evaluation of stress concentrators and their effect ... · • compressive residual stress from...
TRANSCRIPT
![Page 1: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/1.jpg)
Session Title
Presented by: (First and Last name of presenter(s)
H O S T E D B Y :
Evaluation of Stress Concentrators and Their Effect on Fatigue Life
![Page 2: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/2.jpg)
Evaluation of Stress Concentrators and Their Effect on Fatigue Life
Thursday, Oct. 3 2019
8 a.m – 8:50 a.m.
Jason Sicotte
NPD Engineering Manager
Associated Spring
![Page 3: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/3.jpg)
Outline
• Four Factors of fatigue approach to evaluation of stress concentrators
• Visual examination
• Real-world examples
• Questions
![Page 4: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/4.jpg)
Four Factors of Fatigue
Full
evaluation
of stress concentration
1. Applied Stress
2. Residual Stress
3. Material Fatigue
Strength
4. Geometric Stress
Concentrators
![Page 5: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/5.jpg)
• Load applied to the spring during use
• Is different depending on location on the spring and wire cross-section– The highest operating stresses in springs are at the wire
surface
1. Applied Stress
Spring ID Spring OD
Compression Spring
Example
![Page 6: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/6.jpg)
• The stress present in the spring in the free state (absence of any external load or force)
• Stress relieving lowers the residual tension on the spring ID
• Shot peening creates residual compression at and just below the wire surface
0 25 50 75 100 125 150 175 200 225 250
-750
-650
-550
-450
-350
-250
-150
-50
50
150
250
350
450
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
0 1 2 3 4 5 6 7 8 9 10
Depth below ID (µm)
Resid
ual
Str
ess (
MP
a)
Resid
ual
Str
ess (
ks
i)
Depth below ID (0.001")
Residual Stress
Coil + Stress Relieve
Shot Peened + Heat Set
2. Residual Stress
![Page 7: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/7.jpg)
• Compressive residual stress from shot peening helps minimize the effect of stress concentrators
– But, it does not “heal” defects in the material!
– It does reduce the likelihood that defects within the compressive residual stress zone will induce failure
0 25 50 75 100 125 150 175 200 225 250
-750
-650
-550
-450
-350
-250
-150
-50
50
150
250
350
450
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
0 1 2 3 4 5 6 7 8 9 10
Depth below ID (µm)
Resid
ual
Str
ess (
MP
a)
Resid
ual
Str
ess (
ksi)
Depth below ID (0.001")
Residual Stress
Shot Peened + Heat Set
Defects within compressiveresidual stress zone less likely to induce failure
2. Residual Stress
![Page 8: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/8.jpg)
“Net” Stress Concept• Net Stress = Summation of applied and residual stresses
• Coil + stress relieve only spring
1. Applied Stress 2. Residual Stress
-415
-315
-215
-115
-15
85
185
285
385
485
585
685
785
885
0 25 50 75 100 125 150 175 200 225 250
-60
-40
-20
0
20
40
60
80
100
120
140
0 1 2 3 4 5 6 7 8 9 10
Re
sid
ua
l S
tre
ss
(M
Pa
)
Depth below ID (µm)
Re
sid
ua
l S
tre
ss
(k
si)
Depth below ID (0.001") Coil + SR Residual Stress
Moderate Applied Stress
Net Stress
![Page 9: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/9.jpg)
“Net” Stress Concept• Net Stress = Summation of applied and residual stresses
• Shot peened and heat set spring
1. Applied Stress 2. Residual Stress
-825
-625
-425
-225
-25
175
375
575
775
975
1175
0 25 50 75 100 125 150 175 200 225 250
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
180
0 1 2 3 4 5 6 7 8 9 10
Re
sid
ua
l S
tre
ss
(M
Pa
)
Depth below ID (µm)
Re
sid
ua
l S
tre
ss
(k
si)
Depth below ID (0.001")
SP + HS Residual Stress
Higher Applied Stress
Net Stress
![Page 10: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/10.jpg)
• The maximum stress amplitude, S, level that a material can withstand for a specified of cycles without failure
Callister, William D. Materials Science and Engineering: An Introduction. New York: John Wiley & Sons, 2000.
3. Material Fatigue Strength
![Page 11: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/11.jpg)
Example: S/N curve for music wire helical compression spring
3. Material Fatigue Strength
Design Handbook: Engineering Guide to Spring Design. Connecticut: Barnes Group Inc., 1987.
![Page 12: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/12.jpg)
4. Geometric Stress Concentrators
• Stress concentrator, definition: a small flaw (internal or surface) or structural discontinuity at which applied stress will be amplified and from which a crack may initiate
• Geometric stress concentrators include any feature which may locally increase the stress, examples include – Raw material surface defects– Non-metallic inclusions– Spring manufacturing induced defects– Rust/corrosion pits– Contact wear in the application
• Evaluation– Must consider size, shape, and location
![Page 13: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/13.jpg)
Stress Concentration• Surface or internal flaws are a detriment to the fracture strength because
the applied stress is amplified or concentrated at the tip. The magnitude of the amplification depends on the flaw orientation and geometry
Callister, W. D. (2000). Materials Science and Engineering: An introduction. New York: John Wiley & Sons.
Nominal applied tensile stress
Maximum stress at the flaw tip
![Page 14: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/14.jpg)
Stress Concentration
𝜎𝑚 = 𝜎0[1 + 2 𝑎/ρ𝑡]
• 𝜎𝑚 – maximum stress at flaw tip
• 𝜎0 – nominal applied stress
• 𝑎 – length of surface flaw or ½ length of internal flaw
• 𝜌𝑡 – radius of flaw tip
•𝜎𝑚
𝜎0
is denoted as 𝐾𝑡 – stress concentration factor
Kt= 1 + 2 𝑎/ρ𝑡
One estimation calculation,
there are many!
Callister, W. D. (2000). Materials Science and Engineering: An introduction. New York: John Wiley & Sons.
![Page 15: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/15.jpg)
Stress ConcentrationExample
Sharp DefectCorrosion pit
SeamDie Mark
Wide DefectPressure Mark from Tooling
![Page 16: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/16.jpg)
Stress Concentration• The sharper the discontinuity, the more severe the stress
concentration:
Sharp defect (small 𝜌𝑡 ) vs. Wide defect (large 𝜌𝑡 )
𝜎𝑚 = 𝜎0[1 + 2 𝑎/ρ𝑡]
𝑎 = 10 µm 𝑎 = 10 µm
𝜌𝑡 = 5 µm 𝜌𝑡 = 2000 µm
𝜎𝑚 = 3.8𝜎0 𝜎𝑚 = 1.1𝜎0
Stress concentration is over 3 times greater for the sharp defect!
![Page 17: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/17.jpg)
Four Factors of Fatigue
Applied
Stress
Residual Stress
Stress Concentrator
Factor
Material Fatigue
Strength+ x>or<
𝐼𝑓 𝜎𝑚 ≥ 𝑆, 𝑡ℎ𝑒𝑛 𝐹𝑟𝑎𝑐𝑡𝑢𝑟𝑒𝐼𝑓 𝜎𝑚 < 𝑆, 𝑡ℎ𝑒𝑛 𝑁𝑂 𝐹𝑟𝑎𝑐𝑡𝑢𝑟𝑒
𝜎𝑚 = 𝜎𝑛𝑒𝑡 𝑥 𝐾𝑡
compare to S
![Page 18: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/18.jpg)
Visual Examination of Stress Concentrators
• Use of progressively higher magnification instruments to find and study the stress concentrator
• Naked eye observation
• Stereo microscope or digital microscope analysis
• Scanning electron microscope (SEM)
![Page 19: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/19.jpg)
Visual Examination of Stress Concentrators
• Cell phone camera!
• Even better with inexpensive clip on lens
• Find correct lighting to highlight feature
– good use of shadows
![Page 20: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/20.jpg)
Real-World Examples
![Page 21: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/21.jpg)
Example 1: ID Coiling Tool MarkNon-Shot Peened Compression Spring• Visual examination using a stereomicroscope
![Page 22: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/22.jpg)
Tool Mark• Visual examination using SEM
![Page 23: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/23.jpg)
Tool Mark
• Visual examination using your phone
![Page 24: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/24.jpg)
1. Applied Stress 2. Residual Stress
Tool Mark
-825
-725
-625
-525
-425
-325
-225
-125
-25
75
175
275
375
475
0 25 50 75 100 125 150 175 200 225 250
-120
-100
-80
-60
-40
-20
0
20
40
60
80
0 1 2 3 4 5 6 7 8 9 10
Resid
ual
Str
ess (
MP
a)
Depth below ID (µm)
Resid
ual
Str
ess (
ksi)
Depth below ID (0.001")
Residual Stress
Coil + SRResidualStress
ID Surface Residual Stress = +40 ksi
ID Surface Applied Stress = +87 ksi
ID OD
![Page 25: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/25.jpg)
3. Stress Concentration 4. Material Strength
Tool Mark
𝐾𝑡 = 1 + 2 𝑎/ρ𝑡𝑎 = 20 µm
𝜌𝑡 = 2112 µm𝐾𝑡 = 1.19
ASTM A401 CrSi alloy Material strength at 107
cycles, S = 114 ksi
Assuming 38% UTS max allowable stress for a non-peened and non-set out
compression spring 0.062” wire diameter, UTS = 300 ksi
𝑎 = 20 µm𝜌𝑡 = 2110 µm
Cross-sectional metallographic mount
![Page 26: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/26.jpg)
Tool Mark
AppliedStress87 ksi
ResidualStress40 ksi
Stress Concentration
Factor1.19
Material Fatigue Strength
114 ksi
151 ksi > 114 ksi∴ 𝐹𝑟𝑎𝑐𝑡𝑢𝑟𝑒
𝜎𝑚 = 𝜎𝑛𝑒𝑡 𝑥 𝐾𝑡, compare to S𝜎𝑚 = 127 𝑘𝑠𝑖 𝑥 1.19
![Page 27: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/27.jpg)
1. Applied Stress 2. Residual Stress
Move the same Tool Mark to the OD
OD Surface Residual Stress = -40 ksi
ID
OD Surface Applied Stress = +60 ksi
OD
While a helical compression spring ID surface is in residual
tension after spring coiling, the OD surface is in residual
compression
![Page 28: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/28.jpg)
AppliedStress60 ksi
ResidualStress-40 ksi
Stress Concentration
Factor1.19
Material Fatigue Strength
114 ksi
24 ksi < 114 ksi∴ 𝑁𝑂 𝐹𝑟𝑎𝑐𝑡𝑢𝑟𝑒
𝜎𝑚 = 𝜎𝑛𝑒𝑡 𝑥 𝐾𝑡, compare to S𝜎𝑚 = 20 𝑘𝑠𝑖 𝑥 1.19
Move the same tool mark to the OD
![Page 29: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/29.jpg)
Where are Stress Concentrators a Problem on a Compression Spring?
![Page 30: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/30.jpg)
Example 2: Non-Metallic Inclusion
Init
iati
on
Init
iati
on
• Visual examination using a stereomicroscope
![Page 31: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/31.jpg)
Non-Metallic Inclusion• Visual examination using your phone
![Page 32: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/32.jpg)
Inclusion• Visual examination using SEM
277 µm (0.0109”)
![Page 33: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/33.jpg)
Inclusion• Visual examination using SEM
32.0 µm25.0 µm
![Page 34: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/34.jpg)
-825
-725
-625
-525
-425
-325
-225
-125
-25
75
175
275
375
475
0 25 50 75 100 125 150 175 200 225 250
-120
-100
-80
-60
-40
-20
0
20
40
60
80
0 1 2 3 4 5 6 7 8 9 10
Resid
ual
Str
ess (
MP
a)
Depth below ID (µm)
Resid
ual
Str
ess (
ksi)
Depth below ID (0.001")
Residual Stress
SP + HS ResidualStress
1. Applied Stress 2. Residual Stress
Inclusion
Applied Stress at sub-surface initiation depth = +182 ksi
Residual Stress at sub-surface initiation depth = +50 ksi
![Page 35: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/35.jpg)
3. Stress Concentration 4. Material Strength
Inclusion
𝐾𝑡 = 1 + 2 𝑎/ρ𝑡𝑎 = 16 µm𝜌𝑡 = 11 µm𝐾𝑡 = 3.42
ASTM A877 Grade A – Valve spring quality CrSi alloy Material strength at 107
cycles, S = 143 ksi
Assuming 55% UTS max allowable stress for a shot peened and set
removed spring 0.225” wire diameter, UTS = 260 ksi
𝜌𝑡 = 11 µm
2𝑎 = 32 µm
![Page 36: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/36.jpg)
Inclusion
AppliedStress182 ksi
ResidualStress50 ksi
Stress Concentration
Factor3.42
Material Fatigue Strength
143 ksi
793 ksi > 143 ksi∴ 𝐹𝑟𝑎𝑐𝑡𝑢𝑟𝑒
𝜎𝑚 = 𝜎𝑛𝑒𝑡 𝑥 𝐾𝑡, compare to S𝜎𝑚 = 232 𝑘𝑠𝑖 𝑥 3.42
![Page 37: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/37.jpg)
Inclusion
0 25 50 75 100 125 150 175 200 225 250 275 300 325
-750
-650
-550
-450
-350
-250
-150
-50
50
150
250
350
450
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Depth below ID (µm)
Resid
ual S
tress (
MP
a)
Resid
ual S
tress (
KS
I)
Depth below ID (0.001")
Shot Peened Helical Compression Spring Fatigue Test Results
1.8M
cycles
190ksi
60.4M
cycles
150ksi
3.8M
cycles
170ksi
65.8M
cycles
150ksi
Red circles correspond to
inclusion size & depth
1.6M
cycles
200ksi
![Page 38: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/38.jpg)
InclusionLarge Inclusion (31.6 X 34.2 µm)
3.76M cycles to failure at 170ksi
Small Inclusion (12.6 X 12.9 µm)
60.4M cycles to failure at 150 ksi
![Page 39: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/39.jpg)
Questions?
![Page 40: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/40.jpg)
Raw Material Surface Defects
![Page 41: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/41.jpg)
Wire Drawing Defect
![Page 42: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/42.jpg)
Wire Drawing Defect
Defect Depth
![Page 43: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/43.jpg)
Check Streak Wire Drawing Defect
![Page 44: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/44.jpg)
Check Streak Wire Drawing Defect
![Page 45: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/45.jpg)
Check Streak Wire Drawing Defect
Crack Depth
![Page 46: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/46.jpg)
Wire Surface Defect
![Page 47: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/47.jpg)
Wire Surface Defect
![Page 48: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/48.jpg)
Raw Wire Quench Crack
![Page 49: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/49.jpg)
Wire Drawing Defect / Scab
![Page 50: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/50.jpg)
Wire Drawing Defect / Scab
![Page 51: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/51.jpg)
Non-Metallic InclusionsSteel Mill Imperfection
![Page 52: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/52.jpg)
Flapper Valve InclusionInitiation
![Page 53: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/53.jpg)
Flapper Valve Inclusion
![Page 54: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/54.jpg)
Flapper Valve Inclusion
![Page 55: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/55.jpg)
Spring Manufacturing Induced Defects
![Page 56: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/56.jpg)
Coiling Crack
![Page 57: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/57.jpg)
Post-Spring Manufacturing Defects
![Page 58: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/58.jpg)
Flapper Valve Edge Abrasion
![Page 59: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/59.jpg)
Flapper Valve Edge Abrasion
![Page 60: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/60.jpg)
Flapper Valve Edge Abrasion
![Page 61: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/61.jpg)
Spring Abrasion1.29M cycles to failure at 200ksi
![Page 62: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/62.jpg)
Flapper Valve Corrosion
![Page 63: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/63.jpg)
Flapper Valve Corrosion
![Page 64: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/64.jpg)
Flapper Valve Corrosion
![Page 65: Evaluation of Stress Concentrators and Their Effect ... · • Compressive residual stress from shot peening helps minimize the effect of stress concentrators –But, it does not](https://reader034.vdocuments.site/reader034/viewer/2022042417/5f32b8cfeff3b0064f16cd4b/html5/thumbnails/65.jpg)
Thursday Reminders
Exhibit Hall Open 10:00am – 2:00pm Hall C
Thank you for Attending the Metal Engineering eXpo 2019! See you in 2021!
Scan your badge at exhibitors’ booths to be automatically entered to win one of ten $100 Amazon gift cards!