Recommendations for deck primary supporting members design as applied to pillarless construction of ro-ro ships

2021 ◽  
pp. 79-88
Author(s):  
К.В. Плотников ◽  
В.Н. Тряскин ◽  
В.В. Чижевский
Keyword(s):  
Bending Moment ◽  
Minimum Thickness ◽  
Local Loads ◽  
Early Stages ◽  
Local Strength ◽  
Beam Analysis ◽  
Early Design Stages ◽  
The Stability ◽  
Web Plates ◽  
Wheeled Vehicles

Статья посвящена вопросам определения размеров набора грузовых стационарных палуб морских стальных судов типа Ro-Ro на ранних стадиях проектирования. В силу большого расстояния между поперечными переборками в случае отсутствия пиллерсов карлингсы палуб не являются опорами для рамных бимсов. Однако, как показывает практика, они всегда включаются в конструктивную схему палубы, так как позволяют разнести локальную нагрузку между соседними рамными бимсами, обеспечивают устойчивость их стенок, а также вовлекаются в работу в составе перекрытия при некоторых сценариях нагружения. В литературе отсутствуют рекомендации по выбору расчётной ширины их присоединенного пояска, расчётных значений изгибающих моментов и перерезывающих сил при восприятии нагрузки от разного типа груза. Исследование выполнялось на примере перекрытия грузовой палубы длиной 64,4 м на основе МКЭ. Были разработаны КЭ-модели палубы в балочной и оболочечно-балочной идеализациях. Вторая модель использовалась для оценки адекватности результата, получаемого на более простой модели. Рассмотрены 8 сценариев нагрузки. При определении ширины присоединенного пояска за величину условного пролёта принималось расстояние между точками, в которых величина изгибающего момента принимает нулевое значение. Показано, что карлингсы активно вовлекаются в работу при частичной загрузке трюма контейнерами в несколько ярусов, а также при работе погрузчика. Расчётная ширина их присоединенного пояска составила 0,60…0,75 расстояния между карлингсами при действии нагрузки от колёсной техники и оказалась близка к этому расстоянию при восприятии нагрузки от контейнеров при их поперечной укладке. Авторами предложено в качестве первого приближения значение расчётного изгибающего момента для карлингсов определять в долях от соответствующего значения для рамных бимсов. The paper deals with a design of deck primary structures of Ro-Ro vessels at early design stages. Due to the large distance between transverse bulkheads, in the case of no pillar construction, deck girders cannot be considered as supports for deck transverses. The common practice however, is to provide deck structures with deck girders anyway. It helps to distribute the local loads between transverses and to ensure the stability of deck transverses web plates. In addition, for a localized loads on deck structures girders to some extent contribute to local strength of the deck. Practically, deck girder scantlings are usually larger than those based on the minimum thickness, web depth and slenderness requirements of classification society rules. There are no publications proposing recommendations for deck girders design in pillarless structures of ro-ro ships at the early stages. Prescriptive recommendations should primarily include design bending moment value and effective breadth of the attached plate in different loading scenarios. The results presented in this paper are based on the linear finite element (FE) analysis of Ro-Ro deck having a length of 64.4 meters. Since the goal of the study was to develop recommendations for structural design aligned with prescriptive requirements of RS rules the research is provided with beam analysis carried out for 8 different loading scenarios. All of the reference calculations were made in FESTA-2020 software developed in SMTU as a part of CAD/СAE software ALMAZ-K. Verification is made with more sophisticated shell model analysis carried out in ANSYS with similar assumptions. The effective breadth of deck girders attached plate is calculated considering a distance between zero bending moment points as a nominal span. It is shown that the deck girders are highly stressed in loading cases with stacked containers and working fork lift. The calculated width of their attached plate which is in range from 0.60 to 0.75 of the distance between girders S under the load from the wheeled vehicles turns out to be close to Sin case of loading of transversely stacked containers. The authors propose to determine value of the design bending moment for deck girders at the early stages depending on span and loading of deck transverses.

scholarly journals The effect of flexural–torsional buckling on the stability of timber members: a case study

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Osama A. B. Hassan
Keyword(s):  
Axial Compression ◽  
Bending Moment ◽  
List Type ◽  
Torsional Buckling ◽  
Solution Methods ◽  
Simplified Solution ◽  
The Stability ◽  
Flexural Torsional Buckling ◽  
Building Engineering

Abstract This study investigates the stability of timber members subjected to simultaneously acting axial compression and bending moment, with possible risk for torsional and flexural–torsional buckling. This situation can occur in laterally supported members where one side of the member is braced but the other side is unbraced. In this case, the free side will buckle out of plane while the braced side will be prevented from torsional and flexural–torsional buckling. This problem can be evident for long members in timber-frame structures, which are subjected to high axial compression combined with bending moments in which the member is not sufficiently braced at both sides. This study is based on the design requirement stated in Eurocode 5. Solution methods discussed in this paper can be of interest within the framework of structural and building Engineering practices and education in which the stability of structural elements is investigated. Article Highlights This case study investigates some design situations where the timber member is not sufficiently braced. In this case, a stability problem associated with combined torsional buckling and flexural buckling can arise. The study shows that the torsional and/or flexural–torsional buckling of timber members can be important to control in order to fulfil the criteria of the stability of the member according to Eurocode 5 and help the structural engineer to achieve safer designs. The study investigates also a simplified solution to check the effect of flexural torsional buckling of laterally braced timber members.

Stability and collapse of holes in liquid layers

2018 ◽  
Vol 855 ◽  
pp. 1130-1155 ◽  
Author(s):  
Cunjing Lv ◽  
Michael Eigenbrod ◽  
Steffen Hardt
Keyword(s):  
Liquid Film ◽  
Power Laws ◽  
Theoretical Models ◽  
Liquid Volume ◽  
Capillary Length ◽  
Minimum Thickness ◽  
The Stability ◽  
Film Profile ◽  
Hole Closure ◽  
Good Agreement

We investigate experimentally and theoretically the stability and collapse of holes in liquid layers on bounded substrates with various wettabilities. It is shown that for a liquid layer with a thickness of the order of the capillary length, a stable hole exists when the hole diameter is bigger than a critical value $d_{c}$. Consequently, a further increase of the liquid volume causes the hole to collapse. It is found that$d_{c}$increases with the size of the container, but its dependence on the contact angle is very weak. The experimental results are compared with theory, and good agreement is obtained. Moreover, we present investigations of the dynamics of the hole and the evolution of the liquid film profile after the collapse. The diameter of the hole during collapse and the minimum thickness of the liquid film shortly after the collapse obey different power laws with time. Simple theoretical models are developed which indicate that the collapse of the hole is triggered by surface tension and the subsequent closure process results from inertia, whereas the growth of the liquid column after hole closure results from the balance between the capillary force and inertia. Corresponding scaling coefficients are determined.

scholarly journals Flexural-Torsional Vibration of Thin-Walled Beams Subjected to Combined Initial Axial Load and End Bending Moment: Application to the Design of Saw Tooth Blades

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Van Binh Phung ◽  
Anh Tuan Nguyen ◽  
Hoang Minh Dang ◽  
Thanh-Phong Dao ◽  
V. N. Duc
Keyword(s):  
Boundary Conditions ◽  
Axial Load ◽  
Stability Boundary ◽  
Bending Moment ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Rayleigh Method ◽  
Thin Walled ◽  
The Stability ◽  
Fixed End

The present paper analyzes the vibration issue of thin-walled beams under combined initial axial load and end moment in two cases with different boundary conditions, specifically the simply supported-end and the laterally fixed-end boundary conditions. The analytical expressions for the first natural frequencies of thin-walled beams were derived by two methods that are a method based on the existence of the roots theorem of differential equation systems and the Rayleigh method. In particular, the stability boundary of a beam can be determined directly from its first natural frequency expression. The analytical results are in good agreement with those from the finite element analysis software ANSYS Mechanical APDL. The research results obtained here are useful for those creating tooth blade designs of innovative frame saw machines.

scholarly journals Dynamics and stability of skyrmions in a bended nano-beam

2021 ◽  
Author(s):  
Anruo Zhong ◽  
Xiaoming Lan ◽  
Yangfan Hu ◽  
Biao Wang
Keyword(s):  
Energy Cost ◽  
High Mobility ◽  
Bending Moment ◽  
Elastic Fields ◽  
Spintronic Devices ◽  
Bulk Stress ◽  
The Stability ◽  
Magnetic Skyrmions ◽  
Nontrivial Topology ◽  
A Current

Abstract Magnetic skyrmions are attracting much attention due to their nontrivial topology and high mobility to electric current. Nevertheless, suppression of the skyrmion Hall effect and maintaining high velocity of skyrmions with low energy cost are two major challenges concerning skyrmion-based spintronic devices. Here we show theoretically that in a nano-beam suffering appropriate bending moment, both Bloch-type and Néel-type skyrmions move with a vanishing Hall angle under a current density smaller than that required when the bending is absent. Moreover, bending alone can be used to move skyrmions, whose velocity is solved analytically from the Thiele equation. Generally speaking, inhomogeneous elastic fields affect the stability and dynamics of skyrmions, where the local stability is dominantly determined by the local bulk stress. These findings throw new light on how to drive skyrmions straightly with lower energy cost, which is vital for utilizing skyrmions as information carriers.

Measurement of free-circulating cis-dichlorodiammineplatinum(II) in plasma.

1977 ◽  
Vol 23 (12) ◽  
pp. 2258-2262 ◽  
Author(s):  
S J Bannister ◽  
L A Sternson ◽  
A J Repta ◽  
G W James
Keyword(s):  
Exchange Resin ◽  
Cation Exchange Resin ◽  
Free Drug ◽  
Platinum Compounds ◽  
Minimum Thickness ◽  
X Ray ◽  
Drug Plasma ◽  
Detection Capabilities ◽  
The Stability ◽  
Bound Drug

Abstract Dichlorodiammineplatinum(II) is an anti-neoplastic agent that is currently undergoing clinical evaluation. We describe an analytical method for monitoring the free drug (or its breakdown products) in plasma. The method is able to distinguish between free and protein-bound drug. Plasma samples are deproteinized by centrifugal ultrafiltration. The platinum in the ultrafiltrate is converted to a cationic species by reaction with ethylenediamine and then collected on paper impregnated with cation-exchange resin. This process concentrates the samples, increases the stability of the platinum compounds (by removing the compound from solution), and places the sample in a uniform matrix of minimum thickness, which maximizes detection capabilities. Platinum was measured directly on the ion-exchange disks by X-ray fluorescence. The detection limit for free drug is 240 microgram/liter of plasma at the 3s level and fluorescence intensity is linearly related to drug concentration in the range from 570 to 5700 microgram/liter.

The Lateral Buckling of Steel-Concrete Composite П-Beam

2008 ◽  
Vol 400-402 ◽  
pp. 287-293
Author(s):  
Li Zhong Jiang ◽  
Lin Lin Sun ◽  
Xing Li
Keyword(s):  
Bending Moment ◽  
Computing Methods ◽  
Lateral Buckling ◽  
Computing Model ◽  
Negative Moment ◽  
Numerical Computing ◽  
Negative Bending ◽  
The Stability ◽  
Simplified Calculation ◽  
Elastic Stage

Based on the theoretical analysis of steel-concrete composite П-beam’s lateral buckling, the computing model and simplified computing model on the stability of composite П-beams are brought forward. According to above two models, composite beam’s lateral buckling is studied in negative moment regions using the energy method, and the formulas which are used to calculate critical bending moment in negative moment regions in the elastic stage are deduced. Compared with other stability theories and methods, this paper represents the design correction and suggestion about the stability of composite П-beam in negative bending regions. Moreover, the simplified calculation method, which is used to compute the lateral critical buckling moment of steel-concrete composite П-beam loaded by equal-end moment, not only simplifies the computing process, the computing results also have the equivalent accuracy with numerical computing methods.

scholarly journals Effect of Deformation Structure and Annealing Temperature on Corrosion of Ultrafine-Grain Fe-Cr Alloy Prepared by Equal Channel Angular Pressing

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Muhammad Rifai ◽  
Motohiro Yuasa ◽  
Hiroyuki Miyamoto
Keyword(s):  
Grain Boundaries ◽  
Equal Channel Angular Pressing ◽  
Annealing Temperature ◽  
Surface Region ◽  
Passivation Layer ◽  
Ultrafine Grain ◽  
Deformation Structure ◽  
Early Stages ◽  
Angular Pressing ◽  
The Stability

The effect of the deformation structure and annealing temperature on the corrosion of ultrafine-grain (UFG) Fe-Cr alloys with 8 to 12% Cr prepared by equal channel angular pressing (ECAP) was investigated with particular emphasis on the stability of the passivation layer. Fe-Cr alloys were processed by ECAP using up to eight passes at 423 K by the Bc route, followed by annealing at temperatures of 473 to 1173 K for 1 h. Passivity appeared in all alloys as a result of ECAP, and the stability of the passivation layer was evaluated by anodic polarization measurements in a 1000 mol·m−3 NaCl solution. The stability of the passivation layer increased as the degree of deformation became more extensive with successive ECAP passes, and distinct escalation occurred with the formation of a UFG microstructure. In the early stages of annealing at moderate temperatures, the stability of the passivation layer deteriorated, although no visible grain growth occurred, and this effect increased monotonically with increasing annealing temperature. The high degree of stability of the passivation layer on UFG alloys following ECAP can be attributed to the large number of high-angle nonequilibrium grain boundaries, which may lead to Cr enrichment of the surface region. The deterioration of the passivation layer in the early stages of annealing may be attributed to a change in the grain boundaries to an equilibrium state. The present results show that the superiority of as-ECAPed materials of the Fe-Cr alloy to recovered ones by heat treatment can be achieved with 8–10% Cr as observed in 20% Cr.

Explicit Expressions for Buckling Analysis of Thin-Walled Beams Under Combined Loads with Laterally-Fixed Ends and Application to Stability Analysis of Saw Blades

2020 ◽  
pp. 2150032
Author(s):  
Van Binh Phung ◽  
Ngoc Doan Tran ◽  
Viet Duc Nguyen ◽  
V. S. Prokopov ◽  
Hoang Minh Dang
Keyword(s):  
Critical State ◽  
Bending Moment ◽  
Critical Issue ◽  
Eccentric Load ◽  
Concentrated Load ◽  
Combined Loads ◽  
Distributed Load ◽  
Thin Walled ◽  
The Stability ◽  
2D And 3D

This paper studies the critical issue of thin-walled beams with laterally fixed ends. The method for defining the formulae of twist moment for the beams subjected to combined loads was elucidated. Based on this, the governing differential equations of the beam were developed. The procedure for determining the critical state of the beam by the energy method was presented. With this procedure, the critical state of the beam concerned under three types of loadings such as axial force [Formula: see text], bending moment [Formula: see text] and distributed load [Formula: see text] (or concentrated load [Formula: see text]) was examined deliberately. The outcomes were presented in explicit closed-form, which can be illustrated in 2D and 3D graphs. Also, the analytical solution obtained was in agreement with the numerical one obtained by the commercial software NX Nastran. Furthermore, the analytical solutions were applied straightforwardly to explore the stability and design optimization of the tooth-blade for the new frame-type saw machine under an eccentric load. The result can also be promisingly used to study problems of thin-walled beams with laterally fixed ends subjected to other types of loads.

scholarly journals Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

2019 ◽  
Vol 7 (6) ◽  
pp. 175 ◽  
Author(s):  
Long Yu ◽  
Heyue Zhang ◽  
Jing Li ◽  
Xian Wang
Keyword(s):  
Bending Moment ◽  
Vertical Force ◽  
Leg Length ◽  
Element Analysis ◽  
Centrifuge Tests ◽  
Flat Base ◽  
Key Factor ◽  
The Stability ◽  
Resultant Forces ◽  
Theoretical Analyses

Most existing research on the stability of spudcans during reinstallation nearing footprints is based on centrifuge tests and theoretical analyses. In this study, the reinstallation of the flat base footing, fusimform spudcan footing and skirted footing near existing footprints are simulated using the coupled Eulerian–Lagrangian (CEL) method. The effects of footprints’ geometry, reinstallation eccentricity (0.25D–2.0D) and the roughness between spudcan and soil on the profiles of the vertical force, horizontal force and bending moment are discussed. The results show that the friction condition of the soil–footing interface has a significant effect on H profile but much less effect on M profile. The eccentricity ratio is a key factor to evaluate the H and M. The results show that the geometry shape of the footing also has certain effects on the V, H, and M profiles. The flat base footing gives the lowest peak value in H but largest in M, and the performances of the fusiform spudcan footing and the skirted footing are similar. From the view of the resultant forces, the skirted footing shows a certain potential in resisting the damage during reinstallation near existing footprints by comparing with commonly used fusiform spudcan footings. The bending moments on the leg–hull connection section of different leg length at certain offset distances are discussed.

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