بحث بعنوان Limit-Cycle Oscillation of Shape Memory Alloy Hybrid Composite Plates at Elevated Temperatures

بحث بعنوان
Limit-Cycle Oscillation of Shape Memory Alloy Hybrid Composite Plates at Elevated Temperatures
Hesham Hamed Ibrahim,1 Mohammad Tawfik,2 and Hani Mohammed Negm3
1 Space Division, National Authority for Remote Sensing and Space Sciences, Cairo, Egypt
2 Noorn for Research and Development, Cairo, Egypt
3 Aerospace Engineering Department, Cairo University, Cairo, Egypt
A traditional composite plate impregnated with pre-strained
shape memory alloy fibers and subject to combined thermal and
aerodynamic loads is investigated to demonstrate the effectiveness of using the SMA fiber embeddings in improving the static
and dynamic response of composite plates. The problems investigated can be categorized into: thermal buckling subject to aerodynamic loading, linear flutter boundary at elevated temperatures,
nonlinear flutter limit-cycle, and chaotic oscillations at elevated
temperatures. A nonlinear finite element model based on the von
Karman strain displacement relations and first-order shear deformable plate theory is derived. Aerodynamic pressure is modeled using the quasi-steady first-order piston theory. The governing
equations are obtained using the principle of virtual work based
on thermal strain being a cumulative physical quantity. NewtonRaphson iteration is employed to obtain the static aero-thermal
large deflection at each temperature step and the dynamic response
at each time step of the Newmark numerical integration scheme.
A frequency domain solution is presented for predicting the flutter
boundary at elevated temperatures, while the time domain method
along with modal transformation is applied to numerically investigate periodic, non-periodic, and chaotic limit-cycle oscillations.
The results show that the critical buckling temperature of the plate
is greatly increased, and hence the thermal post-buckling deflection is suppressed by using SMA fiber embeddings. The SMA fiber
embeddings caused an increase in the critical dynamic pressure
at elevated temperatures, and enlargement of the static flat and
dynamically stable region of the panel.
Keywords
shape memory alloy, nonlinear panel flutter, thermal buckling, chaos
CONCLUSIONS
In this paper, for the first time, a finite element formulation based on the first-order shear deformable plate theory was
presented for the analysis of supersonic panel flutter and thermal buckling characteristics of SMA hybrid composite plate.
The SMA is included in the proposed plate to utilize the aerodynamic heating, which activates the SMA, in enhancing the
buckling, postbuckling, and limit cycle characteristics. Nonlinear temperature-dependent material properties and von Karman
moderately large deflection were considered in the formulation.
The aerodynamic forces were modeled using the quasi-steady
first-order piston theory. A frequency domain solution is presented for predicting the flutter boundaries at elevated temperatures, and the time domain method is applied to numerically
investigate limit-cycle oscillations. The finite element modal
formulation and solution procedures are developed for the time
domain method. Results showed that SMA fiber embeddings can
be very useful in thermal buckling and flutter control through
suppressing thermal postbuckling deflections, and enlarging the
flat and dynamically stable performance domains at elevated temperatures.
كلمة سر فك الضغط : books-world.net
The Unzip Password : books-world.net