1. Bend Testing

2. What is it?
Long beam has an applied load perpendicular to its main (longitudinal) axis.

3. What is it?
Often accompanied with two or more point supports.

4. What is it? Measures flexural strength, σ Also used for testing welds
Remember that strength and “stress” here are used interchangeably
Also used for testing welds

5. Bend Test Bend tests, not to be confused with drop tests.
Gradual application of load instead of instant shock.

6. Bend! Three kinds of bend tests discussed today
Wrap-Around Bend Test (Simple)
3 – Point Bend Test
4 – Point Bend Test

7. Wrap-Around Guided Bend Test
A specimen of thickness, T, is bent using a hand tool similar to a plumber’s pipe bender.

8. Wrap-Around Guided Bend Test
A specimen of thickness, T, is bent using a hand tool similar to a plumber’s pipe bender.

9. Wrap-Around Guided Bend Test
Welds are often tested using this method.

10. 3 – Point Bend Test
Like a compression test, but with three points

11. 3 – Point Bend Test

12. 3 – Point Bend Test
Insert Video

13. 3 – Point Bend Test
Measuring Stress F b d L

14. 3 – Point Bend Test Measuring Stress F = Load (N)
L = Length between supports (mm)
b = width (mm)
d = thickness (mm)

15. Application Testing structural components like Glulams
Layers of timber glued together, often used in structures

16. Application
Glulam

17. Application
Glulam

18. Application
Glulam

19. Application
Glulam Testing

20. Application Why? What was different about the test in the video?
Characterize limits
What was different about the test in the video?

21. 4 – Point Bend Test

22. 4 – Point Bend Test
Measuring Stress
F/2 F/2 b d L

23. 4 – Point Bend Test
Measuring Stress
F/2 F/2 b d L
Loading Span

24. 4 – Point Bend Test Measuring Stress
IF Loading Span is 1/3 of support span:
IF Loading Span is 1/2 of support span:

25. Bend Tests What’s the difference? Type of Bend Test 3-Point 4-Point
Type of Material
Homogeneous (plastics)
Non-Homogeneous (composites & wood)
Stress Concentration
Small and concentrated under the center loading point
Larger region to avoid premature failure
Specimen Deflection
Typically measured with the crosshead position
Typically measured with a deflectometer

26. Bend Tests Deflectometer is to transverse loading (bend testing)
Extensometer is to longitudinal loading (tensile testing)

27. Internal Behavior
Beam experiences both compression AND tension during bend testing

28. Sources: Title slide image: http://www. mpa. uni-stuttgart
Sources: Title slide image: Wrap-Around guided bend test: