Fall 2011 ME423 Homework set3 (due 9/21, Wednesday)
1.
The uniaxial of yield strength of annealed AISI 1015 steel is 386MPa. Estimate
the shear stress at first yield in the torsion test for this mater
Fall 2011 ME423 Homework set1 (due 9/7, Wednesday)
1. Two prismatic bars of 50 mm x 75 mm rectangular cross section are adhesively bonded
as shown. The allowable normal and shear stresses for the bond
ME 423 08/31/2011
Lecture 1
Introduction
Introduce syllabus, class rules
The course learning objective
Determine the stresses and deformation in engineering devices and structures
(1)
Forces and stres
ME 423 09/7/2011
Lecture 3
Transformation of stresses
2.1.1 Review of 2D stresses
AB=1, OA=cos, OB=sin
Stress transformation equations
'
xx = xx cos 2 + yy sin 2 + 2 xy sin cos
'
yy = xx sin 2 + yy
ME 423 09/9/2011
Lecture 4
3D Stresses
p
Unit vectors to the (x,y,z) axes : i, j, k
Unit normal vector to plane ABC: p
Direction cosines of p: l = i p ; m = j p ; n = k p
l 2 + m2 + n2 = 1
If area ABC
http:/www.youtube.com/user/e1m1s#p/u/72/p3bkZBJV7X8
Structure of Metals and alloys
Yield and Fracture
1
What happens at
the yield point?
Slip lines
2
Single crystal
Slip occurs when the shear stress o
ME 423 09/16/2010
Lecture 7
Failure theories
2.2.3 Ductile failure (yield criteria)
Trescas maximum shear stress criterion
1 2 2 3 3 1
,
,
2
2
2
S
y - shear stress at yield, y = Y
2
S y - uniaxial y
ME 423 09/19/2010
Lecture 8
Brittle Failure (2.2.4)
Maximum Tensile Stress Theory
Maximum ( 1 , 2, 3 ) = S t
S t - the uniaxial tensile strength
Modified Mohr criterion
S t - the uniaxial tensile stre