Allowable Stress

Question 1

To properly design a structural member or mechanical element it
is necessary to ________ in the material to a level that will be
safe.

Answer 1

restrict the stress

Question 2

To ensure this safety, it is therefore necessary to choose an
allowable stress that restricts the applied load to one that is ______
the load the member can fully support.

Answer 2

less than

Question 3

The intended measurements
of a structure or machine may not be exact, due to _______
or in the _______ of its component parts.

Answer 3

errors in fabrication ; assembly

Question 4

_______ can occur that may not be accounted for in the
design.

Answer 4

Unknown vibrations, impact,
or accidental loadings

Question 5

______ tend to cause
materials to deteriorate during service.

Answer 5

Atmospheric corrosion, decay, or weathering

Question 6

Some materials such as _______ can show high
variability in mechanical properties

Answer 6

wood, concrete, or fiber-reinforced composites

Question 7

One method of specifying the allowable load for a
member is to use a number called the _______

Answer 7

factor of safety

Question 8

Is a ratio of the failure load F(fail) to the
allowable load F(allow).

Answer 8

factor of safety (F.S.)

Question 9

Here F(fail) is found from _______ of the
material, and the factor of safety is selected based on
experience so that the above mentioned uncertainties are
accounted from when the member is used under similar
conditions of ________

Answer 9

experimental testing ; loading and geometry.

Question 10

Formula of F.S.

Answer 10

F.S. = F(fail)/F(allow) ; F.S. = 𝝈 fail /𝝈 allow