MechE Mat Quiz 7
_______ 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
