LESSON 2: (PART 1-4)

Question 1

_____________ is the rigidity of an object- the extent to which it resists ____________ in response to an applied force.

Answer 1

stiffness, deformation

Question 2

_____________ is a measure of how resistant solid matter is to various kinds of permanent shape change when a compressive force is applied.

Answer 2

Hardness

Question 3

_______ is a solid material’s ability to deform under tensile stress; this is often characterized by the material’s ability to be stretched into a wire.

Answer 3

Ductility

Question 4

__________ is the ability of material to absorb energy when impacted.

Answer 4

Toughness

Question 5

This test is used primarily to determine the relationship between the average normal stress and average normal strain in common engineering materials, such as metals, ceramic, polymers, and composites.

Answer 5

tension or compression test

Question 6

it is obtained by plotting the various values of the stress and corresponding strain in the specimen.

Answer 6

Stress-strain diagram

Question 7

this limit is the straight line in the stress strain diagram.

Answer 7

Proportional limit

Question 8

it is the stress beyond which the material will not return to its original shape when unloaded but will retain permanent deformation called permanent set.

Answer 8

Elastic limit

Question 9

it is the point at which there is an appreciable elongation or yielding of the material without any corresponding increase of load; indeed, the load may be actually decrease while the yielding occurs.

Answer 9

Yield point

Question 10

it is closely associated with the yield point. for materials that do not have a well-defined yield point, it is determined by the offset method.

Answer 10

Yield strength

Question 11

it is the highest ordinate on the stress-strain diagram

Answer 11

Ultimate strength

Question 12

stress of failure

Answer 12

rupture strength

Question 13

formula of strain

Answer 13

e= deformation/ length

Question 14

formula of Axial deformation

Answer 14

δ= PL/AE

Question 15

formula for modulus of elasticity

Answer 15

σ= Ee

Question 16

there are certain combinations of axially loaded members in which the equations of static equilibrium are not sufficient for a solution. this condition exists in structures where the reactive forces or the internal resisting forces over a cross section exceed the number of independent equations of equilibrium. such cases are called?

Answer 16

Statically indeterminate

Question 17

formula of thermal stresses

Answer 17

δt= aL(t2-t1)