Fatigue & Fracture of Engineering Materials & Structures
May 12, 2021
Dear Editor,
I am pleased to submit an original research article entitled “On the
relationship between mechanical energy rate and heat dissipated rate
during fatigue for a C45 steel depending on stress ratio” by Rosa De
Finis, Davide Palumbo and Umberto Galietti for consideration for
publication in the Fatigue & Fracture of Engineering Materials &
Structures . We previously presented a new procedure to analyze
temperature data acquired during a rapid fatigue test and to evaluate
the endurance limit of different stainless steels and this manuscript
builds on our prior study to investigate more in depth, in frequency
domain, the thermal signal acquired during a rapid, stepwise fatigue
test. In particular, we focus on the second amplitude harmonic (SAH) of
thermal signal, a very well-known parameter to estimate the damage under
specific test conditions (fully-reversed applied load). We investigate
the capability of SAH of temperature signal to represent an useful
parameter to estimate the heat dissipated energy at different stress
ratio conditions (R=-1 and R=0.1). In addition, we study the frequency
spectrum of the strain energy rate, as well, in order to understand the
energy distribution among the harmonics for different stress ratios.
In this manuscript, we show that in presence of the mean stress
in the load, the frequency spectrum of the strain energy density rate
presents different harmonic components (not just one as occurs at R=-1 )
while heat dissipated energy rate spectrum presents different harmonics,
so that the SAH is not the only one but it can be used to estimate the
heat dissipated energy. In addition, we show that the second
amplitude harmonic (SAH) of the heat energy rate dissipated by a unit
volume of material is linearly related to the SAH of strain energy
density rate. Such a relationship depends only on material and do not
depend on loading conditions or damage level. The relationship is also
valid, independently on signal stabilisation.
We believe that this manuscript is appropriate for publication by theFatigue & Fracture of Engineering Materials & Structuresbecause it regards the use of innovative characterization methods
associated with fatigue such as the energy-based methods for carrying
out the damage monitoring of the C45 steel. Our manuscript can create a
paradigm for future studies for the understanding of the relationship
between mechanical energy rate and heat dissipated rate during fatigue
tests under different loading conditions.
This manuscript has not been published and is not under consideration
for publication elsewhere. We have no conflicts of interest to disclose.
Thank you for your consideration.
Sincerely,
Rosa De Finis, PhD
Post doctoral research fellow, Department of Mechanical Mathematics and
Management
Politecnico di Bari-Via Orabona 4, 70125-Bari, Italy