Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=SENB-Prüfkörper}} {{PSM_Infobox}} SENB-specimen FORCETOC The English abbreviation SENB stands for "single-edge notched bend" and the SENB test specimen is referred to in German as a three-point bending test specimen. ==Requirements for the test specimen geometry== In the experimental determination of fracture mechanical values, the following basic conditions must be observed:..."

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Created page with "{{Language_sel|LANG=ger|ARTIKEL=SENB-Prüfkörper}} {{PSM_Infobox}} SENB-specimen __FORCETOC__ The English abbreviation SENB stands for "single-edge notched bend" and the SENB test specimen is referred to in German as a three-point bending test specimen. ==Requirements for the test specimen geometry== In the experimental determination of fracture mechanical values, the following basic conditions must be observed:..."

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{{Language_sel|LANG=ger|ARTIKEL=SENB-Prüfkörper}}
{{PSM_Infobox}}
SENB-specimen
__FORCETOC__
The English abbreviation SENB stands for "single-edge notched bend" and the SENB test specimen is referred to in German as a three-point bending test specimen.

==Requirements for the test specimen geometry==

In the experimental determination of fracture mechanical values, the following basic conditions must be observed:

# The test specimen dimensions must be substantially greater than the extent of the plastic zone at the crack tip under the respective test conditions.
# The load, the crack-tip-opening displacement, and the load-load line displacement must be continuously detectable.
# For the calculation of the [[Fracture Mechanics|stress intensity factor ''K'']] at the moment of the unstable crack propagation, the load on the test [[specimen]] and the critical crack length must be exactly determinable.
# For the corresponding test body geometry, the determination equation, e.g. the relationship between loading and crack length should be known.

In order to meet these requirements, a number of specifications have been adopted that have been adopted from the ASTM standard E 399 [1] into the existing standards.

==Test specimen==

{| border="0"
|[[file:senb_1a.jpg|400px]]
|
{| border=0
|-valign="top"
|W
|–
|specimen width
|-valign="top"
|B
|–
|specimen thickness
|-valign="top"
|L
|–
|specimen length
|-valign="top"
|s
|–
|support span
|-valign="top"
|N
|–
|notch width
|-valign="top"
|a
|–
|notch depth
|-valign="top"
|F
|–
|load
|}
|}
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Schematic representation of the SENB specimen
|}

'''Dimensions (according to [1, 2]):'''
 
W = 2 B, special case: W = B up to 4 B
 
s = 4 W <math>\rightarrow</math> s/W = 4, s = 40 mm
 
L = 4,5 W
 
a = (0,45–0,55) W
 
N <math>\ge</math> 1,5 mm for U- und V-notch for metals
 
'''Typical dimensions for plastics (according to [3, 4]):'''
 
W = 10 mm
 
B = 4 mm (variation B = 2...10 mm)
 
L = 80 mm
 
s = 40 mm (variation s = 40...70 mm)
 
a = 2 mm (variation a = 0,5...7,5 mm)
 
N <math>\ge</math> 1,5 mm
 
l <math>\ge</math> 1,3 mm (razor blade, notch length)
 
r <math>< \!\ </math> 0,25 mm (notch radius)
 
r <math>\approx</math> 0,125 µm (razor blade, notch radius)

==Conditional equation==
{|
|-
|width="20px"|
|width="500px" | <math>K_I = \frac{F \cdot s}{B \cdot W^{3/2}} f(a/W)</math>
|}

{|
|-
|width="20px"|
|width="500px" | <math>f(a/W) \!\ </math> für <math>s/W = 4 \!\ </math>
|}

'''Tada [5]:'''
{|
|-
|width="20px"|
|width="500px" | <math>f_1(a/W) = 2,9(a/W)^{1/2}-4,6(a/W)^{3/2}+21,8(a/W)^{5/2}-37,6(a/W)^{7/2}+38,7(a/W)^{9/2} \!\ </math>
|}

'''Srawley und Gross [6]:'''
{|
|-
|width="20px"|
|width="500px" | <math>f_2(a/W) = \frac32(a/W)^{1/2} \cdot \frac{[1,99-a/W \cdot(1-a/W) \cdot (2,15-3,93a/W+2,7(a/W)^2)]}{(1+2a/W) \cdot (1-a/W)^{3/2}} \!\ </math>
|}

for s/W = 4
 
f2(a/W) shows correspondence with f1 in the range 0 < a/W < 0,6, then lower values

'''Geometry criterion for metals:'''
{|
|-
|width="20px"|
|width="500px" | <math>B, a, (W-a) \geq 2,5 \bigg(\frac {K_I}{R_e}\bigg)^2</math>
|}

'''Geometry criterion for plastics:'''
{|
|-
|width="20px"|
|width="500px" | <math>B, a, (W-a) \geq \beta \bigg(\frac {K}{\sigma_y}\bigg)^2</math>
|}

where: Re = <math>\sigma</math>y = tensile yield stress (yield strength)
 
The geometry constant <math>\beta</math> is material-dependent. (see [[Geometry Criterion | geometry criterion]], [[Fracture Mechanics | fracture toughness]]) 
A comprehensive assortment of suitable test specimens for fracture mechanics investigations in plastics and composites is contained in fracture mechanics test specimens.

==See also==

*[[Notch | notch]]
*[[Notch Sensitivity | notch sensitivity]]
*[[Notch Geometry | notch geometry]]
*[[Specimen | specimen]]

'''References'''
{|
|-valign="top"
|[1]
|ASTM E 399 (2024): Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness of Metallic Materials
|-valign="top"
|[2]
|Blumenauer, H., Pusch, G.: Technische Bruchmechanik. Deutscher Verlag für Grundstoffindustrie, Leipzig Stuttgart (1993) 3. Auflage, (ISBN 3-342-00659-5; see under [[AMK-Büchersammlung|AMK-Library]] E 29-3)
|-valign="top"
|[3]
|[[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser Munich (2022) 3. Edition, (ISBN 978-1-56990-806-8; see under [[AMK-Büchersammlung|AMK-Library]] A 22)
|-valign="top"
|[4]
|MPK-Procedure MPK-ICIT (2016): Testing of Plastics – Instrumented Charpy Impact Test: Procedure for Determining the Crack Resistance Behaviour Using the Instrumented Impact Test
|-valign="top"
|[5]
|Tada, H., Paris, P. C., Irwin, G. R.: The Stress Analysis of Cracks Handbook, 3rd Ed., ASME Press, New York (2000) DOI: https://doi.org/10.1115/1.801535
|-valign="top"
|[6]
|Srawley, J. E., Gross, B.: Stress Intensity Factors for Bend and Compact Specimens. Engineering Fracture Mechanics (1972) 587–589. DOI: https://doi.org/10.1016/0013-7944(72)90069-0
|}

[[Category:Bend Test]]
[[Category:Fracture Mechanics]]
[[Category:Instrumented Impact Test]]
[[Category:Specimen]]

SENB-Specimen - Revision history