• 沒有找到結果。

第四章 結論與未來展望

4.2 未來展望

本研究雖然花了很大的篇幅在整理雙材料介面裂紋的破壞力學理論,然 而很可惜地實際上在分析過程中僅有少部分的應用。由於介面裂紋的破壞 理論在一般破壞力學書籍上較少被提及,期望該章節的文獻整理可供有興 趣的後進者一個較快的學習管道以便於更深入的研究。奈米複合材料中,

基材與補強材料介面的剝離現象是很常見的破壞模式,期望未來能看到介 面裂紋的破壞理論在這方面有更廣泛的應用與延伸探討。

參考文獻

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表1 基材、補強材料之材料參數以及不同體積分率下複合材料之有效材料 性質[2,32,33]

Effective Properties Material properties Vinyl ester SiO2

5 vol% 10 vol% 20 vol%

E (GPa) 3.5 70 3.76 4.07 4.83

ν 0.35 0.2 0.35 0.34 0.33

表2 體積分率為 5 vol%、不同顆粒尺寸下之顆粒表面間距 d RP (μm) The distance between particle surface d (μm)

0.25 1.48

0.5 2.96

5 29.63

表 3 補強材料顆粒半徑 5 μm、不同體積分率下顆粒表面之間距 d Vol% The distance between particle surface d (μm)

5 29.63

10 18.03

20 9.82

x y

z x y

z

x y

z x y

z

y x

z y x

z

Mode I Mode II Mode III

圖 2.1 三種獨立的裂紋破壞變形模式(由左至右):開裂模式(Open mode)、

剪裂模式(In-plane shear mode)、撕裂模式(Tearing mode)

2a

r

θ

σ

0

σ

0

2a

r

θ

σ

0

σ

0

圖 2.2 均質材料含有一段長度為 2a 之裂紋承受拉伸外力σ0

2a

r

θ

S

S

2a

r

θ

S

S

圖 2.3 均質材料含有一段長度為 2a 之裂紋承受剪外力 S

r

θ

δ

a a

uy

x

y r

θ

δ

a a

uy

x y

Near-tip Stress

δ

a a

Near-tip Stress

δ

a

a

(b)

(a)

圖 2.4 裂紋關閉積分法示意圖(a)裂紋增長一微小量δa (b)關閉δa長度裂紋 所需之應力

b a

a’

δ a δ a

b

f

y

b

f

x

b a

a’

δ a δ a

b

f

y

b

f

x

圖 2.5 均質材料中的裂紋,使用有限元素法之四節點元素(4-nodes element) 進行分析

p3

δ a δ a

p1 p2

p3 p4

p1’ p2’ f

xp3

3 p

f

y

4 p

f

x 4 p

f

y p3

δ a δ a

p1 p2

p3 p4

p1’ p2’ f

xp3

3 p

f

y

4 p

f

x 4 p

f

y

圖 2.6 均質材料中的裂紋,使用有限元素法之八節點元素(8-nodes element) 進行分析

r θ

“2”

“1”

r θ

“2”

“1”

圖 2.7 兩種等向性材料介面之半無限裂紋(semi-infinite crack)

“2”

“1”

r σ

bi-material

“2”

“1”

r σ

“2”

“1”

“2”

“1”

r σ

bi-material

圖 2.8 雙材料介面裂紋應力場的震盪特徵(oscillating character)示意圖

x y

a

x δ

x y

x y

a

x δ

圖 2.9 定義裂紋尖端一小段長度δ = ax

x y

10

-4

1.2542 × 10

-12

1.9737 × 10

-20

3.1056 × 10

-28

4.8865 ×

Overlap

a

x y

x y

10

-4

1.2542 × 10

-12

1.9737 × 10

-20

3.1056 × 10

-28

4.8865 ×

Overlap

a

圖 2.10 兩種材料介面裂紋尖端鄰近區域的位移震盪、重疊現象

“1”

“2”

2a X, X*

Y Y*

σ

yy

τ

xy

τ

xy

τ

xy

τ

xy

)

1

( σ

xx

σ

yy

)

2

( σ

xx

)

1

( σ

xx

)

2

( σ

xx

“1”

“2”

2a X, X*

Y Y*

σ

yy

τ

xy

τ

xy

τ

xy

τ

xy

)

1

( σ

xx

σ

yy

)

2

( σ

xx

)

1

( σ

xx

)

2

( σ

xx

圖 2.11 承受拉伸與剪切外力之雙材料無限大平板,材料介面之有限長度裂 紋示意圖(裂紋長度為 2a)

Effective Properties 40L

L

60L

Effective Properties 40L

L L

60L

圖3.1 顆粒型複合材料鑲埋模型 A (含長度為 2a 之裂紋)

Effective Properties 40L

L

60L

Effective Properties 40L

L L

60L

圖3.2 顆粒型複合材料鑲埋模型 B (含長度為 2a 之裂紋)

Effective Properties 40L

L

60L

Effective Properties 40L

L L

60L

圖3.3 顆粒型複合材料鑲埋模型 C (含長度為 2a 之裂紋)

Effective Properties

σ

σ σ

σ Rp

σ

σ Rp Rp σ

σ L

L

圖 3.4 球型顆粒複合材料之有效材料性質(Effective Properties)

σ

y

Effective Properties

L

20L

30L

crack

u

y

=0 u

x

=0

σ

y

Effective Properties

L L

20L

30L

crack

u

y

=0 u

x

=0

x y

x y

圖3.5 鑲埋模型 A (四分之一模型)

Crack Crack

m a = 1 . 5625 × 10

4

μ Δ

Crack Crack

m a = 1 . 5625 × 10

4

μ Δ

圖3.6 鑲埋模型 A 之有限元素模型(Δa 為裂紋尖端之元素尺寸)

d d d

d d

圖 3.7 相同體積分率、不同顆粒尺寸之含裂紋複合材料示意圖

particle size effect (5vol%)(a=0.1μm)

107.99 109.07 109.45

76.3181.17 76.2681.32 76.2481.37

0 20 40 60 80 100 120

1 RP (μm)2 3

GT ( μJ/m2 )

model A model B model C

0.25 0.5 5

89.64 pure matrix

圖3.8 體積分率 5 vol%、半裂紋長度 a 為 0.1 μm 之裂紋,在不同顆粒尺寸 之複合材料鑲埋模型中承受 1 MPa 之外力下的應變能釋放率

particle size effect (5vol%)(a=0.1μm)

0.91 0.91 0.91

1.08 1.08 1.08

1.05 1.05 1.05

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15

0.25 0.5 5

RP (μm)

Normalized tensile strength

model A model B model C

pure matrix

圖3.9 體積分率 5 vol%、半裂紋長度 a 為 0.1 μm 之裂紋,在不同顆粒尺寸 之複合材料鑲埋模型中的標準化拉伸強度

particle size effect (5vol%)(a=0.5μm)

452.36

508.43

546.09

393.29 383.21 380.84

361.22

399.6 406.35

0 100 200 300 400 500 600

1 2 3

RP (μm) GT ( μJ/m2 )

model A model B model C

0.25 0.5 5

447.74 pure matrix

圖3.10 體積分率 5 vol%、半裂紋長度 a 為 0.5 μm 之裂紋,在不同顆粒尺寸 之複合材料鑲埋模型中承受 1 MPa 之外力下的應變能釋放率

particle size effect (5vol%)(a=0.5μm)

0.99

0.94

0.91

1.07 1.08 1.08

1.11

1.06 1.05

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15

0.25 0.5 5

RP (μm)

Normalized tensile strength

model A model B model C

pure matrix

圖3.11 體積分率 5 vol%、半裂紋長度 a 為 0.5 μm 之裂紋,在不同顆粒尺寸 之複合材料鑲埋模型中的標準化拉伸強度

particle size effect (5vol%)(a=0.7μm)

763.54 677.16

540.16 547.18 533 568.58

0 100 200 300 400 500 600 700 800 900

1 2

RP (μm) GT ( μJ/m2 )

model A model B model C

0.5 5

626.64 pure matrix

圖3.12 體積分率 5 vol%、半裂紋長度 a 為 0.7 μm 之裂紋,在不同顆粒尺寸 之複合材料鑲埋模型中承受 1 MPa 之外力下的應變能釋放率

particle size effect (5vol%)(a=0.7μm)

0.96

0.91

1.08 1.08

1.07

1.05

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15

0.5 5

RP (μm)

Normalized tensile strength

model A model B model C

pure matrix

圖3.13 體積分率 5 vol%、半裂紋長度 a 為 0.7 μm 之裂紋,在不同顆粒尺寸 之複合材料鑲埋模型中的標準化拉伸強度

y

= 1MP a σ

x y

y

= 1MP a σ

y

= 1MP a σ

x y

x y

y

= 1MP a σ

圖3.14 承受 1 MPa 拉伸應力之顆粒型複合材料 RVE 模型

X1 (%) σydistribution (5vol%) RP=5 σydistribution (5vol%) RP=5 σydistribution (5vol%)

RP=5 RP=0.5 σydistribution (5vol%)

圖3.16 體積分率為 5 vol%之顆粒型複合材料 RVE 模型,承受 y 方向 1 MPa 拉伸應力下,沿x2線上之

σ

y應力分佈曲線。箭號標示處為不同顆粒尺寸之

奈米複合材料中裂紋尖端出現位置。

X3 (%) σ y y

0 20 40 60 80 1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

00 σydistribution (5vol%)

RP=5 RP=0.5 RP=0.25

x3

X3 (%) σ y y

0 20 40 60 80 1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

00 σydistribution (5vol%)

RP=5 RP=0.5 RP=0.25 RP=5 RP=0.5 RP=0.25

x3

x3

圖3.17 體積分率為 5 vol%之顆粒型複合材料 RVE 模型,承受 y 方向 1 MPa 拉伸應力下,沿x3線上之

σ

y應力分佈曲線。箭號標示處為不同顆粒尺寸之

奈米複合材料中裂紋尖端出現位置。

d d

d dd

圖3.18 相同顆粒尺寸、不同體積分率之含裂紋複合材料示意圖

volume fraction effect (RP=5μm)(a=0.1μm)

164.58

128.95 109.45

46.88 64.73

76.24

50.55 71.84

81.37

0 20 40 60 80 100 120 140 160 180

5 10 20

Volume fraction (%) GT ( μJ/m2 )

model A model B model C

89.64 pure matrix

圖3.19 顆粒半徑為 5 μm、半裂紋長度 a 為 0.1 μm 之裂紋,在不同體積分 率之複合材料鑲埋模型中承受1 MPa 之外力下的應變能釋放率

volume fraction effect (RP=5μm)(a=0.1μm)

0.91 0.83

0.74 1.38

1.08

1.18

1.33

1.05 1.12

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

5 10 20

Volume fraction (%)

Normalized tensile strength

model A model B model C

pure matrix

圖3.20 顆粒半徑為 5 μm、半裂紋長度 a 為 0.1 μm 之裂紋,在不同體積分 率之複合材料鑲埋模型中的標準化拉伸強度

X1 (%) σ y y

0 20 40 60 80 1

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

00 σydistribution (5vol%) σydistribution (10vol%) σydistribution (20vol%)

x1

x1

圖3.21 不同體積分率之顆粒型複合材料 RVE 模型,承受 y 方向 1 MPa 拉 伸應力下,沿x1線上之

σ

y應力分佈曲線。箭號標示處為不同體積分率之奈

米複合材料中裂紋尖端出現位置。

X2 (%) σ y y

0 20 40 60 80 1

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

00 σydistribution (5vol%)

σydistribution (10vol%) σydistribution (20vol%)

x2 x2

圖3.22 不同體積分率之顆粒型複合材料 RVE 模型,承受 y 方向 1 MPa 拉 伸應力下,沿x2線上之

σ

y應力分佈曲線。箭號標示處為不同體積分率之奈

米複合材料中裂紋尖端出現位置。

X3 (%) σyy

0 20 40 60 80 1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

00 σydistribution (5vol%)

σydistribution (10vol%) σydistribution (20vol%) x3

x3

圖 3.23 不同體積分率之顆粒型複合材料 RVE 模型,承受 y 方向 1 MPa 拉 伸應力下,沿x3線上之

σ

y應力分佈曲線。箭號標示處為不同體積分率之奈

米複合材料中裂紋尖端出現位置。

volume fraction effect (RP=5μm)(a=0.5μm)

641.71 546.09

809.5

323.42 380.84

234.43 251.1 406.35

358.56

0 100 200 300 400 500 600 700 800 900

5 10 20

Volume fraction (%) GT ( μJ/m2 )

model A model B model C

447.74 pure matrix

圖3.24 顆粒半徑為 5 μm、半裂紋長度 a 為 0.5 μm 之裂紋,在不同體積分 率之複合材料鑲埋模型中承受1 MPa 之外力下的應變能釋放率

volume fraction effect (RP=5μm)(a=0.5μm)

0.91 0.84

0.74 1.38

1.18 1.08

1.34

1.05 1.12

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

5 10 20

Volume fraction (%)

Normalized tensile strength

model A model B model C

pure matrix

圖3.25 顆粒半徑為 5 μm、半裂紋長度 a 為 0.5 μm 之裂紋,在不同體積分 率之複合材料鑲埋模型中的標準化拉伸強度

volume fraction effect (RP=5μm)(a=0.7μm)

1116.49

894.99 763.54

328.41 452.72

533

349.4 501.4

568.58

0 200 400 600 800 1000 1200

5 10 20

Volume fraction (%) GT ( μJ/m2 )

model A model B model C

626.64 pure matrix

圖3.26 顆粒半徑為 5 μm、半裂紋長度 a 為 0.7 μm 之裂紋,在不同體積分 率之複合材料鑲埋模型中承受1 MPa 之外力下的應變能釋放率

volume fraction effect (RP=5μm)(a=0.7μm)

0.91 0.84

0.75 1.08

1.18

1.38 1.34

1.05 1.12

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

5 10 20

Volume fraction (%)

Normalized tensile strength

model A model B model C

pure matrix

圖3.27 顆粒半徑為 5 μm、半裂紋長度 a 為 0.7 μm 之裂紋,在不同體積分 率之複合材料鑲埋模型中的標準化拉伸強度

(a) (b)

x y

x y

圖3.28 鄰近補強材料顆粒之裂紋示意圖(a)基材中鄰近補強材料顆粒之裂 紋 (b)雙材料介面層之裂紋

Crack Crack

圖3.29 補強材料與基材介面之裂紋有限元素模型

dcp d

dcp d

dcp/ d G T,μJ/m2

0 0.1 0.2 0.3 0.4 0.5

40 60 80 100 120 140 160 180 200

Nanocomposites with crack close to the particle Nanocomposites with crack on the interface Pure matrix with crack

Totalstrainenergyreleaserate,

圖3.30 裂紋位置對應變能釋放率的影響

dcp/ d

Normalizedtensilestrength

0 0.1 0.2 0.3 0.4 0.5

0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05

Nanocomposites with crack close to the particle Pure matrix with crack

dcp d

dcp d

圖3.31 裂紋位置對含裂紋複合材料之標準化拉伸強度的影響

dag

d dag

d d

圖3.32 發生局部群聚現象之複合材料中的裂紋示意圖

σ

y

Effective Properties

L

20L

30L

crack

uy=0 ux=0

x y

σ

y

Effective Properties

L

20L

30L

crack

uy=0 ux=0

x y

x y

圖3.33 裂紋在發生局部群聚現象之複合材料中的鑲埋模型 (四分之一模 型)

dag dag

dag/ d G T,μJ/m2

0 0.2 0.4 0.6 0.8 1

0 100 200 300 400 500 600 700

Nanocompostes with particle local aggregation Pure matrix

Totalstrainenergyreleaserate,

圖3.34 局部群聚現象對複合材料中的裂紋應變能釋放率的影響

dag/ d

Normalizedtensilestrength

0 0.2 0.4 0.6 0.8 1

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

Nanocompostes with particle local aggregation Pure matrix

dag dag

圖3.35 局部群聚現象對含裂紋複合材料之標準化拉伸強度的影響

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