Page 31 - Mechanical Engineer's Data Handbook

20 MECHANICAL ENGINEER’S DATA HANDBOOK

Incomplete
penetration

n
I
Incomplete penetration
Cracking Slag inclusions
(due to poor weldability)

Porosity
Bad profile Improved profile
Incomplete weld
1.3.4 Stress concentration factors
Stress concentration factors are given for various
common discontinuities; for example, it can be seen dJw 0.00 0.10 0.20 0.30 0.40 0.50 0.55
that for a ‘wide plate’ with a hole the highest stress is 3
times the nominal stress. General values are also given K 3.00 3.03 3.14 3.36 3.74 4.32 4.70
for keyways, gear teeth, screw threads and welds.
Note: In this case the area of maximum cross-section is
Stress concentration factor is defined as: used.
Highest value of stress at a discontinuity
K=
Nominal stress at the minimum cross-section
Plate with hole at centre of width

K = u,,$o; a = PJwh
a,,, occurs at A and B.

Semi-injinite plate with hole near edge

a, = stress at A
nb = stress at B
n = stress away from hole
K,=aJa; K,=oda

r/c 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.85

K, 3.00 3.05 3.15 3.25 3.40 3.70 4.12 4.85 6.12 7.15
K, 3.00 3.03 3.07 3.10 3.15 3.18 3.25 3.32 3.42 3.50