{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 9: COMBINED STRESSES" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.10: Chapter9_Example_10.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "b=2 //cm\n", "h=2 //cm\n", "T=2000 //kg-cm\n", "V=250 //kg\n", "M=2000 //kg-cm\n", "// calculations\n", "Mmax=M*6/(b*h*b)\n", "Vmax=3*V/(2*b*h)\n", "Zt=0.208*b^2*h\n", "Tmax=T/(Zt)\n", "\n", "sigma=Mmax\n", "printf('points A,B,')\n", "printf('\n sigma=%d kg/cm^2 (tension)',sigma)\n", "printf('\n points C,D,')\n", "printf('\n sigma=%d kg/cm^2 (cmpression)',sigma)\n", "tau=Vmax+Tmax\n", "printf('\n point E')\n", "printf('\n tau=%.2f kg/cm^2 shear',tau)\n", "tau=Vmax-Tmax\n", "printf('\n tau=%.2f kg/cm^2 shear',tau)\n", "// at G\n", "sigma_x=sigma\n", "sigma_y=0\n", "tau_xy=Tmax\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "// results\n", "printf('\n at point G')\n", "printf('\n sigma_1 = %d kg/cm^2 (tension)',sigma_1)\n", "printf('\n sigma_2 = %d kg/cm^2 (compression)',sigma_2)\n", "\n", "// Question was asked only to find out at A,B,C,D,E,F and G" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.11: Chapter9_Example_11.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "w=10 //cm\n", "s=2.8 //m\n", "P=1 //tonne\n", "Ft=1.4 //cm\n", "Wt=0.8 //cm\n", "Ix=13989.5 //cm^4\n", "Z=699.5 //cm^3\n", "// calculations\n", "BM= 2.8 \n", "T=P*1000*8.21\n", "SF=P*1000\n", "BS=BM*10^5/(Z)\n", "sigmaXA=BS*18.6/20\n", "K=w*Ft*19.3+18.6*Wt*9.3\n", "tau_xy_C=SF/(Ix*Wt)*K\n", "tau_xy_A=tau_xy_C*(w*Ft*19.3)/K \n", "tau_xy_B=tau_xy_A*0.5*Wt/w\n", "sigmaXB=sigmaXA*19.3/20\n", "\n", "tau_max=3*Ft*8210/(w*Ft^3+37.2*Wt^3)\n", "tau_A=3*Wt*8210/(w*Ft^3+37.2*Wt^3)\n", "\n", "//For point A\n", "Shear=tau_xy_A-tau_A\n", "sigma_x=sigmaXA\n", "sigma_y=0\n", "tau_xy=Shear\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "\n", "printf('For point A')\n", "printf('\n Total shear= %.1f kg/cm^2 ',Shear)\n", "printf('\n Bending stress = %d kg/cm^2 (Compr.)',sigma_x)\n", "printf('\n Principal stresses are %d (tension), %d (comp.) kg/cm^2 ',sigma_1,sigma_2)\n", "\n", "//For point B\n", "printf('\n FOr point B')\n", "printf('\n Bending shear stress is %.2f k/cm^2',tau_xy_B)\n", "sigmaXB=BS*19.3/20\n", "sigma_x=sigmaXB\n", "sigma_y=0\n", "tau_xy=tau_max\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "printf('\n Principal stresses are %d (tension), %d (comp.) kg/cm^2 ',sigma_1,sigma_2)\n", "\n", "// Answers in the text are approximations" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.12: Chapter9_Example_12.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "b=10 //cm\n", "h=10 //cm\n", "P=5 //tonne\n", "e=1 //cm\n", "E=12*10^4 //kg/cm^2\n", "str=130 // kg/cm^2\n", "n=3\n", "L=2 //m\n", "// calculations\n", "L=L*100 //cm\n", "Pcr=%pi^2*E*b*h^3/(12*L^2)\n", "Pcr=Pcr/1000\n", "Smax=-P*1000/(b*h)-(P*1000*1*5*12/10^4)*1/(1-(n*P/Pcr))\n", "// results\n", "printf('permissible stress = %d kg/cm^2',str)\n", "printf('\n develoed stress = %.1f kg/cm^2',Smax)\n", "printf('\n Since it is below the permissible stress, the design is safe')\n", "" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.13: Chapter9_Example_13.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initializatio of variables\n", "clear\n", "// linked to 9.13\n", "b=10 //cm\n", "h=10 //cm\n", "P=5 //tonne\n", "e=1 //cm\n", "E=12*10^4 //kg/cm^2\n", "str=130 // kg/cm^2\n", "n=3\n", "L=2 //m\n", "// calculations\n", "L=L*100 //cm\n", "Pcr=%pi^2*E*b*h^3/(12*L^2)\n", "Pcr=Pcr/1000\n", "Smax=-P*1000/(b*h)-(P*1000*1*5*12/10^4)*1/(1-(n*P/Pcr))\n", "Smax=abs(Smax)\n", "\n", "rr=b*h^3/(12*100)\n", "Smax_se=P*1000/(b*h)*(1+e*5/rr*sec(%pi/2*sqrt(n*P/Pcr)))\n", "Perror=(Smax-Smax_se)/Smax\n", "Perror=Perror*100\n", "Perror=abs(Perror)\n", "// results\n", "printf('Using secent formula, stress obtained is %d kg/cm^2',Smax_se)\n", "printf('\n hence, the percentage error %.2f',Perror)\n", "// approximate answees in the text" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.14: Chapter9_Example_14.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "P=400 //kg/m\n", "L=10 //m\n", "F=10 //tonne\n", "n=3\n", "Ixx=5943.1 //cm^4\n", "A=52.03 //cm^2\n", "rx=10.69 //cm\n", "E=2*10^6 //kg/cm^2\n", "// calculations\n", "Pcr=%pi^2*E*Ixx/((L*100)^2)\n", "Pcr=Pcr/1000\n", "e=P*L^2/(8*F*1000)\n", "g=e*12.5*100/rx^2\n", "Smax=F*1000/A*(1+g*1/(1-n*(F/Pcr)))\n", "// results\n", "printf('The maximum stress developed is %d kg/cm^2',Smax)\n", "\n", "// approximate calculations involved in the text book" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.15: Chapter9_Example_15.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "// linked to 9_14\n", "// calculations\n", "P=400 //kg/m\n", "L=10 //m\n", "F=10 //tonne\n", "n=3\n", "Ixx=5943.1 //cm^4\n", "A=52.03 //cm^2\n", "rx=10.69 //cm\n", "E=2*10^6 //kg/cm^2\n", "Pcr=%pi^2*E*Ixx/((L*100)^2)\n", "Pcr=Pcr/1000\n", "e=P*L^2/(8*F*1000)\n", "g=e*12.5*100/rx^2\n", "Smax=F*1000/A*(1+g*1/(1+n*(F/Pcr)))\n", "// results\n", "printf('The maximum stress developed is %d kg/cm^2',Smax)\n", "\n", "// approximate answer in the text" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.1: Chapter9_Example_1.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "//case (a)\n", "A=72.9 //cm^2\n", "Iy=633 //cm^4\n", "Ix=1199 //cm^4\n", "t=24/(5*Ix)+13.5/(5*Iy)\n", "r=1/(A*t)\n", "printf('case (a) \n r = %.3f cm',r)\n", "// case (b)\n", "t=24/(5*Ix)-13.5/(5*Iy)\n", "r=1/(A*t)\n", "printf('\n case (b) \n r = %.1f cm',r)\n", "//case (c)\n", "t=-24/(5*Ix)+13.5/(5*Iy)\n", "r=1/(A*t)\n", "printf('\n case (a) \n r = %.1f cm',r)\n", "printf('\n So the load is to be placed on the leg OD, at a distance of %.1f cm from O',r )\n", "" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.3: Chapter9_Example_3.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "b=14 //cm\n", "d=20 //cm\n", "rx=8.46 //cm\n", "ry=2.99 //cm\n", "// calculations\n", "ex=2*rx^2/d\n", "ey=2*ry^2/b\n", "h=2*ex\n", "w=2*ey\n", "// results\n", "printf('for steel height=%.3f cm and width=%.3f cm',h,w)\n", "// ISHB 225\n", "b=22.5 //cm\n", "d=22.5 //cm\n", "rx=9.8 //cm\n", "ry=4.96 //cm\n", "// calculations\n", "ex=2*rx^2/d\n", "ey=2*ry^2/b\n", "h=2*ex\n", "w=2*ey\n", "// results\n", "printf('\n for an ISHB height=%.3f cm and width=%.3f cm',h,w)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.4: Chapter9_Example_4.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "t=280 //kg/cm^2\n", "c=840 //kg/cm^2\n", "xbar=7.5 //cm from AB\n", "A=210 //cm^2\n", "// calculations\n", "e=50+xbar //cm\n", "Iyy=7433 //cm^2\n", "k=(1/210+e*xbar/Iyy)\n", "P=t/k\n", "k1=(-1/210+e*(xbar+5)/Iyy)\n", "P1=c/k1\n", "P_safe=min(P1,P)\n", "// results\n", "printf('The safe load is %d kg',P_safe)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.5: Chapter9_Example_5.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of the variables\n", "clear\n", "s=1.6 //m\n", "s1=4 //m\n", "pi=28 //degrees\n", "w=16 //kg/m^2\n", "p=100 //kg/m^2\n", "pl=20 //cm\n", "pb=10 //cm\n", "r=500 //kg/m^3\n", "// calculations\n", "pi=pi*%pi/180 //radians\n", "W=w*s+(r*pl*pb/(100*100))\n", "P=p*s\n", "L=P+W*cos(pi)\n", "Mx=L*s1^2*100/8\n", "sigma_1=Mx*6/(pb*pl^2)\n", "My=W*sin(pi)*s1^2*100/8\n", "sigma_2=My*6/(pl*pb^2)\n", "sigma=sigma_1+sigma_2\n", "// results\n", "printf('Due to bending in the noth the planes, D experiences maximum \n compression of %.2f kg/cm^2 and B has maximum tension of %.2f kg/cm^2',sigma,sigma)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.6: Chapter9_Example_6.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of the problems\n", "clear\n", "s=1.6 //m\n", "s1=4 //m\n", "pi=28 //degrees\n", "w=16 //kg/m^2\n", "p=100 //kg/m^2\n", "pl=20 //cm\n", "pb=10 //cm\n", "r=500 //kg/m^3\n", "Zx=54.8 //cm^3\n", "Zy=3.9 //cm^3\n", "// calculations\n", "pi=pi*%pi/180 //radians\n", "W=w*s+8.1\n", "P=p*s\n", "L=P+W*cos(pi)\n", "Mx=L*s1^2*100/8\n", "sigma_1=Mx/Zx\n", "My=W*sin(pi)*s1^2*100/8\n", "sigma_2=My/Zy\n", "sigma=sigma_1+sigma_2\n", "// results\n", "printf('Maximum stresses are %d kg/cm^2, tension or compression',sigma)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.7: Chapter9_Example_7.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "s=1.6 //m\n", "s1=4 //m\n", "pi=28 //degrees\n", "w=16 //kg/m^2\n", "p=100 //kg/m^2\n", "pl=20 //cm\n", "pb=10 //cm\n", "r=500 //kg/m^3\n", "sg=5 //cm\n", "E=12*10^4\n", "pi=pi*%pi/180 //radians\n", "// calculations\n", "W=w*s+(r*pl*pb/(100*100))\n", "P=p*s\n", "L=P+W*cos(pi)\n", "Mx=L*s1^2*100/8\n", "sigma_1=Mx*6/(pb*pl^2)\n", "My=W*sin(pi)*s1^2*100/8\n", "sigma_2=My*6/(pl*pb^2)\n", "st=sigma_1*sg/10\n", "Ts=st-sigma_2\n", "ez=Ts/E\n", "// results\n", "printf('The strain gauge, aligned to the z axis will give compression strain of %.1e',ez)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.8: Chapter9_Example_8.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "P=3 //tonne/m\n", "s=6 //m\n", "l=50 //cm\n", "b=20 //cm\n", "k=0.5 //m\n", "//calculations\n", "R=P*s/2\n", "sf=R-k*P\n", "bm=R*k-P*k^2/2\n", "tau_xy=1.5*sf*1000/(l*b)\n", "tau_max=tau_xy\n", "str=bm*s*10^5/(b*l*l)\n", "\n", "// consider the line a-a\n", "\n", "sigma_x=str*12.5/25\n", "sigma_y=0\n", "tau_xy=tau_xy*(1-(12.5/25)^2)\n", "\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "\n", "printf('For the line a-a the bending stress and shearing stress are \n respectively %.2f kg/cm^2, %.2f kg/cm^2 ',sigma_x,tau_xy)\n", "printf('\n The principal stresses are %.2f kg/cm^2 (tension) %.2f kg/cm^2 (compression) ',sigma_1,sigma_2)\n", "\n", "//consider the line c-c\n", "printf('\n For the line c-c the bending stress and shearing stress are \n respectively %.2f kg/cm^2, %.2f kg/cm^2 ',sigma_x,tau_xy)\n", "printf('\n The principal stresses are %.2f kg/cm^2 (compression) %.2f kg/cm^2 (tension) ',sigma_2,sigma_1)\n", "\n", "//for the line b-b\n", "tau_xy=tau_max\n", "sigma_x=0\n", "sigma_y=0\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "// results\n", "printf('\n For the line b-b the bending stress and shearing stress are \n respectively %.2f kg/cm^2, %.2f kg/cm^2 ',sigma_x,tau_xy)\n", "printf('\n The principal stresses are %.2f kg/cm^2 (tension) %.2f kg/cm^2 (compression) ',sigma_1,sigma_2)" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 9.9: Chapter9_Example_9.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc\n", "//initialization of variables\n", "clear\n", "P=3 //tonne/m\n", "s=6 //m\n", "l=50 //cm\n", "b=20 //cm\n", "k=0.5 //m\n", "//calculations\n", "R=P*s/2\n", "sf=R-k*P\n", "bm=R*k-P*k^2/2\n", "tau_xy=1.5*sf*1000/(l*b) //max shear stress\n", "tau_max=tau_xy \n", "str=bm*s*10^5/(b*l*l) //max bending stress\n", "\n", "// consider the line a-a\n", "\n", "sigma_x=str*12.5/25\n", "sigma_y=0\n", "tau_xy=tau_xy*(1-(12.5/25)^2)\n", "\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "\n", "theta=1/2*atan(2*tau_xy/(sigma_x-sigma_y))\n", "sigma_p=sigma_1/cos(theta)\n", "P=sigma_p*2*l*b/(3*1000)\n", "printf('A prestressing force of %.2f Tonne must be applied to balance the tension at a-a',P)\n", "\n", "//At bottom point D or C\n", "pre_str=P*2*1000/(l*b)\n", "net=str-pre_str\n", "printf('\n At bottom point D or C')\n", "printf('\n Net tension = %.2f kg/cm^2 ',net)\n", "\n", "//consider the line b-b\n", "pre_str=P\n", "sigma_x=pre_str\n", "sigma_y=0\n", "tau_xy=tau_max\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "printf('\n At section b-b')\n", "printf('\n pre-stress=%.2f kg/cm^2',pre_str)\n", "printf('\n principal stresses are %.2f, %.2f kg/cm^2 ',sigma_1,sigma_2)\n", "\n", "//for the line c-c\n", "sigma_x=str*12.5/25\n", "sigma_y=0\n", "tau_xy=tau_xy*(1-(12.5/25)^2)\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "pre_str=pre_str/2\n", "net=sigma_1+pre_str\n", "sigma_x=net\n", "sigma_y=0\n", "sigma_1=(sigma_x+sigma_y)/2+sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "sigma_2=(sigma_x+sigma_y)/2-sqrt((1/2*(sigma_x-sigma_y))^2+tau_xy^2)\n", "// results\n", "printf('\n At section c-c')\n", "printf('\n the direct stress is %.2f kg/cm^2',net)\n", "printf('\n pre-stress = %.2f kg/cm^2',pre_str)\n", "printf('\n principal stresses are %.2f, %.2f kg/cm^2 ',sigma_1,sigma_2)\n", "\n", "// wrong calculations in the thext for some parts\n", "" ] } ], "metadata": { "kernelspec": { "display_name": "Scilab", "language": "scilab", "name": "scilab" }, "language_info": { "file_extension": ".sce", "help_links": [ { "text": "MetaKernel Magics", "url": "https://github.com/calysto/metakernel/blob/master/metakernel/magics/README.md" } ], "mimetype": "text/x-octave", "name": "scilab", "version": "0.7.1" } }, "nbformat": 4, "nbformat_minor": 0 }