Part III. Local Buckling of Monocoque Structures

1938 ◽  
Vol 42 (328) ◽  
pp. 319-333
Keyword(s):  
Cross Section ◽  
Slenderness Ratio ◽  
Local Buckling ◽  
Critical Distance ◽  
Free Length ◽  
Buckling Stress ◽  
The Cross

In case of normal monocoque aeroplane fuselages relatively strong rings are spaced at distances equal to diameter of the fuselage, failure of the structure always occurs by instability of the most stressed stringer. The buckling stress, however, is mostly very low, especially, when the number of stringers is great and consequently the cross section of one stringer is small. The value of the stress at failure may be raised by spacing the rings nearer and reducing thereby the free length and, consequently, the slenderness ratio of the stringers. In this case the rings should be constructed of lighter sections in order to balance the increment of weight of the whole structure due to the greater number of rings.By decreasing gradually the interval between rings a critical distance is reached when the most stressed stringer does not buckle between adjacent rings, but forces one or more supporting rings to deform simultaneously. This form of instability will in the following be termed local buckling of the monocoque structure.

scholarly journals Computation of Thin-Walled Cross-Section Resistance to Local Buckling with the Use of the Critical Plate Method

2016 ◽  
Vol 62 (2) ◽  
pp. 229-264 ◽  
Author(s):  
A. Szychowski
Keyword(s):  
Cross Section ◽  
Critical Stress ◽  
Analytical Calculation ◽  
Local Buckling ◽  
Stability Loss ◽  
Longitudinal Stress ◽  
Plate Method ◽  
Thin Walled ◽  
The Cross ◽  
Elastically Restrained

Abstract Thin-walled bars currently applied in metal construction engineering belong to a group of members, the cross-section res i stance of which is affected by the phenomena of local or distortional stability loss. This results from the fact that the cross-section of such a bar consists of slender-plate elements. The study presents the method of calculating the resistance of the cross-section susceptible to local buckling which is based on the loss of stability of the weakest plate (wall). The “Critical Plate” (CP) was identified by comparing critical stress in cross-section component plates under a given stress condition. Then, the CP showing the lowest critical stress was modelled, depending on boundary conditions, as an internal or cantilever element elastically restrained in the restraining plate (RP). Longitudinal stress distribution was accounted for by means of a constant, linear or non-linear (acc. the second degree parabola) function. For the critical buckling stress, as calculated above, the local critical resistance of the cross-section was determined, which sets a limit on the validity of the Vlasov theory. In order to determine the design ultimate resistance of the cross-section, the effective width theory was applied, while taking into consideration the assumptions specified in the study. The application of the Critical Plate Method (CPM) was presented in the examples. Analytical calculation results were compared with selected experimental findings. It was demonstrated that taking into consideration the CP elastic restraint and longitudinal stress variation results in a more accurate representation of thin-walled element behaviour in the engineering computational model.

scholarly journals The Ovalisation of Steel Circular Hollow Sections under Bending

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Manahel Sh. Khalaf ◽  
Amer M. Ibrahim
Keyword(s):  
Cross Section ◽  
Local Buckling ◽  
Bending Moment ◽  
Thickness Ratio ◽  
Experimental Results ◽  
Experimental Program ◽  
Specimen Length ◽  
Specimen Cross Section ◽  
The Cross

This paper investigates the ovalisation behavior of the Steel Circular Hollow Sections (CHSs) when subjected to bending moment. The experimental program included testing of ten specimens in four groups in order to examine the influence of changing the diameter, thickness, length and the presence of openings on the ovalisation phenomenon of these specimens.The experimental results showed that the ovalisation of the specimen cross-section appears clearly when the diameter to thickness ratio (D/t) is ranging from 17 to 50, while the ovalisation of the specimens that have D/t ratio greater than 50 is very little or unclear because the instability of these specimens are controlled by the local buckling. In addition, the change of the specimen length and the presence of openings didn’t cause the cross-section ovalisation

Fire Assessment of Steel Beam Members With Partial Passive Fire Protection Coverage

2012 ◽  
Author(s):  
Hunter Smith ◽  
Yavuz Ayhan ◽  
Ali Sari
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Fire Protection ◽  
Mechanical Response ◽  
Local Buckling ◽  
Offshore Structures ◽  
Heat Transfer Analysis ◽  
Passive Fire Protection ◽  
Non Linear ◽  
The Cross

In offshore structures there are instances where the application of passive fire protection (PFP) is not possible or desired on certain portions of a structural member’s surface area. The most common cases are those where the top surface is left unprotected due to the presence of deck grating or plating. Current code and standard provisions on heat transfer and strength assessment of restrained flexural members are not directly applicable to these cases. Thus, a case study is presented for performing a fire assessment of a restrained plate girder subjected to jet fire impingement with the top flange surface left unprotected. To assess residual strength and perform non-linear analyses under combined thermal and static loading, a heat transfer analysis was first performed to obtain the time histories of the two dimensional heat distributions throughout the studied cross-section. The results showed that the top flange heats up rapidly and the heat conducts very slowly down the web to the rest of the cross-section, with a very large thermal gradient occurring over the height of the section. Approximate screening calculations for the cross-section, based on AISC capacity equations, indicated that the member will quickly exceed its elastic capacity and that local buckling may occur prior to yielding. Advanced non-linear finite element analysis of the mechanical response confirmed large amounts of plasticity and local buckling occur, but showed that global integrity of the member is maintained for the duration of the fire due to redundancy and catenary action. Recommendations and conclusions on analysis methods for partially protected deck members are made based on the results of this study.

scholarly journals Elastic Web Buckling Stress and Ultimate Strength of H-Section Beams Dominated by Web Buckling

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Jiaxing Ma ◽  
Tao Wang ◽  
Yinhui Wang ◽  
Kikuo Ikarashi
Keyword(s):  
Ultimate Strength ◽  
Shear Force ◽  
Slenderness Ratio ◽  
Local Buckling ◽  
Elastic Buckling ◽  
Buckling Stress ◽  
Web Buckling ◽  
Buckling Coefficient ◽  
The Web ◽  
Good Agreement

Numerical analyses and theoretic analyses are presented to study the elastic buckling of H-section beam web under combined bending and shear force. Results show that the buckling stress of a single web with clamped edges gives a good agreement with the buckling stress of an H-section beam web when the local buckling of the beam is dominated by the web buckling. Based on theoretic analyses, a parametric study is conducted to simplify the calculation of buckling coefficients. The parameters involved are clarified first, and the improved equations for the buckling coefficient and buckling stress are suggested. By applying the proposed method, the web buckling slenderness ratio is defined. It is verified that the web buckling slenderness ratio has a strong correlation with the normalized ultimate strength of H-section beams when the buckling of the beams is dominated by web buckling. Finally, a design equation is proposed for the ultimate strength of H-section beams.

On the use of non-cylindrical specimens in a split-Hopkinson pressure bar

2011 ◽  
Vol 46 (8) ◽  
pp. 866-878 ◽  
Author(s):  
O Sen ◽  
S A Tekalur ◽  
P Maity
Keyword(s):  
Cross Section ◽  
Split Hopkinson Pressure Bar ◽  
Slenderness Ratio ◽  
Kolsky Bar ◽  
Image Correlation ◽  
Cylindrical Shape ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
The Cross ◽  
Pressure Bar

Despite the practice of using cylindrical specimens in a split-Hopkinson pressure bar (Kolsky bar) experiment, the use of non-cylindrical prismatic specimens is not uncommon. This is convenient when testing extra-soft materials like brain tissues, muscles, or samples that are brittle and cannot be machined to an exact cylindrical shape (like bone-samples). The use of a non-cylindrical sample with a flat surface also renders the specimen amenable to a two-dimensional image correlation algorithm. This research aims to show the feasibility of using non-cylindrical specimens in a Kolsky bar. For this, experiments were conducted with a model material for different model cross-sections at a nearly constant strain rate in the split-Hopkinson pressure bar. The findings suggest the use of a suitable characteristic cross-section dimension of the specimen to determine the critical slenderness ratio while selecting a non-cylindrical prismatic specimen. It has been shown that if the specimen design is governed by the suggested slenderness criterion, then there is no effect of specimen length or cross-sectional shape on the stress–strain curve of the material. Through the use of a computational code, the research also shows the effect of non-uniform axial stress distribution along the cross-section of the specimen, resulting due to specimen geometry. On quantification of the stress non-uniformity along the cross-section of the specimen, the findings indicate that the magnitude of the non-uniformity is both small and temporary.

Comparison of the Bearing Capacity of LST- Profile Depending on the Thickness of its Elements

2015 ◽  
Vol 725-726 ◽  
pp. 752-757 ◽  
Author(s):  
Darya Trubina ◽  
Dzhamal Abdulaev ◽  
Egor Pichugin ◽  
Vladimir Rybakov ◽  
Marsel Garifullin ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Local Buckling ◽  
Transverse Bending ◽  
Thin Walled ◽  
The Cross

The influence of local buckling on the bearing capacity of light steel thin-walled profiles is a hot topic today. In this paper we evaluated the effect of the thickness of the elements of the cross section on bearing capacity the profile in a transverse bending.

scholarly journals Axial behaviour of concrete filled steel tube stub columns: a review

2018 ◽  
Author(s):  
Soner Güler ◽  
Fuat Korkut ◽  
Namik Yaltay ◽  
Demet Yavuz
Keyword(s):  
Cross Section ◽  
Axial Load ◽  
Load Capacity ◽  
Local Buckling ◽  
Bending Moment ◽  
Steel Tube ◽  
High Rise ◽  
Axial Load Capacity ◽  
The Cross ◽  
Cfst Columns

Concrete-filled steel tubular (CFST) columns are widely used in construction of high-rise buildings and peers of bridges to increase the lateral stiffness of the buildings, the axial load capacity, ductility, toughness, and resistance of corrosion of the columns. The CFST columns have much superior characteristics compared with traditionally reinforced concrete columns. The position of the concrete and steel tube in the cross-section of the CFST column is the most appropriate solution in terms of the strength and ductility. The steel tube, which is placed outside of the cross-section of the column, withstand the bending moment effectively. The concrete that is placed into the steel tube delay the local buckling of the steel tube and increase the axial load capacity of the column due to continually lateral confining. This paper presents a review on experimental results of the axial behavior of CFST columns performed by various researchers.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

Research in the cross-section of community psychology and global climate change: A call for action

2009 ◽  
Author(s):  
Marci Culley ◽  
Holly Angelique ◽  
Courte Voorhees ◽  
Brian John Bishop ◽  
Peta Louise Dzidic ◽  
...  
Keyword(s):  
Climate Change ◽  
Cross Section ◽  
Global Climate Change ◽  
Community Psychology ◽  
Global Climate ◽  
The Cross
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