This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Georgia Institute of Technology
ME 3180: Machine Design
Spring 2012: Sections A, RCC, and RPY Homework #4
Assigned on Feb. 3, 2012
Due in class on Feb. 9, 2012 Problem 1 The AISI 1060 HR steel shaft shown in the ﬁgure experiences a fullreversed bending at
the machined groove. Assume the shaft is rotating, operates at 200 °F, and must have a
reliability of at least 90%. Draw the SN diagram and calculate either the safety factor for infinite lifetime or number of cycles to failure for a maximum nominal stress
amplitude of (a) 15 kpsi and (b) 35 kpsi. DJ in. radius T 2.0 I'M. .L Problem 2 The ﬂat bar of AISI 1018 CD steel shown in the figure experiences a timevarying axial
force that ﬂuctuates between 8000 lbs. in tension and 2000 lbs. in compression. Assume
room temperature operation and 90% reliability. Neglecting column action, determine
the appropriate safety factor(s) for the bar. 03?; in. Mali“: T NOTE '. The
T w . .734. ,7 . .
ll: 2 rm 0.533441%)
Wells. Problem 3 A part experiences a combination of bending, axial, and torsional loading such that the
following stresses are created at a critical location: Bending: Completely reversed, with a maximum stress of 60 MPa
Axial: Constant stress of 20 MPa
Torsion: Repeated load, varying from 0 MPa to 50 MPa Assume the timevarying stresses are in phase with each other and the part contains a
notch such that Kﬁbendmg = 1.4, Kﬁaxial = 1.1, and Kﬁtorsion = 2.0. The material properties are
Sy = 300 MPa and Su = 400 MPa. The completely adjusted endurance limit is found to be S6 = 200 MPa. Find the factor of safety for fatigue based on infinite life. Be sure to
check for yielding. ...
View
Full Document
 Spring '08
 Staff
 Machine Design

Click to edit the document details