By Dave Santos on Aug. 8, 201928027Local Melting Failure Mode of Kite LinesBranching
topic from line-twist to the curious thermodynamics of line failure. We
knew that when line breaks it must be a melting effect right at the
break, but we had not connected with supporting academic science until
now. We knew working line rings and throbs with energy that can
concentrate into shockwaves at knots or nicks, causing failure.
Here
again we find the DNA model of polymer dynamics applicable
"...Remarkably,
the propensity to kink correlated with the thermodynamic
destabilization of the mismatched DNA relative the perfectly
complementary strand, suggesting that the kinked state is locally
melted. The molecular vise is exquisitely sensitive to the
sequence-dependent linear and nonlinear elastic properties of dsDNA."
The
"molecular vise" applies compression force, and we can see that kite
line failure modes based on bending and twisting contain local
compression forces. Perhaps compression transients in tensile media are
a key failure dynamic. Sudden compression causes temperature to easily
spike to UHMWPE melting temp not much higher than 100C.
This
is a critical failure mode; that a fast massive kiteplane may slack its
line and then snub up hard, and a bit of twist force can create a
hockle that jams and melts either partially, as damage, or melts apart
(breakaway), in conditions that standard tether engineering
calculations are not yet accounting for.
Multi-line
topologies continue to look more and more essential to prevent AWES
single-line single-point catastrophic failure modes.
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low-complexity
quote-of-the-day-
"The
more ingenious our apparatus, the coarser and more unskillful are our
senses."
Jean
Jacques Rousseau
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