Describe what viscoelastic behavior means

1 answer:

5 0

This refers to the mechanical properties of the materials tested by means of a stress stimulus or deformation. The mechanical behavior of a material will depend on its viscosity / elasticity characteristics. Depending on the response to mechanical stimulus, the material may be classified as elastic or viscous. For a perfectly elastic or Hookian solid the deformation is proportional to the applied stress. A viscous material obeys Newton's law, which states that stress and shear rate are related through an intrinsic characteristic that is viscosity.

However, there are materials that correspond to both properties. Polymers have an intermediate mechanical behavior to elastic and viscous, being called viscoelastic. The elastic and viscous contribution to the mechanical behavior of the polymer depends on the temperature and time scale of the experiment.

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One kilogram of air, initially at 5 bar, 350 K, and 3 kg of carbon dioxide (CO2), initially at 2 bar, 450 K, are confined to opp

pentagon [3]

Answer:

Check the explanation

Explanation:

Energy alance of 2 closed systems: Heat from CO2 equals the heat that is added to air in

$m_{a} c_{v,a}(T_{eq} -T_{a,i)} =m_{co2} c_{v,co2} (T_{co2,i} -T_{eq)}$

1x0.723x $(T_{eq} -350)$ =3x0.780x $(450-T_{eq} )$ ⇒ $T_{eq}$ = 426.4 °K

The initail volumes of the gases can be determined by the ideal gas equation of state,

$V_{a,i} = \frac{mRT_{a,i} }{P_{a,i} }$ = $\frac{1x (8.314 28.97 kJ kg • °K)x 350°K}{5 bar x 100KPa bar}$ = 0.201 $m^{3}$

The equilibrium pressure of the gases can also be obtained by the ideal gas equation

$P_{eq=\frac{(m_{a}R_{a}T_{eq})+(m_{a}R_{a}T_{eq} ) }{(V_{a,eq}+V_{CO2,eq)} } =\frac{(m_{a}R_{a}T_{eq})+(m_{a}R_{a}T_{eq} ) }{(V_{a,i}+V_{CO2,i)} }$

$P_{eq}$ = 1x(8.314 28.97)x426.4+3x(8.314 44)x426.4

(0.201+1.275)

= 246.67 KPa = 2.47 bar

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2 years ago

As the impurity concentration in solid solution of a metal is increased, the tensile strength:________.a) decreasesb) increasesc

valkas [14]

Answer:

Increases

Explanation:

By inhibiting the motion of dislocations by impurities in a solid solutions, is a strengthening mechanism. In solid solutions it is atomic level strengthening resulting from resistance to dislocation motion. Hence, the strength of the alloys can differ with respect to the precipitate's property. Example, the precipitate is stronger (ability to an obstacle to the dislocation motion) than the matrix and it shows an improvement of strength.

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2 years ago

In a steady flow device, the properties of the system remains constant with time. a)True b) False

Leviafan [203]

Answer:

True

Explanation:

By definition of steady flow we have

$\frac{\partial f(x,y,z,t) }{\partial t}=0$