Theories of failure and tensile testing

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SUMMARY

The discussion centers on the development of theories of failure derived from 1-D tensile testing and the limitations of extending these theories to 2-D and 3-D testing. Participants highlight the significance of fatigue in material failure, particularly how geometric shapes can concentrate flexural damage, leading to failure initiation. A notable example mentioned is the recent research on bent spaghetti, which demonstrated that pre-stressing through torsion can influence the fracture behavior of materials. The conversation emphasizes the need for further exploration of multi-dimensional testing methodologies.

PREREQUISITES
  • Understanding of tensile testing principles
  • Familiarity with material fatigue concepts
  • Knowledge of failure theories in materials science
  • Basic grasp of geometric influences on material behavior
NEXT STEPS
  • Research advanced theories of failure in 2-D and 3-D contexts
  • Explore the impact of geometric shapes on material fatigue
  • Investigate the mechanics of torsion in material testing
  • Study case examples of multi-dimensional tensile testing applications
USEFUL FOR

Materials scientists, mechanical engineers, and researchers focused on material testing methodologies and failure analysis will benefit from this discussion.

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Why theories of failure have been developed from 1-D tensile testing. Why can't we go 2-D testing or 3-D testing?
 
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Can you give any examples of where these additional types of testing would be beneficial?
 
There was recent work on why bent spaghetti shatters rather than 'just' snaps.
https://phys.org/news/2018-08-mathematicians-age-old-spaghetti-mystery.html
IIRC, they found that applying torsion to um, pre-stress it made it snap clean when bent...

Per OP's query, I think the answer lies in the study of 'fatigue', where unfortunate shape concentrates flexure damage to initiate failure. Once that begins, a simpler model may approximate...
 
JBA said:
Can you give any examples of where these additional types of testing would be beneficial?
I am just asking why we are using theories of failure to determine 2-D faliure stresses why not practically test it as it is done with 1-D
 
Nik_2213 said:
There was recent work on why bent spaghetti shatters rather than 'just' snaps.
https://phys.org/news/2018-08-mathematicians-age-old-spaghetti-mystery.html
IIRC, they found that applying torsion to um, pre-stress it made it snap clean when bent...

Per OP's query, I think the answer lies in the study of 'fatigue', where unfortunate shape concentrates flexure damage to initiate failure. Once that begins, a simpler model may approximate...
I have a just simple question why theories of faliure was developed for 2-D and 3-D failure??
 

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I have encountered a vertically oriented hydraulic cylinder that is designed to actuate and slice heavy cabling into sections with a blade. The cylinder is quite small (around 1.5 inches in diameter) and has an equally small stroke. The cylinder is single acting (i.e. it is pressurized from the bottom, and vented to atmosphere with a spring return, roughly 200lbs of force on the spring). The system operates at roughly 2500 psi. Interestingly, the cylinder has a pin that passes through its...
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