On the Choice of Initial Geometric Imperfections in Externally Pressurized Shells

1999 ◽  
Vol 121 (1) ◽  
pp. 71-76 ◽  
Author(s):  
J. Błachut ◽  
O. R. Jaiswal
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
Load Carrying Capacity ◽  
Geometric Imperfections ◽  
Elliptical Cross ◽  
Buckling Strength ◽  
Load Carrying ◽  
Initial Geometric Imperfections

Localized and global, of eigenmode type, initial geometric imperfections were superimposed on perfect torispherical, ellipsoidal, and toroidal shells of circular and elliptical cross section. Reduction of the load-carrying capacity was then calculated numerically for various geometries and the yield point of material which was assumed to be mild steel. Results show that the buckling strength of torispheres and ellipsoids could be strongly affected by imperfections, but reduction of its magnitude was dependent on the choice of imperfection shape and, more importantly, on the imperfection’s location. Calculations carried out for closed toroids of circular cross section show that these shells are not sensitive to eigenmode-type imperfections, while toroids with elliptical cross sections are sensitive to eigen-imperfections.

scholarly journals Load carrying capacity of the eccentric joint in the truss made of open cross-sections

2018 ◽  
Vol 219 ◽  
pp. 02002
Author(s):  
Małgorzata Gordziej-Zagórowska ◽  
Elżbieta Urbańska-Galewska
Keyword(s):  
Numerical Analysis ◽  
Cross Section ◽  
Experimental Research ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Main Achievement ◽  
Joint Area ◽  
Load Carrying ◽  
Open Cross Section

The influence of eccentricity at intersections of truss members on the load carrying capacity of the truss joint is presented in the paper. The research truss elements were designed as cold-formed open cross section. Analytical calculations, numerical analysis and experimental research were conducted to reveal how the eccentricity affects the effort of material in the joint area. The results of analysis and investigations are compared and discussed. The main achievement of the tests carried out is statement that slender plane members of the compression chords are safe compared with the results of analytical calculations.

Part V.

1938 ◽  
Vol 42 (328) ◽  
pp. 343-346
Keyword(s):  
Cross Section ◽  
Carrying Capacity ◽  
Local Buckling ◽  
Circular Cross Section ◽  
Load Carrying Capacity ◽  
Pure Bending ◽  
Longitudinal Stiffeners ◽  
Load Carrying

In the present paper two forms of instability of monocoque structures in pure bending have been discussed in extenso, viz., the flattening and the local buckling. For ease of calculation it is assumed that the structure is cylindrical, of circular cross section and consisting of a great number of evenly spaced uniform longitudinal stiffeners, denoted stringers and of several evenly spaced uniform transverse stiffeners, called rings. The applicability of the results obtained to practical fuselages of non-circular cross section and the effect of different neglections have been dealt with in §§15 and 20.I.—Preliminary to the discussion of the above problems, the results obtained by different authors concerning both the load carrying capacity of panels after buckling and the failure of stringers have been collected in Part I.

Collapse Tests on Externally Pressurized Toroids

2003 ◽  
Vol 125 (1) ◽  
pp. 91-96 ◽  
Author(s):  
J. Błachut
Keyword(s):  
Mild Steel ◽  
Cross Section ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
External Pressure ◽  
Outer Diameter ◽  
Load Carrying Capacity ◽  
The Third ◽  
Load Carrying ◽  
Toroidal Shells

The paper discusses the load-carrying capacity of toroidal shells with closed circular cross section and loaded by static external pressure. Details about the manufacturing, pre-experiment measurements and testing of three, nominally different, steel toroids are provided. Two of them were manufactured from mild steel by spinning two halves and then welding them around the inner and outer equatorial perimeters. The third one has been assembled by welding four 90-deg stainless elbows. The outer diameter of these models was about 300 mm and the wall thickness varied from 2.0 to 3.0 mm. The hoop radius-to-thickness ratio, r/t, varied from about 15 to 30. The experimental collapse pressures were in the range from 4 to 8 MPa. Comparisons with numerical results are also provided.

Collapse Tests on Externally Pressurised Toroids

2002 ◽  
Author(s):  
J. Blachut
Keyword(s):  
Mild Steel ◽  
Cross Section ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
External Pressure ◽  
Outer Diameter ◽  
Load Carrying Capacity ◽  
The Third ◽  
Load Carrying ◽  
Toroidal Shells

The paper discusses the load carrying capacity of toroidal shells with closed circular cross-section and loaded by static external pressure. Details about the manufacturing, pre-experiment measurements and testing of three, nominally different, steel toroids are provided. Two of them were manufactured from mild steel by spinning two halves and then welding them around the inner and outer equatorial perimeters. The third one has been assembled by welding four 90 deg, stainless elbows. The outer diameter of these models was about 300 mm and the wall thickness varied from 2.0 mm to 3.0 mm. The hoop radius-to-thickness ratio, r/t, varied from about 15 to 30. The experimental collapse pressures were in the range from 4 MPa to 8 MPa. Comparisons with numerical results are also provided.

Analysis of the Carrying Capacity for Tubes Under Oblique Loading

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Wei Wang ◽  
Xinming Qiu
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Deformation Mechanism ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Beam Length ◽  
Initial Failure ◽  
Load Carrying ◽  
Oblique Loading ◽  
The Cross

In this study, the plastic deformation mechanism of a fully clamped beam under oblique loading at its free end is analyzed. Supposing the cross sections are variable along the beam length, a characteristic length L∗≡MP/NP, defined as the ratio between fully plastic bending moment MP and fully compression force NP, is employed to estimate the load carrying capacity of each cross section. By finite element (FE) simulations of the conical tubes, it is validated that if the initial failure positon locates in the middle of the beam, it will not change with the total beam length. Then, based on the analytical analysis and FE simulation, a progressive deformation mechanism triggered by bending, notated as progressive bending, is proposed for the first time. From the optimization result of maximizing loading force that the unit mass can withstand, the tubes with constant thickness are found to be better than tubes with graded thickness, when they are used as supporting structures. The multi-objective optimization for tubes with varying cross sections under oblique loading with different angles is also given. Then, two methods to improve the load carrying capacity of tubes are given: (1) to design the cross section of the tube, which is corresponding to let the critical loading force of all the cross sections be equal; (2) to optimize the initial failure point, so as to produce repeated failure modes.

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

scholarly journals Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3468
Author(s):  
Zbigniew Kolakowski ◽  
Andrzej Teter
Keyword(s):  
Cross Sections ◽  
Carrying Capacity ◽  
Ultimate Load ◽  
Equilibrium Path ◽  
Load Carrying Capacity ◽  
Nonlinear Buckling ◽  
Elastic Range ◽  
Load Carrying ◽  
Thin Walled ◽  
Ultimate Load Carrying Capacity

The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.

Analysis of Seismic Performance of RC Frames with Centrally Reinforced Columns

2013 ◽  
Vol 671-674 ◽  
pp. 1319-1323
Author(s):  
Zi Xue Lei ◽  
Yu Hang Han ◽  
San Sheng Dong ◽  
Jun Qing Guo
Keyword(s):  
Seismic Performance ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Pushover Analysis ◽  
Seismic Load ◽  
Load Carrying Capacity ◽  
Rc Columns ◽  
Rc Column ◽  
Rc Frames ◽  
Load Carrying

A centrally reinforced column is a new type of RC columns, formed by providing a reinforcement skeleton at the central part of the cross section of an ordinary RC column. Tests have shown that as compared with an ordinary RC column, this type of columns has a higher load carrying capacity and ductility. From the pushover analysis of a frame composed of ordinary RC columns and one consisting of centrally reinforced columns, their seismic performance under seismic load of 9-degree intensity was studied according to Chinese code, including target displacements, story-level displacements, interstory drifts, appearance and development of plastic hinges. The results indicate that although the dimensions of cross sections of columns in the frame with centrally reinforced columns are smaller than those of the ordinary frame, the former still has a higher overall load carrying capacity and seismic performance than the latter.

A study into the ability of SPD to restore the buckling strength and modes of rib stiffened panels with simulated stress corrosion cracks

2017 ◽  
Vol 8 (1) ◽  
pp. 63-78 ◽  
Author(s):  
Rhys Jones ◽  
Neil Matthews ◽  
Daren Peng ◽  
Nicholas Orchowski
Keyword(s):  
Experimental Study ◽  
Stress Corrosion ◽  
Carrying Capacity ◽  
Particle Deposition ◽  
Load Carrying Capacity ◽  
Load Path ◽  
Premature Failure ◽  
Content Type ◽  
Buckling Strength ◽  
Load Carrying

Purpose The purpose of this paper is to describe the results of a combined numerical and experimental study into the ability of supersonic particle deposition (SPD) to restore the load carrying capacity of rib stiffened wing planks with simulated stress corrosion cracking (SCC). Design/methodology/approach In this context the experimental results reveal that SCC can result in a dramatic reduction in the load carrying capacity of the structure and catastrophic failure via cracking that tears the length of the structure through buckling. A combined numerical and experimental study then reveals how this reduction, in the load carrying capacity can be overcome by using SPD. Findings This paper is the first to show that SPD can be used to restore the load carrying capacity of rib stiffened structures with SCC. It also shows that SPD repairs can be designed to have only a minimal effect on the local stiffness and hence on the load path. However, care should be taken to ensure that the design is such that premature failure of the SPD does not occur. Originality/value This is the first paper to show that a thin layer of SPD deposited 7,075 aluminium alloy powder on either side of the SCC-simulated stiffener has the potential to restore the load carrying capability of a rib stiffened structure. As such it represents an important first step into establishing the potential for SPD to restore the buckling strength of rib stiffened wing panels containing SCC.

Sign in / Sign up

Export Citation Format

Share Document