Solutions Manual for Theory and Analysis of Elastic Plates and Shells (2nd Edition, 2007) by Reddy – Covers All 12 Chapters

All 12 Chapters Covered




SOLUTIONS

, Contents


Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv


1. Vectors, Tensors, and Equations of Elasticity . . . . . . . . . . . . . . . . . . . . . . . . 1

2. Energy Principles and Variational Methods . . . . . . . . . . . . . . . . . . . . . . . . .19

3. Classical Theory of Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

4. Analysis of Plate Strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

5. Analysis of Circular Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

6. Bending of Simply Supported Rectangular Plates . . . . . . . . . . . . . . . . . . 91

7. Bending of Rectangular Plates with Various
Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

8. General Buckling of Rectangular Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

9. Dynamic Analysis of Rectangular Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

10. Shear Deformation Plate Theories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

11. Theory and Analysis of Shells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139

12. Finite Element Analysis of Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157




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, 1
Vectors, Tensors, and
Equations of Elasticity


1.1 Prove the following properties of δij and εijk (assume i, j = 1, 2, 3 when they
are dummy indices):
(a) Fij δjk = Fik
(b) δij δij = δii = 3
(c) εijk εijk = 6
(d) εijk Fij = 0 whenever Fij = Fji (symmetric)

Solution:
1.1(a) Expanding the expression

Fij δjk = Fi1 δ1k + Fi2 δ2k + Fi3 δ3k

Of the three terms on the right hand side, only one is nonzero. It is equal to Fi1 if
k = 1, Fi2 if k = 2, or Fi3 if k = 3. Thus, it is simply equal to Fik .
1.1(b) By actual expansion, we have

δij δij = δi1 δi1 + δi2 δi2 + δi3 δi3
= (δ11 δ11 + 0 + 0) + (0 + δ22 δ22 + 0) + (0 + 0 + δ33 δ33 )
=3

and
δii = δ11 + δ22 + δ33 = 1 + 1 + 1 = 3

Alternatively, using Fij = δij in Problem 1.1a, we have δij δjk = δik , where i and k
are free indices that can any value. In particular, for i = k, we have the required
result.
1.1(c) Using the ε-δ identity and the result of Problem 1.1(b), we obtain

εijk εijk = δii δjj − δij δij = 9 − 3 = 6


@Seismicisolation
@Seismicisolation

, 2 Theory and Analysis of Elastic Plates and Shells


1.1(d) We have
Fij εijk = −Fij εjik (interchanged i and j)
= −Fji εijk (renamed i as j and j as i)
Since Fji = Fij , we have
0 = (Fij + Fji ) εijk
= 2Fij εijk

The converse also holds, i.e., if Fij εijk = 0, then Fij = Fji . We have
0 = Fij εijk
1
= (Fij εijk + Fij εijk )
2
1
= (Fij εijk − Fij εjik ) (interchanged i and j)
2
1
= (Fij εijk − Fji εijk ) (renamed i as j and j as i)
2
1
= (Fij − Fji ) εijk
2
from which it follows that Fji = Fij .

♠ New Problem 1.1: Show that

∂r xi
=
∂xi r

Solution: Write the position vector in cartesian component form using the index
notation
r = xj êj (1)
Then the square of the magnitude of the position vector is
r2 = r · r = (xi êi ) · (xj êj ) = xi xj δij
= xi xi = xk xk (2)
Its derivative of r with respect to xi can be obtained from
∂r2 ∂
= (xk xk )
∂xi ∂xi
∂xk ∂xk
= xk + xk
∂xi ∂xi
∂xk
=2 xk = 2δik xk = 2xi
∂xi
Hence
∂r xi
= (3)
∂xi r



@Seismicisolation
@Seismicisolation