Stationary and Transient Response of Cylindrical Shells Under Random Excitation

1988 ◽  
Vol 110 (2) ◽  
pp. 205-209
Author(s):  
A. V. Singh
Keyword(s):  
Transient Response ◽  
Random Vibration ◽  
Time History ◽  
Wide Band ◽  
Random Excitation ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
History Of ◽  
The Mean ◽  
Random Vibration Analysis

This paper presents the random vibration analysis of a simply supported cylindrical shell under a ring load which is uniform around the circumference. The time history of the excitation is assumed to be a stationary wide-band random process. The finite element method and the condition of symmetry along the length of the cylinder are used to calculate the natural frequencies and associated mode shapes. Maximum values of the mean square displacements and velocities occur at the point of application of the load. It is seen that the transient response of the shell under wide band stationary excitation is nonstationary in the initial stages and approaches the stationary solution for large value of time.

Wide-Band Random Axisymmetric Vibration of Cylindrical Shells

1979 ◽  
Vol 46 (2) ◽  
pp. 417-422 ◽  
Author(s):  
I. Elishakoff ◽  
A. Th. van Zanten ◽  
S. H. Crandall
Keyword(s):  
Circular Cylindrical Shell ◽  
Time History ◽  
Wide Band ◽  
Axisymmetric Vibration ◽  
Mean Square ◽  
Mean Square Response ◽  
History Of ◽  
Cross Correlations ◽  
The Mean ◽  
Band Limited

Analytical and numerical results are reported for the random vibrations of a uniform circular cylindrical shell excited by a ring load which is uniform around the circumference and random in time. The time history of loading is taken to be a stationary wide-band random process. The shell response is essentially one-dimensional but differs qualitatively and quantitatively from the response distributions for point-excited uniform strings and beams because of the large modal overlaps at the low end of the spectrum of shell natural frequencies. The contributions from the modal cross-correlations (which can usually be neglected for strings and beams) introduce an asymmetry into the distribution of mean-square response and can alter the magnitude of the local response considerably. For example, in a thin shell with a radius-to-length ratio of 0.5 the contribution to the mean-square velocity at the driven section due to the modal cross-correlations can be more than three times that due to the modal autocorrelations when the excitation is a band-limited white noise which includes 81 modes.

The Time Domain Simulation of Non-Stationary Road Roughness

2013 ◽  
Vol 423-426 ◽  
pp. 1238-1242
Author(s):  
Hao Wang ◽  
Xiao Mei Shi
Keyword(s):  
Power Spectrum ◽  
Time Domain ◽  
Ride Comfort ◽  
Time History ◽  
Random Excitation ◽  
Power Spectrum Density ◽  
The Road ◽  
Road Roughness ◽  
Spectrum Density ◽  
History Of

The input of road roughness, which affects the ride comfort and the handling stability of vehicle, is the main excitation for the running vehicle. The time history of the road roughness was researched with the random phases, based on the stationary power spectrum density of the road roughness determined by the standards. Through the inverse Fourier transform, the random phases can be used to get the road roughness in time domain, together with the amplitude. Then, the time domain simulation of the non-stationary random excitation when the vehicle ran at the changing speed, would also be studied based on the random phases. It is proved that the random road excitation for the vehicle with the changing speed is stationary modulated evolution random excitation, and its power spectrum density is the stationary modulated evolutionary power spectrum density. And the numerical results for the time history of the non-stationary random inputs were also provided. The time history of the non-stationary random road can be used to evaluate the ride comfort of the vehicle which is running at the changing speed.

Time Progression of Hemolysis of Erythrocyte Populations Exposed to Supraphysiological Temperatures

1979 ◽  
Vol 101 (3) ◽  
pp. 213-217 ◽  
Author(s):  
N. A. Moussa ◽  
E. N. Tell ◽  
E. G. Cravalho
Keyword(s):  
Statistical Model ◽  
Distribution Curve ◽  
Time History ◽  
Kinetic Scheme ◽  
First Order ◽  
Arrhenius Dependence ◽  
History Of ◽  
The Mean ◽  
Two Parameters ◽  
Microscope Stage

Populations of erythrocytes in solution were heated “instantaneously” to and maintained at temperatures in the range of 44 to 60°C on a microscope stage specifically designed for this purpose. Simultaneously, the visually observed hemolysis-time history of these cells was measured. The results were successfully correlated on the basis of two models: 1) a kinetic scheme assuming two sequential, first-order reactions by which the cells are first reversibly altered and then irreversibly damaged; and 2) a statistical model for which the number of cells that are damaged at each instant is assumed to be normally distributed. From the experimental data the rate constants for the two reactions in the kinetic model were determined and were found to have an Arrhenius dependence on temperature. By applying the statistical model to the data, we were able to determine the mean and standard deviation of the distribution curve for this model. The logarithms of these latter two parameters vary with temperature in a linear fashion.

An efficient method for non-stationary random vibration analysis of beams

2011 ◽  
Vol 17 (13) ◽  
pp. 2015-2022 ◽  
Author(s):  
Jie Yang ◽  
De-you Zhao ◽  
Ming Hong
Keyword(s):  
Efficient Method ◽  
Random Vibration ◽  
High Efficiency ◽  
Theoretical Method ◽  
Random Excitation ◽  
The Finite Element Method ◽  
Euler Beam ◽  
Time Step ◽  
Random Loads ◽  
Pseudo Excitation

An efficient method is presented to investigate the non-stationary random vibration response of structures. This method has the advantage of the accuracy of theoretical method in dealing with random loads and the versatility of the finite element method (FEM) in dealing with structures. In this paper, the Euler beam is adopted in the derivation of the governing equation. The uncoupled approach of the frequency-dependent system matrices is presented for solving the motion equation of forced vibration. The time-variance random dynamic response of the beam is analyzed by the precise integral method, meanwhile, the pseudo-excitation is applied to transform the non-stationary random excitation into deterministic pseudo one to simplify the solution of the dynamic equation. Solutions calculated by the FEM with different time step and theoretical analysis are also obtained for comparison. Numerical examples demonstrate the accuracy and high efficiency of the proposed method.

Transient Response of a Rigid Spherical Inclusion in an Elastic Medium

1965 ◽  
Vol 32 (3) ◽  
pp. 637-642 ◽  
Author(s):  
C. C. Mow
Keyword(s):  
Exact Solution ◽  
Elastic Medium ◽  
Transient Response ◽  
Integral Method ◽  
Spherical Inclusion ◽  
Time History ◽  
Fourier Integral ◽  
Incident Pulse ◽  
History Of

The transient response of a rigid spherical inclusion of arbitrary density embedded in an elastic medium owing to an incident pulse is examined in this paper. The Fourier-integral method is used, and an exact solution of the response is obtained. It is found that the acceleration and velocity of the inclusion are substantially different from those of the medium. A slight difference in the time history of the displacement between the inclusion and the medium is also noted.

Hayward fault slippage in the Irvington-Niles districts of Fremont, California

1966 ◽  
Vol 56 (2) ◽  
pp. 257-279 ◽  
Author(s):  
Lloyd S. Cluff ◽  
Karl V. Steinbrugge
Keyword(s):  
Fault Zone ◽  
Time History ◽  
Wide Band ◽  
Strong Earthquakes ◽  
The Past ◽  
Parallel Lines ◽  
History Of ◽  
Surface Ruptures ◽  
Warm Springs

abstract Right lateral slippage on the Hayward fault has faken place in the Irvington and Niles districts of Fremont since the well known 1868 Hayward earthquake which produced surface ruptures from San Leandro to Warm Springs. This post-1868 movement has been occurring without being identified with strong earthquakes. Structures and railroads crossing the Hayward fault in the area under study date back to 1866. Fault slippage can be observed at ten separate locations along the strike of the Hayward fault in the Irvington-Niles districts of Fremont, California. One location predates the 1868 earthquake. There is no evidence for parallel lines of fault slippage within the approximately 200-foot wide fault zone. The slippage appears to have occurred within a 10-foot wide band parallel to the strike of the fault. Structures and railroads built at different times during the past 100 years give a time-history of the slippage. The slippage, if any, between 1868 and 1909 is unknown. From 1909 until as late as 1949 or early 1950, there was no observed fault slippage. Approximately one-half foot of slippage occurred between about 1949 or early 1950 and about 1957, and no measurable slippage since 1957.

A Method for Double Random Vibration Analysis

2014 ◽  
Vol 577 ◽  
pp. 119-124
Author(s):  
Jun Liao ◽  
Da Fu Xu ◽  
Bing Yan Jiang
Keyword(s):  
Numerical Procedure ◽  
Random Parameter ◽  
Random Excitation ◽  
Energy Concentration ◽  
Parameter System ◽  
Precise Integration ◽  
Gegenbauer Polynomial ◽  
Small Band ◽  
The Mean ◽  
Random Vibration Analysis

A numerical procedure to compute the mean and covariance matrix of the random response of stochastic structures modeled by FE models is presented. With the help of Gegenbauer polynomial approximation, the calculation of dynamic response of random parameter system is transformed into an equivalent certainty expansion order system's response calculation. Non-stationary, non-white, non-zero means, Gaussian distributed excitation is represented by the well-known Karhunen-Loeve (K-L) expansion. The Precise Integration Method is employed to obtain the K-L decomposition of the non-stationary filtered white noise random excitation. A very accurate result is obtained by a small amount of K-L vectors with the vector characteristic of energy concentration, especially for the small band-width excitation. Correctness of the method is verified by the simulations.

Hermetically Metal Sealing Random Vibration Damage Mechanism and Fatigue Life Prediction

2013 ◽  
Vol 423-426 ◽  
pp. 1501-1505 ◽  
Author(s):  
Teng Han ◽  
Xiao Qi He ◽  
Yun Fei En
Keyword(s):  
Fatigue Life ◽  
Vibration Analysis ◽  
Random Vibration ◽  
Time History ◽  
Simulation Method ◽  
Damage Mechanism ◽  
Von Mises Stress ◽  
History Data ◽  
Von Mises ◽  
Random Vibration Analysis

Finite element simulation method of random vibration analysis was used for hermetically metal sealing. According to the results of the random vibration analysis and the theory of fatigue fracture mechanics, the hermetically metal sealing on the PCB plate cracking damage mechanism was analyzed. The danger point of the Von Mises stress was obtained, and the Von Mises stress - time history data was accessed through inverse Fourier transformation. And rain flow count method was used to calculate Von Mises stress-time history data of cycle count. The linear cumulative damage theory and the material S-N curve were used to calculate the fatigue life of Hermetically metal sealing.

scholarly journals The Case Study of Pseudoexcitation Method Combining Self-Adaptive Gauss Integration in Random Vibration Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Ning Chen ◽  
Siyu Zhu ◽  
Yongle Li
Keyword(s):  
Vibration Analysis ◽  
Random Vibration ◽  
Critical Frequency ◽  
Damping Ratio ◽  
Structural Response ◽  
Coupled System ◽  
Random Excitation ◽  
Wide Frequency Range ◽  
Random Vibration Analysis ◽  
Self Adaptive

The pseudoexcitation method (PEM) can improve efficiency of random vibration analysis. However, for large-sized structures with wide frequency range of response, the workload of calculation is heavy if conventional integration methods, such as trapezoidal integration, are used to combine with the PEM to calculate structural response. In such case, self-adaptive technology is induced to combine with the PEM to form an efficient method for solving random vibration. During calculation, this method can realize the adaptability of random excitation to actual structural response, identify automatically critical frequency intervals of random excitation, and process intelligently the identified critical frequency intervals and noncritical frequency intervals. Based on the identified frequency intervals, Gauss integration is carried out to obtain response results with random characteristics. The computational efficiency and accuracy of PEM-SGI are verified by wind-induced performance of the slender bridge tower. Finally, the influence of damping ratio of the bridge structure and train marshalling on vehicle-bridge coupled system is investigated to further verify the application of the proposed method. Results show that the efficiency of solving random vibration can be improved by the present method.

Isolated Heat Transfer Gaskets for Medium Energy X-Ray Telescope MED Electric Control Box Effect on Random Vibration Performance Study Based on the Finite Element Method

2013 ◽  
Vol 753-755 ◽  
pp. 1812-1815
Author(s):  
Nian Peng Wu ◽  
Chun Ling Meng ◽  
Yun Long Li ◽  
Wen Hua Zhang
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Random Vibration ◽  
Dynamic Performance ◽  
The Finite Element Method ◽  
Performance Study ◽  
X Ray ◽  
Electric Control ◽  
Vibration Performance ◽  
Random Vibration Analysis

In order to understand Isolated Heat Transfer Gaskets placement scheme's influence on the dynamic performance of the MED electric control box,on the basis of theoretical analysis, Finite Element Modal analysis and random vibration analysis have proceeded for different Isolated Heat Transfer Gaskets placement program, and comparative analysis of the two results. Analysis results provide the basis for further optimal design of the MED electric control box.

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