AIRCRAFT STRUCTURES

If loads are applied to a member so that it tends to twist about an axis, internal shear stresses are set up in the member at any section between the application of load and the reaction to resist the twisting force. In such a case the member is said to be subjected to _______.

a.) Torsion

b.) Shear

c.) Bending

d.) Compression

a

Longitudinal (fore and aft) structural members of a semi-monocoque fuselage are called _______.

a.) spars and ribs

b.) spars and stringers

c.) longerons and stringers

d.) bulkhead and formers

c

The total moment due to internal stresses of a shaft or tube is equal in magnitude to the external torque, and is given by the equation T=[G(theta)/L][integral of (r^2)dA]. The quantity is known as the _______.

a.) Polar moment of inertia

b.) Radius of gravitation

c.) Moment of inertia about a base

d.) Product of inertia about inclined axis through a centroid

a

Normally designed to provide restraint against rotation and all translations; therefore, reactive forces and moments are developed along the directions where movements are not permitted.

a.) Fixed support

b.) Hinge support

c.) Roller support

d.) Wedge support

a

What is the purpose of the wing main spar?

a.) To withstand bending and torsional loads

b.) To withstand compressive and torsional loads

c.) To withstand compressive and shear loads

d.) To withstand bending and shear loads

a

When a load is applied to a member normal to its axis and the member is held fixed at another section, at any section between the load and reaction the particles on one side of the section tend to move in a transverse direction with respect to the other side; that is, they tend to slide by each other. This set up internal stresses in the member called _______.

a.) Shear stress

b.) Bending stress

c.) Torsional stress

d.) Tensile stress

a

Members which are loaded so that they are compressed axially and therefore have developed within them compressive resistances or stresses.

a.) Beams

b.) Columns

c.) Shafts

d.) Trusses

a

The ratio of shear stress to strain below the proportional limit is called shear modulus of elasticity or _______.

a.) Poisson's Ratio

b.) Stress-strain relationship

c.) Modulus ratio

d.) Modulus of rigidity

d

It is a structure composed of slender members joined together at their end points, in which the members are subjected to only axial loads.

a. Beam structure

b.) Monocoque structure

c.) Semi-monocoque structure

d.) Truss structure

d

What is the purpose of stringers?

a.) To absorb the torsional and compressive stresses

b.) To produce stress risers and support the fatigue metres

c.) To prevent buckling and bending by supporting and stiffening the skin

d.) To support the primary control surfaces

c

The monocoque fuselage relies largely on the strength of _______.

a.) longerons and formers

b.) bulkheads and longerons

c.) skin or covering

d.) all of the choices

c

A piece of formed sheet metal or extrusion riveted to a larger piece of thin sheet metal to give it rigidity and stiffness.

a.) spar

b.) strut

c.) stiffener

d.) bulkhead

c

The axial strain in a member is always accompanied by a lateral strain of opposite sign. Thus, if a member stretches under load, its cross-sectional area becomes smaller at the same time. The relationship of the lateral strain to axial strain is expressed by _______.

a.) Modulus ratio

b.) Stress-strain relationship

c.) Hooke's Law

d.) Poisson's Ratio

d

It is a measure of the intensity of load acting on a definite plane passing through a given point in the material.

a.) Shear

b.) Torque

c.) Stress

d.) Strain

c

Which area of the aircraft is subject to hoop stress?

a.) Control surfaces

b.) Pressure cabin

c.) Wings

d.) Engine firewall

b

Structural members designed to support loadings applied perpendicular to their axes. They are long, straight bars having a constant cross-sectional area.

a.) Shafts

b.) Plates

c.) Beams

d.) Bulkhead

c

What is the purpose of wing ribs?

a.) To withstand the fatigue stresses

b.) To shape the wing and support the skin

c.) To house the fuel and the landing gear

d.) To provide local support for the skin

b

Which of the following is an example of a fail-safe structure?

a.) Spar

b.) Longeron

c.) Stringer

d.) Wing tip

c

The point at which there is an appreciable elongation of the material without any corresponding increase of load.

a.) Elastic Point

b.) Proportional limit

c.) Rupture point

d.) Yield Point

d

It is the combination of compressive and tensile loads.

a.) Bending

b.) Gust

c.) Shear

d.) Torsion

a

Friction always acts _______ to the contact surface.

a.) diagonally at 45 degrees

b.) normal

c.) parallel

d.) the same angle of static friction

c

It is defined as the measure of the structure's resistance to change in shape when subjected to force.

a.) Ductility

b.) Resilience

c.) Stiffness

d.) Toughness

c

It is the ratio of modulus of elasticity and material density.

a.) Specific strength

b.) Specific stiffness

c.) Specific volume equivalence

d.) Specific toughness

b

What parameter is at its maximum when shear is equal to zero?

a.) Bending

b.) Moment

c.) Force

d.) Stability

b

It is a flat sheet triangular shape used to reinforce the corners of structure.

a.) Webs

b.) Fittings

c.) Caps

d.) Gussets

d

The tangent of this angle where the opposite side is the frictional force and the adjacent side is the normal force is called _______.

a.) bank

b.) friction

c.) incidence

d.) attack

b

A transverse load on a member tends to make the member rotate about an axis at a section away from that where the load is applied and normal to the axis of the member. If the member is restrained from rotating at any section other than that at which the load is applied, internal tension stresses are set up at one side of the member and compression at the other. At any section where such stresses are present the member is said to be subjected to _______.

a.) Torsion

b.) Shear

c.) Bending

d.) Compression

c

It is a soft metal or plastic used to protect the airframe from damage caused by the cable system.

a.) Fairlead

b.) Gusset plates

c.) Phenolic tape

d.) Plastic lugs

a

Any deformable solid body which is capable of carrying loads and transmitting these loads to other parts of the body is referred to as _______.

a.) bar elements

b.) fuselage elements

c.) shear panels

d.) structural systems

d

It is type of deformation in which the material does not anymore return to its original shape.

a.) plastic deformation

b.) yield deformation

c.) elastic deformation

d.) fracture

b

In the stress strain diagram, the constant of proportionality E stands for?

a.) Hooke's Law

b.) Modulus of Rigidity

c.) Modulus of Turbidity

d.) Young's Modulus

d

It is a rotational force produced on an axis by a linear force applied at a distance away from the axis.

a.) Inertia

b.) Equilibrium

c.) Moment

d.) Couples

c

States that the moment of the resultant is equivalent to the moment sum of its components.

a.) State postulate

b.) Pascal's principle

c.) Varignon's Theorem

d.) Hooke's Law

c

The CG of a helicopter is ideally located _______.

a.) aft location of its main rotor hub

b.) directly in the line of axis of the hub

c.) forward the hub

d.) near the tail

b

A given truss structure had been found to have three unknowns, which of the following best describes the solution.

a.) The problem is unsolvable

b.) We must make 3 independent equations

c.) Use method of joint

d.) It is a type of indeterminate structure

b

It is the ratio of the lateral to the longitudinal deformation.

a.) Euler's ratio

b.) Stress to strain ratio

c.) Poisson's ratio

d.) Fines ratio

c

It is an axis in the cross section of a beam (a member resisting bending) or shaft along which there are no longitudinal stresses or strains.

a.) axial axis

b.) neutral axis

c.) lateral axis

d.) vertical axis

b

States that external effect of a force on a body is independent of the point of application.

a.) Law of rotation

b.) Parallelogram law

c.) Principle of transmissibility

d.) Law of translation

c

A support designed to allow only rotation at the point of connection, and thus reactive forces (reactions) are developed in the other directions where movements are not allowed.

a.) Fixed support

b.) Hinge support

c.) Hinge-roller support

d.) Wedge support

b

Definite amount of matter, the part of which are fixed in position relative to each other.

a.) Rigid body

b.) Deformable body

c.) Solid

d.) Matter

a

Changes or tends to alter the state of motion of a body.

a.) Acceleration

b.) Momentum

c.) Force

d.) Dynamic

c

What causes the object momentum increase?

a.) Impulse

b.) Velocity

c.) Acceleration

d.) Mass

a

Branch of dynamics which describes the motion of bodies without reference to the forces that either cause the motion or are generated as a result of a motion.

a.) Statics

b.) Kinetics

c.) Dynamics

d.) Kinematics

d

What is another term for moment of inertia?

a.) Third moment of area

b.) Second moment of area

c.) Radius of gyration

d.) Centroid

b

Forces which holds parts of a rigid body together.

a.) Fixed attachment

b.) Molecular bond

c.) Internal forces

d.) Adhesion forces

c

Force that acts perpendicular to the surface.

a.) Tangent force

b.) Normal force

c.) Abnormal force

d.) Bending force

b

What law expressed relation between stress and strain?

a.) Hooke's law

b.) Poisson's ratio

c.) Varignon's law

d.) Young's law

a

What loading occurs when the load is not applied through the centroid?

a.) Non-centroidal loading

b.) Moment

c.) Inertia

d.) Eccentric loading

d

Stress that has an area perpendicular to the force.

a.) Shearing stress

b.) Axial stress

c.) Bearing stress

d.) Torsion

b

Which type of loading does fatigue occurs?

a.) Repeated loads

b.) Bending loads

c.) Compressive loads

d.) Tensile loads

a

Stress developed when material attempt to expand or contract due to change in temperature.

a.) Heat expansion

b.) Compression ratio

c.) Thermal stress

d.) Tensile strength

c

A pair of forces equal in magnitude, parallel, opposite direction, and non-concurrent.

a.) Moment

b.) Torque

c.) Couple

d.) Resultant

c

Work done on a unit volume of a material as the forces gradually increase up to proportional limit.

a.) Modulus of resilience

b.) Modulus of elasticity

c.) Modulus of safety

d.) Modulus of endurance

a

Stress developed when material undergoes twisting.

a.) Torsional stress

b.) Torque

c.) Moment

d.) Centroid

a

Combination of compressive and tensile loads.

a.) Torsion

b.) Bending

c.) Tensile loads

d.) Double axial loads

b

It is a two force member.

a.) Truss

b.) Beams

c.) Plates

d.) Struts

a

Limiting amount of resistance to sliding between two bodies in contact.

a.) Centrifugal force

b.) Centripetal force

c.) Parallel force

d.) Friction force

d

Refers to stress at failure.

a.) Yield

b.) Rupture strength

c.) Elastic limit

d.) Proportional limit

b

Percentage of elongation to the original dimension.

a.) Strain

b.) Sprain

c.) Spring Constant

d.) Elastic Constant

a

Stress with area parallel to the load.

a.) Shear

b.) Tensile

c.) Migraine

d.) Bending

a