AAE 556 Aeroelasticity Lecture 9 Differential equation models Purdue Aeroelasticity
Goal – Construct torsional equilibrium equations for a diff. eq. model Define stability conditions for idealizations with differential equations Reading - Section 2.19 Purdue Aeroelasticity
The aerodynamics model x Purdue Aeroelasticity
The distributed torsional loads-including weight x Purdue Aeroelasticity
The structural model with FBD Purdue Aeroelasticity
The equation of torsional equilibrium Purdue Aeroelasticity
Purdue Aeroelasticity The math problem Purdue Aeroelasticity
The divergence problem x Purdue Aeroelasticity
The divergence problem x Purdue Aeroelasticity
The stability determinant Purdue Aeroelasticity
Purdue Aeroelasticity The eigenvalues Purdue Aeroelasticity
The eigenvector (mode shape) Purdue Aeroelasticity
Stiffness? Place a torque To at the ¾ span position Purdue Aeroelasticity
Typical section stiffness Purdue Aeroelasticity
Typical section stiffness Purdue Aeroelasticity
Problems in high speed flight Purdue Aeroelasticity
Increasing Tu-144 SST elevon effectiveness - a classic MDO problem Subsonic vs. supersonic deformation Control effectiveness Fuel management? Larger engine? Canards? Stiffening? Problem - trim drag is too high - suggest a fix Purdue Aeroelasticity
Purdue Aeroelasticity Loading conditions Subsonic cruise take-off elevon element IV loading elevon element II loading special loading Purdue Aeroelasticity
Purdue Aeroelasticity Solution-add weight Thicken skin panels 1 2 3 4 Elevons Purdue Aeroelasticity