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Graphite fibres are used to make undirectional Al-matrix composites. Young's modulus of graphite and aluminium are 400 GPa respectively. If a composite contains 60 volume % of fiber and is loaded along the fiber direction, the Youngs Modulus of the composite is . . . . . . . . GPa.
A
60
B
164
C
264
D
364
Correct Answer:
264
A glass reinforced polymer composite comprises of 35 volume % glass fiber and 65 volume % of polymer resin. The elastic moduli of glass and polymer resin are respectively 70 GPa and 3 GPa. The elastic modulus of the composite (in GPa) under iso-strain state is
A
4.51
B
25.45
C
26.45
D
27.45
A glass fibre reinforced epoxy composite is made with 60 wt.% unidirectional continuous glass fibres. The elastic moduli of the glass fibre and the epoxy matrix are 72.5 and 2.4 GPa, respectively. What is the elastic modulus of this composite along the fibre direction, in GPa? The densities of glass fibre and epoxy are 2.58 g/cm
3
and 1.14 g/cm
3
, respectively
A
10.5
B
20.5
C
30.5
D
4.5
An aluminium alloy rod of diameter 15 mm and length 120 mm is subjected to a tensile load of 35,000 N along its axis. The Young's modulus and Poisson's ratio for aluminium are 70 GPa and 0.33 respectively.
A
0.11
B
0.014
C
0.018
D
0.021
A polymer matrix composite is reinforced with long continuous ceramic fibers aligned in one direction. The young's moduli of the matrix and fibers are Em and Er respectively and the volume fraction of the fibers is f. Assuming iso-stress condition, Young's modulus of the composite Ec in a direction perpendicular to the length of fibers, is given by the expression
A
Ec = (1 - f) E<sub>m</sub> + f E<sub>f</sub>
B
Ec = f Em + (1 - f) Er
C
$$\frac{1}{{Ec}} = \frac{{\left( {1 - f} \right)}}{{{E_m}}} + \frac{f}{{Ef}}$$
D
$$\frac{1}{{Ec}} = \frac{f}{{{E_m}}} + \frac{{\left( {1 - f} \right)}}{{Ef}}$$
The modulus of rigidity and the modulus of elasticity of a material are 80 GPa and 200 GPa. What will be the Poissons ratio of the material?
A
0.25
B
0.30
C
0.40
D
0.50
Calculate the shear modulus for steel in GPa, if given that young modulus is 215 GPa and possion’s ratio is 0.33?
A
40 GPa
B
50 GPa
C
80 GPa
D
100 GPa
The maximum harbour depth below lowest low water is generally equal to
(i) loaded draft + 1.2 m when bottom is rock
(ii) loaded draft + 1.8 m when bottom is soft
(iii) loaded draft + 1.2 m when bottom is soft
(iv) loaded draft + 1.8 m when bottom is rock
A
(i) and (ii) are correct
B
(i) and (iii) are correct
C
(ii) and (iv) are correct
D
(iii) and (iv) are correct
After 3 semesters in college , jim has a 3.0 GPA. What GPA must jim attain in his fourth semesters if he wishes to raise his GPA to a 3.1 ?
A
2.7
B
3.1
C
3.3
D
3.4
100 জন ছাত্রের সবাই হয় গণিতে না হয় ইংরেজীতে GPA 5 পেয়েছে। 80 জন গণিতে এবং 75 জন ইংরেজীতে GPA 5 পেলে কতজন ছাত্র উভয় বিষয়ে GPA 5 পেয়েছে?
A
5
B
25
C
55
D
70
The stacking fault energy of aluminium is 200 mJ m-2. Find the equilibrium spacing between partial dislocation of aluminium. If the shear modulus of the material is 27 GPa and lattice parameter is 3.57 A°.
A
20 A°
B
1000 A°
C
1 A°
D
20 micron