Files
MultiPhysicsVault/.raw/AFirstCourseInTheFiniteElementMethod/AFirstCourseInTheFiniteElementMethod_031.md
T
김경종 b7f84e1c0f
Tests / Hermetic test suite (push) Has been cancelled
Tests / Skill frontmatter validation (push) Has been cancelled
add documents
2026-05-29 15:59:56 +09:00

855 lines
16 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
<!-- source-page: 301 -->
neutral axis to the top or bottom of the beam cross section, as used in the bending stress formula $\sigma = ( M c / I )$ .
![](images/page-301_d029304ac93384ebefd734a07f100abfea25235e1d13fac74369f833579791c4.jpg)
<details>
<summary>text_image</summary>
1000 lb
4
8
12
2000 lb
3
7
11
2000 lb
2
6
10
1
1
5
9
30 ft
30 ft
10 ft
10 ft
10 ft
</details>
Figure P522
5.235.38 For the rigid frames or beams shown in Figures P523—P538, determine the displacements and rotations at the nodes, the element forces, and the reactions.
![](images/page-301_6831678c92122c701fd7d6dfc4b9ba984dbc30267f15ff9648d9a468fde63495.jpg)
![](images/page-301_b7f7f78e34bd9f86d62de45fc7de05b5c1b46e9aa991058bdb570152d48f3ff7.jpg)
<details>
<summary>text_image</summary>
3000 lb-ft
1200 lb
A = 10 in²
I = 150 in⁴
(for elements 3 and 4)
2400 lb
3
300 in⁴
A = 12 in²
15 ft
15 ft
2
2
25 ft
For cross members:
I = 1.0 in⁴
A = 2.0 in²
E = 30 × 10⁶ psi
(for all members)
</details>
Figure P523
![](images/page-301_6af6213021c5eaa282ba3837ee56998c43bee1978e62dcd2637f6d48229379f6.jpg)
<details>
<summary>text_image</summary>
300 lb/ft
25 ft
5
6
15 ft
3
4
1
15 ft
2
E = 30 × 10⁶ psi
I = 200 in⁴
A = 15 in²
</details>
Figure P524
<!-- source-page: 302 -->
![](images/page-302_a0760e502009715e9bb920a817b56a1a4bf2dbd65b12a661f6a97732c16d428b.jpg)
<details>
<summary>text_image</summary>
125 lb
2
25 lb
1
3
4
5
6
</details>
(a)Design 1
![](images/page-302_10ff53cc707f33a6c6c5a9a7ea107208ad1f5abb75928c3297e331950ce84147.jpg)
<details>
<summary>text_image</summary>
125 lb
2
25 lb
1
2
3
4
5
6
7
</details>
(bDesign 2
![](images/page-302_3f4c4576ae5f507981687c89c58279c9eb1b789c49e165aa83363396f1704cf0.jpg)
<details>
<summary>text_image</summary>
(10, 15)
(30, 15)
(10, 15)
(32, 11.25)
(38, 0)
(0, 0)
(20, 0)
(32, 11.25)
(38, 0)
</details>
(a)Design 1
![](images/page-302_f2d963aa1c1faeac1e3d63932ac330b70c255274bb117cf2704eaf401038b38e.jpg)
<details>
<summary>text_image</summary>
y
1
2 (10, 15)
3
4
5
6
(30, 15)
(32, 11.25)
(38, 0)
(20, 0)
(38, 0)
x
</details>
(bDesign 2
$$
\begin{array}{l} \text { Case 1 } \\ E = 3 0 \times 1 0 ^ {6} \mathrm{psi} \\ \text { Case 2 } \\ E = 1 0 \times 1 0 ^ {6} \mathrm{psi} \\ A _ {1} = 0. 1 \text { in } ^ {2} \\ A _ {2} = A _ {3} = A _ {4} = A _ {5} = 0. 1 5 \mathrm{in} ^ {2} \\ A _ {6} = A _ {7} = A _ {8} = 0. 3 \text { in } ^ {2} \\ I _ {1} = 0. 0 1 \mathrm{in} ^ {4} \\ I _ {2} = I _ {3} = I _ {4} = I _ {5} = 0. 0 2 \text { in } ^ {4} \\ I _ {6} = I _ {7} = I _ {8} = 0. 1 \mathrm{in} ^ {4} \\ \end{array}
$$
Figure P525 Two bicycle frame models (coordinates shown in inches)
![](images/page-302_dbeef8cb905e1ffdc033e763e83091d3806f80d6f6bb821606e5b03c1e64a069.jpg)
<details>
<summary>text_image</summary>
1000 lb/ft
3
8 ft
2
I₂, A₂
5
8 ft
6
I₁, A₁
12 ft
I₁, A₁
1
4
12 ft
E = 30 × 10⁶ psi
I₁ = 300 in⁴
I₂ = 600 in⁴
A₁ = 15 in²
A₂ = 30 in²
</details>
Figure P526
<!-- source-page: 303 -->
![](images/page-303_d40dbfdf4e2022aa71508d66b18474dd86a587ab9c156d1063edb309673a840f.jpg)
<details>
<summary>text_image</summary>
60 kN
4 m
4 m
2
3
4
6 m
1
5
E = 210 GPa
I = 1.0 × 10⁻⁴ m⁴
A = 1.0 × 10⁻² m²
</details>
Figure P5-27
![](images/page-303_2367be9e23b3a4aaf809c7b9aead7aeb0ccaaaf3a6c689081875e7d6cb4375d6.jpg)
<details>
<summary>text_image</summary>
10 m
4
4 m
2
4 m
1
300 kN/m
5
E = 210 GPa
I = 0.5 × 10⁻⁴ m⁴
A = 0.5 × 10⁻² m²
</details>
Figure P5-28
![](images/page-303_3c0d9a38764972b2ff41b26f73bf5437e3031bafcf046081beca8c27ead73b6c.jpg)
<details>
<summary>text_image</summary>
E = 30 × 10⁶ psi
I = 150 in⁴
A = 10 in²
1
2
16 kip
16 kip
4 kip
3
4
5
6
30 ft
14 ft
7 ft
7 ft
30 ft
</details>
Figure P529
<!-- source-page: 304 -->
$$
\begin{array}{l} E = 3 0 \times 1 0 ^ {6} \mathrm{psi} \\ I = 2 0 0 \mathrm{in} ^ {4} \\ A = 1 2 \mathrm{in} ^ {2} \end{array}
$$
![](images/page-304_1bbc13fff2c8421655754c70c14c54d281afcff2e935c62de1e5205baf92092f.jpg)
<details>
<summary>text_image</summary>
30 kip
30 kip
15 ft
20 ft
15 ft
3
4
2
5
10 ft
30 ft
1
6
50 ft
</details>
Figure P530
![](images/page-304_4362c84070580fb5881b0bc3f7a0eba0bd1a89a68770b228f16aacb47835bb4f.jpg)
<details>
<summary>text_image</summary>
E = 30 × 10⁶ psi
I = 100 in⁴
A = 8 in²
500 lb/ft
10 ft
15 ft
3
4
1
45°
</details>
Figure P531
![](images/page-304_89dbab9f0172aabd661ab8b94fca38332659740376ce71acffee358f0999060c.jpg)
<details>
<summary>text_image</summary>
15 kN
10 kN · m
2
6 m
3
6 m
1
4
</details>
$$
\begin{array}{l} E = 2 1 0 \mathrm{GPa} \\ I = 2 \times 1 0 ^ {- 4} \mathrm{m} ^ {4} \\ A = 2 \times 1 0 ^ {- 2} \mathrm{m} ^ {2} \\ \end{array}
$$
Figure P532
<!-- source-page: 305 -->
![](images/page-305_280cc911c51fcf4e3f0ff44131b26d7c23a610ff7b3a7c34187e0a749692dcad.jpg)
<details>
<summary>text_image</summary>
20 kN
7
60 kN·m
I₁, A₁
8
I₃, A₃
I₁, A₁
I₃, A₃
20 kN
5
6
I₂, A₂
I₂, A₂
20 kN
3
I₁, A₁
4
I₂, A₂
2
1
2
10 m
3 m
3 m
4 m
</details>
$$
\begin{array}{l} E = 2 1 0 \mathrm{GPa} \\ I _ {1} = 2 \times 1 0 ^ {- 4} \mathrm{m} ^ {4} \\ A _ {1} = 2 \times 1 0 ^ {- 2} \mathrm{m} ^ {2} \\ I _ {2} = 1 \times 1 0 ^ {- 4} \mathrm{m} ^ {4} \\ A _ {2} = 1 \times 1 0 ^ {- 2} \mathrm{m} ^ {2} \\ I _ {3} = 0. 5 \times 1 0 ^ {- 4} \mathrm{m} ^ {4} \\ A _ {3} = 0. 5 \times 1 0 ^ {- 2} \mathrm{m} ^ {2} \\ \end{array}
$$
Figure P5-33
![](images/page-305_14bce21969aac05af905a91014cebfb00ae542f2fe8bb762b4832ca61910bd2f.jpg)
<details>
<summary>text_image</summary>
7000 N/m
1
① 2 ② 3 ③ 4
7 m 7 m 7 m
</details>
$$
E = 2 1 0 \mathrm{GPa}
$$
$$
I = 1 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
$$
A = 1 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
Figure P5-34
![](images/page-305_7630926db9bcea87d2ce2ff4e44630c7c093ac9e55516d7643b6af91cf825b75.jpg)
<details>
<summary>text_image</summary>
2800 N · m
4000 N → 9 → 2A₁, 3I₁ 10
A₃, I₃ 4 m
8000 N → 7 → 2A₁, 3I₁ 8
A₃, I₃ 4 m
8000 N → 5 → 2A₁, 3I₁ 6
A₂, I₂ 4 m
12,000 N → 3 → 2A₁, 3I₁ 4
A₁, I₁ 6 m
1 → 2
10 m
</details>
$$
E = 2 1 0 \mathrm{GPa}
$$
$$
A _ {1} = 2. 0 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
$$
I _ {1} = 2. 0 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
$$
A _ {2} = 1. 5 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
$$
I _ {2} = 1. 5 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
$$
A _ {3} = 1. 0 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
$$
I _ {3} = 1. 0 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
Figure P5-35
$$
A _ {1} = 2. 0 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
$$
I _ {1} = 2. 0 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
$$
A _ {2} = 1. 5 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
$$
I _ {2} = 1. 5 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
$$
A _ {3} = 1. 0 \times 1 0 ^ {- 2} \mathrm{m} ^ {2}
$$
$$
I _ {3} = 1. 0 \times 1 0 ^ {- 4} \mathrm{m} ^ {4}
$$
<!-- source-page: 306 -->
![](images/page-306_9fbe709df85385c5ca5487721b532df08d1f8449225445e2448156fa0ca9afe8.jpg)
<details>
<summary>text_image</summary>
E = 210 GPa
I = 1 × 10⁻⁴ m⁴
A = 1 × 10⁻² m²
10 kN
10 kN
4
6
20 kN
13
0.8m
2.5 m
2
1 m
2
3
5
6
7
8
9
10
11
12
13
14
1
2
3
2 m
2 m
</details>
Figure P536
![](images/page-306_e3d1a580dccfcf2d450ca03cb90bfbecb1db5528d4e1eeb3ae46ca482b7b4eab.jpg)
<details>
<summary>text_image</summary>
E = 210 GPa
I = 4 × 10⁻⁴ m⁴
A = 4 × 10⁻² m²
18 kN 72 kN 72 kN
6 m 4 m 3 m 5 m 6 m
1 3 4 5 6 7
10 m
2 8
10 m
</details>
Figure P537
![](images/page-306_650a018989bfe3630e662a2765f3eedf956779f2598928977fc9914c1bb1028e.jpg)
<details>
<summary>text_image</summary>
15 kN/m
80 kN
3.5 m
E = 210 GPa
I = 2.0 × 10⁻⁴ m⁴
A = 1.0 × 10⁻² m²
300 kN/m
1
3
7
8 m
7 m
7 m
</details>
Figure P538
![](images/page-306_690883477d7fcc50cc6c0fb37bc5ebedddac2108fec7e046a5fd4d8c8ffb5b54.jpg)
5.39 Consider the plane structure shown in Figure P539. First assume the structure to be a plane frame with rigid joints, and analyze using a frame element. Then assume the structure to be pin-jointed and analyze as a plane truss, using a truss element. If the structure is actually a truss, is it appropriate to model it as a rigid frame? How
<!-- source-page: 307 -->
![](images/page-307_858f12efb76614aaec0c464c260d269864e41e3ca8e030e55a6baed1f87edd41.jpg)
<details>
<summary>text_image</summary>
10 kN
7
4 m
8
3 m
20 kN
5
6
3 m
20 kN
3
4
20 kN
1
2
3
4
3 m
1
2
</details>
Figure P539
can you model the truss using the frame (or beam) element? In other words, what idealization could you make in your model to use the beam element to approximate a truss?
![](images/page-307_8e77d4c26ae8cc0b17d156543849b0334ca1d03f745d3ac1d38333b15ff48fb0.jpg)
5.40 For the two-story, two-bay rigid frame shown, determine (1) the nodal displacement components and (2) the shear force and bending moments in each member. Let $E = \mathsf { 2 0 0 ~ G P a } , I = \overset { \cdot } { 2 } \times 1 0 ^ { - 4 } \mathrm { m } ^ { 4 }$ for each horizontal member and $I = 1 . 5 \times 1 0 ^ { - 4 } \mathrm { m } ^ { 4 }$ for each vertical member.
![](images/page-307_a6e6d8487eaca049ecc1992fb9b54cb23cd0d99e1ad4ed8122f37a0bd25ca894.jpg)
<details>
<summary>text_image</summary>
12 kN/m
G
H
12 kN/m
I
5 m
D
E
F
5 m
A
B
C
10 m
10 m
</details>
Figure P540
![](images/page-307_a7f346d7faf3f988b8d87def81b98c499f85cd980684e81c40481779562d9c1c.jpg)
5.41 For the two-story, three-bay rigid frame shown, determine (1) the nodal displacements and (2) the member end shear forces and bending moments. (3) Draw the shear force and bending moment diagrams for each member. Let E ¼ 200 GPa; $I = 1 . 2 9 \times 1 0 ^ { - 4 } \mathrm { m } ^ { 4 }$ for the beams and $I = 0 . 4 6 2 \times 1 0 ^ { - 4 } \mathrm { m } ^ { 4 }$ for the columns.
<!-- source-page: 308 -->
The properties for I correspond to a W $6 1 0 \times 1 5 5$ and a W $4 1 0 \times 1 1 4$ wide-flange section, respectively, in metric units.
![](images/page-308_18481d500e2004926371d287502dd7eb4dfb5282fd523512335fba6f90efa766.jpg)
<details>
<summary>text_image</summary>
25 kN
50 kN
I J K L
E F G H
A B C D
4 m
6 m
8 m 6 m 8 m
</details>
Figure P541
![](images/page-308_b8ea0a00e69c3cda01c3501f6f537249c17987e12136cc0e1ac85aa1b9e4b3f1.jpg)
5.42 For the rigid frame shown, determine (1) the nodal displacements and rotations and (2) the member shear forces and bending moments. Let $E = 2 0 0$ GPa, $\dot { I } = 0 . 7 9 5 \times 1 0 ^ { - 4 } \mathrm { m } ^ { 4 }$ for the horizontal members and $I = 0 . 3 1 6 \times 1 0 ^ { - 4 } \mathrm { m } ^ { 4 }$ for the vertical members. These I values correspond to a W $4 6 0 \times 1 5 8$ and a W $4 1 0 \times 8 5$ wide-flange section, respectively.
![](images/page-308_22829d3e1b0c8e91be0fdd9334662349088bf96f951c23071bbf6d772224a3cc.jpg)
<details>
<summary>text_image</summary>
20 kN → G H I
40 kN → D E F
A B C
3 m
3 m
5 m 5 m
</details>
Figure P542
![](images/page-308_61988fc918db061c8d650750556c41f94fec6e53f7cb7d90d0feeeb3414ffd78.jpg)
5.43 For the rigid frame shown, determine (1) the nodal displacements and rotations and (2) the shear force and bending moments in each member. Let $E = 2 9 \times 1 0 6$ psi, $I = 3 1 0 0 ~ \mathrm { i n } . ^ { 4 }$ for the horizontal members and $I = 1 1 1 0 ~ \mathrm { i n } . ^ { 4 }$ for the vertical members. The I values correspond to a ${ \textsf { W } } 2 4 \times 1 0 4$ and a ${ \bf W } 1 6 \times 7 7 \mathrm { ~ \AA ~ }$ :
![](images/page-308_07430bfc649f31ee4cbe956fe4dbd1bca4ff1de607f88c98716644f9bf4e7fe5.jpg)
<details>
<summary>text_image</summary>
7.5 kip
M N
15 kip
I J K L
15 kip
E F G H
A B C D
30 ft 20 ft 30 ft
15 ft
15 ft
15 ft
</details>
Figure P543
<!-- source-page: 309 -->
![](images/page-309_701957435210eabfc7397a95a2a7f4095fde875fcf7b29ef41c54c33a27e28cf.jpg)
5.44 A structure is fabricated by welding together three lengths of I-shaped members as shown in Figure P544. The yield strength of the members is 36 ksi, $E = 2 9 \mathrm { e 6 p s i }$ , and Poissons ratio is 0.3. The members all have cross-section properties corresponding to a W18 by 76. That is, $A = 2 2 . 3 \mathrm { i n } ^ { 2 }$ , depth of section is $d = 1 8 . 2 1$ in., $I _ { x } = 1 3 3 0 \mathrm { i n } ^ { 4 }$ , $S _ { x } = 1 4 6 \mathrm { { i n } } ^ { 3 }$ , $I _ { \nu } = 1 5 2 \mathrm { i n } ^ { 4 }$ , and $S _ { \nu } = 2 7 . 6 \mathrm { i n } ^ { 3 }$ . Determine whether a load of $Q = 1 0 { , } 0 0 0$ lb downward is safe against general yielding of the material. The factor of safety against general yielding is to be 2.0. Also, determine the maximum vertical and horizontal deflections of the structure.
![](images/page-309_de63caead321a38a110f0890f6792ff7a4f5bfe8b0235c2c5ead38410f538117.jpg)
<details>
<summary>text_image</summary>
90"
90"
Q
</details>
Figure P544
![](images/page-309_23351f57c5a120637cffcb466d0e72c8ac1547b103aa1a89841bbf3b3447d777.jpg)
5.45 For the tapered beam shown in Figure P545, determine the maximum deflection using one, two, four, and eight elements. Calculate the moment of inertia at the midlength station for each element. Let $E = 3 0 \times 1 0 ^ { 6 }$ psi, $I _ { 0 } = 1 0 0 ~ \mathrm { i n } ^ { 4 }$ , and $L = 1 0 0$ in. Run cases where $n = 1 , 3 .$ , and 7. Use a beam element. The analytical solution for $n = 7$ is given by Reference [7]:
$$
v _ {1} = \frac {P L ^ {3}}{4 9 E I _ {0}} (1 / 7 \ln 8 + 2. 5) = \frac {1}{1 7 . 5 5} \frac {P L ^ {3}}{E I _ {0}}
$$
$$
\theta_ {1} = \frac {P L ^ {2}}{4 9 E I _ {0}} (\ln 8 - 7) = - \frac {1}{9 . 9 5} \frac {P L ^ {2}}{E I _ {0}}
$$
$$
I (x) = I _ {0} \left(1 + n \frac {x}{L}\right)
$$
where n ¼ arbitrary numerical factor and $I _ { 0 } = \mathrm { m o m e n t }$ of inertia of section at $x = 0$ .
![](images/page-309_e55909ee0371b4c0353b387f9c0ba871355e7e19d0467d836f010a019538c429.jpg)
<details>
<summary>text_image</summary>
P = 500 lb
1
A
2
x
w
h(x)
A-A
1
2
y
L
One-element approximation
</details>
Figure P545 Tapered cantilever beam
<!-- source-page: 310 -->
5.46 Derive the stiffness matrix for the nonprismatic torsion bar shown in Figure P546. The radius of the shaft is given by
$$
r = r _ {0} + (x / L) r _ {0}, \text { where } r _ {0} \text { is the radius at } x = 0.
$$
![](images/page-310_5c7739c8efef44558a47fba40b028e179eed9fb1a128bf711638f3ce2bd332d9.jpg)
<details>
<summary>text_image</summary>
r₀工
x
L
</details>
Figure P546
5.47 Derive the total potential energy for the prismatic circular cross-section torsion bar shown in Figure P547. Also determine the equivalent nodal torques for the bar subjected to uniform torque per unit length (lb-in./in.). Let G be the shear modulus and J be the polar moment of inertia of the bar.
![](images/page-310_7f5609c6c8b20fa87b45a21c55f09ecc5e70c0efa16c10af0b272af9b639b9fc.jpg)
<details>
<summary>text_image</summary>
T (lb-in./in.)
1
2
L
</details>
Figure P547
5.48 For the grid shown in Figure P548, determine the nodal displacements and the local element forces. Let $E = 3 0 \times 1 0 ^ { 6 }$ psi, G ¼ 12  106 psi, $I = 2 0 0 \mathrm { i n } ^ { 4 }$ , and $J = 1 0 0 \mathrm { i n } ^ { 4 }$ for both elements.
![](images/page-310_946f176f3d51f5bc684c317e4daa47b64d2c06992fb3a99aa0400f3df2c48592.jpg)
<details>
<summary>text_image</summary>
5000 lb
10 ft
10 ft
x
y
z
1
2
3
</details>
Figure P548
5.49 Resolve Problem 548 with an additional nodal moment of 1000 k-in. applied about the x axis at node 2.
5.505.51 For the grids shown in Figures P550 and P551, determine the nodal displacements and the local element forces. Let E ¼ 210 GPa, G ¼ 84 GPa, $I = 2 \times 1 0 ^ { - 4 } \mathrm { ~ m } ^ { 4 }$ , $J = 1 \times 1 0 ^ { - 4 } ~ \mathrm { m } ^ { 4 }$ , and $A = 1 \times 1 0 ^ { - 2 } \mathrm { m } ^ { 2 }$ .