Cumulative Fatigue Damage Under Stress-Controlled Conditions

1971 ◽  
Vol 93 (4) ◽  
pp. 691-698 ◽  
Author(s):  
Thang Bui Quoc ◽  
J. Dubuc ◽  
A. Bazergui ◽  
A. Biron
Keyword(s):  
Theoretical Analysis ◽  
Fatigue Damage ◽  
Experimental Results ◽  
Published Data ◽  
Mean Stress ◽  
Remaining Life ◽  
Random Loading ◽  
Controlled Conditions ◽  
Cumulative Fatigue Damage ◽  
Good Agreement

A theoretical analysis of uniaxial cumulative fatigue damage is presented together with a large number of experimental results on unnotched specimens of A-201 and A-517 steels. The theory developed permits the prediction of fatigue curves for stress-controlled conditions with zero or positive mean stress as well as the evaluation of the damage accumulated during a fatigue test and hence the prediction of the remaining life of a specimen. Theory is in good agreement with the experimental results as well as with published data on other materials. The development may be extended to other types of tests such as strain-controlled or random loading conditions.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

Estimation of Cumulative Fatigue Damage Under Random Loading

1976 ◽  
Vol 98 (1) ◽  
pp. 348-353 ◽  
Author(s):  
A. K. Abu-Akeel
Keyword(s):  
Fatigue Damage ◽  
Computation Time ◽  
Straight Line Segment ◽  
Computer Applications ◽  
Accurate Estimation ◽  
Random Loading ◽  
Structural Element ◽  
Load Curve ◽  
Straight Line ◽  
Cumulative Fatigue Damage

A method is presented that leads to accurate estimation of the cumulative fatigue damage incurred in a randomly loaded structural element when loading is given in the form of spectral density load, or stress, plots. The load plots are here approximated by a series of straight lines and a closed formula is obtained to yield the damage incurred by the load within each straight line segment. The method avoids the errors that result from human misjudgment in the commonly used curve-stepping approach. It is also adaptable for computer applications and can be incorporated in a stress calculation program to save on computation time. In comparison to curve stepping, five straight-line segments may give the same accuracy as a hundred curve steps. This contrast, however, depends on the degree of irregularity of the load curve.

Collision–induced absorption in gaseous methane at low temperatures

1986 ◽  
Vol 64 (7) ◽  
pp. 763-767 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Low Frequency ◽  
Frequency Region ◽  
Experimental Results ◽  
Published Data ◽  
Frequency Range ◽  
Simple Method ◽  
Induced Absorption ◽  
Good Agreement

A recently developed theory for collision-induced absorption in methane is compared with experimental results over a wider spectral range and at lower temperatures than previously reported. The present experimental results covering the frequency range below 400 cm−1 exhibit good agreement with other recently published data. The theory shows excellent agreement with experiment in the low-frequency region below approximately 200 cm−1 but underestimates the experimental data somewhat at higher frequencies. Possible theoretical reasons for this discrepancy are given. The theory represents a simple method of obtaining a good estimate of the collision-induced absorption spectra of methane in this frequency region and for extrapolating to lower temperatures for which experimentation is not feasible. In addition, the moments α1 and γ1are compared with earlier determinations and indicate good agreement with the previously obtained values for the octupole and hexadecapole moments of methane.

Cumulative Damage in Composites

1990 ◽  
Vol 112 (3) ◽  
pp. 358-361 ◽  
Author(s):  
H. A. Whitworth
Keyword(s):  
Experimental Data ◽  
Fatigue Damage ◽  
Stress Level ◽  
Present Model ◽  
Damage Model ◽  
Fatigue Loading ◽  
Damage Function ◽  
Epoxy Composites ◽  
Remaining Life ◽  
Cumulative Fatigue Damage

The problem of cumulative fatigue damage in composites is analyzed based upon the development of a phenomenological damage model. In this modeling, a damage function is defined based on the degradation of the residual stiffness and used to predict the remaining life of composite specimens subjected to dual stress level fatigue loading. Available experimental data for graphite/epoxy composites are compared with the predictions of the present model.

The Separation of Light Gaseous Isotopes by Mass Diffusion Columns II

1964 ◽  
Vol 19 (6) ◽  
pp. 747-755
Author(s):  
W. J. De Wet ◽  
J. Los
Keyword(s):  
Theoretical Analysis ◽  
Mass Diffusion ◽  
Experimental Results ◽  
The Other ◽  
Countercurrent Flow ◽  
Gas Solubility ◽  
Flow Rates ◽  
Mixing Effects ◽  
Other Hand ◽  
Good Agreement

The design of mass diffusion columns operated with partition membranes, for the separation of light gaseous isotopes, is discussed. A theoretical analysis of experimental results obtained indicates that a good agreement between experimental results and theory is only obtained at low column pressures and moderate countercurrent flow rates. At fairly low countercurrent flow rates mixing effects due to viscous dragging and gas solubility by the condensate appear to be considerable whereas excessively high countercurrent flow rates, on the other hand, also seem undesirable. Some suggestions are proposed to obviate impairing effects at least to some extent.

Numerical study of fatigue damage under random loading using Rainflow cycle counting

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tayeb Kebir ◽  
José A.F.O. Correia ◽  
Mohamed Benguediab ◽  
Abilio M.P. De Jesus
Keyword(s):  
Fatigue Damage ◽  
Numerical Study ◽  
Scientific Work ◽  
Stress Effect ◽  
Mean Stress ◽  
Random Loading ◽  
Content Type ◽  
Rainflow Cycle Counting ◽  
The Mean ◽  
Rainflow Counting

PurposeThe purpose of this scientific work is to simulate the fatigue damage under random loading, taking into account the mean stress effect on fatigue lifetime and using the Rainflow counting technique to assess the fatigue damage by the Ansys software. The used material is aluminum alloy 6082-T6. A comparison with literature results has confirmed this investigation in this paper.Design/methodology/approachThe study of fatigue under random loading is based on the same concepts as constant loading with the addition of damage summation. The proportion of damage caused by a stress cycle depends not only on the alternating stress but also on the mean stress.FindingsAnalysis of the fatigue damage shows that the number of relative damage due to each cycle.Originality/valueThis paper aims to simulate the fatigue damage under random loading for aluminum alloys.

Cumulative Fatigue Damage With Random Loading

1962 ◽  
Vol 84 (3) ◽  
pp. 403-408 ◽  
Author(s):  
R. R. Gatts
Keyword(s):  
Fatigue Damage ◽  
Stress Amplitude ◽  
Amplitude Distribution ◽  
General Concept ◽  
Time Function ◽  
Discrete Distributions ◽  
Random Loading ◽  
Linear Rule ◽  
Cumulative Fatigue Damage ◽  
Distribution Of Stress

A general concept of the accumulation of fatigue damage is applied where stress amplitude is a random time function with a specified amplitude distribution. A differential equation relating damage accumulation to the amplitude distribution of stress is derived. This equation is applicable to both continuous and discrete distributions. Solutions of the equation are used to predict life under random loading on the basis of constant amplitude S-N data. Such predictions are compared for both continuous and discrete stress amplitude distributions and found in better over-all agreement with the data than comparable predictions by the linear rule.

Numerical study of fatigue damage under random loading using rainflow cycle counting

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tayeb Kebir ◽  
José Correia ◽  
Mohamed Benguediab ◽  
Abilio M.P. de Jesus
Keyword(s):  
Fatigue Damage ◽  
Numerical Study ◽  
Hysteresis Loops ◽  
Scientific Work ◽  
Simulation Method ◽  
Stress Effect ◽  
Mean Stress ◽  
Random Loading ◽  
Content Type ◽  
The Mean

PurposeThe purpose of this scientific work is to simulate the fatigue damage under random loading taking into account the mean stress effect on fatigue lifetime and using the rainflow counting technique to assess the fatigue damage.Design/methodology/approachThe study of fatigue under random loading is based on same concepts which as constant loading with addition of damage summation. The damage of materials due a stress cycle depends not only on the alternating stress but also on the mean stress.FindingsThe cycles counting simulation method allows quantifying the hysteresis loops, even if for small amplitude stresses.Originality/valueThe cycles are low or medium; the damage occurs most often, the higher values of alternating stresses cause the most failure of materials.

A Microstrip Stepped-Impedance Resonator Bandpass Filter Based on Inductive Coupling

Frequenz ◽  
2019 ◽  
Vol 73 (1-2) ◽  
pp. 7-11
Author(s):  
X. C. Zhang ◽  
X. Chen ◽  
L. Sun ◽  
Y. S. Huang ◽  
X. F. Gao
Keyword(s):  
Theoretical Analysis ◽  
Bandpass Filter ◽  
Higher Order ◽  
Experimental Results ◽  
Inductive Coupling ◽  
Successful Design ◽  
Stepped Impedance Resonator ◽  
Good Agreement

Abstract A simple and successful design for a microstrip stepped-impedance resonator (SIR) bandpass filter (BPF) based on inductive coupling is presented. It is well known that SIRs are used to shift or suppress the higher order frequencies. In order to achieve compact circuit size, a perceptual stepped-impedance resonator is utilized. Based on theoretical analysis, this resonator can shift the spurious frequency to 3.8f0. The experimental results show good agreement with theory and simulations.

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