Aeroelastic Design of the oLAF Configuration using Load Alleviation Techniques within cpacs-MONA

Kurzfassung

cpacs-MONA is a highly parameterized and automatized aeroelastic structural design process developed at the DLR Institute of Aeroelasticity. The process can mainly be categorized into three main steps: a parametric model set-up, an extensive loads analysis campaign of the flexible aircraft structure, and a structural optimization taking aeroelastic requirements into account. Since load alleviation (LA) techniques have shown a growing utilization in the aircraft design, the possibility to use aggressive LA within the load analysis step has been implemented into cpacs-MONA. Thereby a selection of the trailing edge (TE) devices (flaps and ailerons) of the global finite element model (GFEM) are passively deflected for the design driving pull-up maneuvers (nz=2.5g). To reduce the loads evoked from dynamic gust encounters, a passive turbulence alleviation (PTA) has been used, where the TE devices are deflected for the simulation of the static 1g-trim solution. The aim of the LA techniques is to reduce the lifting shear forces at the outer part of the wing and shift them more inboard to reduce the dimensioning bending moments acting on the main wing. For this publication cpacs-MONA was run twice for the same aircraft with two different set of LA, resulting in two different models: Model A: Aggressive LA techniques Model B: Default LA techniques The aggressive LA settings lead to a reduction of the maximum wing root bending moment of about 15 % and a reduction of about 11 % for the primary wing mass, compared to the default LA settings. Since cpacs-MONA comprises of an iterative load analysis and structural optimization loop, beside the question on how the different LA techniques effect the loads and the structural mass, moreover the influence on the dynamic behavior and the resulting aeroelastic stability of the complete aircraft is addressed within this paper.