{ "metadata": { "name": "", "signature": "sha256:4899a3f156bb3463e97f6b375e9947501acc46cec2332bed6d0ada61bec0b1d0" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Ch-10, Mechanical tests and factors affecting mechanical properties" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.1 : page no-298" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "#given\n", "#initial gauge length of the specimen\n", "l0=50*10**-3 #m\n", "#initia l gauge diameter of the specimen\n", "d0=12*10**-3 #m\n", "#extended gauge length of fracture\n", "lf=58*10**-3 #m\n", "#reduced gauge diameter\n", "df=7*10**-3 #m\n", "#initial an final cross sectional areas are\n", "A_i=3.14/4*d0**2 #m**2\n", "A_f=3.14/4*df**2 #m**2\n", "#various applied loads are in k N\n", "P1=0\n", "P2=5\n", "P3=10\n", "P4=15\n", "P5=20\n", "P6=25\n", "P7=30\n", "P8=32\n", "P9=33\n", "P10=32\n", "P11=31\n", "P12=35\n", "P13=40\n", "P16=130\n", "#corresponding to these load we have recorded elongation as\n", "delta1=0\n", "delta2=0.011\n", "delta3=0.022\n", "delta4=0.035\n", "delta5=0.048\n", "delta6=0.059\n", "delta7=0.073\n", "delta8=0.088\n", "delta9=0.100\n", "delta10=0.125\n", "delta11=0.150\n", "delta12=0.230\n", "delta13=0.400\n", "delta16=8.000\n", "#stress and strain corresponding to these loads and elongations are\n", "sigma1=P1/A_i\n", "strain1=delta1/l0\n", "sigma2=P2/A_i\n", "strain2=delta2/l0\n", "sigma3=P3/A_i\n", "strain3=delta3/l0\n", "sigma4=P4/A_i\n", "strain4=delta4/l0\n", "sigma5=P5/A_i\n", "strain5=delta5/l0\n", "sigma6=P6/A_i\n", "strain6=delta6/l0\n", "sigma7=P7/A_i\n", "strain7=delta7/l0\n", "sigma8=P8/A_i\n", "strain8=delta8/l0\n", "sigma9=P9/A_i\n", "strain9=delta9/l0\n", "sigma10=P10/A_i\n", "strain10=delta10/l0\n", "sigma11=P11/A_i\n", "strain11=delta11/l0\n", "sigma12=P12/A_i\n", "strain12=delta12/l0\n", "sigma13=P13/A_i\n", "strain13=delta13/l0\n", "sigma16=P16/A_i\n", "strain16=delta16/l0\n", "#part(a)\n", "#modulus of elasticity\n", "E=(sigma4-sigma1)/(strain4-strain1)/10**3 #G Pa\n", "#part(b)\n", "#ultimate stress (maximum)\n", "ultimate_sigma=P16/A_i*10**3/10**6 #M N/m**3\n", "#part (c)\n", "#upper yield point at C (shown in fig 10.3)\n", "u_yield=P9/A_i*1000/10**6 #M N/m**2\n", "#lower yield point at D (shown in fig 10.3)\n", "l_yield=P11/A_i*1000/10**6 #M N/m**2\n", "#part(d)\n", "#percentage reduction in area\n", "percent_A=(d0**2-df**2)/d0**2*100 #%\n", "#part (e)\n", "#percentage elongation\n", "percent_l=(lf-l0)/l0*100 #%\n", "#part(f)\n", "#apparent breaking stress\n", "app_breaking_stress=P16*1000/A_i/10**6 #M N/m**2\n", "#actual breaking stress\n", "actual_breaking_stress=P16*1000/A_f/10**6 #M N/m**2\n", "print \"\"\"the modulus of elasticity is %0.3f G Pa\n", "the ultimate (maximum) stress is %0.3f M n/m**2 \n", "upper yield point is %0.3f M N/m**2 \n", "lower yield point is %0.3f M n/m**2\n", "percentage reduction in area is %0.3f \n", "percentage elongation in length %0.3f\n", "apparent breaking stress is %0.3f M n/mm**2\n", "actual breaking point is %0.3f M n/m**2\"\"\"%(E,ultimate_sigma,u_yield,l_yield,percent_A,percent_l,app_breaking_stress,actual_breaking_stress)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "the modulus of elasticity is 189.566 G Pa\n", "the ultimate (maximum) stress is 1150.035 M n/m**2 \n", "upper yield point is 291.932 M N/m**2 \n", "lower yield point is 274.239 M n/m**2\n", "percentage reduction in area is 65.972 \n", "percentage elongation in length 16.000\n", "apparent breaking stress is 1150.035 M n/mm**2\n", "actual breaking point is 3379.696 M n/m**2\n" ] } ], "prompt_number": 12 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.2 : page no-303" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#given\n", "#initial length of the specimen\n", "h0=24.02*10**-3 #m\n", "#initial gauge diameter of the specimen\n", "d0=18.74*10**-3 #m\n", "#final length of specimen\n", "hf=18.70*10**-3 #m\n", "#final diameter\n", "df=21.54*10**-3 #m\n", "#initial an final cross sectional areas are\n", "A_i=3.14/4*d0**2 #m**2\n", "A_f=3.14/4*df**2 #m**2\n", "#various applied loads are in k N\n", "P1=0\n", "P2=5\n", "P3=10\n", "P4=15\n", "P5=20\n", "P6=25\n", "P7=30\n", "P8=35\n", "P9=40\n", "P10=45\n", "P11=50\n", "P12=55\n", "P13=60\n", "P14=65\n", "P15=70\n", "P16=75\n", "P17=80\n", "P18=85\n", "P19=131\n", "#corresponding to these load we have recorded contraction as\n", "delta1=0\n", "delta2=0.004\n", "delta3=0.008\n", "delta4=0.012\n", "delta5=0.015\n", "delta6=0.017\n", "delta7=0.020\n", "delta8=0.023\n", "delta9=0.025\n", "delta10=0.028\n", "delta11=0.032\n", "delta12=0.036\n", "delta13=0.040\n", "delta14=0.044\n", "delta15=0.049\n", "delta16=0.054\n", "delta17=0.061\n", "delta18=0.069\n", "#stress and strain corresponding to these loads and elongations are\n", "sigma1=P1/A_i\n", "strain1=delta1/h0\n", "sigma2=P2/A_i\n", "strain2=delta2/h0\n", "sigma3=P3/A_i\n", "strain3=delta3/h0\n", "sigma4=P4/A_i\n", "strain4=delta4/h0\n", "sigma5=P5/A_i\n", "strain5=delta5/h0\n", "sigma6=P6/A_i\n", "strain6=delta6/h0\n", "sigma7=P7/A_i\n", "strain7=delta7/h0\n", "sigma8=P8/A_i\n", "strain8=delta8/h0\n", "sigma9=P9/A_i\n", "strain9=delta9/h0\n", "sigma10=P10/A_i\n", "strain10=delta10/h0\n", "sigma11=P11/A_i\n", "strain11=delta11/h0\n", "sigma12=P12/A_i\n", "strain12=delta12/h0\n", "sigma13=P13/A_i\n", "strain13=delta13/h0\n", "sigma14=P14/A_i\n", "strain14=delta14/h0\n", "sigma15=P15/A_i\n", "strain15=delta15/h0\n", "sigma16=P16/A_i\n", "strain16=delta16/h0\n", "sigma17=P17/A_i\n", "strain17=delta17/h0\n", "sigma18=P18/A_i\n", "strain18=delta18/h0\n", "#part(a)\n", "#modulus of elasticity\n", "E=(sigma13-sigma1)/(strain13-strain1)/10**3 #G Pa\n", "#part(b)\n", "# yield stress at D (shown in fig 10.6)\n", "Yield=P15/A_i*1000/10**6 #M N/m**2\n", "#part (c)\n", "#ultimate stress (maximum)\n", "ultimate_sigma=P19/A_i*10**3/10**6 #M N/m**3\n", "#part (d)\n", "#percentage contraction\n", "percent_l=(h0-hf)/h0*100 #%\n", "#part(e)\n", "#percentage increase in area\n", "percent_A=(df**2-d0**2)/d0**2*100 #%\n", "#part(f)\n", "#apparent breaking stress\n", "app_breaking_stress=P19*1000/A_i/10**6 #M N/m**2\n", "#actual breaking stress\n", "actual_breaking_stress=P19*1000/A_f/10**6 #M N/m**2\n", "print \"\"\"The modulus of elasticity is %0.3f G Pa \n", "Yield stress is %0.3f M n/m**2\n", "The ultimate (maximum) stress is %0.3f M n/m**2 \n", "Percentage contraction in length %0.3f\n", "Percentage increase in area is %0.3f \n", "Apparent breaking stress is %0.3f M n/mm**2\n", "Actual breaking point is %0.3f M n/m**2\"\"\"%(E,Yield,ultimate_sigma,percent_l,percent_A,app_breaking_stress,actual_breaking_stress)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The modulus of elasticity is 130.694 G Pa \n", "Yield stress is 253.915 M n/m**2\n", "The ultimate (maximum) stress is 475.185 M n/m**2 \n", "Percentage contraction in length 22.148\n", "Percentage increase in area is 32.115 \n", "Apparent breaking stress is 475.185 M n/mm**2\n", "Actual breaking point is 359.675 M n/m**2\n" ] } ], "prompt_number": 13 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.3 page no-307" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#given\n", "#length of glass piece\n", "l=1.1*10**3 #mm\n", "#width of glass piece\n", "b=225 #mm\n", "#height or thicness of plate\n", "h=10 #mm\n", "#load\n", "P=250 #N\n", "#for a simply supported beam subjected to concentrated load in the middle of its span,\n", "M=P*l/4 #N mm\n", "#and force\n", "F=P/2 #N\n", "#part(a)\n", "#flexure strength\n", "sigma=6*M/b/h**2 #N/mm**2\n", "#part (b)\n", "#shear strength\n", "tau=3*F/2/b/h #N/mm**2\n", "#part (c)\n", "P1=350 #N\n", "M1=P1*l/4\n", "#ineria\n", "I=b*h**3/12 #mm**4\n", "y=h/2 #mm\n", "#the modulus of rupture is given by\n", "sigmar=M1*y/I\n", "print \"The flexture strength, shear strength and modulus of rupture are :\\n%0.3f N/mm**2, %0.3f N/mm**2 and %0.3f N/mm**2 resp\"%(sigma, tau, sigmar)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The flexture strength, shear strength and modulus of rupture are :\n", "18.333 N/mm**2, 0.083 N/mm**2 and 25.667 N/mm**2 resp\n" ] } ], "prompt_number": 16 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.4 page no-313" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import pi, sqrt\n", "#given\n", "#diameter of ball\n", "D=0.5*10 #mm\n", "#indentation diameter\n", "d=32.5/10 #mm (diveided by 10 because it is 10 times magnified)\n", "#from table- 10.3 of book , the load for steel specimen is\n", "P=30*D**2 #kg f\n", "#hardness\n", "BHN=P/((pi)*D/2*(D-sqrt(D**2-d**2))) \n", "print \"The hardness is %0.3f\" %(BHN)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The hardness is 79.556\n" ] } ], "prompt_number": 17 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.5 page no-321" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sin, cos, acos\n", "#given\n", "#dimension of steel specimen\n", "l=75 #mm\n", "b=10 #mm\n", "t=10 #mm\n", "#depth of V-notch is t/5\n", "#in the absence of specimen, frictional and windage loss\n", "L1=0.1 #kg f.m\n", "#in the presence ofspecimen, which is placed on support breaks\n", "L2=5.9 #kg f m\n", "#rupture energy\n", "U=L2-L1 #kg f m\n", "#since the depth of V-notch is t/5\n", "#so t/5=2\n", "te=t-2 #mm\n", "#volume of specimen\n", "Ve=l*b*te*10**-9 #m**3\n", "#modulus of rupture\n", "Ur=U/Ve #kg f/m**2\n", "#effective area of cross section\n", "Ae=b*te*10**-6 #m**2\n", "#notch impact strength\n", "Is=U/Ae #kg/m\n", "#given that \n", "Ui=30 #kg f.m\n", "alpha=160*(pi)/180 #radians\n", "#swing diameter\n", "D=1600 #mm\n", "R=D/2*10**-3 #m\n", "#weight of hammer\n", "#as we know that\n", "#Ut=W*R(1-cos(aplha))\n", "#so\n", "W=Ui/R/(1-cos(alpha)) #kg f.m\n", "#capacity of izod impact testing machine\n", "L3=30 #kg f.m\n", "#so Uf will be\n", "Uf=L3-L2 #kbg f.m\n", "#we know that energy after rupture\n", "#Uf=W*R(1-cos(beta))\n", "bet=acos(1-Uf/W/R) #radins\n", "#beta in degrees\n", "Beta=bet*180/(pi) #degrees\n", "#also we know that Uf=W*hf\n", "#so hf will be\n", "hf=Uf/W #m\n", "print \"\"\"rupture energy is %0.3f kg f.m \n", "modulus of rupture %0.3f kg f/m**2 \n", "notch impact strength %0.3f kg/m \n", "angle of hammer after striking %0.3f degrees\n", "height risen by hammer after breaking %0.3f m\"\"\"%(U,Ur,Is,Beta,hf)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "rupture energy is 5.800 kg f.m \n", "modulus of rupture 966666.667 kg f/m**2 \n", "notch impact strength 72500.000 kg/m \n", "angle of hammer after striking 123.933 degrees\n", "height risen by hammer after breaking 1.247 m\n" ] } ], "prompt_number": 18 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.6 page no-323" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#given\n", "#diameter of circular section of bean\n", "d=60 #mm\n", "#length of circular section of beam\n", "l=500 #mm\n", "#maximum and minimum load \n", "Pmin= 20 #kN\n", "Pmax= 50 #kN\n", "#ultimate strength\n", "sigmau=650 #MPa\n", "#yoeld strength\n", "sigmay=520 #MPa\n", "#factor of safety\n", "fos=1.8\n", "#maximum bending moment\n", "Mmax=Pmax*l/4 #kN mm\n", "#minimum bending moment\n", "Mmin=Pmin*l/4 #kN mm\n", "#mean bending moment\n", "Mm=(Mmax+Mmin)/2 #kN mm\n", "#alerting (variable) bending moment\n", "Ma=(Mmax-Mmin)/2 #kN mm\n", "#section modulus of beam\n", "Z=(pi)*d**3/32 #mm**3\n", "#mean bending stress\n", "sigmam=Mm/Z*1000 #MPa\n", "#variable bending stress\n", "sigmaa=Ma/Z*1000 #MPa\n", "#endurance stress from\n", "#(i) gerber's parabolic relation\n", "sigmae1=sigmaa/(1/fos-(sigmam/sigmau)**2*fos) #MPa\n", "#(ii) goodman's straight line relation\n", "sigmae2=sigmaa/(1/fos-sigmam/sigmau) #MPa\n", "#(iii) soderberg's straight line realtion\n", "sigmae3=sigmaa/(1/fos-sigmam/sigmay) #MPa\n", "print \"\"\"Endurance strength of the material are :\n", "Gerbers parabolic fomula %0.3f MPa\n", "goodmans straight line formula %0.3f MPa\n", "sodergerbs straight line relation %0.3f MPa \"\"\"%(sigmae1,sigmae2,sigmae3)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Endurance strength of the material are :\n", "Gerbers parabolic fomula 236.280 MPa\n", "goodmans straight line formula 371.272 MPa\n", "sodergerbs straight line relation 556.791 MPa \n" ] } ], "prompt_number": 19 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.7 page no-329" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#given\n", "#yeild strength of polycrystalline material increases from sigmay1 to sigmay2\n", "sigmay1=118 #MPa\n", "sigmay2=207 #MPa\n", "#decreasing grain diameter from d1 to d2\n", "d1=0.253*10**-3 #m\n", "d2=0.0224*10**-3 #m\n", "#to find the yield strngth at \n", "d=0.095*10**-3 #m\n", "#as we know that according to hall and petch equation,\n", "#sigmay=sigma0+C/sqrt(d)\n", "#putting sigmay1,sigmay2,d1 and d2.. we get 2 equations\n", "#sigma0+C/sqrt(d1)=sigmay1 -------(1)\n", "#and sigma0+C/sqrt(d2)=sigmay2 -----(2)\n", "#solving equation 1 and 2 we get\n", "sigma0=80.3 #MPa\n", "#and\n", "C=0.1896 #MN/m**(3/2)\n", "#so the yield stress for the grain size\n", "d=0.095*10**-3 #m\n", "sigma=sigma0+C/sqrt(d) #MPa\n", "print \"The yield stress for a grainof size of 0.095 mm is %0.3f MPa\"%(sigma)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The yield stress for a grainof size of 0.095 mm is 99.753 MPa\n" ] } ], "prompt_number": 20 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.8 page no-330" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#given\n", "#ASTM number\n", "n=12\n", "#as we know that\n", "N=2**(n-1) \n", "#1 square inch=645 mm**2\n", "#so grain diameter for ASTM number 12 will be\n", "d=1/sqrt((N/645)*10**4) #mm\n", "print \"The grain diameter of ASTM number 12 is %0.4f mm\"%(d)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The grain diameter of ASTM number 12 is 0.0056 mm\n" ] } ], "prompt_number": 22 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.9 page no-330" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#given\n", "#ASTM number of grain\n", "n=5\n", "#as we know that\n", "N=2**(n-1) #grains/inche**2 at magnification 100*\n", "# as lineal and areal magnifications are related as *100=10,000 areal\n", "N1=N/0.01/0.01 #grains/inch**2 at 1*\n", "#average area of one grain\n", "A=2.54*2.54/N1 #cm**2\n", "#now N1 grains/ inch**2 of surface is = sqrt(160,000)=400 grain/inch of length and this is equal to =(400)**3=6.4*10**7 grains/m**3 of volume\n", "#surface area of eaxh cubic surface\n", "S=(1/400)**2 #inch**2\n", "#there are 6 surfaces in a cubic grain\n", "#so total surface area of each grain\n", "TS=6*S #inch**2\n", "#each boundary is composed of two grain surfaces, therefore , total boundary in the volume is\n", "TotS=1/2*TS*(400)**3 #inch**2 boundary per cubic of steel\n", "#total suface area in cm**2\n", "TotalS=TotS/(2.54) #cm**2 boundary per cubic cm of steel\n", "print \"total boundary in the volume is %0.3f cm**2 per cm**3 of steel\"%(TotalS)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "total boundary in the volume is 472.441 cm**2 per cm**3 of steel\n" ] } ], "prompt_number": 23 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "example-10.16 page no-332" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "#given\n", "#ASTM number\n", "n=4\n", "#as we know that\n", "N=2**(n-1) #per inch**2 at a magnification of 100\n", "#let r be the radius of grain\n", "#so\n", "#N*A=1/100 inch**2 where A=(pi)*r**2\n", "#so\n", "r=sqrt(1/100/N/(pi)) #inch\n", "#radius of grain in mm\n", "R=r*25.4 #mm\n", "print \"the radius of grain is %0.3f mm\"%(R)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "the radius of grain is 0.507 mm\n" ] } ], "prompt_number": 24 } ], "metadata": {} } ] }