We4Ce’s Solution for Stronger Blade Root Bushings

Allen Hall and Joel Saxum discuss the critical issue of failed
blade bolt inserts with Edo Kuipers of We4Ce. Edo explains the
problem, its widespread impact on the wind energy sector, and
introduces We4Ce's innovative solution - an upgraded blade bolt
insert that can be retrofitted in the field, potentially saving
operators significant downtime and repair costs. Sign up now for
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www.weatherguardwind.comIntelstor - https://www.intelstor.com Allen
Hall: Welcome to the Uptime Wind Energy Podcast. I'm your host,
Allen Hall, along with my co host, Joel Saxum. On this episode,
we're addressing a critical issue that is plaguing the wind energy
sector, the problem of failed blade bolt inserts in wind turbine
blades. And these failures have a significant concern for wind
energy operators, leading to downtime, costly repairs, and the
potential for liberated blades. Our guest is Edo Kuipers, owner and
engineering manager of We4Ce. And We4Ce is based in the
Netherlands. We foresee offers a range of services related to the
design and engineering of wind turbine rotor blades. And they have
designed an upgraded blade bolt insert that can be retrofitted in
the field. And this new insert product could dramatically lower a
wind turbine operator's downtime and blade repair costs. Edo,
welcome to the show. Edo Kuipers: Thanks for having me here, Allen
and Joel. Allen Hall: So this is a really interesting product, but
I first, I want to get to how big of a problem do we have in the
industry? And Joel and I have been traveling around the United
States quite a bit. And pretty much every farm we stopped at had
blade bolt insert issues. They didn't know why they were having
them, but they had them and they were deeply concerned about it
because of what could happen to the turban. And Edo, are you seeing
the same thing? Are you getting a lot of reach out that way? Edo
Kuipers: Yeah, more and more we see this. I think in 2021, we were
contacted by the Indian market for the first time. Those were 40
meter long blades, 1. 5 megawatt platform. And those blades were
like 13 years on the turbine. And then all suddenly started flying
off basically. And more and more recently, this is popping up
basically not after 13 years, but after six years, for example,
already on a 2. x platform. So yeah, we have been contacted first
on the Indian side. We have seen it in Brazil. We have seen it in
Thailand, for example, also. So it's more and more addressing the
problem. Also from the Northern America, we have the first context.
Joel Saxum: So I think that if we describe basically the breadth of
the problem so there's the, when you bolt the blades on, and if
you're in a, if you're a wind technician, this stuff, right? You've
seen it, you've done it. You've been around these things. For some
people that are, yeah, some people that aren't as technician
minded, you may not know exactly what the problem is, but what it
is basically when you bolt the blades onto the hub, there's all
these studs, right? And the studs come through, or the studs stick
out, you stick it into the receptor on the basically on the hub,
and then you bolt 'em on. But if the, where the stud connects into
the blade. It doesn't stay true to its design and becomes loose, it
starts to move, then however it's bolted doesn't matter at all. Edo
Kuipers: Correct. Also, it's not a bolt problem, it's the
connection between the steel bushing itself. This is like a plug in
the wall when you hang up a painting, for example. This plug in the
wall is getting loose from the laminate. Allen Hall: All right. So
if the inserts are becoming loose. What's the scale of the, what we
think the scale of the problem is. Do we, is it like a 50 percent
of blades have this issue? 20 percent of blades have this issue?
Cause it sounds like it's more than 10 percent at the moment. Edo
Kuipers: It can be what we have seen, what we've noticed that in
the past, blade designs had quite a lot of margin, safety margin in
them. And what we've seen is that, yeah, in time we are as wind
energy, we are reducing our margins. And because we are losing.
these margins are getting closer to 1. 0. Let's say like then where
we had in the past like 6. These margins are getting lower and then
the chance of loose bushings is also getting earlier with the,
let's say, the 2. x or the 3 megawatt turbines. If you Build it in
exactly the same way, of course, and I'm not sure, we don't know if
the manufacturer has built it always throughout all these years in
a consistent way. We don't know that, of course. The only what we
can do is observe what we see now. And what we see now is
basically, first of all, the reserves or the mass moment,
basically. The mass is getting higher with the given pit circle
diameters and longer blades. remain on the same pitch circle
diameter with the same number of balls for longer distances of
rotor blades. So lower reserve margin, that's one of them already.
What we then also noticed, because we did three root cause analysis
projects on different locations in the market. And what we noticed
is that in all these cases, it was concerning polyester blades. It
was concerning a special mat, which was basically wrapped around
the bushing as an interface material. And this mat had what we have
seen an irregular distribution of the polyester resin in it. And it
had these dog bone shaped, yeah, it was prefabricated parts in
there. And what happens there is basically, due to this, unregular
distribution of the polyester resin, we get differences in curing
cracks, basically, our curing features. Polyester resin is more
sensitive to curing cracks, shrinkage cracks, basically, shrinkage
cracks at the curing than an epoxy is. And if you then have this
irregular distribution of your resin around these bushings, then
you can also imagine that on different location, you get these
micro cracks already from the start. And then it depends a little
bit on the reserve factors, which you had from the start, how long
this will last. So what happens is due to these micro cracks, we
are losing a certain amount of the bonding area of the area that
has to transfer the loads from the tip to the pitch bearing, for
example. If we are losing this load carrying area, that means that
the stress levels, they are going up, they are rising. And when we
realize that there is a non linear relation between stress level on
the, let's say on the vertical axis of your diagram and your
lifetime on the horizontal axis of your diagram, this is not
linear, but it's, let's say a logarithmic. And. Realizing that if
you are losing, let's say 10 percent of your area of your load
carrying area and, or with other words, if your stress levels are
raising with 10%, you can already lose like 50%. You can halfen
your lifetime already. Allen Hall: If I have a polyester blade, how
would I know I have this defect in the blade? Is there any way to
detect it before the insert becomes loose? Edo Kuipers: When you're
a park owner, you have always these six months inspection intervals
or one year inspection intervals. Then you go inside the hub and
there's, let's say like a sealing done between your blade root and
your pitch bearing. This is this little line with sealing component
filler. Check for cracks in that area, especially on the trailing
edge, for example, and on the leading edge. If you see there are
some kind of cracks inside, then cut it away with a knife and go
with a filler cage inside. Check how the distance is and do it on
different pitch settings. So turn the blade, different pitch
orientation, and see again this distance. Then you can measure if
there is a variable cap going on, yes or no. And if you see a
variable cap, for sure you have some way a loose bushing there.
Especially check for the trailing edge and the leading edge. Allen
Hall: Is there an audio component to this? Can you hear it when the
turbine is running? Can you hear the blade shift around a little
bit? Cause it's such a massive load. Is it making noise? Edo
Kuipers: No, I would, I don't expect that. I don't expect. Maybe a
little bit on your torque drives. You could see it in the pitching
because you have a little bit more sweeping forward and backwards
of your blades, if you are, but then you're already really far and
then you really have huge, loosened boostings, but you can imagine
that the pitch inertia changes in that respect. So you will feel it
on your pitch drives, but I guess Okay. Apart from that, the blade
has then not flew off yet, but you're already too far. Joel Saxum:
It's already too far off. That's the question I want to ask. I want
to get into here a little bit is okay. I'm now I'm asking from an
operator standpoint. So if I'm an operator, if we're doing a yearly
inspection or end of warranty or whatever that may be, and we
discover some of these gaps or we have, we go, Oh, here we're
suspecting that there's something going on here. Okay. What is
that, basically the delta in time between, I know you can't say
it's 16 hours or, 22 days, but what does it look like? Do you have,
if it starts to loosen up, does an operator have a year or do they
have a day? Like, how long before his up blade decides to come off?
Edo Kuipers: You have to ask a blade, but it depends in the mood
when it's maybe when it's autumn earlier than it's spring. Not sure
about that,