A CAD/CAE based
multidisciplinary process for
aircraft structure design
PhD Candidate: Haiqiang Wang
Department: AWEP
Section: Flight Performance and Propulsion
Supervisor: G. La Rocca
Promoter: M.J.L. van Tooren
Start date: 1-9-2009
Funding: Chinese Scholarship Council
Cooperations: Fokker Aerostructures
Background
Aerospace structures are complex systems and the
components are highly interrelated with each other. The
design process is multidisciplinary in nature, involving
several design aspects, such as manufacturing cost, weight
and structural integrity. Multidisciplinary design and
optimization (MDO) will be used to find the well
compromised design for a complex system during the
conceptual design phase.
Knowledge based engineering (KBE) is an technique for
implementing MDO while the design and engineering
engine (DEE) is a set of advance software tools which
support and accelerate the design process of a complex
product through elimination of non-repetitive activities. The
paradigm of the DEE is shown in Figure 1.
Aerospace Engineering
Figure 1: The DEE and its components
Fuselage DEE: a physics-based weight prediction
tool set
Traditionally aircraft fuselage weight is estimated based on
the statistical weight data from previous projects. The
method could not be used for unconventional
configurations. In addition, the method is difficult to
quantify the weight saving due to different material systems
and structural layouts. A set of tools are developed for
fuselage: a parametric fuselage model generating the outer
mould line and cabin arrangement and Patran session files
for automating FE model generation process; a global FE
model for generating running loads for panel skin elements
under typical flight, grounding and landing load cases
according CAR 25; a local stiffened panel sizing module
determining the panel dimensions with the giving loads
from global FE model.
Wing like structure DEE: a tool set for cost and
weight trade-off study
Cost and weight are sometimes contradicting objectives for
aerospace structure design. It is challenging for designers
to try more designs in order to find the well balanced
design. A set of tools is developed to investigate the cost
and weight variations due to different structure layouts,
material systems and manufacturing techniques. The tool
set is comprised by the following components: the wing-like
structure parametric model generating the CAD model of
the outer module lines and internal structures, Patran
session files for automating the generating process of FE
model, and inputs for cost analysis; a global FE model to
calculate the running loads for the plate; a local composite
plate sizing model determining the ply numbers under each
ply orientation; a bottom-up parametric cost estimation
module to estimate manufacturing cost.
Figure 2: Validation cases for conventional configuration
aircraft: A330B2, A320-200, Fokker100, B737-200,ATR42.
Figure 3: An application case for predicting fuselage weight of Prandtl plane, an
unconventional configuration.
Figure 4: Comparison with the predicted and actual
fuselage weight of the considered aircrafts.
Figure 5: Weight tendency under different
combinations of frame pitch and panel efficiency.
Angle
Hinge line
TE rib
Conclusions and recommendations
The fuselage and wing-like DEE have been successfully
developed to support the MDO study of aerospace
structure. The MMG is the core of the DEEs, generating the
CAD models and preparing the inputs for FEA software and
cost analysis tools. A large range of fuselage and wing-like
structures can be modelled by the DEEs, as shown in Figure
2,3,6. The product knowledge and process knowledge are
captured and restored, and can be reused for future
projects. Compared with the several days the traditional
design method takes, the DEEs is able to converge within
several hours.
Integrated with more realistic analysis tools from industry,
the DEEs could be able to find the optimum design.
Publications
LE rib
Endcap
Figure 6: Example CAD models of the wing-like
structures which the DEE is able to generate.
Spar
Design
Weight [kg]
Cost ($)
Baseline
60.2
35840
Baseline - 1 rib
60.4
35664
Baseline + 1 rib
58.6
35680
Figure 7: A design case for G650 rudder: what if a
rib is added or removed
Wang, H. and van Tooren, M.J.L., “Knowledge Based Engineering Platform for Multidisciplinary Fuselage Design and Analysis,” Proceedings of 2010 Asia-Pacific International Symposium on
Aerospace and Technology[CD-ROM], Chinese Society of Aeronautics and Astronautics, Xi’an, China, Sept. 2010.
Wang, H. and van Tooren, M.J.L., “Bi-level Fuselage Structural Design in a Knowledge Based Engineering Environment”, Proceedings of Eurogen 2011 Conference, Capua, Italy, Sept. 2011.
Zhao, X., Wang, H., Curran, R. and van Tooren, M.J.L., “Concurrent Aerospace Thermoplastic Stiffened Panel Conceptual Design and Cost Estimation using Knowledge Based Engineering”,
Proceedings of 19th ISPE International Conference on Concurrent Engineering, Trier, Germany, Sept. 2012.
Wang, H., Zhao, X., Curran, R. and van Tooren, M.J.L., “Parametric Modeling of Fuselage Panels for Structural Analysis and Cost Estimation”, Proceedings of 3rd Aircraft Structural Design
Conference, Delft, the Netherlands, Oct. 2012.
van Dijk, R., Zhao, X. , Wang, H., and van Dalen, F., “Multidisciplinary Design and Optimisation of Aircraft Box Structures”, Proceedings of 3rd Aircraft Structural Design Conference, Delft,
the Netherlands, Oct. 2012.