Why Blades Fail Early w/ Morten Handberg of WInd Power LAB

Wind Power LAB's blade expert Morten Handberg explains a critical
wind industry problem: new turbine blades are failing years too
early. These massive blades - now stretching over 100 meters - are
experiencing unexpected structural damage due to complex
aerodynamic forces. Handberg shares Wind Power LAB's essential
strategies for detecting and preventing these costly blade failures
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www.weatherguardwind.comIntelstor - https://www.intelstor.com Allen
Hall: As wind turbines reach unprecedented heights and blade
lengths stretch beyond 100 meters, unexpected challenges are
emerging from the field. This week we welcome back Morten Handberg.
The renowned Blade Whisperer from Wind Power LAB. In this
eye-opening discussion, Morten reveals why modern blade designs are
showing structural issues earlier than expected and what operators
need to watch for to protect their turbines. Stay tuned. Welcome to
Uptime Spotlight, shining Light on Wind Energy's brightest
innovators. This is the Progress Powering tomorrow. Allen Hall:
Morten, welcome back to the show. Morten Handberg: Thanks, Allen.
It's great to be, be back again. Allen Hall: You are one of our
most popular guests. You are the Blade Whisperer. And any time I'm
at a trade show, people ask, how's Morten doing? How's the Blade
Whisperer doing? Like, well, Morten's great. Morten's super busy,
but Morten is great. And they want to have you back on. So here we
are. We're back on again. And. The topic of today's discussion is
about aerodynamic stresses that happen to blades, and we're seeing
more problems with that than some of the quality issues. I think
it's a combination of quality and aerodynamic issues. What is
happening in the field right now with aerodynamic loading on some
of these new, longer, more flexible blades? Morten Handberg: Well,
it's, it's something that's been been happening over time. So if we
look 10, 15 years back, then the blades were of course shorter. The
and they were a lot stiffer than they were today. They were heavily
reinforced and you could say maybe they were. They were under
optimized that they had a lot more load capacity and that were then
what they needed. And, and in, in process of the, in, in, as the
blades have been become longer than the, then that buffer have gone
away, so, because the, in order to build a logger blade, you had to
reduce the the, the thickness of your laminates to avoid an overly,
you know, bulky structure, but something that could harness the
wind in a more efficient way So that leads to slender, thinner
blades that are a lot softer. And we can see that in the natural
frequency that the, that the flap wise and edge wise frequencies,
they have kind of gone down. And that's because the blades become
softer. And that also means that the way that the blade behaves
with the wind direction means that the gravity loads are still a
major, a major component, but Aeroelastic loading, which adds to
shear and torsion loads, have become much more prominent loading
conditions on the blades that we see today. Allen Hall: That's
interesting. Yeah, obviously the blades are lighter than they ever
been for the length. I remember being at DTU a year or so ago and
looking at one of the first offshore wind blades that Vestas had
made, and it was beautiful. back into DTU's laboratory being
examined. And that blade was so stiff and so overdesigned that it
could have lasted, it had, it could last another 20 years. It had
been out in service for 20 years. It could have lasted easily
another 20, maybe another 30 years because of the way it was
designed, how stiff it was, how short it was. It was like a 20
meter blade. It wasn't that big. But today when we're talking 60,
80, 100 meters, those blades are just Dynamically different. Is it
a combination of just trying to lower the cost of the blade or just
the mere fact that the weight is so high? We're trying to transport
it. What's driving down the margins here in terms of the blade
design and making them a lot more flexible? Morten Handberg: Well,
it is, it is an effective of well, by increasing the length, you
also increases the power that you can harness from the blade. You
know, that so, so it is a, it is a desire to create larger turbines
and one of the. Easiest ways to do that is simply by making the
blade longer because you have to, it, you can do it. It's, it's
compared to increasing the sweat barrier or optimizing. And in
other ways, it is a, it is a low hanging fruit and by lowering the
rate of the blades, you can also live with a lighter drive train,
less steel in the tower, smaller foundation. So all of these things
play in into why that the blade is such a, so much in focus in
terms of. Driving down cost overall is by reducing the the weight
of the blades. And that comes as a consequence of it being more it,
yeah, it has, has less design buffer and it also will have less
lifetime compared to the, to the more conservative blades that
we've seen before. You can say that, you know, some of the two
megawatt turbines, I wouldn't be surprised if you can from a blade
perspective that you can, you know elongate the lifetime to 30, 40
years, because they're, they're so conservatively designed compared
to what we see today. Allen Hall: Okay, so adding a kilogram to a
blade has consequences all the way down to the foundation, which
makes sense when you say it. Okay, so that just adds cost and
complexity to every other component in that wind turbine. So the
drive then is to lighten the blades and also lengthen the blades at
the same time. Now, when we do that, I, as I talk to operators
around the world, they come back and say to me, okay, yeah, sure
we're using longer blades, of course it creates more power, but
they're all being qualified. They're all being tested, right? So we
shouldn't have anything to worry about what they're in service. Has
the test standards kept up with the rapid design changes that have
been made? Not at all. Morten Handberg: As I said before, you know,
gravity loads was the predominant load on all the blades. And that
was also what did. Testing and certification standards focused on.
And that's still what it's, what's being, being done today. There
are, you know more being done on hybrid loading, combining stepwise
and edgewise, but that's still gravity based loads. We're not
taking into account aeroelastic loads when, when, when testing and
certifying, but that's all only done in simulation. And then we
learn about what have, what's happening in, in operation. In
operation. So. So the testing and certification has not kept up
with the with, with the load conditions that are, that, that, that
we see on, on the modern blade. Allen Hall: So I have a existing
OEM that I like using, and I just want to go to the next generation
of wind turbines, which is what is happening today. That design of
that new wind turbine may not have the same robustness as the one
you are used to using, particularly if you'd let 5, 10 years go by.
And so then if you're thinking about the blade design, you're
trying to evaluate blade design, you really don't have the data in
front of you then. If they haven't tested that for torsional
loading, aero loading effects, you really don't know what the
history of that blade will be. Just because you don't have the
data, right? You Morten Handberg: have no idea what the, what the
fatigue lifetime is from these new combined loads and, and we are
seeing, you know blades, structural blade damages, blade failures
happening on, on wind farms. From a variety of wind turbine types,
where there is no, no, no sign of manufacturing defects, there is
no lightning strike, there is no sign of transport damage or failed
repair. So, you know, it's very difficult to prove exactly what
kind of load it is without having the exact model or having other
kinds of other types of data. But, you know, When leaving
everything out, then you are starting to think about, is there
something, some load condition going on here since we're seeing
these buckling related failures in areas where they, the blade
simply shouldn't shouldn't have any kind of structural damage.
We're seeing a lot on On on shell sandwich panels where we, where
we see deformation the damage and related to deformation defects.
And very early on, actually, you know the blades are designed for
25 years, but in a wind farm, we can see, you know, multiple blades
with long transverse cracks over the, over the, the, the shell
panels, and there's nothing to suggest any kind of manufacturing
issue. otherwise that would have allowed for this defect to
develop. And that's again, one of the, one of the things that I
think we need, we need to be mindful of with these new, new
turbines. So how prevalent is this issue? What should I be looking
for in the field? The need for inspection. We've been saying this
for many years, also for the older blades, but it's, Absolutely
equally true. So you need to do, at least yearly inspection, maybe
in the early years, do it a bit more often, you know, and do both
internal and external because whatever you see on the outside, on
the outside will likely have started on the inside.