Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
Residual Strength and Fatigue Lifetime of ... - Solid Mechanics Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
75), which illustrates possible inaccuracies in the measurement of the debond growth at these points due to the negligence of GIII in the debond growth FE routine. 120 135 105 G(J/m 2 ) (a) 165 180 195 150 600 450 300 150 0 90 75 60 45 30 15 0 345 210 330 225 315 240 255 270 300 285 a/b=1.7 a/b=1.4 a/b=1.1 Figure 4.14: Distribution of (a) GI+II and (b) related phase angle in the debond front. 165 180 195 150 120 135 105 60 40 20 0 90 To evaluate the accuracy of the implemented cycle jump method, the fatigue debond propagation simulation was conducted for 500 cycles. To study the effect of the control parameter on the accuracy and computational efficiency of the simulation, simulations with different control parameters, qy, were conducted. A reference simulation, simulating all individual cycles was performed to verify the accuracy of the simulations based on the cycle jump method. The debond growth at different points along the debond front vs. cycles is shown in Figure 4.16 (a) from the reference simulation. Because of a larger strain energy release rate, the debond front in the 0degree position (short radius of the ellipse) grows more than at the other points. The crack 80 () 165 180 195 75 60 150 120 135 105 -5 -6 -7 -8 -9 -10 90 75 60 45 30 15 0 345 210 330 225 315 240 255 270 285 300 a/b=1.7 a/b=1.4 a/b=1.1 45 30 210 330 225 315 240 255 270 300 285 a/b=1.7 a/b=1.4 Figure 4.15: Distribution of mode III strain energy release rate in the debond front. (b) 15 0 345
growth descreases as the 90-degree position (large radius of the ellipse) is approached. Figure 4.16 (b) illustrates the variation of the mode III strain energy release rate as the debond propagates. The mode III effects decrease significantly as the debond propagates and turns into a circle from its initial elliptical shape. 80 Debond front locations at: (a) 60 (b) 9 27 45 Crack length (mm) 70 60 50 40 0 18 36 54 72 90 0 100 200 300 400 500 0 100 200 300 400 500 Cycle Cycle Figure 4.16: (a) Debond growth and (b) mode III strain energy release rate vs. cycles at different points along the debond front from the reference simulation. Figures 4.17 (a) and 4.18 (b) show GI+II and phase angle vs. cycles from the reference simulation. The largest change in both diagrams occurs in the debond front location close to 0 degree due to the large crack growth in this location. It is seen that GI+II decreases from 0 until approximately 54 and increases as the 90 degree position is approached. The mode-mixity variation along the debond front decreases as the debond shape changes from an ellipse to a circle. G I+II (J/m 2 ) 500 400 300 200 100 0 Debond front locations at: Debond front locations at: 0 18 36 54 72 90 (a) 0 100 200 300 400 500 Cycle Figure 4.17: (a) GI+II and (b) phase angle vs. cycles at different points along the debond front from the reference simulation. 81 G III (J/m 2 ) Phase angle (degree) 50 40 30 20 10 0 -4 -5 -6 -7 -8 -9 63 81 Cycle 0 100 200 300 400 500 (b) Debond front locations at: 0 18 36 54 72 90
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75), which illustrates possible inaccuracies in the measurement <strong>of</strong> the debond growth at these<br />
points due to the negligence <strong>of</strong> GIII in the debond growth FE routine.<br />
120<br />
135<br />
105<br />
G(J/m 2 )<br />
(a)<br />
165<br />
180<br />
195<br />
150<br />
600<br />
450<br />
300<br />
150<br />
0<br />
90<br />
75 60<br />
45<br />
30<br />
15<br />
0<br />
345<br />
210<br />
330<br />
225<br />
315<br />
240<br />
255<br />
270<br />
300<br />
285<br />
a/b=1.7 a/b=1.4 a/b=1.1<br />
Figure 4.14: Distribution <strong>of</strong> (a) GI+II <strong>and</strong> (b) related phase angle in the debond front.<br />
165<br />
180<br />
195<br />
150<br />
120<br />
135<br />
105<br />
60<br />
40<br />
20<br />
0<br />
90<br />
To evaluate the accuracy <strong>of</strong> the implemented cycle jump method, the fatigue debond propagation<br />
simulation was conducted for 500 cycles. To study the effect <strong>of</strong> the control parameter on the<br />
accuracy <strong>and</strong> computational efficiency <strong>of</strong> the simulation, simulations with different control<br />
parameters, qy, were conducted. A reference simulation, simulating all individual cycles was<br />
performed to verify the accuracy <strong>of</strong> the simulations based on the cycle jump method. The debond<br />
growth at different points along the debond front vs. cycles is shown in Figure 4.16 (a) from the<br />
reference simulation. Because <strong>of</strong> a larger strain energy release rate, the debond front in the 0degree<br />
position (short radius <strong>of</strong> the ellipse) grows more than at the other points. The crack<br />
80<br />
()<br />
165<br />
180<br />
195<br />
75 60<br />
150<br />
120<br />
135<br />
105<br />
-5<br />
-6<br />
-7<br />
-8<br />
-9<br />
-10<br />
90<br />
75<br />
60<br />
45<br />
30<br />
15<br />
0<br />
345<br />
210<br />
330<br />
225<br />
315<br />
240<br />
255<br />
270<br />
285<br />
300<br />
a/b=1.7 a/b=1.4 a/b=1.1<br />
45<br />
30<br />
210<br />
330<br />
225<br />
315<br />
240<br />
255<br />
270<br />
300<br />
285<br />
a/b=1.7 a/b=1.4<br />
Figure 4.15: Distribution <strong>of</strong> mode III strain energy release rate in the debond front.<br />
(b)<br />
15<br />
0<br />
345
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