MechE Mat Quiz 7

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_______ is the analysis of stresses produced by multiple internal loads or moments that act simultaneously on a member's cross section.

combined loadings

The subscripts for shear stresses are _______.

commutative

The normal and shear stresses acting at a point can be summarized on a stress _______.

element

A shear stress is negative if it acts in the negative coordinate direction on a negative face of the stress element.

false

A shear stress is negative if it acts in the positive coordinate direction on a positive face of the stress element.

false

A shear stress is positive if it acts in the negative coordinate direction on a positive face of the stress element.

false

A shear stress is positive if it acts in the positive coordinate direction on a negative face of the stress element.

false

A stress transformation angle measured counterclockwise from the reference x axis is negative. Conversely, an angle measured clockwise from the reference x axis is positive.

false

An arbitrary interior point on a body experiencing applied loads cannot be studied by cutting a section through the body at the point.

false

Components commonly found in engineering design are rarely subjected to plane stress.

false

Compression normal stresses are positive.

false

Equilibrium involves forces and stresses.

false

Equilibrium only applies to translation, not rotation.

false

For a stress element, the thickness perpendicular to the x-y plane is dx.

false

For a stress element, the thickness perpendicular to the x-y plane is dy.

false

For a stress element, the thickness perpendicular to the x-z plane is dx.

false

For a stress element, the thickness perpendicular to the x-z plane is dz.

false

For a stress element, the thickness perpendicular to the y-z plane is dz.

false

For both axial and torsion members, the free body diagram approach is efficient for the determination of maximum normal and shear stresses.

false

For shear stresses, the first subscript indicates the direction in which the stress acts, and the second subscript indicates the face of the stress element on which the shear stress acts.

false

If an object is in equilibrium, there can exist small portions of the object that are not in equilibrium.

false

If the normal of a surface lies in the x-y plane, then the stresses that act on that surface are termed out-of-plane stresses.

false

If the shear stress on a plane is maximum, then that plane must be a principle plane.

false

If the term ox - oy is negative, ep indicates the orientation of op1.

false

If the term ox - oy is positive, ep indicates the orientation of op2.

false

Normal stresses are positive if they cause compression in the material.

false

Normal stresses vanish on planes where maximum shear stresses occur.

false

Planes free of shear stress are termed participation planes.

false

Shear stresses acting on *parallel* planes must have the same magnitude.

false

Shear stresses are labeled with two subscripts. The first subscript designates the direction in which the shear stress acts.

false

Shear stresses are labeled with two subscripts. The second subscript designates the plane on which the shear stress acts.

false

Stress *variants* are not dependent on the orientation of the coordinate system.

false

Stress distributions are always uniform on arbitrary internal planes.

false

Stress invariance explains that the sum of normal stresses acting on any two orthogonal faces is *not a constant* value.

false

Stress invariants are dependent on the orientation of the coordinate system.

false

Stress is *independent* of the orientation of the plane surface upon which the stress acts.

false

Stress is a scalar quantity.

false

Tension normal stresses are negative.

false

The method of *substitution* is used to combine the various stresses acting at a particular point.

false

The planes on which the maximum in-plane shear stresses occur are rotated 90° from the principal planes.

false

The process of changing stresses from one set of coordinate axes to another set of axes is termed stress *transportation*

false

The state of stress can be uniquely defined by three stress components acting on each of three mutually parallel planes.

false

The sum of the normal stresses on any two orthogonal planes is dependent of the angle e .

false

There is only one method for computing the magnitudes of the principle stresses.

false

Plane stress describes the state of stress for all _______ of structural elements and machine components.

free surfaces

The resultant force acting on an arbitrary cut surface can be broken down into two components. The perpendicular component is a _______ force, and the parallel component is a _______ force.

normal; shear

The normal stress x acts on _______ faces of a stress element and is _______ in magnitude on both sides.

opposite; equal

For pure torsion in a circular shaft, maximum _______ stresses occur on transverse planes and maximum _______ stresses occur on planes inclined at 45° to the axis of the shaft.

shear; normal

The resultant force acting on an arbitrary cut surface can be broken down into two components. The parallel component is a _______ force, and the perpendicular component is a _______ force.

shear; normal

The state of stress at a particular point in a solid body can be represented by a _______.

stress element

Stresses in different coordinate systems can be related through a mathematical process called _______.

stress transformation

_______ is the process of changing stresses from one set of coordinate axes to another.

stress transformation

There is only one unique state of stress at a point, but the state of stress can have different representations, depending on the orientation of the axes used.

true

The stress transformation equations are valid for nonlinear, elastic materials.

true

The stress transformation equations are valid for nonlinear, inelastic materials.

true

There are two methods for computing the magnitudes of the principle stresses.

true

Select the following statements that are true.

If ox-oy is negative, ep indicates the orientation of op2; If ox-oy is postive, ep indicates the orientation of op1;

A point subjected to plane stress has three principal stresses.

true

A shear stress is negative if it acts in the negative coordinate direction on a positive face of the stress element.

true

A shear stress is positive if it acts in the negative coordinate direction on a negative face of the stress element.

true

A shear stress is positive if it acts in the positive coordinate direction on a positive face of the stress element.

true

A stress transformation angle measured counterclockwise from the reference x axis is positive. Conversely, an angle measured clockwise from the reference x axis is negative.

true

An arbitrary interior point on a body experiencing applied loads can be studied by cutting a section through the body at the point.

true

Compression normal stresses are negative.

true

Equilibrium involves forces, not stresses.

true

For a stress element, the thickness perpendicular to the x-y plane is dz.

true

For a stress element, the thickness perpendicular to the x-z plane is dy.

true

For a stress element, the thickness perpendicular to the y-z plane is dx.

true

For a successful design, an engineer must be able to determine critical stresses at any point of interest in a material object.

true

For both axial and torsion members, the free body diagram approach is not efficient for the determination of maximum normal and shear stresses.

true

For design purposes, the critical stresses at a point are often the maximum and minimum normal stresses and the maximum shear stress.

true

For shear stresses, the first subscript indicates the face of the stress element on which the shear stress acts, and the second subscript indicates the direction in which the stress acts.

true

If a plane is a principal plane, then the shear stress acting on the plane must be zero.

true

If a shear stress exists on any plane, there must also be a shear stress of the same magnitude acting on a perpendicular plane.

true

If an object is in equilibrium, any stress element one chooses to examine must also be in equilibrium.

true

If the normal of a surface lies in the x-y plane, then the stresses that act on that surface are termed in-plane stresses.

true

If the shear stress on a plane is zero, then that plane must be a principle plane.

true

If the term ox - oy is negative, ep indicates the orientation of op2.

true

If the term ox - oy is positive, ep indicates the orientation of op1.

true

If the values of on and ot are known, the value of oavg can be computed.

true

Normal stresses are labeled with a single subscript that indicates the plane on which the stress acts.

true

Normal stresses are positive if they cause tension in the material.

true

Once the proper shear stress direction has been established on one face of a stress element, the shear stress directions on the other three faces are known.

true

Planes free of shear stress are termed principal planes.

true

Shear stress vanishes on planes where maximum and minimum normal stresses occur.

true

Shear stresses acting on *orthogonal* planes must have the same magnitude.

true

Shear stresses are labeled with two subscripts. The first subscript designates the plane on which the shear stress acts.

true

Stress *invariants* are not dependent on the orientation of the coordinate system.

true

Stress distributions are not always uniform on arbitrary internal planes.

true

Stress invariance explains that the sum of normal stresses acting on any two orthogonal faces is a *constant* value

true

Stress is *dependent* on the orientation of the plane surface upon which the stress acts.

true

Tension normal stresses are positive.

true

The method of *superposition* is used to combine the various stresses acting at a particular point.

true

The planes on which the maximum in-plane shear stresses occur are rotated 45° from the principal planes.

true

The process of changing stresses from one set of coordinate axes to another set of axes is termed stress *transformation*

true

The shear stresses Txy and Tyx are equal to each other.

true

The shear stresses Txz and Tzx are equal to each other.

true

The shear stresses Tyz and Tzy are equal to each other.

true

The stress transformation equations are valid for linear, elastic materials.

true

The stress transformation equations are valid for linear, inelastic materials.

true


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