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"cell_type": "heading",
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"source": [
"Chapter 15: Fatigue"
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"metadata": {},
"source": [
"Example 15.1 Pg.No.445"
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"input": [
"from __future__ import division\n",
"from scipy import integrate\n",
"from sympy import symbols\n",
"import math\n",
"\n",
"#eqn 15.30 K=S(pi*a)^1/2*alpha\n",
"S=175 #stress range (N/mm^2)\n",
"K=1708 #fracture toughness (n/mm^3/2)\n",
"alpha=1 #constant\n",
"n=4 #constant\n",
"C=40*10**-15 #rate of crack growth (mm/cycle)\n",
"ai=0.1 #initial crack length\n",
"\n",
"alpha_f=K**2/S**2/math.pi\n",
"\n",
"\n",
"Nf=2/C/(n-2)/(S*math.pi**0.5)**n*(1/ai**((n-2)/2)-1/alpha_f**((n-2)/2))\n",
"print \"Number of cycles to failure = %5.0f cycles\\n\"%(Nf)"
],
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{
"output_type": "stream",
"stream": "stdout",
"text": [
"Number of cycles to failure = 26919 cycles\n",
"\n"
]
}
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"prompt_number": 4
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