12 files changed, 673 insertions, 0 deletions
diff --git a/3774/CH9/EX9.1/Ex9_1.sce b/3774/CH9/EX9.1/Ex9_1.sce
new file mode 100644
index 000000000..4749d57e1
--- /dev/null
+++ b/3774/CH9/EX9.1/Ex9_1.sce
@@ -0,0 +1,32 @@
+// exa 9.1 Pg 256
+clc;clear;close;
+
+// Given Data
+d=26;// mm
+p=5;// mm
+W=10;// kN
+Do=50;// mm
+Di=20;// mm
+mu=0.2;// coefficient of thread friction
+mu_c=0.15;// coefficient of collar friction
+N=15;// rpm
+pb=6;// MPa
+
+dm=d-p/2;// mm
+dc=d-p;// mm
+t=p/2;//mm
+l=2*p;// mm
+alfa=atand(l/(%pi*dm));// degree
+fi=atand(mu);// degree
+Tf=W*dm/2*tand(alfa+fi);// N.mm
+Tc=mu_c*W/4*(Do+Di);// N.mm
+T=Tf+Tc;// N.mm
+printf('\n (a) Stress in the screw')
+sigma_c=4*W*10**3/(%pi*dc**2);// N/mm.sq.
+printf('\n Direct compressive stress = %.2f N/mm.sq',sigma_c)
+tau=16*T*10**3/(%pi*dc**3);//N/mm.sq.
+printf('\n Tortional shear stress = %.2f N/mm.sq',tau)
+tau_max=sqrt(sigma_c**2/4+tau**2);//MPa
+printf('\n Maximum shear stress = %.2f N/mm.sq',tau_max)
+n=W*10**3/(%pi*dm*t*pb);
+printf('\n\n (b) number of threads of nut in engagement = %.f',n)
diff --git a/3774/CH9/EX9.11/Ex9_11.sce b/3774/CH9/EX9.11/Ex9_11.sce
new file mode 100644
index 000000000..915002ead
--- /dev/null
+++ b/3774/CH9/EX9.11/Ex9_11.sce
@@ -0,0 +1,22 @@
+// exa 9.11 Pg 273
+
+clc;clear;close;
+
+// Given Data
+d=26;// mm
+L=0.25;//m
+F=300;// N
+mu=0.14;// coefficient of thread friction
+p=5;// mm (for normal series)
+
+dc=d-p;// mm
+dm=d-p/2;// mm
+l=2*p;// mm
+alfa=atand(l/%pi/dm);// degree
+fi=atand(mu);// degree
+To=F*L;// N.m (Torque applied by the operator)
+//Tf=W*dm/2*tand(alfa+fi);// N.mm
+// And Tf=To
+W=To*1000/(dm/2*tand(alfa+fi));// N
+printf('The force required for the job is : %.f N',W)
+// Note - answer in the textbook is wrong.
diff --git a/3774/CH9/EX9.13/Ex9_13.sce b/3774/CH9/EX9.13/Ex9_13.sce
new file mode 100644
index 000000000..c34980b95
--- /dev/null
+++ b/3774/CH9/EX9.13/Ex9_13.sce
@@ -0,0 +1,108 @@
+// exa 9.13 Pg 274
+
+clc;clear;close;
+
+// Given Data
+W=50;// kN
+lift=200;// mm
+gc=300;// mm (ground clearance)
+pb=16;// MPa
+mu=0.14;// coefficient of collar friction
+
+//Screw C-35
+Sut=288;// MPa
+n=3;// factor of safety for screw
+// Nut : phosphor-bronze
+sigma_t=100;// MPa
+sigma_c=90;// MPa
+tau=80;// MPa
+n2=3;// factor of safety for nut
+
+sigma_ts=Sut/n;// MPa
+sigma_cs=Sut/n;// MPa
+tau_s=sigma_ts/2;// MPa
+// sigma_cs=4*W/(%pi*dc**2)
+dc= sqrt(4*W*10**3/(%pi*sigma_cs));// mm
+printf('\n Screw diameter - \n Core diameter, dc = %.2f mm. Use 30 mm',dc)
+dc=30;// mm (adopted for design)
+p=6;// mm (for normal series square threads)
+d=dc+p;//mm
+printf('\n outside diameter = %.f mm',d)
+dm=dc+p/2;// mm
+printf('\n mean diameter = %.1f mm',dm)
+t=p/2;// mm
+printf('\n thread thickness = %.1f mm',t)
+
+printf('\n Maximum tensile & shear tress in screw -')
+sigma_c=4*W*1000/%pi/dc**2;// MPa
+alfa=atand(p/(%pi*dm));// degree
+fi=atand(mu);// degree
+Tf=dm*W*10**3/2*tand(alfa+fi);// where TfByW = Tf/W
+tau=16*Tf/(%pi*dc**3);// MPa
+sigma12=(1/2)*(sigma_c+sqrt(sigma_c**2+4*tau**2));// MPa
+printf('\n Maximum tensile stress = %.1f MPa < %.f MPA. Hence design is safe.',sigma12,sigma_ts)
+tau_max=sqrt((sigma_c/2)**2+tau**2);// MPa
+printf('\n Maximum shear stress = %.2f MPa < %.f MPA. Hence design is safe.',tau_max,tau_s)
+
+printf('\n Height of nut-')
+n=W*10**3/(%pi/4)/pb/(d**2-dc**2);// no. of threads
+n= round(n);// no. of threads (rounding)
+h=n*p;// mm
+printf('\n h=%.f mm',h)
+
+printf('\n Check for stress in screw and nut')
+tau_screw=W*10**3/(%pi*n*dc*t);// MPa
+printf('\n shear stress in screw = %.2f MPa\',tau_screw)
+tau_nut=W*10**3/(%pi*n*d*t);// MPa
+printf('\n shear stress in nut = %.2f MPa',tau_nut)
+printf('\n These are within permissible limits. Hence design is safe.')
+
+printf('\n Nut collar size-')
+// %pi/4*(D1**2-d**2)*sigma_tn=W
+D1=sqrt(W*10**3/(%pi/4)/(50)+d**2);// mm
+printf('\n Inside diameter of collar = %.2f mm. Use D1=52 mm',D1)
+D1=52;//mm (adopted for design)
+// %pi/4*(D2**2-D1**2)*sigma_cn=W
+D2=sqrt(W*10**3/(%pi/4)/45+D1**2);// mm
+printf('\n Outside diameter of collar = %.1f mm. Use D2=65 mm',D2)
+D2=65;//mm (adopted for design)
+
+// %pi*D1*tc*tau_cn=W
+tau_cn=40;// MPa
+tc=W*10**3/(%pi*D1*tau_cn);// mm
+printf('\n thickness of nut = %.2f mm. Use tc=8 mm.',tc)
+tc=8;// mm (adopted for design)
+
+printf('\n Head Dimensions-')
+D3=1.75*d;// mm
+printf('\n Diameter of head on top of screw = %.2f mm. use D3=64 mm.',D3)
+D3=64;// mm (adopted for design)
+D4=D3/4;// mm
+printf('\n pin diameter in the cup = %.f mm',D4)
+
+printf('\n Torque required between cup and head-')
+Tc=mu*W*10**3/3*((D3**3-D4**3)/(D3**2-D4**2));// N.mm
+printf('\n Tc=%.f N.mm (acc. to uniform pressure theory)',Tc)
+T=Tf+Tc;// N.mm
+printf('\n Total Torque, T=%.f N.mm',T)
+
+F=300;// N (as a normal person can apply 100-300 N)
+l=T/F;//mm
+printf('\n length of lever = %.f mm. Use 1075 mm',l)
+
+M=F*l;// N.mm
+dl=(32*M/%pi/sigma12)**(1/3);// mm
+printf('\n Diameter of lever, dl=%.1f mm.',dl)
+
+H=2*dl;// mm
+printf('\n Height of head, H=%.f mm',H)
+
+printf('\n Check for screw in buckling-')
+L=lift+0.5*h;// mm
+K=dc/4;// mm
+C=0.25;// spring index
+sigma_y=288;// MPa
+Ac=%pi/4*dc**2;//mm.sq.
+Wcr=Ac*sigma_y*(1-(sigma_y/4/C/%pi**2/(200*10**3))*(L/K)**2)/1000;// kN
+printf('\n Buckling or critical load for screw, Wcr = %.f kN > 50kN',Wcr)
+printf('\n Hence design is safe.')
diff --git a/3774/CH9/EX9.14/Ex9_14.sce b/3774/CH9/EX9.14/Ex9_14.sce
new file mode 100644
index 000000000..ac537e623
--- /dev/null
+++ b/3774/CH9/EX9.14/Ex9_14.sce
@@ -0,0 +1,40 @@
+// exa 9.14 Pg 278
+
+clc;clear;close;
+
+// Given Data
+d=32;// mm
+p=5;// mm
+W=12;// kN
+D3=50;// mm
+D4=20;// mm
+mu=0.15;// coefficient of thread friction
+mu_c=0.20;// coefficient of collar friction
+N=24;// rpm
+pb=6;// N/mm.sq.
+tau_s=30;// MPa
+tau_n=30;// MPa
+
+dm=d-p/2;// mm
+dc=d-p;// mm
+t=p/2;// mm
+l=2*p;//mm
+alfa=atand(l/%pi/dm);// degree
+fi=atand(mu);// degree
+Tf=W*10**3*dm/2*tand(alfa+fi);// N.mm
+Tc=mu_c*W*10**3/4*(D3+D4);// N.mm
+T=Tf+Tc;// N.mm
+printf('\n (i) Torque required to rotate the screw = %.f N.mm',T)
+
+printf('\n (ii) Stresses induced in screw - ')
+sigma_c=4*W*10**3/(%pi*dc**2);// N/mm.sq.
+printf('\n Direct compressive stress = %.2f N/mm.sq',sigma_c)
+tau=16*T/(%pi*dc**3);// N/mm.sq.
+printf('\n Tortional shear stress = %.2f N/mm.sq',tau)
+tau_max=sqrt((sigma_c/2)**2+tau**2);// MPa 
+printf('\n Maximum shear stress = %.2f MPa < %.f MPa',tau_max,tau_s)
+printf('\n Hence design is safe.')
+n=W*10**3/(%pi*dm*t*pb);// no. of threads
+n=ceil(n);// rounding
+h=n*p;//mm
+printf('\n (iii) Height of nut = %.f mm',h)
diff --git a/3774/CH9/EX9.15/Ex9_15.sce b/3774/CH9/EX9.15/Ex9_15.sce
new file mode 100644
index 000000000..26caa5ae5
--- /dev/null
+++ b/3774/CH9/EX9.15/Ex9_15.sce
@@ -0,0 +1,131 @@
+// exa 9.15 Pg 279
+
+clc;clear;close;
+
+// Given Data
+W=100;// kN
+lift=260;// mm
+pb=15;// N/mm.sq.
+mu=0.15;// coefficient of thread friction
+mu_c=0.20;// coefficient of collar friction
+//Screw
+Suts=800;// N/mm.sq.
+sigma_ss=340;// N/mm.sq.
+ns=4;// factor of safety
+//Nut
+Sutn=552;// N/mm.sq.
+sigma_sn=260;// N/mm.sq.
+nn=5;// factor of safety
+
+sigma_ts=Suts/ns;// N/mm.sq.
+sigma_cs=Suts/ns;// N/mm.sq.
+tau_s=sigma_ss/ns;// N/mm.sq.
+sigma_tn=Sutn/nn;// N/mm.sq.
+sigma_cn=Sutn/nn;// N/mm.sq.
+tau_n=sigma_sn/nn;// N/mm.sq.
+
+//sigma_cs=4*W/(%pi*dc**2)
+dc=sqrt(4*W*10**3/(%pi*sigma_cs));// mm
+printf('\n Screw Diameter-\n Core diameter of screw, dc=%.2f mm. Use dc=33 mm',dc)
+dc=33;// mm
+p=7;// mm (for normal series square threads)
+d=dc+p;//mm
+printf('\n outside diameter = %.f mm',d)
+dm=dc+p/2;// mm
+printf('\n mean diameter = %.1f mm',dm)
+t=p/2;// mm
+printf('\n thread thickness = %.1f mm',t)
+
+printf('\n Maximum stresses in screw -')
+sigma_c=4*W*1000/%pi/dc**2;// MPa
+alfa=atand(p/(%pi*dm));// degree
+fi=atand(mu);// degree
+Tf=dm*W*10**3/2*tand(alfa+fi);// where TfByW = Tf/W
+tau=16*Tf/(%pi*dc**3);// MPa
+sigma12=(1/2)*(sigma_c+sqrt(sigma_c**2+4*tau**2));// MPa
+printf('\n Maximum tensile stress = %.1f N/mm.sq. < %.f N/mm.sq.. Hence design is safe.',sigma12,sigma_ts)
+tau_max=sqrt((sigma_c/2)**2+tau**2);// MPa
+printf('\n Maximum shear stress = %.2f N/mm.sq. < %.f N/mm.sq.. Hence design is safe.',tau_max,tau_s)
+
+printf('\n Height of nut-')
+n=W*10**3/(%pi/4)/pb/(d**2-dc**2);// no. of threads
+n= ceil(n);// no. of threads (rounding)
+h=n*p;// mm
+printf('\n h=%.f mm. Use 120 mm.',h)
+h=120;// mm
+
+printf('\n Check for stress in screw and nut')
+tau_screw=W*10**3/(%pi*n*dc*t);// MPa
+printf('\n shear stress in screw = %.2f MPa < %.f MPa',tau_screw,tau_s)
+tau_nut=W*10**3/(%pi*n*d*t);// MPa
+printf('\n shear stress in nut = %.2f MPa < %.f MPa',tau_nut,tau_n)
+printf('\n These are within permissible limits. Hence design is safe.')
+
+printf('\n Nut collar size-')
+// %pi/4*(D1**2-d**2)*sigma_tn=W
+D1=sqrt(W*10**3/(%pi/4)/sigma_tn+d**2);// mm
+printf('\n Inside diameter of collar = %.2f mm. Use D1=55 mm',D1)
+D1=55;//mm (adopted for design)
+// %pi/4*(D2**2-D1**2)*sigma_cn=W
+D2=sqrt(W*10**3/(%pi/4)/sigma_cn+D1**2);// mm
+printf('\n Outside diameter of collar = %.2f mm. Use D2=70 mm',D2)
+D2=70;//mm (adopted for design)
+
+// %pi*D1*tc*tau_n=W
+tc=W*10**3/(%pi*D1*tau_n);// mm
+printf('\n thickness of nut = %.f mm. Use tc=15 mm.',tc)
+tc=15;// mm (adopted for design)
+
+printf('\n Head Dimensions-')
+D3=1.75*d;// mm
+printf('\n Diameter of head on top of screw = %.2f mm.',D3)
+D4=D3/4;// mm
+printf('\n pin diameter in the cup = %.1f mm. Use 20 mm.',D4)
+D4=20;// mm (adopted for design)
+
+printf('\n Torque required between cup and head-')
+Tc=mu_c*W*10**3/3*((D3**3-D4**3)/(D3**2-D4**2));// N.mm
+printf('\n Tc=%.f N.mm (acc. to uniform pressure theory)',Tc)
+T=Tf+Tc;// N.mm
+printf('\n Total Torque, T=%.f N.mm',T)
+
+F=300;// N (as a normal person can apply 100-300 N)
+l=T/F;//mm
+printf('\n length of lever = %.f mm or %.2f m',l,l/1000)
+
+M=F*l;// N.mm
+sigma_b=100;// N/mm.sq. (assumed)
+dl=(32*M/%pi/sigma_b)**(1/3);// mm
+printf('\n Diameter of lever, dl=%.1f mm. Use dl=45 mm.',dl)
+dl=45;// mm (adopted for design)
+
+H=2*dl;// mm
+printf('\n Height of head, H=%.f mm',H)
+
+printf('\n Check for screw in buckling-')
+L=lift+0.5*h;// mm
+K=dc/4;// mm
+C=0.25;// spring index
+sigma_y=200;// MPa
+Ac=%pi/4*dc**2;//mm.sq.
+Wcr=Ac*sigma_y*(1-(sigma_y/4/C/%pi**2/(200*10**3))*(L/K)**2)/1000;// kN
+printf('\n Buckling or critical load for screw, Wcr = %.f kN > 100kN',Wcr)
+
+To=W*10**3*dm/2*tand(alfa);// N.mm
+eta=To/T*100;// %
+printf('\n Efficiency of screw = %.2f %%',eta)
+
+printf('\n Body dimensions-')
+D5=1.5*D2;// mm
+t2=2*tc;// mm
+t3=0.25*d;//mm
+D6=2.25*D2;// mm
+printf('\n Diameter of body at top, D5 = %.f mm', D5)
+printf('\n Thickness of base, t2 = %.f mm', t2)
+printf('\n Thickness of body, t3 = %.f mm', t3)
+printf('\n Inside diameter of bottom, D6 = %.1f mm. Use D6=160 mm.', D6)
+D6=160;// mm (adopted for design)
+D7=1.75*D6;// mm
+hb=lift+h+100;// mm
+printf('\n Outside diameter at the bottom, D7 = %.2f mm.', D7)
+printf('\n Height of body = %.f mm.',hb)
diff --git a/3774/CH9/EX9.2/Ex9_2.sce b/3774/CH9/EX9.2/Ex9_2.sce
new file mode 100644
index 000000000..f4f7f1259
--- /dev/null
+++ b/3774/CH9/EX9.2/Ex9_2.sce
@@ -0,0 +1,29 @@
+// exa 9.2 Pg 257
+clc;clear;close;
+
+// Given Data
+d=50;// mm
+p=8;// mm
+W=2;// kN
+Do=100;// mm
+Di=50;// mm
+mu=0.15;// coefficient of thread friction
+mu_c=0.10;// coefficient of collar friction
+N=25;// rpm
+two_beta=29;// degree
+
+dm=d-p/2;// mm
+dc=d-p;// mm
+t=p/2;//mm
+l=2*p;// mm
+alfa=atand(p/(%pi*dm));// degree
+mu_e=mu/cosd(two_beta/2);// virtual coefficient of friction
+fi=atand(mu_e);// degree
+Tf=W*dm/2*tand(alfa+fi);// N.mm
+Tc=mu_c*W/4*(Do+Di);// N.mm
+T=Tf+Tc;// N.mm
+P=2*%pi*N*T/(60*10**3);// kW
+printf('\n (a) Power required = %.3f kN',P)
+To=W*dm/2*tand(alfa);// N.mm
+eta=To/T*100;// % (efficiency)
+printf('\n (b) Efficiency of screw = %.2f %%',eta)
diff --git a/3774/CH9/EX9.3/Ex9_3.sce b/3774/CH9/EX9.3/Ex9_3.sce
new file mode 100644
index 000000000..a818e5233
--- /dev/null
+++ b/3774/CH9/EX9.3/Ex9_3.sce
@@ -0,0 +1,45 @@
+// exa 9.3 Pg 259
+clc;clear;close;
+
+// Given Data
+d=10;// mm
+p=3;// mm
+mu=0.15;// coefficient of thread friction
+mu_c=0.20;// coefficient of collar friction
+dc=15;// mm
+F=60;// N
+W=4;// kN
+two_beta=30;// degree
+h=25;// mm
+lf=150;// mm (screw free length)
+
+dm=d-p/2;// mm
+alfa=atand(p/(%pi*dm));// degree
+mu_e=mu/cosd(two_beta/2);// virtual coefficient of friction
+fi=atand(mu_e);// degree
+Tf=W*10**3*dm/2*tand(alfa+fi);// N.mm
+Tc=mu_c*W*10**3/2*dc;// N.mm
+T=Tf+Tc;// N.mm
+//F*l=T
+l=T/F;// mm (Length of handle)
+printf('\n (a) Length of handle = %.1f mm',l)
+
+printf('\n\n (b) Maximum shear stress in screw')
+printf('\n Section 1-1 : ')
+dc=d-p;//mm
+tau=16*T/(%pi*dc**3);// N/mm.sq.
+M=F*lf;// N.mm
+sigma_b=32*M/(%pi*dc**3);// N/mm.sq.
+tau_max=sqrt((sigma_b/2)**2+tau**2);// MPa
+printf('\n Maximum shear stress = %.2f MPa',tau_max)
+printf('\n Section 2-2 : ')
+sigma_c=4*W*10**3/(%pi*dc**2);// N/mm.sq. (Direct compressive stress)
+tau2=16*Tc/(%pi*dc**3);//;// N/mm.sq. (Tortional shear stress)
+tau_max=sqrt((sigma_c/2)**2+tau2**2);// MPa
+printf('\n Maximum shear stress = %.2f MPa',tau_max)
+
+//h=n*p;// height of nut
+n=ceil(h/p);// no. of threads
+t=p/2;// mm (thickness of threads)
+pb=W*10**3/(%pi*dm*t*n);// MPa
+printf('\n\n (b) Bearing pressure on threads = %.1f MPa',pb)
diff --git a/3774/CH9/EX9.4/Ex9_4.sce b/3774/CH9/EX9.4/Ex9_4.sce
new file mode 100644
index 000000000..b9c2a6b60
--- /dev/null
+++ b/3774/CH9/EX9.4/Ex9_4.sce
@@ -0,0 +1,38 @@
+// exa 9.4 Pg 260
+clc;clear;close;
+
+// Given Data
+W=25;// kN
+two_beta=29;// degree
+v=0.96;// m/min
+mu=0.14;// coefficient of thread friction
+Di=30;// mm
+Do=66;// mm
+mu_c=0.15;// coefficient of collar friction
+d=36;// mm
+p=6;// mm
+Sut=630;// MPa
+Syt=380;// MPa
+
+dm=d-p/2;// mm
+dc=d-p;// mm
+l=2*p;// mm
+alfa=atand(l/(%pi*dm));// degree
+mu_e=mu/cosd(two_beta/2);// virtual coefficient of friction
+fi=atand(mu_e);// degree
+Tf=W*10**3*dm/2*tand(alfa+fi);// N.mm
+Tc=mu_c*W*10**3/4*(Do+Di);// N.mm
+T=Tf+Tc;// N.mm
+N=v*10**3/l;// rpm
+
+P=2*%pi*N*T/(60*10**3)*10**-3;// kW
+printf('\n Power required to drive the slide = %.2f kN',P)
+sigma_c=4*W*10**3/(%pi*dc**2);// MPa
+tau=16*T/(%pi*dc**3);// MPa
+sigma1=1/2*(sigma_c+sqrt(sigma_c**2+4*tau**2));// MPa
+tau_max=sqrt((sigma_c/2)**2+tau**2);// MPa
+n_t=Syt/sigma1;// factor of safety in tension
+printf('\n factor of safety in tension = %.2f ',n_t)
+n_s=Syt/2/tau_max;// factor of safety in shear
+printf('\n factor of safety in shear = %.2f ',n_s)
+// Note- Answer in the textbook are not accurate.
diff --git a/3774/CH9/EX9.5/Ex9_5.sce b/3774/CH9/EX9.5/Ex9_5.sce
new file mode 100644
index 000000000..6f5741295
--- /dev/null
+++ b/3774/CH9/EX9.5/Ex9_5.sce
@@ -0,0 +1,28 @@
+// exa 9.5 Pg 262
+clc;clear;close;
+
+// Given Data
+d=12;// mm
+dc=10;// mm
+p=2;// mm
+Do=10;//mm
+mu=0.15;// coefficient of thread friction
+mu_c=0.18;// coefficient of collar friction
+F=100;// N
+l=150;// mm
+
+dm=dc+p/2;// mm
+alfa=atand(p/(%pi*dm));// degree
+fi=atand(mu);// degree
+TfByW=dm/2*tand(alfa+fi);// where TfByW = Tf/W
+TcByW=mu_c/3*Do;// where TcByW = Tc/W
+TByW=TfByW+TcByW;// N.mm (total torque at B-B)
+Tapplied=F*l;// N.mm (torque applied by the operator)
+//putting T= Tapplied
+W= Tapplied/TByW;// N
+printf('\n (a) Clamping force between the jaws = %.f N',W)
+eta=W*dm/2*tand(alfa)/Tapplied*100;// % 
+printf('\n (b) Efficiency of vice = %.2f %%',eta)
+Tf=TfByW*W;// N.mm
+printf('\n (c) Torque at A-A, Tf = %.1f N.mm & Torque at B-B = %.f N.mm',Tf,Tapplied)
+// Note- Answer in the textbook are not accurate.
diff --git a/3774/CH9/EX9.6/Ex9_6.sce b/3774/CH9/EX9.6/Ex9_6.sce
new file mode 100644
index 000000000..c548c7e98
--- /dev/null
+++ b/3774/CH9/EX9.6/Ex9_6.sce
@@ -0,0 +1,120 @@
+// exa 9.6 Pg 267
+
+clc;clear;close;
+
+// Given Data
+W=100;// kN
+lift=400;// mm
+sigma_ts=100;// MPa
+sigma_cs=100;// MPa
+tau_s=60;// MPa
+tau_tn=50;// MPa
+sigma_cn=45;// MPa
+tau_n=40;// MPa
+pb=15;// MPa
+mu=0.2;// coefficient of thread friction
+mu_c=0.15;// coefficient of collar friction
+
+//sigma_cs=4*W/(%pi*dc**2)
+dc=sqrt(4*W*10**3/(%pi*sigma_cs));// mm
+printf('\n Screw Diameter-\n Core diameter of screw, dc=%.2f mm. Use dc=40 mm',dc)
+dc=40;// mm
+p=7;// mm (for normal series square threads)
+d=dc+p;//mm
+printf('\n outside diameter = %.f mm',d)
+dm=dc+p/2;// mm
+printf('\n mean diameter = %.1f mm',dm)
+t=p/2;// mm
+printf('\n thread thickness = %.1f mm',t)
+
+printf('\n Maximum tensile & shear stress in screw -')
+sigma_c=4*W*1000/%pi/dc**2;// MPa
+alfa=atand(p/(%pi*dm));// degree
+fi=atand(mu);// degree
+Tf=dm*W*10**3/2*tand(alfa+fi);// where TfByW = Tf/W
+tau=16*Tf/(%pi*dc**3);// MPa
+sigma12=(1/2)*(sigma_c+sqrt(sigma_c**2+4*tau**2));// MPa
+printf('\n Maximum tensile stress = %.f MPa < %.f MPA. Hence design is safe.',sigma12,sigma_ts)
+tau_max=sqrt((sigma_c/2)**2+tau**2);// MPa
+printf('\n Maximum shear stress = %.2f MPa < %.f MPA. Hence design is safe.',tau_max,tau_s)
+
+printf('\n Height of nut-')
+n=W*10**3/(%pi/4)/pb/(d**2-dc**2);// no. of threads
+n= ceil(n);// no. of threads (rounding)
+h=n*p;// mm
+printf('\n h=%.f mm',h)
+
+printf('\n Check for stress in screw and nut')
+tau_screw=W*10**3/(%pi*n*dc*t);// MPa
+printf('\n shear stress in screw = %.2f MPa < %.f MPa',tau_screw,tau_s)
+tau_nut=W*10**3/(%pi*n*d*t);// MPa
+printf('\n shear stress in nut = %.2f MPa < %.f MPa',tau_nut,tau_n)
+printf('\n These are within permissible limits. Hence design is safe.')
+
+printf('\n Nut collar size-')
+// %pi/4*(D1**2-d**2)*sigma_tn=W
+D1=sqrt(W*10**3/(%pi/4)/tau_tn+d**2);// mm
+printf('\n Inside diameter of collar = %.2f mm. Use D1=70 mm',D1)
+D1=70;//mm (adopted for design)
+// %pi/4*(D2**2-D1**2)*sigma_cn=W
+D2=sqrt(W*10**3/(%pi/4)/sigma_cn+D1**2);// mm
+printf('\n Outside diameter of collar = %.2f mm. Use D2=90 mm',D2)
+D2=90;//mm (adopted for design)
+
+// %pi*D1*tc*tau_n=W
+tc=W*10**3/(%pi*D1*tau_n);// mm
+printf('\n thickness of nut = %.2f mm. Use tc=12 mm.',tc)
+tc=12;// mm (adopted for design)
+
+printf('\n Head Dimensions-')
+D3=1.75*d;// mm
+printf('\n Diameter of head on top of screw = %.2f mm. use D3=84 mm.',D3)
+D3=84;// mm (adopted for design)
+D4=D3/4;// mm
+printf('\n pin diameter in the cup = %.f mm',D4)
+
+printf('\n Torque required between cup and head-')
+Tc=mu_c*W*10**3/3*((D3**3-D4**3)/(D3**2-D4**2));// N.mm
+printf('\n Tc=%.f N.mm (acc. to uniform pressure theory)',Tc)
+T=Tf+Tc;// N.mm
+printf('\n Total Torque, T=%.f N.mm',T)
+
+F=300;// N (as a normal person can apply 100-300 N)
+l=T/F;//mm
+printf('\n length of lever = %.f mm. Use 3300 mm',l)
+
+M=F*l;// N.mm
+dl=(32*M/%pi/sigma12)**(1/3);// mm
+printf('\n Diameter of lever, dl=%.1f mm. Use dl=48 mm.',dl)
+dl=48;// mm (adopted for design)
+
+H=2*dl;// mm
+printf('\n Height of head, H=%.f mm',H)
+
+printf('\n Check for screw in buckling-')
+L=lift+0.5*h;// mm
+K=dc/4;// mm
+C=0.25;// spring index
+sigma_y=200;// MPa
+Ac=%pi/4*dc**2;//mm.sq.
+Wcr=Ac*sigma_y*(1-(sigma_y/4/C/%pi**2/(200*10**3))*(L/K)**2)/1000;// kN
+printf('\n Buckling or critical load for screw, Wcr = %.f kN > 100kN',Wcr)
+
+To=W*10**3*dm/2*tand(alfa);// N.mm
+eta=To/T*100;// %
+printf('\n Efficiency of screw = %.1f %%',eta)
+
+printf('\n Body dimensions-')
+D5=1.5*D2;// mm
+t2=2*tc;// mm
+t3=0.25*d;//mm
+D6=2.25*D2;// mm
+printf('\n Diameter of body at top, D5 = %.f mm', D5)
+printf('\n Thickness of base, t2 = %.f mm', t2)
+printf('\n Thickness of body, t3 = %.f mm', t3)
+printf('\n Inside diameter of bottom, D6 = %.1f mm. Use D6=205 mm.', D6)
+D6=205;// mm (adopted for design)
+D7=1.75*D6;// mm
+hb=lift+h+100;// mm
+printf('\n Outside diameter at the bottom, D7 = %.2f mm. Use 360 mm.', D7)
+printf('\n Height of body = %.f mm. Use 600mm',hb)
diff --git a/3774/CH9/EX9.7/Ex9_7.sce b/3774/CH9/EX9.7/Ex9_7.sce
new file mode 100644
index 000000000..0adbaae08
--- /dev/null
+++ b/3774/CH9/EX9.7/Ex9_7.sce
@@ -0,0 +1,25 @@
+// exa 9.7 Pg 267
+
+clc;clear;close;
+
+// Given Data
+two_beta=30;// degree
+W=400*10**3;// N
+d=100;// mm
+p=12;// mm
+mu=0.15;// coefficient of thread friction
+
+dm=d-p/2;// mm
+dc=d-p;// mm
+l=2*p;// mm
+alfa=atand(l/%pi/dm);// degree
+mu_e=mu/cosd(two_beta/2);// virtual coefficient of friction
+fi=atand(mu);// degree
+Tf=W*dm/2*tand(alfa+fi);// N.mm (Frictional torque for raising load)
+T=W*dm/4*tand(fi);// N.mm
+To=W*dm/2*tand(alfa);// N.mm (Torque without friction)
+eta1=To/Tf*100;// % 
+printf('\n Efficiency during raising the load = %.2f %%',eta1)
+eta2=T/To*100;// %
+printf('\n Efficiency during lowering the load = %.2f %%',eta2)
+// Note - answer & solution is wrong in the textbook.
diff --git a/3774/CH9/EX9.9/Ex9_9.sce b/3774/CH9/EX9.9/Ex9_9.sce
new file mode 100644
index 000000000..b9fd634e2
--- /dev/null
+++ b/3774/CH9/EX9.9/Ex9_9.sce
@@ -0,0 +1,55 @@
+// exa 9.9 Pg 272
+
+clc;clear;close;
+
+// Given Data
+d=70;// mm
+mu=0.13;// coefficient of thread friction
+mu_c=0.15;// coefficient of collar friction
+Do=90;// mm
+Di=26;// mm
+L=450;// mm
+// C-25 steel screw
+sigma_t1=275;// MPa
+sigma_c1=275;// MPa
+tau1=137.5;// MPa
+// Phosphor bronze nut
+sigma_t2=100;// MPa
+sigma_c2=90;// MPa
+tau2=80;// MPa
+pb=15;//MPa
+n=2;// factor of safety
+//screw
+sigma_ts=137.5;// MPa
+sigma_cs=137.5;// MPa
+tau_s=68.75;// MPa
+//Nut
+sigma_tn=50;// MPa
+sigma_cn=45;// MPa
+tau_n=40;// MPa
+
+p=10;// mm (for normal series square threads)
+dc=d-p;//mm
+dm=d-p/2;//mm
+t=p/2;//mm
+alfa=atand(p/%pi/dm);// degree
+fi=atand(mu);// degree
+
+K=dc/4;// mm
+C=0.25;// spring index
+sigma_y=275;// MPa
+Ac=%pi/4*dc**2;//mm.sq.
+Wcr=Ac*sigma_y*(1-(sigma_y/4/C/%pi**2/(200*10**3))*(L/K)**2);// N
+printf('\n (a) Safe Capacity of press or critical load for the screw = %.f N',Wcr)
+
+n=Wcr/(%pi*dm*t*pb);// no. of threads
+n=ceil(n);// rounding 
+h=n*p;// mm
+printf('\n (b) Height of nut, h=%.f mm',h)
+
+W=Wcr;// N
+Tf=W*dm/2*tand(alfa+fi)/1000;// N.mm (Frictional torque)
+Tc=mu_c*W/4*(Do+Di)/1000;// N.mm (Collar torque)
+T=Tf+Tc;// N.mm
+printf('\n (c) Necessary torsional moment or total torque = %.2f N.mm',T)
+// Note - answer in the textbook is wrong.