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Volume 1 is devoted to
sinusoidal
vibration (North
America) and to swept sine vibration, widely used in tests to characterize
the dynamic behavior of structures (natural frequencies, damping).
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Volume 2 addresses the topic of
mechanical shock (North
America), presenting the shock response spectrum (S.R.S.) with its different
definitions, its properties and the precautions to be observed in its calculation.
The shocks most widely used in the usual facilities are identified, with
their characteristics, indicating how test specifications with the same
degree of severity as that of the real measured environment can be drafted.
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This volume
then describes how these specifications can be reached using classic laboratory
facilities : shock machines, electrodynamic exciters controlled from a
time signal or from a response spectrum, specifying the limitations, advantages
and disadvantages of each solution. |
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Volume 3 examines the analysis
of
random vibrations (North
America), which account for the vast majority of the vibrations encountered in the
real environment. This volume describes the overall properties of the process
enabling a simplification of analysis, before presenting the analysis of
the signal in the frequency domain. The definition of the power spectral
density is recalled, specifying the precautions to be taken in its calculation,
together with the processes employed to improve results (windowing, overlapping).
A additional third avenue consists of analyzing the statistical properties
of the time history.
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This study makes
it possible to determine, in particular, the law of distribution of the
maxima of a random Gaussian signal and to simplify the calculation of fatigue
damage by avoiding direct peak counting.
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Volume 4, after establishing relationships
providing the response of a linear system with one degree of freedom to
a random vibration, is devoted to the calculation of
fatigue
damage (North
America). It presents the hypotheses adopted to describe the behavior
of a material subjected to fatigue, the laws governing the accumulation
of damage, together with methods for counting the peaks of the response,
used to draw a histogram when it is impossible to use the probability density
of the peaks obtained with a Gaussian signal. The expressions of mean damage
and its standard deviation are established, followed by the examination
of a few cases using other hypotheses (static mean stress, taking account
of the limit of endurance, non linear accumulation law, etc.).
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Volume 5 is more particularly
designed to present the
method
for drafting test specifications (North
America) according to the principle of tailoring.
The extreme response
and fatigue damage spectra
are defined for each type of stress (sinusoidal vibrations, swept sine,
shocks, random vibrations, etc.). The process for establishing a specification
as from the life cycle profile of the material is then detailed, taking
account of an uncertainty coefficient (or safety factor)
intended to cover the uncertainties related to the dispersion of the real
environment and of mechanical resistance, together with another coefficient,
the test factor, which takes account of the number of tests performed
to demonstrate the resistance of the material.
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