1,720,974 research outputs found
Improvements on a Green's Function Method for the Solution of Linearized Unsteady Potential Flows
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PyPAD: a Multidisciplinary Framework for Preliminary Airframe Design
Full text linkPurpose: The purpose of this paper is to describe the development of an integrated framework suitable for preliminary airframe design, called PyPAD (Python module for Preliminary Aircraft Design), providing the capability to define models to compute loads and to perform the structural sizing. Design/methodology/approach: The modules developed until now allow for the definition of multi-fidelity aero-structural models starting from a Common Parametric Aircraft Configuration Schema (CPACS) input file and to compute static loads (trim) and flutter margin with minimum user effort. PyPAD take advantages of Abaqus-CAE, and the main functions are developed in Python, to take advantages of the simplicity in terms of software development and maintenance, but the core routines are developed in Fortran, taking advantages of parallel programming to get the best performances. Findings: A complete test case, starting from the CPACS input and ending with the definition of structural, aerodynamic and aero-elastic models, with the computation of different design loads, is reported. An example will show that the framework developed is able to handle different problematics of the preliminary projects using quite complex global models. Practical implications: All the tools developed in the framework, and the ones currently under development, could be a valid help during the preliminary design of a new aircraft, speeding up the iterative process and improving the design solution. Originality/value: PyPAD is the first framework developed around Abaqus-CAE for the preliminary aircraft design and is one of the few tools looking at the different problematics involved in a preliminary airframe design: design, loads and aero-elasticity, sizing and multi-disciplinary optimization
Preliminary Sizing of the Wing-Box Structure by Multi-Level Approach
No full textThe paper describes a procedure, dedicated to the preliminary sizing of an aircraft wing-box, based on a two level decomposition and on two independent optimizations. An engineering approach is followed and the most suitable model is exploited at each level in order to generate information about the wing-box structure without the need of a previous knowledge, a very important feature in the case of unconventional structures. The first level uses a commercial structural multidisciplinary optimization code and a stick model of the wing primary structure to minimize the structural mass under global design constraints; a set of physical design variables are used referring to a schematic representation of the cross-section in terms of equivalent axial thickness supporting pure axial stress and the thickness of a box resisting to both axial and shear stresses. The second level, based on a genetic optimization, provides the minimum mass optimal design of the wing cross sections, in terms of local design variables, which safely support the internal loads supplied by the first level, under local constraints, e.g. panel buckling and stiffeners crippling, providing also a cross section stiffness in compliance with the first level. The reported example, concerning the B747-100 wing structure, shows the capability of the approach to predict the structural weight of the wing box, an information to be used mainly in an early stage of the aircraft design, and to suggest a set of cross sections design solutions all in compliance with both global and local requirements
A Parametric Pilot/Control Device Model for Rotorcraft Biodynamic Feedthrough Analysis
No full textThis work presents a numerical model of the pilot/control device subsystem. The model is related to the left arm of a helicopter pilot holding a conventional collective control inceptor. A detailed biomechanical model of the pilot is developed within a general purpose multibody dynamics formulation. Linearized models about reference conditions are computed from the general analysis, for specific reference positions of the control inceptor and settings of the neuro-musculo-skeletal system that characterize specific flight conditions and tasks. The linearized models of the biodynamic feedthrough are used to produce coupled pilot/control device subsystem models that are parametrized with respect to the pilot biodynamic feedthrough characteristics and the mechanical properties of the control inceptor
PyPAD: a Multidisciplinary Framework for Preliminary Airframe Design
No full textThe preliminary design of an aircraft is a complex task involving a lot of different disciplines and it is becoming more challenging in the future due to the reduced budget and compressed time. At the same time new projects present new technical challenges due to the request for highly demanding performances, in order to reduce the fuel consumption (cost and environment impact) and to increase the payload. The preliminary design problem involves different disciplines, like: Aerodynamics, Controls, Regulations, Performances, Systems Definition, Design, Loads & Aeroelasticity, Structural Sizing, etc.. The present work focuses on the development of an integrated framework suitable for preliminary airframe design, called PyPAD (Python module for Preliminary Aircraft Design). The modules developed until now allow for the definition of multi fidelity aero-structural models starting from a CPACS input file and to compute static loads (trim) and flutter margin with the minimum effort by the user. Moreover PyPAD is able to compute the dynamic response under all the different load conditions, including discrete and continuous gust, nodal forces, command inputs. The tool is also able to export the state-space aeroelastic models tacking advantage of the modern state space model realization. In this way all the loads prescribed by the regulations can be computed in a fully automatic approach. A complete test case, starting from the CPACS input and ending with the definition of structural, aerodynamic and aeroelastic models and with the computation of different design loads is reported
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