Mechanics of Composite Materials 2nd. Edition by Autar K. Kaw | 9780849313431 | 849313430 | Holooly

Mechanics of Materials

Mechanics of Composite Materials

78 SOLVED PROBLEMS

Question: 6.4

In Example 6.3, the width-to-height ratio in the cross-section of the beam is b/h = 5/1 = 5. This may be considered as a narrow-beam cross-section. If the b/h ratio were large, the cross-section may be considered to be wide beam. What are the results of Example 6.3 if one considers the beam to be a ...

Verified Answer:

In the case of the wide beams, we consider

...

Question: 6.2

In Example 6.1, the width-to-height ratio in the cross-section of the beam is b/h = 5/1 = 5. This may be considered as a narrow-beam cross-section. If the b/h ratio were large, the cross-section may be considered to be wide beam. What are the results of Example 6.1 if one considers the beam to be a ...

Verified Answer:

In the case of wide beams, we consider

κ_y=...

Question: 5.8

Drive shafts (Figure 5.3) in cars are generally made of steel. An automobile manufacturer is seriously thinking of changing the material to a composite material. The reasons for changing the material to composite materials are that composites 1. Reduce the weight of the drive shaft and thus reduce ...

Verified Answer:

1. STEEL DESIGN. Torsional strength: The primary l...

Question: 5.3

Find the ply-by-ply failure loads for a [0/90]s graphite/epoxy laminate. Assume the thickness of each ply is 5 mm and use properties of unidirectional graphite/epoxy lamina from Table 2.1. The only load applied is a tensile normal load in the x-direction — that is, the direction parallel to the ...

Verified Answer:

Because the laminate is symmetric and the load app...

Question: 5.4

Repeat Example 5.3 for the first ply failure and use Tsai–Wu failure theory now with an additional thermal load: a temperature change of –75°C. ...

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The laminate is symmetric and the load applied is ...

Question: 5.5

1. An electronic device uses an aluminum plate of cross-section 4 in. × 4 in. to take a pure bending moment of 13,000 lb-in. The factor of safety is 2. Using the properties of aluminum given in Table 3.4, find the thickness of the plate. 2. The designer wants at least to halve the thickness of the ...

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1. The maximum normal stress in a plate under bend...

Question: 5.6

An electronic device uses an aluminum plate of 1-in. thickness and a top cross–sectional area of 4 in. × 4 in. to take a pure bending moment. The designer wants to replace the aluminum plate with graphite/epoxy unidirectional laminate. The ply thickness of graphite/epoxy is 0.125 mm (0.0049213 ...

Verified Answer:

1. The bending stiffness,

E_b

, of t...

Question: 5.7

A 6-ft-long cylindrical pressure vessel (Figure 5.2) with an inner diameter of 35 in. is subjected to an internal gauge pressure of 150 psi. The vessel operates at room temperature and curing residual stresses are neglected. The cost of a graphite/epoxy lamina is 250 units/lbm and cost of a glass ...

Verified Answer:

LOADING. For thin-walled cylindrical pressure vess...

Question: 5.2

Show that the extensional stiffness matrix for a general N-ply quasi-isotropic laminate is given by [A] = [U1 U4 0 U4 U1 0 0 0 U_1-U_4/2]h. where U1 and U4 are the stiffness invariants given by Equation (2.132) and h is the thickness of the laminate. Also, find the in-plane engineering stiffness ...

Verified Answer:

From Equation (2.131a), for a general angle ply wi...

Question: 5.1

A [0/±60] graphite/epoxy laminate is quasi-isotropic. Find the three stiffness matrices [A], [B], and [D] and show that 1. A11 = A22; A16 = A26 = 0; A66 = A11 – A12 / 2. 2. [B] ≠ 0, unlike isotropic materials. 3. [D] matrix is unlike isotropic materials. Use properties of unidirectional graphite ...

Verified Answer:

From Example 2.6, the reduced stiffness matrix [Q]...

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