Chapter6-Fasteners and Fastening Methods

Ex1-pg120

In [1]:
import math

print('MACHINE DESIGN \n Timothy H. Wentzell, P.E. \n EXAMPLE-6.1 Page No.120\n');

As=0.334;              ##[in^2] Tensile stress area (Table 6.1)
Sp=85000.;              ##[lb/in^2] Proof strength (Table 6.3)
D=3/4.;                 ##[in] Nominal diameter of thread

Fi=0.85*As*Sp;         ##[lb] Desired intial preload
C=0.2;                 ##[] Torque coefficient

T=C*D*Fi;              ##[in*lb] Torque

print'%s %.2f %s '%('\n The required torque is ',T,' lb*in.');

MACHINE DESIGN 
 Timothy H. Wentzell, P.E. 
 EXAMPLE-6.1 Page No.120


 The required torque is  3619.73  lb*in.

Ex2-pg121

In [2]:
import math

print('MACHINE DESIGN \n Timothy H. Wentzell, P.E. \n EXAMPLE-6.2 Page No.121\n');

L=5.;                   ##[in] Length of engagement
E=30*10**6;             ##[lb/in^2] Modulus of elasticity
As=0.334;              ##[in^2] Tensile stress area (Table 6.1)
Sp=85000.;              ##[lb/in^2] Proof strength (Table 6.3)
Fi=0.85*As*Sp;         ##[lb] Desired intial preload

Delta=Fi*L/(As*E)      ##[in] Elongation

pitch=0.1;             ##[in] Pitch for 3/4 UNC
TA=Delta*360./pitch;    ##[Degree] Torque angle

print'%s %.2f %s '%('\n The angle of rotation needed is ',TA,' degree.');

MACHINE DESIGN 
 Timothy H. Wentzell, P.E. 
 EXAMPLE-6.2 Page No.121


 The angle of rotation needed is  43.35  degree.

Ex3-pg122

In [3]:
import math

print('MACHINE DESIGN \n Timothy H. Wentzell, P.E. \n EXAMPLE-6.3 Page No.122\n');

Alpha=6.5*10**-6;       ##[in/(in*F)] Thermal expansion coefficient (Appendix 8)
L=5.;                   ##[in] Length of engagement

Delta=0.01204;       ##[Degree] Elongation

DT=Delta/(Alpha*L);    ##[F] The temperature we would need to heat this bolt above the sevice temperature

print'%s %.2f %s '%('\n The temperature we would need to heat this bolt above the sevice temperature is ',DT,' F.');

MACHINE DESIGN 
 Timothy H. Wentzell, P.E. 
 EXAMPLE-6.3 Page No.122


 The temperature we would need to heat this bolt above the sevice temperature is  370.46  F.

Ex4-pg124

In [5]:
import math

print('MACHINE DESIGN \n Timothy H. Wentzell, P.E. \n EXAMPLE-6.4 Page No.124\n');

Dp=20.;                 ##[in] Pressure vessel head diameter
Ds=1.25;               ##[in] Stud diameter
Ls=6.;                  ##[in] Stud length
Af=50.;                 ##[in^2] Clamped area of flanges

E=30*10**6;             ##[lb/in^2] Modulus of elasticity
C=0.15;                ##[] Torque coefficient
Si=120000.;             ##[lb/in^2] Proof strength (Table 6.3)
A=1.073;               ##[in^2] Tensile stress area (Table 6.1)

Fi=0.9*Si*A;           ##[lb] Desired intial load

T=C*Ds*Fi;             ##[lb*in] Torque

print'%s %.2f %s '%('\n1. The required torque is ',T,' lb*in.');

Pp=500.;                 ##[lb/in^2] Pressure inside the pressure vessel
Ap=math.pi*Dp**2/4.;          ##[in^2] Pressure vessel head cross section area

Kb=A*E/Ls;              ##[lb/in] Stiffness per stud
Kf=Af*E/Ls;             ##[lb/in] Stiffness per flange
Fe=Pp*Ap;               ##[lb] Force on pressure vessel head

Ft=10*Fi+(10*Kb/(10*Kb+Kf))*Fe;  ##[lb] Total load on the bolt

print'%s %.2f %s '%('\n2. The total load on the bolt is ',Ft,' lb.');

MACHINE DESIGN 
 Timothy H. Wentzell, P.E. 
 EXAMPLE-6.4 Page No.124


1. The required torque is  21728.25  lb*in. 

2. The total load on the bolt is  1186593.41  lb.