Experimental Validation of Wave Vibration Analysis of Complex Vibrations in a Two-Story Metallic Space Frame Based on the Timoshenko Bending Theory

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
C. Mei
Keyword(s):  
Cross Sections ◽  
Torsional Rigidity ◽  
Experimental Studies ◽  
Space Frame ◽  
Bending Vibrations ◽  
Space Frames ◽  
Out Of Plane ◽  
Vibration Responses ◽  
Steel Space Frame ◽  
Numerical Approaches

In a space frame, there exist in- and out-of-plane bending, axial, and torsional vibrations. The analysis of complex vibrations in such structures has relied mostly on numerical approaches. In this study, a wave-based analytical approach is applied to obtain solutions to vibrations in space frames. Both free and forced wave vibration responses are obtained, with bending vibrations modeled using the Timoshenko theory. A two-story steel space frame is built to validate the analytical results, and good agreements have been reached between the analytical and experimental studies. The effect of torsional rigidity adjustment on the accuracy of predicted vibrational responses in structures involving rotationally nonsymmetric cross sections is also examined.

Vibrations in a spatial K-shaped metallic frame: an exact analytical study with experimental validation

2016 ◽  
Vol 23 (19) ◽  
pp. 3147-3161
Author(s):  
C Mei
Keyword(s):  
Cross Section ◽  
Experimental Validation ◽  
Analytical Study ◽  
Torsional Rigidity ◽  
Space Frame ◽  
Bending Vibrations ◽  
Beam Elements ◽  
Out Of Plane ◽  
Vibration Responses ◽  
Shear Distortion

In a spatial K-shaped metallic frame, there exist in- and out-of-plane bending, axial, and torsional vibrations. A wave-based vibration analysis approach is applied to obtain free and forced vibration responses in a space frame. In order to validate the analytical approach, a steel K-shaped space frame was built by welding four beam elements of rectangular and square cross-section together. Bending vibrations are modeled using both the classical Euler–Bernoulli theory and the advanced Timoshenko theory. This allows the effects of rotary inertia and shear distortion, which were neglected in the classical Euler–Bernoulli theory, to be studied. In addition, the effect of torsional rigidity adjustment for structures of rotationally non-symmetric cross-section is also examined.

Coupled Axial-Flexural-Torsional Vibration of Internally Damped Timoshenko Frames

2010 ◽  
Author(s):  
Adil Yucel ◽  
Alaeddin Arpaci ◽  
Ekrem Tufekci
Keyword(s):  
Cross Sections ◽  
Torsional Vibration ◽  
Complex Modulus ◽  
Linear Equations ◽  
Frame Structure ◽  
Rotational Inertia ◽  
Bending Vibrations ◽  
Element Analysis ◽  
Out Of Plane ◽  
Simultaneous Linear Equations

In this study, free in-plane and out-of-plane bending vibrations of frame structures have been analyzed together with torsional vibration. Axial extension, rotational inertia and shear effects have also been considered. The frame structure has been constructed as having two beams with doubly symmetric cross-sections and connected at any angle to each other. These types of frames frequently appear on ships as bridge wings which are probably the most problematic members experiencing severe vibration. Internal damping has been incorporated into the analyses by using a complex modulus of elasticity. Natural frequencies have been obtained analytically by solving simultaneous linear equations of complex coefficients. A finite element analysis has also been conducted to verify the analytical results. Furthermore, an experimental modal analysis has been carried out and the results have been compared with theoretical ones in tables for various connection angles and damping factors. The agreement among results has been found to be good.

An Exact Analytical Approach for Free Vibration Analysis of Built-Up Space Frames

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
C. Mei ◽  
H. Sha
Keyword(s):  
Free Vibration ◽  
Analytical Approach ◽  
Free Vibration Analysis ◽  
Structural Elements ◽  
Space Frames ◽  
Out Of Plane ◽  
Vibration Responses ◽  
Numerical Tools ◽  
Classical Vibration ◽  
Exact Analytical Method

Coupled in- and out-of-plane bending, axial, and torsional vibrations exist in a built-up space frame, which greatly challenges the conventional modal approach. A wave-based exact analytical method is applied to study vibrations in built-up multistory space frames. From the wave vibration standpoint, vibrations are described as waves propagating along uniform structural elements and being reflected and transmitted at structural discontinuities. Free vibration responses are studied based on classical vibration theories. Numerical examples are given with comparison to results available in the literature. Good agreements have been reached. This study not only provides an exact analytical approach to complex vibration problems in built-up multistory space frames that have mostly been studied numerically but also provides a benchmark to existing numerical tools.

scholarly journals EXPERIMENTAL RESEARCH METHODOLOGY OF FULL-SCALE STEEL AND CONCRETE COMPOSITE CABLE SPACE FRAME PROTOTYPE

2017 ◽  
Vol 2 (49) ◽  
pp. 270-276
Author(s):  
L. I. Storozhenko ◽  
G. M. Hasii
Keyword(s):  
Research Methodology ◽  
Strain State ◽  
Experimental Studies ◽  
Full Scale ◽  
Space Systems ◽  
Uniform Load ◽  
Space Frame ◽  
Space Frames ◽  
New Space ◽  
Definition Of

The article describes the main features of experimental studies methodology of new space systems constructive solutions effectiveness. Research methodology is developed by the example of full-scale prototype of the steel and concrete composite cable space frame, which consists of space steel and concrete composite modules and flexible bottom chord. Methodology for study stress-strain state of the prototype by testing in the uniform load applied to nodes is developed. It also provides the nodes displacement definition of the prototype. According to the developed technique, stressed state of full-scale prototype of the steel and concrete composite cable space frame was studied with tensionmetric and photogrammetric methods. Equipment and devices arrangement schemes for measuring deformations and displacements of the full-scale steel and concrete composite cable space frames prototype are presented.

3-D reconstruction and analysis of mammalian mitotic spindle structure

1992 ◽  
Vol 50 (1) ◽  
pp. 578-579
Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh
Keyword(s):  
Cross Sections ◽  
Mitotic Spindle ◽  
Experimental Studies ◽  
Video Camera ◽  
Three Dimensions ◽  
Mitotic Spindles ◽  
Black And White ◽  
Reconstruction Methods ◽  
Spindle Structure ◽  
Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

scholarly journals Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 27
Author(s):  
Jean-Paul Mosnier ◽  
Eugene T. Kennedy ◽  
Jean-Marc Bizau ◽  
Denis Cubaynes ◽  
Ségolène Guilbaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Rydberg Series ◽  
R Matrix ◽  
Resonance Strengths ◽  
Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

Stress concentration factors for the torsion of curved beams of arbitrary cross-section

2006 ◽  
Vol 220 (12) ◽  
pp. 1709-1726 ◽  
Author(s):  
R E Cornwell
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Cross Section ◽  
Cross Sections ◽  
Shear Stresses ◽  
Curved Beams ◽  
Finite Element Implementation ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Stress Concentration Factors

There are numerous situations in machine component design in which curved beams with cross-sections of arbitrary geometry are loaded in the plane of curvature, i.e. in flexure. However, there is little guidance in the technical literature concerning how the shear stresses resulting from out-of-plane loading of these same components are effected by the component's curvature. The current literature on out-of-plane loading of curved members relates almost exclusively to the circular and rectangular cross-sections used in springs. This article extends the range of applicability of stress concentration factors for curved beams with circular and rectangular cross-sections and greatly expands the types of cross-sections for which stress concentration factors are available. Wahl's stress concentration factor for circular cross-sections, usually assumed only valid for spring indices above 3.0, is shown to be applicable for spring indices as low as 1.2. The theory applicable to the torsion of curved beams and its finite-element implementation are outlined. Results developed using the finite-element implementation agree with previously available data for circular and rectangular cross-sections while providing stress concentration factors for a wider variety of cross-section geometries and spring indices.

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