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Answer: First of all, I am unable to understand the question. Forward swept wings have a divergence speed which is less than the sweptback wing. Where did you get this Mach number 36?
Answer: In the same order as the lectures.
Answer: The non-linearities can arise from structural or from aerodynamic aspects. In structural aspect, the non-linearity can be due to: (i) geometric non-linearity (strain-displacement relation is non-linear) or material non-linearity (stress-strain relation is non-linear). In aerodynamics, the transonic problems are non-linear and also in subsonic case, if the flow over the airfoil has dynamic stall effects, then the problem is non-linear. In this lecture series, we have addressed only linear aeroelasticity problems.
Answer: Composite materials can be used in the construction of the structure to obtain the required sectional properties (like bending and torsion stiffness properties) of the aircraft wing/ rotor blade etc. This may help in improving the aeroelastic behaviour of the wing. This is known as aeroelastic tailoring using composite materials. You can also use smart structure construction to improve the aeroelastic characteristics of the lifting surface. This can be called aeroelastic tailoring by smart structure concept.
Answer: I have already given the answer for the same question once. I do not know why this question is being sent again and again.
Answer: No I do not have a soft copy.
Answer: Please note that we have applied force at i and moment at j. We are evaluating the total deflection (linear) at 'i' and total angular motion at 'j'. These expressions will be used in the expression for total work done by these two loads. The rotation at 'i' and displacement at 'j' are not required in this case, since there is no associated load (i.e., moment at i and force at j) to provide any work.
Answer: For divergence analysis of swept wing, I normally give an assignment. The solution technique is based on Galerkin method of error minimisation, using the coupled bending and torsion deformation equations. When a request comes from NPTEL, I may have to provide the assignment problems for the entire course.
Answer: If see the basic books on aircraft structural analysis, (BK Donaldson, Analysis of Aircraft Structures) uniform torsion of any arbitrary section (not necessarily circular) is analysed by assuming that sections are free to warp (no end constraints). Based on the stress formulation (Prandtl stress), the twist per unit length is related to applied moment through the torsion constant J (or st. Venant torsion constant). This formulation is generalised to the torsion analysis of large aspect ratio wings. This approach is valid for large aspect ratio wings where the wing can be treated as a beam undergoing bending and torsion deformation. Like bending stiffness (EI), torsion stiffness (GJ) has to be evaluated for each section. In the evaluation of torsion constant J, thin walled structure assumption is made. For solid sections, you need to numerically evaluate it. Therefore the formulation is valid for any arbitrary section, not for only circular sections. The difference between circular and non-circular section is in the evaluation of torsion constant. For circular section torsion constant is equal to area moment (polar moment); but it is not the case for arbitrary sections.