Aerospace Research - ISTC Funded Projects 1994-2009

Unfortunately, with the computational tools,
which were available during project
performance terms (1999­2000), the
numerical simulation was limited with only
local contact interaction in a joint element
with push fit (Specimen No.6). Figure 15a
shows typical realistic interferograms
recorded for Specimen No.6 at the 14 th (σ 0
ranging from 174 to 203 MPa) loading cycle.
Nearly perfect quality of fringe patterns in
the figure has to be pointed out. The
experimental information of this kind was
used for validation of the mathematical
model of the 3 rd complexity level (MM­3),
which was applied for numerical simulation
of local deformation processes in contact
interaction zones at cyclic loading. The
performance of the model was perfectly
(a)
Enhancement of Flight Performance, Economy and Efficiency
demonstrated by so­called reference fringe
patterns. The artificial image of local
displacement component fields obtained by
numerical simulation for the case of Fig. 15a
is presented in Fig. 15b. Virtually perfect
agreement of real interferograms and
reference fringe patterns illustrates a very
high quality of MM­3. In addition, Fig. 16
compares experimental (dots) and numerical
(curve) “local strain vs. net stress” diagrams
for the 14 th loading cycle.
Obtained Results
Novel experimental, numerical, and hybrid
research tools capable of providing the
optimal design of highly­loaded pin/rivet
joints with increased fatigue lifetime have
Fig. 15: Real interferogram (a) and reference fringe patterns (b) obtained in the range
of elastoplastic strains and contact interaction at the 14 th loading cycle
for net stress interval σ 0 from 174 to 203 MPa
(b)
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