HW9 ENME382 S10 Section0201 solution

HW9 ENME382 S10 Section0201 solution - Homework 9 Solutions...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
ENME 382 1.) a. Make an S-N Plot (stress amplitude versus logarithm cycles to failure) use these data. b. What is the fatigue limit for this alloy? From the S-N diagram, the fatigue limit, or S fat , is approximately 290MPa. c. Determine the fatigue lifetimes at stress amplitudes of 415MPa (60,000PSI) and 275MPa (40,000PSI). At 415MPa, the diagram S-N chart would predict a lifetime of about 65,000 cycles. At 275MPa, the life is infinite since it falls below the fatigue limit (S < S fat ) d. Estimate the fatigue strengths at 2x10 4 and 6x10 5 cycles. Via S-N Chart, 2x10 4 cycles would be approximately 447MPa. Via S-N Chart, 6x10 5 cycles would be approximately 332MPa. 2.) a.) Determine the maximum length of surface flaw that is possible without fracture. σ c = {(2*E* γ s )/( π *a)} 1/2 40x10 6 Pa = {(2*69x10 9 Pa*0.3J/m 2 )/( π *a)} 1/2 a = 0.000008m or 0.008mm (pretty small) STEEL ALLOY 0 100 200 300 400 500 1000 100000 10000000 1000000000 Number of Cycles, N Stress (MPa), S
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/28/2010 for the course ENME 250 taught by Professor Shang during the Spring '10 term at Maryland.

Page1 / 3

HW9 ENME382 S10 Section0201 solution - Homework 9 Solutions...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online