MSE Ch. 9

Modulus of a thermoplastic polymer _____ with increasing temperature. This behavior is particularly dominant above glass transition temperature. A. Decreases B. Increases C. Does not change

A

Toughness in tensile test is defined as _______________. A. The area underneath the stress-strain curve B. The highest stress C. The maximum elongational strain D. The fully recoverable strain

A

Which material has the lowest ductility? A. Material I (Shortest, straightest line) B. Material II C. Material III

A

Which one of the following is yield strength? A. 300 MPa (The top of the concave down, point B) B. 350 MPa C. 200 MPa D. None of the above

A

Which one of the following will not lead to plastic deformation? A. Bond stretching B. Dislocation movement C. Sliding of entangled long-chain molecules D. None of the above

A

Which point represents the limit of linear elastic strain? A. Point A (First point, located on tangent line) B. Point B C. Point C D. None of the above

A

Creep behavior is measured at _________. A. Constant strain B. Constant stress

B

A hypothetical material with a Poisson ratio of -0.1 will _____________ in lateral dimensions when under uniaxial tension. A. Expand B. Shrink

A

Aligned thermoplastic polymers exhibit _____ modulus in the direction of alignment than unoriented thermoplastic polymer. A. Higher B. Lower

A

Definition of tensile modulus is __________. A. Stress/strain B. Stress x strain C. Strain/stress D. None of the above

A

Diamond is an example of a very high modulus material. This statement is ______. A. True B. False

A

Elastic deformation is fully recoverable. This statement is ____? A. True B. False

A

For most materials, the true stress is higher than the engineering stress. This statement is _____. A. True B. False

A

Griffith theory predicts that theoretical strength of a material is about 10 % of its Young's modulus. This statement is ______. A. True B. False

A

In Maxwell model, elastic spring and viscous dashpot are connected in _______. A. Series B. Parallel C. Both series and parallel D. None of the above

A

In the Maxwell model, which element dissipates energy? A. Dashpot. B. Spring. C. Both spring and dashpot can dissipate energy. D. None of above is correct.

A

Modulus of BCC iron along <111> is ~ 280 GPa, while along <100> is ~ 125 GPa. The modulus of polycrystalline iron is ~ 200 GPa. These statements are______? A. True B. False

A

Which strain represents the permanent plastic deformation? A. OC (X intercepts of Region 1) B. CD C. OD D. None of the above

A

Young's modulus is also known as ______? A. Elastic modulus B. Plastic modulus C. Loss modulus D. None of the above

A

According to Hooke's law, which of the following is correct? (Symbols have their usual meaning) A.𝜎∝1/𝜖 B.𝜎∝(1/𝜖)^2 C.𝜎∝𝜖 D. None of the above

C

Definition of strain is ________? A. Original length/change in length B. Original length x change in length C. Change in length/ original length None of the above

C

For a viscous material, which one the following equation is applicable? (Symbols have their usual meaning) A.𝜎=𝐸𝜀 B.𝜏=𝐺𝛾 C. σ=η(𝑑𝜖/𝑑𝑡) D. None of the above

C

For an incompressible material, the Young's modulus (E) is ____________ times the elastic shear modulus (G). A.One B. Two C. Three D. Four E. None of the above

C

For an incompressible material, the elastic bulk modulus is equal to ____________. A. 0 B. 1 C. Infinity D. None of above

C

Rubber typically has a Poisson ratio close to____________? A. 0 B. 0.3 C. 0.5 D. 1

C

Which material has the lowest modulus? A. Material I B. Material II C. Material III (Material with smallest initial slope)

C

Which one of the following is the strain to failure? A. 1% B. 2 % C. 6% (Endpoint) D. None of the above

C

On a tensile stress-strain curve, which value is the highest? A. Stress at the elastic limit B. Stress at the yield point C. Stress at fracture D. Tensile strength

D

Which material property has a unit different from the other three?A. Young's modulus B. Tensile strength C. Yield stress D. Poisson ratio

D

Which of the following is an example of high modulus material? A. Plexiglass (PMMA) B. Polypropylene C. Polystyrene D. Stainless steel.

D

Which one of the following figures represents the stress-strain curve of a ceramic material? A. Upside down hook B. Low modulus, long line C. High Toughness D. Brittle, short straight

D

Which one of the following is the initial modulus? A. 100 MPa B. 150 MPa C. 200 MPa D. 20 GPa (initial stress/strain with unit change) E. None of the above

D

Modulus can be measured in which of the following mode? A. Tension B. Compression C. Torsion D. Bending E. Shear F. All of the above

F

Definition of stress is ________? A. Force x cross-sectional area B. Force/cross-sectional area C. Force/change in length Force x change in length

B

For isotropic material, relationship between tensile modulus and shear modulus is given by which of the following equation? A. G=(E/3(1-2v)) B. E/2(1+v) C. 2E/(1+v) D. None of the above

B

In Griffith equation, 𝜎=2𝐸𝛾𝑠𝜋𝑎, a is two times the crack length. This statement is ______. A. True B. False

B

In a stress relaxation test, stress as a function of time can be approximated by which one of the following equations? (Symbols have their usual meaning) A. 𝜎(𝑡)=𝜎0exp (𝑡/𝜏0 ) B. 𝜎(𝑡)=𝜎0exp (―𝑡/𝜏0 ) C.𝜎(𝑡)=exp ( 𝑡/𝜏0 ) D.𝜎0=𝜎(𝑡)exp (―𝑡/𝜏0 )

B

In which test is the strain maintained constant? A. Creep test. B. Stress relaxation test.

B

Plastic deformation is fully recoverable. This statement is ____? A. True B. False

B

The elongation to break increases as the deformation rate increases in silly putty. This statement is ______. A. True B. False

B

Which material has the highest toughness? A. Material I B. Material II (Most area under curve) C. Material III

B

Which region represents the recoverable work? A. Region 1 (left, loading) B. Region 2 (right, unloading) C. Region 1 + Region 2 D. None of the above

B