SENT-Specimen

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SENT-specimen

The Anglo-Saxon abbreviation SENT stands for “single-edge notched tension,” and the SENT-specimen is referred to in German as a single-edge notched tensile test specimen.

Test specimen shape

W – specimen width B – specimen thickness H – specimen length s – distance between the two points of load displacement N – notch width a – notch depth D – hole diameter for adapter F – force (load) M – distance for drilling to accommodate the displacement sensors (inductive)

Fig.:

Schematic presentation of the SENT-specimen

dimensions (according [1, 2]):
W = 2 B
a = B
s = 3 W
D = W/3
c = W/3
d = 4/3 W

typical dimensions for plastics [3]:
W = 40 mm
H = 150 mm
B = 3...10 mm
s = 120 mm
a = 20 mm
N = 3 mm
D = 10 mm
M = 7 mm

designation:
SENT 10 $\rightarrow$ B = 10 mm

Determination equation

$f(a/W)=1.99-0.41(a/W)+18.7(a/W)^{2}-38.48(a/W)^{3}+53.85(a/W)^{4}\!\$

with 0$\leq$a$\leq$0.6

geometry criterion for metals:

$B,a,(W-a)\geq 2.5{\bigg (}{\frac {K_{I}}{R_{e}}}{\bigg )}^{2}$

geometry criterion for polymers:

$B,a,(W-a)\geq \beta {\bigg (}{\frac {K}{\sigma _{y}}}{\bigg )}^{2}$

It is valid: R_e = $\sigma$_y = yield stress (yield point)

The geometry constant $\beta$ depends on the material. (see also: geometry criterion, fracture toughness)

Application

The SENT-specimen can be used, for example, to characterize the crack propagation behaviour of thermoplastic and elastomeric materials under quasi-static stress.

A comprehensive selection of suitable specimens for fracture mechanics testing of plastics and composite materials is included in fracture mechanics specimens.

See also

• Specimen for fracture mechanics tests
• Geometry function
• Pure shear specimen
• RDE-specimen
• Fracture mechanics

References

[1]	Blumenauer, H., Pusch, G.: Technische Bruchmechanik. Deutscher Verlag für Grundstoffindustrie, Leipzig Stuttgart (1993) 3rd Edition, (ISBN 3-342-00659-5; see AMK-Library under E 29-3)
[2]	Anderson, T. L.: Fracture Mechanics. Fundamentals and Applications, 3rd Ed., CRC Press, Boca Raton (2005) (ISBN 978-0849316562; see AMK-Library under E 8-2); DOI https://doi.org/10.1201/9781420058215
[3]	Grellmann, W., Seidler, S. (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 231–236 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-807-5; see AMK-Library under A 22)