The following problems are to be turned in on Monday of 11th week. Theses
problems are from the 4th edition; numbers in (X) are the corresponding problem in
the 3rd edition.
5 (4), 24 (20), 31 (27), 35 (28), 44 (38).
The last t
(B) - CYCLE COUNTING
Cycle Counting - 1
Several methods available for cycle counting.
Will use Rainflow Method for this course.
Covered in most references previously listed.
Accredited to Matsuishi and Endo
YIELD (FAILURE) CRITERIA
In design, need to know why parts fail; and, when are parts predicted
Answer? When component stresses exceed the yield or
ultimate strength of the material? Maybe, maybe not!
Also need to consider viewpoint - part can no
MECH 515: Failure and Material Considerations in Design
Credit: 4 (4-0-4)
Prerequisites: MECH-515 or permission of instructor
Designing components that are safe and reliable requires efficient
use of materials and assurance that f
Work the following problems from Dowlings text(3rd edition):
Make an honest effort to solve each problem. They are to be turned in at the end of the term.
FATIGUE CRACK GROWTH CRITERIA
ARE DIFFERENT CRITERIA AVAILABLE FOR EVALUATING CRACK GROWTH .
LOOKING AT THREE OF THESE IN CLASS (PARIS , WALKER , AND
FORMAN .) YOUR ASSIGNMENT IS TO
RESEARCH THE FOLLOWING , INCLUDING PARI
STRAIN-LIFE PROBLEMS - II
The following problems were taken from JA Collins Failure of Materials in Mechanical
Design, 2nd Edition, Wiley, 1993. This is an excellent reference text.
PROBLEM - 01 (REF-11.4):
Cyclic properties for two steels have been deter
KIC-PROBS - 1
COLLINS - 3.16
A very wide sheet of 7075-T651 aluminum plate, 5/16 inch thick, is found to have a single edge
through-the-thickness crack 1.0 inch long. The loading produces a grss nominal tensile
MEAN STRESS EFFECTS
So far have assumed mean stress, m , is zero.
Now introduce fatigue considerations when m 0.
Plot stresses on a m - a coordinate system.
Three equations will be used to fit data, along with yield line.
Modified Goodman Line
STRESS-LIFE (S-N) APPROACH
III - SN -1
WILL BE LOOKING AT:
YIELD (FAILURE) CRITERIA
STRESS CONCENTRATION FACTORS, WITH INTRO TO STRESS
ZERO- VS. NON-ZERO MEAN STRESS (GERBER PARA
-N (STRAIN-LIFE) METHOD
IV - -N - 1
References used in this development:
JA Bannantine, JJ Comer, JL Handrock,
Fundamentals of Metal Fatigue Analysis, PrenticeHall, 1990.
NE Dowling, Mechanical Behavior of Materials, 2nd
III-SN - 5
As previously mentioned, in statics and solids, never considered
if applied loads or reactions occurred once or many times.
C Were they constant (static) or varying with time (dynamic)?
C Constant - Failure occurs when:
FEQ > FULT or FYP.