Showing papers on "Vibration fatigue published in 1977"

Fatigue Under Wide Band Random Stresses Using the Rain-Flow Method

Abstract: The University of Arizona has developed a fatigue design procedure for structural components, such as offshore platforms, subjected to a stationary, wide-band-gaussian stress process. Resticted to high-cycle fatigue design, this procedure uses available constant-amplitude material-fatigue data, a modified probability-based Palmgren-Miner rule, and the rain-flow method of counting stess cycles. Statistical uncertainty in fatigue behavior and nonstatistical uncertainty in the PM rule are implicitly accounted for by treating the PM index at failure as a random variable. The fatigue design algorithm requires only that the rms and irregularity factor of the stress process be specified in addition to the constant-amplitude stress/cycle curve for the material.

A Fatigue Crack Growth Analysis Method Based on a Simple Representation of Crack-Tip Plasticity

Abstract: A new approach to fatigue crack propagation is described. The key element in the analysis is the inclined strip-yield superdislocation representation of crack-tip plasticity. The basis of the model is given and its potential application in a cycle-by-cycle analysis of fatigue crack growth under arbitrary cycle-by-cycle loads indicated. It is shown that, to perform a fatigue crack growth computation for a given load sequence, only the material's shear modulus, tensile yield strength, and Poisson's ratio need to be specified. In the process, some account is taken of crack closure during the load cycle. Illustrative calculations for uniform cyclic loading are described and comparisons with experimental results made.

Mechanical vibration gexierator for vibration fatigue tester

Abstract: PURPOSE:To offer vibration generator which is concise, very reliable and used as mechanical vibration generating source for fatigue tester et.al.

Use of coherence and frequency response functions to locate and define vibration noise sources in rolling tires

Abstract: The procedure for measuring and analyzing in-service tire vibration and sound data is described. Signal analysis techniques are applied to obtain tire vibration spectral histories, vibration-to-sound coherence, and vibration frequency response functions. Evaluation of the coherence function demonstrates the existence of a statistical relationship between tire vibration and sound. Vibration spectral histories display the decay of energy in the tire structure. Use is made of the frequency response function to determine the relative levels of vibration in the tread and sidewall regions. These results define the vibration noise source location and size. /HSRI/

Use of General Fatigue Data in the Interpretation of Full-Scale Fatigue Tests,

Abstract: : The fatigue behaviour of notched specimens depends on two elasticity parameters, namely the stress concentration factor and the relative stress gradient or the radius of curvature at the notch root. Laboratory fatigue test results are not always representative of the environmental conditions within aircraft structural assemblies, particularly because of water condensation in gaps and recesses. The frequency effect is mainly ascribable to humidity, and therefore to corrosion, owing to hydrogen penetration. In assemblies, stress concentrations due to load transfer through fasteners are investigated for the case of asymmetric single shear. The breakdown of the applied loadings must include the peak-to-peak, ground-air-ground variation. In load transfer by fastener bearing stresses, the low compressive loads may be neglected, the local highest stresses varying from zero to the maximum. Interpretation of full-scale fatigue test results, either for a different loading or for a slightly modified local design of the structure, is essentially comparative.