Hyper Sizer
Hyper Sizer
Hyper Sizer
Ref [2]
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How Fast?
This entire process, excluding FEM setup, but including all HyperSizer user
data entry, project setup, software run time, and results interpretation is
typically accomplished for an early preliminary design in 4 hours.
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Ref [4]
Blade applied external loadings and resulting developed bending moments and blade twist inherent in the design are
quantified and used for performing hundreds of failure analyses within seconds during sizing optimization to achieve
the lightest and safest design.
HyperSizer allows engineers to rapidly analyze over 100 different, non-FEA based failure modes for all load
cases.
Perform flat and cylindrical buckling, local buckling, post-buckling, and crippling for panel and beams
Carry out analyses at both the ply and laminate levels for composite materials. At the ply level perform
standard quadratic failure predictions such as Tsai-Wu
At the laminate level perform Angle-Minus-Load (AML) or the Boeing 787 polynomial coefficient methods
For both approaches, include CAI and BVID damage tolerance and OHC/OHT open-hole allowables that
include customer specific correction factors for process dependent fabrication
In addition to classical lamination theory (CLT) in-plane stresses and strains, compute out-of-plane Z axis
interlaminar shear and peel stresses for multi-axially loaded adhesively bonded joints and bolt/fastener bearing
On a more advanced R&D level, perform micromechanic analysis on the individual fiber and matrix
constituents and compute crack propagation for safe-life or fail-safe designs with fracture mechanics or with a
continuum damage approach
Results of the detailed analyses control the optimization process, are shown graphically on the FEM, and are
reported along with sample calculations in the margin of-safety stress report.
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Anisotropic Laminates
Problem
Now that the blade is strong enough to carry
the wind load without failure due to material
strength or buckling stability, we now turn our
attention to the blade deflection and how to
minimize its potential adverse affect on
aerodynamic performance.
Solution
The amount of blade tip deflection can be
addressed by stiffening up the overall EI of the
cross section by adding uni-directional
composite material in both the spar caps and
upper and lower blade skins. The blade twist is
more complicated to reduce. Blade makers are
exploring the use of anisotropic laminates to
control this deformation by using unbalanced or
biased layups (Ref 5) in addition to placing
carbon fiber in appropriate sectors on the skins
(see figure). Tradeoffs with hybrid laminates
with satin weave fabrics, prepreg tapes,
preform infused woven and braided materials
with differing percentages of glass and carbon
fibers (Ref 6) really opens up the design space
of millions of combinations to achieve desired
stiffness and strength. HyperSizer is capable of
rapidly quantifying these effects for any
arbitrary hybrid laminate
For each candidate combination of materials and hybrid laminates, the overall blade internal loads and
displacement are then quantified by coupling HyperSizer with commercial FEA software packages such as
Abaqus, NX/Nastran, NEI/Nastran , and MSC/Nastran. The HyperFEA commercial software controls
the execution of both the HyperSizer and the FEA solver and provides the capability to specify translational
and rotational constraints on user identified control FEM grids. This approach provided by HyperFEA has
proven valuable by commercial aerospace companies for wing design.
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FEM Coupling
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Ref [1]
Image courtesy of Gurit
Problem
After the analyst has created the Finite Element Model and applied external loadings to compute the
composite ply strains and stresses in the blade, the analyst then suggests changes to the ply schedule based
on the FEA results. At this point the design typically goes back and forth many times between the stress
analyst and the designer and even perhaps someone from manufacturing. The engineer might start by
defining areas of the part with similar thicknesses as zones. The zone information is usually maintained
manually in a spreadsheet. Then the engineer will define a ply stack that delivers the mechanical properties
required in each zone, as indicated by previous experience. Most companies involved in composite design
have design rules that are used to guide this process. For example, the full body continuous plies are defined
on the tool side with ply drops occurring at the laminate mid-plane to maintain balanced and symmetric
layups. This process is very tedious, time-consuming, and error prone, as it is manually tracked in
spreadsheets.
Solution
HyperSizer is able to efficiently track this data and evaluate literally millions of combinations of ply drop off
patterns to simultaneously achieve the most efficient least weight laminate and the fewest amount of ply
drop offs or ply adds. This automated process of exploring all the different manufacturing layup schedules
for every zone includes hybrid laminates with automatic strength and stability stress analysis checks satisfied.
HyperSizer minimizes ply drops for both cost savings from ease of fabrication but also for increased fatigue
life (ref 4). The figure shows the manner in which HyperSizer achieves ply drops going from a thick laminate
to a thin laminate or from a foam core ramp down to solid laminate while also identifying the global ply IDs
(drawing ply dash number).
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Image courtesy of
Problem
Blade makers construct wind blades in sections and then bolt them
together. Because transportation costs increase significantly with blade
length, shipping blades in sections and joining them on site may offer
significant savings. However, the bolted joint in composite materials
requires special analysis and optimization of the laminate padup
thickness to minimize the joints weight (ref 6).
Solution
HyperSizer has two different approaches available for analyzing the
composite bolted-joint strength. The first is a straight-forward approach
in which the engineer defines the bearing allowable as a relationship with
bypass load and percentage of 45-degree plies. The second approach
uses a numerical program used in the aerospace industry called BJSFM
which computes the stress/strain field around the loaded hole. In this
manner failure criteria are then applied to find the worst combination of
multi-axial loading to cause failure. Both approaches account for fastener
type such as counter sunk versus protruding head and fastener diameter
correction factors. These analyses are highly integrated with the
optimization such that the laminate thickness padup can be minimized
and blended most efficiently with the acreage laminate layup.
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Stresses are
computed for every
green point
including integration
points through each
ply and used in the
failure interaction
equation
for every ply and every distance increment , for a total of approximately 4000 points per joint, to
be used in failure criteria such as:
2
2
112 11 33 22
22 33 33
+
+
+
X
X
Y
Y
Z
t c
t c
132
2
13,allow
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232
2
23,allow
122
2
12 ,allow
=1
References
Ref (1). Veers, Paul. Research Directions in Wind Turbine Blades: Materials and Fatigue. Wind Energy Technology
Department, Sandia National Laboratories. Web. 10 August 2009.
Ref (2). Bir, G.S. (January 2006). Users Guide to PreComp (Pre-Processor for Computing Composite Blade Properties).
National Renewable Energy Laboratory. NREL/TP-500-38929. Web. 10 August 2009.
Ref (3). Open-Access Database Covers Wind Blade Composites. RenewableEnergyAccess.com. 22 August 2006. Web.
10 August 2009.
Ref (4). Nijssen, R.P.L. (October 2007). Fatigue Life Prediction and Strength Degradation of Wind Turbine Rotor Blade
Composites. Sandia National Laboratories. SAND2006-7810P. Web. 10 August 2009
Ref (5). Mason, Karen. Anisotropic Wind Blade Design Expected to Reduce Wind-Energy Costs. High Performance
Composites. 1 November 2004. Web. 10 August 2009.
Ref (6). Gardiner, Ginger. Wind Blade Manufacturing, Part I: M&P Innovations Optimize Production. High Performance
Composites. Vol. 16, Number 6. November 2008.
Ref (7). Hogg, Paul. Manufacturing Challenges for Wind Turbines. Northwest Composites Centre, University of
Manchester. Web. 10 August 2009.
HyperSizer Information
Collier Research Corporation has provided methods research and software development to NASA and the aerospace
industry since 1995. A commercial strategy... to combine finite element analysis (FEA) with an automated design
procedure was conceived at NASA Langley Research Center in the early 1980s and has evolved, through a series of
precursor codes into this version of HyperSizer for analyzing the strength and stability of stiffened panels constructed of
any material, including fiber-reinforced composites. Of particular note is the NASA code referred to as ST-SIZE (ST-SIZE
1996 NASA. All rights reserved.). Collier Research Corporation obtained an exclusive, all fields of use license to ST-SIZE in
May 1996. (Collier Research employees were principal developers of ST-SIZE and have been continually developing the
soft ware and analytical methods for the last twelve years).
HyperSizer is a registered trademark of Collier Research Corporation.
HyperFEA is a registered trademark of Collier Research Corporation.
HyperFEMgen is a trademark of Collier Research Corporation.
April 2010
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