scholarly journals Experimental Investigation of the Structural Scattering Due to Impedance Discontinuities on a Cylindrical Shell

2005 ◽  
Author(s):  
Ryan J. Glotzbecker ◽  
Stephen A. Hambric ◽  
Martin L. Pollack
Keyword(s):  
Experimental Investigation ◽  
Weld Seam ◽  
Structural Characteristics ◽  
Structural Response ◽  
Test Results ◽  
Response Matrix ◽  
Cylindrical Structures ◽  
Integer Multiple ◽  
Input Force ◽  
Analytical Work

Experimental, numerical, and analytical work has shown that the response of a shell to a distributed force wave possesses unique characteristics which are dependent on the nature of structure attached to the shell. Specific characteristics which influence the response are the distribution of the discontinuities around the circumference (periodic/a-periodic), the impedance of the discontinuities relative to that of the shell, and the type of impedance (mass or stiffness). An experimental investigation into the harmonic scattering behavior of a shell due to mass discontinuities is presented in this paper. Knowledge of the key structural characteristics which influence scattering and their behavior will allow for a diagnostic tool when assessing the structural response of more complex cylindrical structures. Changes in structural response on a mode number basis as a result of the change in mass discontinuities are explored. Spatial Fourier analysis of both the input force and output response is used to provide a measure of the structural response matrix on a mode-by-mode basis. A distributed input force is simulated by applying forces around the circumference of the shell, then subsequently weighting the phase and amplitude of the measured transfer function according to the input force wave desired. This technique was applied to a shell in its unmodified condition, with periodic masses attached, and with aperiodic masses attached. Test results indicate that some harmonic scattering is present in the clean structure (no attached mass), likely due to non-ideal boundary conditions and the weld seam of the pipe used. Test results for the structure with periodically distributed masses indicate that response harmonics equal to the sum of input the harmonic number and an integer multiple of the number of discontinuities were excited. The structure with a-periodically distributed masses appears to scatter energy from the force harmonic into all response harmonics.

Experimental Investigation on Fire Resistance of CES Columns Subjected to 3-Side Heating

2011 ◽  
Vol 250-253 ◽  
pp. 1657-1666
Author(s):  
Xiao Yong Mao ◽  
Wei Hua Guo ◽  
Li Li Li
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Fire Resistance ◽  
Structural Response ◽  
Load Ratio ◽  
Test Results ◽  
Key Factors ◽  
Fire Condition ◽  
Load Intensity ◽  
Steel Section

Results of experimental study on fire resistance of four concrete encased steel (CES) columns are presented. The four columns have the same steel section and reinforcements but different load intensity and load eccentricity, which were the key factors for fire resistance of CES columns under fire condition. The tested results are utilized to study the effect of various parameters on thermal and structural response of CES columns. Spalling of CES columns under fire condition are also investigated. Test results show that CES columns under 3-side heating have higher fire resistance than that under 4-side heating. Also, load ratio and load eccentricity have noticeable influence on the fire resistance of CES columns. In addition, spalling of concrete decreases the fire resistance of CES columns.

scholarly journals Experimental Investigation on Composite Deck Slab Made of Cold-Formed Profiled Steel Sheeting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 229
Author(s):  
Siva Avudaiappan ◽  
Erick I. Saavedra Flores ◽  
Gerardo Araya-Letelier ◽  
Walter Jonathan Thomas ◽  
Sudharshan N. Raman ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Test Results ◽  
Shear Connectors ◽  
Modes Of Failure ◽  
Deck Slabs ◽  
Load Carrying ◽  
Composite Slabs ◽  
Ultimate Load Carrying Capacity ◽  
Ductility Ratio ◽  
Deck Slab

An experimental investigation is performed on various cold-formed profiled sheets to study the connection behavior of composite deck slab actions using bolted shear connectors. Various profiles like dovetailed (or) re-entrant profiles, rectangular profiles and trapezoidal profiles are used in the present investigation. This experimental investigation deals with the evaluation of various parameters such as the ultimate load carrying capacity versus deflection, load versus slip, ductility ratio, strain energy and modes of failure in composite slab specimens with varying profiles. From the test results the performance of dovetailed profiled composite slabs’ resistance is significantly higher than the other two profiled composite deck slabs.

scholarly journals Investigation of the Time Dependence of Wind-Induced Aeroelastic Response on a Scale Model of a High-Rise Building

2021 ◽  
Vol 11 (8) ◽  
pp. 3315
Author(s):  
Fabio Rizzo
Keyword(s):  
Wind Tunnel ◽  
Time Dependence ◽  
Wind Tunnel Test ◽  
Structural Response ◽  
Cumulative Distribution ◽  
Scale Model ◽  
Acquisition Time ◽  
Test Results ◽  
High Rise ◽  
High Rise Building

Experimental wind tunnel test results are affected by acquisition times because extreme pressure peak statistics depend on the length of acquisition records. This is also true for dynamic tests on aeroelastic models where the structural response of the scale model is affected by aerodynamic damping and by random vortex shedding. This paper investigates the acquisition time dependence of linear transformation through singular value decomposition (SVD) and its correlation with floor accelerometric signals acquired during wind tunnel aeroelastic testing of a scale model high-rise building. Particular attention was given to the variability of eigenvectors, singular values and the correlation coefficient for two wind angles and thirteen different wind velocities. The cumulative distribution function of empirical magnitudes was fitted with numerical cumulative density function (CDF). Kolmogorov–Smirnov test results are also discussed.

Experimental Investigation on Relative Crack Length For Fracture Toughness of Concrete

2010 ◽  
Vol 146-147 ◽  
pp. 1524-1528 ◽  
Author(s):  
Xue Zhi Wang ◽  
Zong Chao Xu ◽  
Zhong Bi ◽  
Hao Wang
Keyword(s):  
Fracture Toughness ◽  
Experimental Investigation ◽  
Crack Length ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Toughness Test ◽  
Wedge Splitting Test ◽  
Splitting Test ◽  
Wedge Splitting

The wedge splitting test specimens with three series of different relative crack length were used to study the influences of relative crack length on the fracture toughness of common concrete. The suitable formulation for fracture toughness of concrete with different relative crack length was gotten on comparing between fracture toughness test results and computation results of the model developed from Hu formula.

Properties comparison of GaN epilayers deposited under different growth temperatures

2011 ◽  
Vol 19 (1) ◽  
Author(s):  
P. Wang ◽  
H. Yan ◽  
B. Cao ◽  
W. Wei ◽  
Z. Gan ◽  
...  
Keyword(s):  
Growth Temperature ◽  
Structural Characteristics ◽  
Chemical Vapour ◽  
Optimal Growth ◽  
Good Method ◽  
Test Results ◽  
Temperature Deposition ◽  
Metalorganic Chemical Vapour Deposition ◽  
Gan Film

AbstractUndoped GaN epilayers were grown on c-plane sapphire substrates under different growth temperatures by metalorganic chemical vapour deposition (MOCVD). The optical and structural characteristics of these grown samples were studied and compared. It was found that the crystalline quality of GaN film deposited at 1050°C was better that of other samples. Photoluminescence spectra showed that the intensities of yellow luminescence band of the samples decreased as the growth temperature increased. All above test results demonstrate that high temperature deposition can serve as a good method for high-quality GaN epilayer growth and there exists an optimal growth temperature.

Experimental Study on Sand and Cement Replacement by Termite Mound Soil

2019 ◽  
pp. 279-287
Author(s):  
Harish R ◽  
Ramesh S ◽  
Tharani A ◽  
Mageshkumar P
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Compressive Strength ◽  
Natural Environment ◽  
Fine Aggregate ◽  
Test Results ◽  
Termite Mound ◽  
Cement Concrete ◽  
Cement Ratio ◽  
Compressive Strength Of Concrete

This paper presents the results of an experimental investigation of the compressive strength of concrete cubes containing termite mound soil. The specimens were cast using M20 grade of concrete. Two mix ratios for replacement of sand and cement are of 1:1.7:2.7 and 1:1.5:2.5 (cement: sand: aggregate) with water- cement ratio of 0.45 and varying combination of termite mound soil in equal amount ranging from 30% and 40% replacing fine aggregate (sand) and cement from 10%,15%,20% were used. A total of 27 cubes, 18 cylinders and 6 beams were cast by replacing fine aggregate, specimens were cured in water for 7,14 and 28 days. The test results showed that the compressive strength of the concrete cubes increases with age and decreases with increasing percentage replacement of cement and increases with increasing the replacement of sand with termite mound soil cured in water. The study concluded that termite mound cement concrete is adequate to use for construction purposes in natural environment.

Experimental Investigation of Stiffened Square CFST Columns under Axial Load

2014 ◽  
Vol 919-921 ◽  
pp. 1794-1800
Author(s):  
Xin Zhi Zheng ◽  
Xin Hua Zheng
Keyword(s):  
Experimental Investigation ◽  
Bearing Capacity ◽  
Cross Sections ◽  
Axial Load ◽  
Local Buckling ◽  
Test Results ◽  
Tubular Columns ◽  
Economical Benefit ◽  
Steel Consumption ◽  
Cfst Columns

Abstract: 7 square steel tubular columns were tested to discuss the ultimate axial bearing capacity, ductility performance and the steel consumption under stiffened by steel belts and binding bars of different cross-sections. Test results indicate that only by increasing fewer amounts of steel usage, stiffened square CFST columns with binding bars can not only improve the overall effects of restraint and alleviate regional local buckling between the binding bars, but also improve the bearing capacity of concrete filled square steel tubular columns. The utility benefits and the economical benefit is considerable, deserving extensive use.

scholarly journals Analytical and Experimental Investigation of the Stability of the Rotor-Bearing System of a New Small Turbocharger

1987 ◽  
Author(s):  
H. R. Born
Keyword(s):  
Experimental Investigation ◽  
Dynamic Stability ◽  
Squeeze Film ◽  
Test Results ◽  
Flow Capacity ◽  
Squeeze Film Dampers ◽  
Rotor Bearing ◽  
The Stability ◽  
Turbine Design ◽  
Bearing System

This paper presents an overview of the development of a reliable bearing system for a new line of small turbochargers where the bearing system has to be compatible with a new compressor and turbine design. The first part demonstrates how the increased weight of the turbine, due to a 40 % increase in flow capacity, influences the dynamic stability of the rotor-bearing system. The second part shows how stability can be improved by optimizing important floating ring parameters and by applying different bearing designs, such as profiled bore bearings supported on squeeze film dampers. Test results and stability analyses are included as well as the criteria which led to the decision to choose a squeeze film backed symmetrical 3-lobe bearing for this new turbocharger design.

scholarly journals Condensation of Novec 649 refrigerant in pipe minichannels

2018 ◽  
Vol 70 ◽  
pp. 02002 ◽  
Author(s):  
Tadeusz Bohdal ◽  
Henryk Charun ◽  
Małgorzata Sikora
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Mass Flux ◽  
Flow Structures ◽  
Test Results ◽  
Calculation Results ◽  
Vapour Quality ◽  
Inner Diameter

The paper presents the results of experimental investigation of Novec 649 refrigerant condensation in tube minichannels. This is a low-pressure refrigerant. This investigations are basis for flow structures visualization during condensation in pipe minichannels. The local and the average values of pressure drop (Δp/L) and heat transfer coefficient α in the whole range of the changes of vapour quality (x = 1 ÷ 0) were calculated. On the basis of the obtained test results there was illustrated the influence of the vapour quality x, the mass flux density G and the inner diameter of channel d changes on the studied parameters. These results were compared with the calculation results based on the dependencies of other authors.

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