Aerospace Structures Flashcards
Neumann boundary condition prescribe the displacement. (T/F)
FALSE
Dirichlett or essential BC precripe the displacement.
Neumann BC’s or natural BC prescribe the stress.
You cannot prescribe a natural BC on the outer surface of a body if no loads are applied there. (T/F)
FALSE.
Natural BC: σ n = 0.
On the constrained part of the body you can compute the applied forces per unit surface as σ n. (T/F)
TRUE
A plain-strain constitutive law:
Has null axial strain.
The exact solution of the elasticity problem satisfied both natural and essential BC’s. (T/F)
TRUE
The assumption of plane stress implies that the deformation along the thickness is zero. (T/F)
FALSE
The equilibrium equations can be obtained by integrating by parts the PVW (T/F)
TRUE
The PCVW is used to find the equilibrium solution. (T/F)
FALSE
The solution of the elastic problem:
Must guarantee equilibrium and compatibility
The PVW can be applied only for hyperelastic constitutive laws (T/F)
FALSE
An hyperelastic constitutive law is not necessarily linear (T/F)
TRUE
The assumption of infinitesimal displacements implies that the equilibrium conditions are referred to the undeformed configuration. (T/F)
True
The equivalence between the PVW and the Principle of Minimum Potential Energy holds for:
Holds for Hyperelastic material law.
The shear flows acting on the rib are:
The flows equilibrating the applied load.
In finite elements, the hourglass phenomenon can be due:
Can be due to an excessively low number of integration points.
The solution due to De Saint Venant does not account for local effects because local effects are always negligible (T/F)
False
The Hooke’s Law is a constitutive law for linear elastic materials (T/F)
True
Shear deformability effects are generally more relevant for thin-walled beams than for compact beams (T/F)
True
Can the elastic problem be formulated in terms of displacement?
Always.
The shear center of an open thin-walled beam section according to the semi-monocoque scheme can be determined by:
By imposing the equivalence of torsional moment.
A beam model cannot be used for evaluating local effects due to load introduction (T/F)
True.
The semi-monocoque approximation provides the exact shear distribution along the panels thickness. (T/F)
False
Essential BC’s are mroe important than natural ones. (T/F)
False.
The semi-inverse approach for the De-Saint Venant solution for isotropic, homogeneous beams leads to:
Leads to the exact solution of the problem.