Plastic Strain is the result of dislocation movement and/or twinning.
Brittle fracture occours instead of deformation. Now think: Would you
think that the stress necessary for plastic deformation increases or
decreases with increasing strain rate? What will happen, when the strain
rate increases more and more?
thanks for your attaention
I know that by increasing strain rate the movement of dislocation
should be increased,but they themselves prevent their movement because
of their transverse of stress field,.. thus by these difficulties slip
and deformation should be decreased,so the yield point of metal should
be increaed,but my question is why this cuase brittle fracture and how
does it explain by formulas,
because I have a ceminerate about it that it should be takes 45
minutes and this is not enough.
email@example.com (mahmood shaikhattar) wrote in message
In cases where there is no plastic, viscous, or creep flow it is often
the case that increasing strain rate increases fracture stress because
of stress corrosion effects.
This is because slow strain rates give lots of time for corrosive
chemicals (like water vapor) to attack a stressed flaw tip.
There are also a few counterexamples where chemical corrosion tends to
broaden rather than sharpen crack tips in which case slow strain rate
gives higher fracture stress.
firstname.lastname@example.org (dave martin) wrote in message
ok thank u,
I find sth in this book" mechanical behavior of metals at extremely
high strain rates" by j.buchar,z.bilek,f.dusek.
It's about high velocity deformation of metals,but I don't know that
in high strain rate what's happen to metal that it causes fracture
because fracture need cracks and in this book talking about shock wave
in high strain rate,but I still don't know how cracks initiate that
high strain rate causes brittle fracture.
thank u very much.
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