{
"metadata": {
"name": "",
"signature": "sha256:d8d637e7ecf72daf7222d9457fa6d30ac8f9c6b3089d299c87aaa45e1504178c"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Ch:17 Sliding contact bearings"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-1 - Page 482"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"from math import pi, sqrt\n",
"Ta=22#\n",
"u=7/10**9#\n",
"nj=20#\n",
"r=25#\n",
"l=2*r#\n",
"Ao=30000#\n",
"Uo=15.3/10**3#\n",
"c=0.025#\n",
"#specific weight of the material is rho\n",
"rho=8.46*(10**-6)#\n",
"Cp=179.8#\n",
"Tf=Ta+(16*pi**3*u*nj**2*l*r**3/(Uo*Ao*c))#\n",
"# avg mean film temperature is Tav\n",
"Tav=(Tf-Ta)/2#\n",
"x= l*c*rho*pi*r*nj*Cp*10**3#\n",
"y=Ao*Tav*Uo#\n",
"delT=y/x#\n",
"print \" Tav is %0.2f degC \"%(Tav)#\n",
"print \"\\n delT is %0.1f degC \"%(delT)#"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" Tav is 47.29 degC \n",
"\n",
" delT is 7.3 degC \n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-2 - Page 482"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"l=60#\n",
"d=60#\n",
"r=d/2#\n",
"ho=0.008#\n",
"c=0.04#\n",
"S=0.0446#\n",
"nj=1260/60#\n",
"W=6000#\n",
"p=W/(l*d)#\n",
"u=S*(c/r)**2*p/nj#\n",
"u=u*10**9#\n",
"print \"u is %0.3f cP \"%(u)#"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"u is 6.293 cP \n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-3 - Page 483"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"d=60#\n",
"r=30#\n",
"l=60#\n",
"c=0.8*10**-3*r#\n",
"ho=0.2*c#\n",
"W=21000/2#\n",
"p=W/(l*d)#\n",
"S=0.0446#\n",
"nj=1440/60#\n",
"u=S*(c/r)**2*p/nj#\n",
"u=u*10**9#\n",
"# since Q/(r*nj*l)=4.62\n",
"Q=4.62*r*c*nj*l#\n",
"Q=Q*60/10**6#\n",
"print \" u is %0.3f cP \"%(u)#\n",
"print \"\\n Q is %0.4f lpm \"%(Q)#"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" u is 3.469 cP \n",
"\n",
" Q is 0.2874 lpm \n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-4 - Page 483"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"l=60#\n",
"d=60#\n",
"r=d/2#\n",
"W=3000#\n",
"p=W/(l*d)#\n",
"u=30*10**-9#\n",
"c=0.06#\n",
"nj=1440/60#\n",
"S=(r/c)**2*u*nj/p#\n",
"#For ratio l/d=1, values of different parameters are given in matrix A corresponding to S\n",
"from numpy import mat\n",
"A=mat([[0,0,0,0,0,0],[0,1, 0.264, 0.6, 5.79, 3.99],[0,1, 0.121, 0.4 ,3.22, 4.33]])#\n",
"#let ho/c=x\n",
"x=(A[1,3])-((A[1,3]-(A[2,3]))*((A[1,2])-S)/((A[1,2])-(A[2,2])))#\n",
"#let y= (r/c)*f=CFV\n",
"y=(A[1,4])-(A[1,4]-(A[2,4]))*((A[1,2])-S)/((A[1,2])-(A[2,2]))#\n",
"#let z=Q/(r*c*nj*l)=FV\n",
"z=(A[1,5])-((A[1,5]-(A[2,5]))*((A[1,2])-S)/((A[1,2])-(A[2,2])))#\n",
"f=y*c/r#\n",
"ho=x*c#\n",
"Q=z*r*c*nj*l#\n",
"Q=Q*60/10**6#\n",
"delT=8.3*p*y/z#\n",
"#let power lost in friction be Pf\n",
"Pf=2*pi*nj*f*W*r/10**6#\n",
"print \" f is %0.5f \"%(f)#\n",
"print \"\\n ho is %0.3f mm \"%(ho)#\n",
"print \"\\n Q is %0.3f lpm \"%(Q)#\n",
"print \"\\n delT is %0.1f degC \"%(delT)#\n",
"print \"\\n Pf is %0.4f KW \"%(Pf)#"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" f is 0.00985 \n",
"\n",
" ho is 0.032 mm \n",
"\n",
" Q is 0.638 lpm \n",
"\n",
" delT is 8.3 degC \n",
"\n",
" Pf is 0.1337 KW \n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-5 - Page 484"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"W=22000#\n",
"nj=960/60#\n",
"p=2.4#\n",
"u=20*10**-9#\n",
"d=sqrt(W/p)#\n",
"d=96#\n",
"r=d/2#\n",
"l=d#\n",
"S=0.0446#\n",
"pact=W/(l*d)#\n",
"#x=r/c#\n",
"x=sqrt(S*pact/(u*nj))#\n",
"c=r/x#\n",
"ho=0.2*c#\n",
"Q=r*c*nj*l*4.62#\n",
"Q=Q*60/10**6#\n",
"print \" d is %0.0f mm \"%(d)#\n",
"print \"\\n l is %0.0f mm \"%(l)#\n",
"print \"\\n ho is %0.4f mm \"%(ho)#\n",
"print \"\\n Q is %0.3f lpm \"%(Q)#\n",
"#The difference in answer to Q is due to rounding -off the value of c."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" d is 96 mm \n",
"\n",
" l is 96 mm \n",
"\n",
" ho is 0.0166 mm \n",
"\n",
" Q is 1.701 lpm \n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-6 - Page 485"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log\n",
"W=400*10**3#\n",
"Ro=200#\n",
"Ri=160#\n",
"ho=0.1#\n",
"t=150#\n",
"# specific gravity is rho\n",
"rho=0.86#\n",
"pi=2*W*log(Ro/Ri)/(pi*(Ro**2-Ri**2))#\n",
"zk=(0.22*t)-(180/t)#\n",
"z=rho*zk#\n",
"u=z/(10**9)#\n",
"Q=pi*pi*ho**3/(6*u*log(Ro/Ri))#\n",
"Q=Q*60/10**6#\n",
"print \" pi is %0.3f MPa \"%(pi)#\n",
"print \"\\n Q is %0.2f lpm \"%(Q)#\n",
" \n",
" #The difference in answer to Q is due to rounding -off of values."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" pi is 3.946 MPa \n",
"\n",
" Q is 25.52 lpm \n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"exa 17-7 - Page 486"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#let number of pads be n\n",
"n=4#\n",
"W=100*10**3#\n",
"Ro=125#\n",
"Ri=50#\n",
"t=200#\n",
"ho=0.15#\n",
"pi=2*W*log(Ro/Ri)/(pi*(Ro**2-Ri**2))#\n",
"zk=(0.22*t)-(180/t)#\n",
"# specific gravity is rho\n",
"rho=0.86#\n",
"z=rho*zk#\n",
"u=z/(10**9)#\n",
"Q=pi*pi*ho**3/(6*u*log(Ro/Ri))#\n",
"Q=Q*60/10**6#\n",
"print \"pi is %0.2f MPa \"%(pi)#\n",
"print \"\\nQ is %0.3f lpm \"%(Q)#"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"pi is 3.54 MPa \n",
"\n",
"Q is 12.441 lpm \n"
]
}
],
"prompt_number": 7
}
],
"metadata": {}
}
]
}