针对车辆燃油箱的使用工况及抑爆考核要求,模拟油箱装填抑爆材料后对油箱开展加油、振动、高温贮存等适用性试验,以及带油补焊、40 mm火箭弹静爆等抑爆试验。结果该材料具有较好的消沫功能,能降低油料中固体颗粒污染物含量,高温长贮后0号柴油与-35号柴油中的固体颗粒污染物含量分别为空白油样的37.6%,52%,对油箱进行带油补焊试验过程中、补焊完成后的射击测试,以及40 mm火箭弹的静爆试验均未发生爆炸。结论共聚型网状聚氨酯抑爆材料与燃油的相容性较好,具有优异的抑爆性能。