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
0σ
02a
r
θ
σ
0σ
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
θS
S
2a
r
θS
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 auy
x
y r
θ
δ
a auy
x y
Near-tip Stress
δ
a aNear-tip Stress
δ
aa
(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
yb
f
xb a
a’
δ a δ a
b
f
yb
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
xp33 p
f
y4 p
f
x 4 pf
y p3δ a δ a
p1 p2
p3 p4
p1’ p2’ f
xp33 p
f
y4 p
f
x 4 pf
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 = a − x
x y
10
-41.2542 × 10
-121.9737 × 10
-203.1056 × 10
-284.8865 ×
Overlap
a
x y
x y
10
-41.2542 × 10
-121.9737 × 10
-203.1056 × 10
-284.8865 ×
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
yEffective Properties
L
20L
30L
crack
u
y=0 u
x=0
∞
σ
yEffective 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
−4μ Δ
Crack Crack
m a = 1 . 5625 × 10
−4μ 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/σ 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/σ 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/σ 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/σ 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 (%) σy/σy∞
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
yEffective Properties
L
20L
30L
crack
uy=0 ux=0
x y
∞
σ
yEffective 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