initial commit / add all books

18 files changed, 539 insertions, 0 deletions

diff --git a/3774/CH4/EX4.1/Ex4_1.sce b/3774/CH4/EX4.1/Ex4_1.sce
new file mode 100644
index 000000000..e68f24ff1
--- /dev/null
+++ b/3774/CH4/EX4.1/Ex4_1.sce
@@ -0,0 +1,34 @@
+// exa 4.1 Pg 102
+clc;clear;close;
+P=6;// kN
+
+//dimensions of plate
+r=5;//mm
+d=40;//mm
+D=50;//mm
+d0=10;//mm
+w=40;//mm
+Sut=200;//MPa
+n=2.5;// factor of safety
+
+//Fillet - 
+rBYd=r/d;
+DBYd=D/d;
+Kt=1.75;// factor
+printf('for stepped plate under tension, Kt=%.2f for r/d = %.3f & D/d = %.2f ',Kt,rBYd,DBYd)
+t=poly(0,'t')
+sigma_max = Kt*P/t;// N per mm sq.
+
+// Hole -
+d0BYw=d0/w;
+Kt=2.42;// factor 
+printf('\n for finite width plate under tension with a hole, Kt=%.2f for d0/w = %.2f',Kt,d0BYw)
+sigma_max_into_t = Kt*P/(w-d0);//N/mm sq.
+
+//Design stress
+sigma_d = Sut/n;// MPa
+//putting sigma_max=sigma_d
+t=sigma_max_into_t/sigma_d*1000;// mm
+printf('\n Thickness of plate = %.2f mm or %.f mm',t,t)
+
+
diff --git a/3774/CH4/EX4.10/Ex4_10.sce b/3774/CH4/EX4.10/Ex4_10.sce
new file mode 100644
index 000000000..d5f0fb62d
--- /dev/null
+++ b/3774/CH4/EX4.10/Ex4_10.sce
@@ -0,0 +1,26 @@
+// exa 4.10 Pg 116
+clc;clear;close;
+
+// Given Data
+Sut=600;//MPa
+Se=280;//MPa
+sigma_x_min=50;// MPa
+sigma_x_max=100;// MPa
+sigma_y_min=20;// MPa
+sigma_y_max=70;// MPa
+
+sigma_xm=(sigma_x_max+sigma_x_min)/2;// MPa
+sigma_xa=(sigma_x_max-sigma_x_min)/2;// MPa
+sigma_ym=(sigma_y_max+sigma_y_min)/2;// MPa
+sigma_ya=(sigma_y_max-sigma_y_min)/2;// MPa
+
+// distortion energy theory - 
+sigma_m=sqrt(sigma_xm**2+sigma_ym**2-sigma_xm*sigma_ym);// MPa
+sigma_a=sqrt(sigma_xa**2+sigma_ya**2-sigma_xa*sigma_ya);// MPa
+theta=atand(sigma_a/sigma_m);// degree
+// Sm/Sut+Sa/Se=1 where Sa=Sm*tan(theta)
+Sm=1/(1/Sut+tand(theta)/Se);// MPa
+Sa=tand(theta)*Sm;// MPa
+n=Sa/sigma_a;// factor of safety
+
+printf('\n factor of safety, n = %.2f',n)
diff --git a/3774/CH4/EX4.11/Ex4_11.sce b/3774/CH4/EX4.11/Ex4_11.sce
new file mode 100644
index 000000000..7319081d3
--- /dev/null
+++ b/3774/CH4/EX4.11/Ex4_11.sce
@@ -0,0 +1,38 @@
+// exa 4.11 Pg 117
+clc;clear;close;
+
+// Given Data
+Sut=600;//MPa
+Syt=400;//MPa
+Se=200;//MPa
+Mmin=200;// N.m
+Mmax=500;// N.m
+Tmin=60;// N.m
+Tmax=180;// N.m
+n=2;// factor of safety
+
+Mm=(Mmax+Mmin)/2;// N.mm
+Ma=(Mmax-Mmin)/2;// N.mm
+Tm=(Tmax+Tmin)/2;// N.mm
+Ta=(Tmax-Tmin)/2;// N.mm
+// sigma_xm=32*Mm/%pi/d**3
+sigma_xm_into_d_cube=(32*Mm*1000)/%pi;
+// sigma_xa=32*Ma/%pi/d**3
+sigma_xa_into_d_cube=(32*Ma*1000)/%pi;
+//Txym=16*Tm/%pi/d**3
+Txym_into_d_cube=16*Tm*1000/%pi;
+//Txya=16*Ta/%pi/d**3
+Txya_into_d_cube=16*Ta*1000/%pi;
+// sigma_m=sqrt(sigma_xm**2+3*Txym**2)
+sigma_m_dash=sqrt(sigma_xm_into_d_cube**2+3*Txym_into_d_cube**2);// taken sigma_m_dash = sigma_m*d**(-3) for calculation
+// sigma_a=sqrt(sigma_xa**2+3*Txya**2)
+sigma_a_dash=sqrt(sigma_xa_into_d_cube**2+3*Txya_into_d_cube**2);// taken sigma_a_dash = sigma_a*d**(-3) for calculation
+//tan(theta) = sigma_a/sigma_m
+theta = atan(sigma_a_dash/sigma_m_dash);// radian
+//Sm/Sut+Sa/Se= 1 where Sa/Sm=0.4348 
+Sm= 1/(1/Sut+0.4348/Se);// MPa
+Sa=0.4348 * Sm;// MPa
+//sigma_a=Sa/n
+d=(Sa/n/sigma_a_dash)**(1/3)*1000;// mm
+printf('\n diameter of shaft, d = %.2f mm',d)
+// Note - Ans in the textbook is wrong.
diff --git a/3774/CH4/EX4.12/Ex4_12.sce b/3774/CH4/EX4.12/Ex4_12.sce
new file mode 100644
index 000000000..9075270f0
--- /dev/null
+++ b/3774/CH4/EX4.12/Ex4_12.sce
@@ -0,0 +1,28 @@
+// exa 4.12 Pg 119
+clc;clear;close;
+
+// Given Data
+Sut=620;//MPa
+Syt=380;//MPa
+R=90/100;// Reliability
+n=2.5;// factor of safety
+Tmin=-200;// N.m
+Tmax=400;// N.m
+
+Se_dash=0.5*Sut;//MPa
+// for ground shaft
+ka=0.92;// surface finish factor
+kb=0.85;// size factor (assuming t<50 mm)
+kc=0.897;// reliability factor
+kd=1;// temperature factor
+ke=0.577;// load factor
+Ses=ka*kb*kc*kd*ke*Se_dash;// MPa( Endurance limit)
+Sys=ke*Syt;// MPa
+Tm=(Tmax+Tmin)/2;// N.mm
+Ta=(Tmax-Tmin)/2;// N.mm
+theta=atan(Ta/Tm);//radian
+Sas=Ses;// MPa
+Sms=Sas/3;// MPa
+//Tda=Sas/n=16*Ta/%pi/d**3
+d=(16*Ta*1000/%pi/(Sas/n))**(1/3);// mm
+printf('\n diameter of shaft, d = %.2f mm or %d mm',d, ceil(d))
diff --git a/3774/CH4/EX4.14/Ex4_14.sce b/3774/CH4/EX4.14/Ex4_14.sce
new file mode 100644
index 000000000..0b811333b
--- /dev/null
+++ b/3774/CH4/EX4.14/Ex4_14.sce
@@ -0,0 +1,14 @@
+// exa 4.14 Pg 121
+clc;clear;close;
+
+// Given Data
+sigma_max=300;// MPa
+sigma_min=-150;// MPa
+n=1.5;// factor of safety
+
+
+sigma_m=(sigma_max+sigma_min)/2;// MPa
+sigma_a=(sigma_max-sigma_min)/2;// MPa
+// Goodman failure line - sigma_m/Sut+sigma_a/Se=1/n
+Sut=(sigma_m+sigma_a/(0.5))*n ;// putted Se=0.5*Sut
+printf('\n Minimum required ultimate strength, Sut = %.1f MPa',Sut)
diff --git a/3774/CH4/EX4.16/Ex4_16.sce b/3774/CH4/EX4.16/Ex4_16.sce
new file mode 100644
index 000000000..a0b425113
--- /dev/null
+++ b/3774/CH4/EX4.16/Ex4_16.sce
@@ -0,0 +1,28 @@
+// exa 4.16 Pg 122
+clc;clear;close;
+
+// Given Data
+Pmin=-15;// kN
+Pmax=25;// kN
+Se_dash=360;// MPa
+Sy=400;// MPa
+Ki=1.25;// impact factor
+n=2.25;// factor of safety
+ka=0.88;// surface finish factor
+Kt=2.25;// stress concentration factor
+Pm=(Pmax+Pmin)/2;// kN
+Pa=(Pmax-Pmin)/2;// kN
+q=0.8;// sensitivity factor
+
+// sigma_m=4*Pm/%pi/d**2
+sigma_m_into_d_sq = 4*Pm*1000/%pi;
+sigma_a_into_d_sq = 4*Pa*1000/%pi;
+Kf=1+q*(Kt-1);// fatigue strength factor
+kf=1/Kf ;// fatigue strength reduction factor
+kb=0.85;// size factor
+ke=0.9;//load factor
+ki=1/Ki;// reverse impact factor
+Se=ka*kb*ke*kf*ki*Se_dash;// MPa
+//soderburg failure equation - sigma_m/Sy+sigma_a/Se=1/n
+d=sqrt((sigma_m_into_d_sq/Sy+sigma_a_into_d_sq/Se)*n)
+printf('\n Size of piston rod, d = %.f mm',d)
diff --git a/3774/CH4/EX4.18/Ex4_18.sce b/3774/CH4/EX4.18/Ex4_18.sce
new file mode 100644
index 000000000..1c87c3fc5
--- /dev/null
+++ b/3774/CH4/EX4.18/Ex4_18.sce
@@ -0,0 +1,25 @@
+// exa 4.18 Pg 123
+clc;clear;close;
+
+// Given Data
+Pmin=-300;// kN
+Pmax=700;// kN
+Se_dash=280;// MPa
+Sy=350;// MPa
+Kf=1.8;//fatigue strength factor
+n=2;// factor of safety
+
+Pm=(Pmax+Pmin)/2;// kN
+Pa=(Pmax-Pmin)/2;// kN
+// sigma_m=4*Pm/%pi/d**2
+sigma_m_into_d_sq = 4*Pm*1000/%pi;
+sigma_a_into_d_sq = 4*Pa*1000/%pi;
+kf=1/Kf ;// fatigue strength reduction factor
+kb=0.85;// size factor
+ke=0.9;//load factor
+ka=0.93;// surface finish factor
+Se=ka*kb*ke*kf*Se_dash;// MPa
+//Goodman failure equation - sigma_m/Sy+sigma_a/Se=1/n
+d=sqrt((sigma_m_into_d_sq/Sy+sigma_a_into_d_sq/Se)*2.25)
+printf('\n Suitable diameter of rod, d = %.f mm',d)
+// Note - Ans in the textbook is wrong.
diff --git a/3774/CH4/EX4.19/Ex4_19.sce b/3774/CH4/EX4.19/Ex4_19.sce
new file mode 100644
index 000000000..0dcbcc259
--- /dev/null
+++ b/3774/CH4/EX4.19/Ex4_19.sce
@@ -0,0 +1,19 @@
+// exa 4.19 Pg 124
+clc;clear;close;
+
+// Given Data
+w=110;// mm
+Pmin=98.1;// kN
+Pmax=250;// kN
+Se=225;// N/mm.sq
+Sy=300;// N/mm.sq
+n=1.5;// factor of safety
+
+Pm=(Pmax+Pmin)/2;// kN
+Pa=(Pmax-Pmin)/2;// kN
+// sigma_m=Pm/w/t
+sigma_m_into_t = Pm/w;
+sigma_a_into_t = Pa/w;
+//Soderburg failure equation - sigma_m/Sy+sigma_a/Se=1/n
+d=(sigma_m_into_t/Sy+sigma_a_into_t/Se)*n*1000;// mm
+printf('\n thickness of plate, t = %.1f mm',d)
diff --git a/3774/CH4/EX4.2/Ex4_2.sce b/3774/CH4/EX4.2/Ex4_2.sce
new file mode 100644
index 000000000..0660587a9
--- /dev/null
+++ b/3774/CH4/EX4.2/Ex4_2.sce
@@ -0,0 +1,36 @@
+// exa 4.2 Pg 104
+clc;clear;close;
+
+// Given Data
+rBYd=0.1;
+DBYd=1.2;
+P=3;// kN
+Syt=300;//MPa
+n=3;// factor of safety
+//dimensions of plate
+l1=400;//mm
+l2=300;//mm
+l3=400;//mm
+
+
+sigma_d=Syt/n;// MPa
+Kt=1.65;// factor for circular fillet radius member
+Rp=P/2;//kN (bearing reaction due to symmetry)
+Mf=Rp*l1;// kN.mm (bending moment at fillet)
+Mc=P*(l1+l2+l3)/4;// kN.mm (bending moment at centre)
+
+//Fillet
+//sigma_max=Kt*32*Mf/(%pi*d**3)
+sigma_max_into_d_cube_1 = Kt*32*Mf*1000/%pi
+
+
+//Centre
+//sigma_max=32*Mc/(%pi*d**3)
+sigma_max_into_d_cube_2 = Kt*32*Mf*1000/%pi
+sigma_max_into_d_cube=max(sigma_max_into_d_cube_1,sigma_max_into_d_cube_2);// (getting max)
+
+//putting sigma_max=sigma_d
+t=(sigma_max_into_d_cube/sigma_d)**(1/3);// mm
+printf('\n Diameter of axle = %.1f mm',t)
+
+
diff --git a/3774/CH4/EX4.20/Ex4_20.sce b/3774/CH4/EX4.20/Ex4_20.sce
new file mode 100644
index 000000000..cacd208e1
--- /dev/null
+++ b/3774/CH4/EX4.20/Ex4_20.sce
@@ -0,0 +1,34 @@
+// exa 4.20 Pg 124
+clc;clear;close;
+
+// Given Data
+Mmin=200;// kN.mm
+Mmax=600;// kN.mm
+Tmin=60;// kN
+Tmax=180;// kN
+Su=550;// MPa
+Sy=400;// MPa
+Se=0.5*Su;// MPa
+n=1.5;// factor of safety
+Ktb=1.5;// stress concentration factor in blending
+Kts=1.2;// stress concentration factor in torsion
+
+Mm=(Mmax+Mmin)/2;// kN.mm
+Ma=(Mmax-Mmin)/2;// kN.mm
+
+//sigma_xm=32*Mm/%pi/d**3
+sigma_xm_into_d_cube=32*Mm/%pi;
+//sigma_xa=32*Ma/%pi/d**3
+sigma_xa_into_d_cube=32*Ma/%pi;
+Tm=(Tmax+Tmin)/2;// kN.mm
+Ta=(Tmax-Tmin)/2;// kN.mm
+Txym_into_d_cube=16*Tm/%pi;
+Txya_into_d_cube=16*Ta/%pi;
+// using distortion energy theory
+// sigma_m=sqrt(sigma_xm**2+3*Txym**2)
+sigma_m_into_d_cube=sqrt(sigma_xm_into_d_cube**2+3*Txym_into_d_cube**2);
+// sigma_a=sqrt((Ktb*sigma_xa)**2+3*(Kts*Txym)**2)
+sigma_a_into_d_cube=sqrt((Ktb*sigma_xa_into_d_cube)**2+3*(Kts*Txya_into_d_cube)**2);
+// Sodeburg equation - sigma_m + (Su/Se)*sigma_a=Sy/n
+d=((sigma_m_into_d_cube + (Su/Se)*sigma_a_into_d_cube)*1000/(Sy/n))**(1/3)
+printf('\n shaft size, d = %.f mm',d)
diff --git a/3774/CH4/EX4.21/Ex4_21.sce b/3774/CH4/EX4.21/Ex4_21.sce
new file mode 100644
index 000000000..fcf97e794
--- /dev/null
+++ b/3774/CH4/EX4.21/Ex4_21.sce
@@ -0,0 +1,23 @@
+// exa 4.21 Pg 126
+clc;clear;close;
+
+// Given Data
+// Hole -
+d=25;//mm
+w=150;//mm
+Kt=2.56;// stress concentration factor
+P=50;// kN
+sigma_max=100;// N/mm.sq
+t=Kt*P*1000/(w-d)/sigma_max;// mm
+printf('Calculating for hole - \n thickness is : %.2f mm',t)
+
+// Notch -
+d=30;//mm
+w=120;//mm
+w=150;//mm
+Kt=2.3;// stress concentration factor
+P=50;// kN
+sigma_max=100;// N/mm.sq
+t=Kt*P*1000/(w-d)/sigma_max;// mm
+printf('\n Calculating for notch - \n thickness is : %.2f mm',t)
+disp('Suggestion, Adopt t = 11 mm')
diff --git a/3774/CH4/EX4.3/Ex4_3.sce b/3774/CH4/EX4.3/Ex4_3.sce
new file mode 100644
index 000000000..9ebd65026
--- /dev/null
+++ b/3774/CH4/EX4.3/Ex4_3.sce
@@ -0,0 +1,25 @@
+// exa 4.3 Pg 105
+clc;clear;close;
+
+// Given Data
+Sut=440;//MPa
+d=25;//mm
+R=95/100;// reliability
+Kt=1.8;// stress concentration factor
+q=0.86;// sensitivity factor
+
+Se_dash = 0.5*Sut;// MPa
+
+// for machined surface
+ka=0.82;// surface finish factor
+kb=0.85;// size factor
+kc=0.868;// reliability factor
+kd=1;// temperature factor
+ke=0.577;// load factor
+
+Kf=1+q*(Kt-1);// fatigue strength factor
+kf=1/Kf ;// fatigue strength reduction factor
+Se=ka*kb*kc*kd*ke*kf*Se_dash;// (MPa) Endurance limit
+printf('\n Endurance limit = %.2f MPa',Se)
+
+
diff --git a/3774/CH4/EX4.4/Ex4_4.sce b/3774/CH4/EX4.4/Ex4_4.sce
new file mode 100644
index 000000000..26b769886
--- /dev/null
+++ b/3774/CH4/EX4.4/Ex4_4.sce
@@ -0,0 +1,33 @@
+// exa 4.4 Pg 105
+clc;clear;close;
+
+// Given Data
+Sut=440;//MPa
+w=60;//mm
+d=12;// mm
+P=20;// kN
+q=0.8;// sensitivity factor
+R=90/100;// reliability
+n=2;// factor of safety
+
+Kt=2.52;// stress concentration factor
+Se_dash = 0.5*Sut;// MPa
+// for hot rollednormalized condition
+ka=0.67;// surface finish factor
+kb=0.85;// size factor (assuming t<50 mm)
+kc=0.897;// reliability factor
+kd=1;// temperature factor
+ke=0.9;// load factor
+dBYw=d/w; //(for circular hole)
+
+Kf=1+q*(Kt-1);// fatigue strength factor
+kf=1/Kf ;// fatigue strength reduction factor
+Se=ka*kb*kc*kd*ke*kf*Se_dash;// (MPa) Endurance limit
+sigma_d=Se/n;// MPa (design stress)
+// sigma_max=P/(w-d)/t
+sigma_max_into_t = P*1000/(w-d);
+// putting sigma_max=sigma_d
+t=sigma_max_into_t/sigma_d;// mm
+printf('\n Thickness of plate = %.2f mm or 20 mm',t)
+
+
diff --git a/3774/CH4/EX4.5/Ex4_5.sce b/3774/CH4/EX4.5/Ex4_5.sce
new file mode 100644
index 000000000..91dfd1de8
--- /dev/null
+++ b/3774/CH4/EX4.5/Ex4_5.sce
@@ -0,0 +1,22 @@
+// exa 4.5 Pg 107
+clc;clear;close;
+
+// Given Data
+Sut=650;//MPa
+N=10**5;// cycles
+Se_dash = 0.5*Sut;// MPa
+of=5;// unit
+ob=6;//unit
+bf=ob-of;// unit
+be=3;//unit
+
+// calculating endurance section wise
+OE=log10(Se_dash);
+OA=log10(0.9*Sut);
+AE=OA-OE;
+//log10_Sf=OD=OE+ED=OE+FC
+log10_Sf=OE+(bf/be)*AE;
+Sf=10**log10_Sf; // (MPa) Endurance
+printf('\n Endurance of specimen = %.2f MPa',Sf)
+
+
diff --git a/3774/CH4/EX4.6/Ex4_6.sce b/3774/CH4/EX4.6/Ex4_6.sce
new file mode 100644
index 000000000..44b67139b
--- /dev/null
+++ b/3774/CH4/EX4.6/Ex4_6.sce
@@ -0,0 +1,42 @@
+// exa 4.6 Pg 108
+clc;clear;close;
+
+// Given Data
+Sut=540;//MPa
+N=10**4;// cycles
+q=0.85;// sensitivity factor
+R=90/100;// reliability
+P=1500;// N
+l=160;// mm
+
+Se_dash = 0.5*Sut;// MPa
+// for cold drawn steel
+ka=0.79;// surface finish factor
+kb=0.85;// size factor (assuming t<50 mm)
+kc=0.897;// reliability factor
+kd=1;// temperature factor
+ke=1;// load factor
+
+Kt=1.33;// under bending
+
+Kf=1+q*(Kt-1);// fatigue strength factor
+kf=1/Kf ;// fatigue strength reduction factor
+Se=ka*kb*kc*kd*ke*kf*Se_dash;// MPa( Endurance limit)
+
+of=4;// unit
+ob=6;//unit
+bf=ob-of;// unit
+be=3;//unit
+
+// calculating endurance section wise
+OE=log10(Se);
+OA=log10(0.9*Sut);
+AE=OA-OE;
+//log10_Sf=OD=OE+ED=OE+FC
+log10_Sf=OE+(bf/be)*AE;
+Sf=10**log10_Sf; // (MPa) Endurance
+
+MB=P*l;// N.mm
+// 32*MB/%pi/d**3 = Sf
+d=(32*MB/%pi/Sf)**(1/3)
+printf('\n diameter of beam %.f mm',d)
diff --git a/3774/CH4/EX4.7/Ex4_7.sce b/3774/CH4/EX4.7/Ex4_7.sce
new file mode 100644
index 000000000..03ead01d3
--- /dev/null
+++ b/3774/CH4/EX4.7/Ex4_7.sce
@@ -0,0 +1,41 @@
+// exa 4.7 Pg 110
+clc;clear;close;
+
+// Given Data
+Sut=600;//MPa
+Syt=380;//MPa
+q=0.9;// sensitivity factor
+R=90/100;// reliability
+n=2;// factor of safety
+Pmin=-100;// N
+Pmax=200;// N
+l=150;// mm
+
+Se_dash = 0.5*Sut;// MPa
+// for cold drawn steel
+ka=0.76;// surface finish factor
+kb=0.85;// size factor (assuming t<50 mm)
+kc=0.897;// reliability factor
+kd=1;// temperature factor
+ke=1;// load factor
+
+Kt=1.4;// under bending
+
+Kf=1+q*(Kt-1);// fatigue strength factor
+kf=1/Kf ;// fatigue strength reduction factor
+Se=ka*kb*kc*kd*ke*kf*Se_dash;// MPa( Endurance limit)
+Mmax=Pmax*l;// N.mm
+Mmin=Pmin*l;// N.mm
+Mm=(Mmax+Mmin)/2;// N.mm
+Ma=(Mmax-Mmin)/2;// N.mm
+theta=atand(Ma/Mm);// degree
+
+//equation of Goodman - sigma_m/Sut+sigma_a/Se=1
+//here sigma_a/sigma_m=3
+sigma_m=1/(1/Sut+3/Se);//MPa
+sigma_a=3*sigma_m;// MPa
+
+sigma_da=sigma_a/n;// MPa
+//sigma_da=32*Ma/%pi/d**3
+d=(32*Ma/%pi/sigma_da)**(1/3);// mm 
+printf('\n diameter d at fillet cross section = %.f mm',d)
diff --git a/3774/CH4/EX4.8/Ex4_8.sce b/3774/CH4/EX4.8/Ex4_8.sce
new file mode 100644
index 000000000..b587914e6
--- /dev/null
+++ b/3774/CH4/EX4.8/Ex4_8.sce
@@ -0,0 +1,30 @@
+// exa 4.8 Pg 112
+clc;clear;close;
+
+// Given Data
+Sut=500;//MPa
+Syt=300;//MPa
+R=90/100;// reliability
+n=2;// factor of safety
+Tmin=-200;// N.m
+Tmax=500;// N.m
+
+Se_dash = 0.5*Sut;// MPa
+// for cold drawn steel
+ka=0.80;// surface finish factor
+kb=0.85;// size factor (assuming t<50 mm)
+kc=0.897;// reliability factor
+kd=1;// temperature factor
+ke=0.577;// load factor
+
+Ses=ka*kb*kc*kd*ke*Se_dash;// MPa( Endurance limit)
+Sys=ke*Syt;// MPa
+Tm=(Tmax+Tmin)/2;// N.m
+Ta=(Tmax-Tmin)/2;// N.m
+theta=atand(Ta/Tm);// degree
+Sms=Ses/tand(theta);//MPa
+Sas=Ses;//MPa
+tau_da=Sas/n;//MPa
+//tua_da=16*Ta/%pi/d**3
+d=(16*Ta*1000/%pi/tau_da)**(1/3);//mm
+printf('\n diameter of shaft = %.f mm',d)
diff --git a/3774/CH4/EX4.9/Ex4_9.sce b/3774/CH4/EX4.9/Ex4_9.sce
new file mode 100644
index 000000000..c2640f651
--- /dev/null
+++ b/3774/CH4/EX4.9/Ex4_9.sce
@@ -0,0 +1,41 @@
+// exa 4.9 Pg 113
+clc;clear;close;
+
+// Given Data
+Sut=860;//MPa
+Syt=690;//MPa
+Pmin=60;// N
+Pmax=120;// N
+R=50/100;// reliability
+l=500;//mm
+d=10;//mm
+Se_dash = 0.5*Sut;// MPa
+// for machines surface
+ka=0.70;// surface finish factor
+kb=0.85;// size factor (assuming t<50 mm)
+kc=1;// reliability factor
+kd=1;// temperature factor
+ke=1;// load factor
+
+Se=ka*kb*kc*kd*ke*Se_dash;// MPa( Endurance limit)
+Mmax=Pmax*l;// N.mm
+Mmin=Pmin*l;// N.mm
+Mm=(Mmax+Mmin)/2;// N.mm
+Ma=(Mmax-Mmin)/2;// N.mm
+Sm=32*Mm/%pi/d**3;//MPa
+sigma_m=Sm;//MPa
+Sa=32*Ma/%pi/d**3;//MPa
+sigma_a=Sa;//MPa
+Sf=Sa*Sut/(Sut-Sm);//MPa
+
+//calculating section
+OB=6;//unit ref. o at 3
+BE=OB-3;//unit
+OC=Sf;// MPa
+AE=log10(0.9*Sut)-log10(Se);//MPa
+AC=log10(0.9*Sut)-log10(Sf);//MPa
+CD=BE*AC/AE;//
+//log10(N)=3+CD
+N=10**(3+CD);// cycle
+printf('\n life of the spring, N = %.f cycles',N)
+//Note : answer in the textbook is wrong.