کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
755844 896067 2014 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Grazing bifurcation in aeroelastic systems with freeplay nonlinearity
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی مکانیک
پیش نمایش صفحه اول مقاله
Grazing bifurcation in aeroelastic systems with freeplay nonlinearity
چکیده انگلیسی


• We investigate the effects of a nonsmooth function on the response of an aeroelastic system.
• This system consists of a plunging and pitching rigid airfoil.
• The nonsmooth function is presented as a freeplay nonlinearity in the pitch spring.
• The results show that there are two different sudden jumps in the system’s response.
• It is demonstrated that these sudden transitions are associated with grazing bifurcations.

A nonlinear analysis is performed to characterize the effects of a nonsmooth freeplay nonlinearity on the response of an aeroelastic system. This system consists of a plunging and pitching rigid airfoil supported by a linear spring in the plunge degree of freedom and a nonlinear spring in the pitch degree of freedom. The nonsmooth freeplay nonlinearity is associated with the pitch degree of freedom. The aerodynamic loads are modeled using the unsteady formulation. Linear analysis is first performed to determine the coupled damping and frequencies and the associated linear flutter speed. Then, a nonlinear analysis is performed to determine the effects of the size of the freeplay gap on the response of the aeroelastic system. To this end, two different sizes are considered. The results show that, for both considered freeplay gaps, there are two different transitions or sudden jumps in the system’s response when varying the freestream velocity (below linear flutter speed) with the appearance and disappearance of quadratic nonlinearity induced by discontinuity. It is demonstrated that these sudden transitions are associated with a tangential contact between the trajectory and the freeplay boundaries (grazing bifurcation). At the first transition, it is demonstrated that increasing the freestream velocity is accompanied by the appearance of a superharmonic frequency of order 2 of the main oscillating frequency. At the second transition, the results show that an increase in the freestream velocity is followed by the disappearance of the superharmonic frequency of order 2 and a return to a simple periodic response (main oscillating frequency).

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Communications in Nonlinear Science and Numerical Simulation - Volume 19, Issue 5, May 2014, Pages 1611–1625
نویسندگان
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