Kinematic and Isotropic Hardening

In summary, Kinematic and Isotropic hardening are two types of hardening that occur in materials when they are subjected to stress. Kinematic hardening involves the yield surface moving while the size remains the same, while Isotropic hardening involves the yield surface growing in size while the center remains in the same place. These concepts are important in understanding material behavior under stress and there are several resources available for further reading on the topic.
  • #1
darkelf
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0
Hello,

Could anyone help explain what Kinematic and Isotropic hardening are. Any brief explanation or reference to a good book that explains these topics would be very useful.

Thank you
 
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  • #2
I don't spend a lot of time dealing with yielding, so my answer is going to be very basic and fundamental. You'll want to get someone like Mapes or Astronuc in here to help.

Imagine the three orthogonal axes about a point of which the axes are [tex]\sigma_1, \sigma_1[/tex] and [tex]\sigma_3[/tex]. Now draw a sphere around that point. That sphere will coincide with the elastic limit. As the stress at a point increases, a path will go from the state of 0 stress to somewhere in this strress space until it eventually hits the yield surface. As you push past the yield surface by increasing stresses, the material will harden and cause a permanent set in the material when the load is released. For isentropic hardening, the yield surface will grow in size and it will have its center remain in the same place in the stress space. For kinematic, the yield surface moves but the size stays the same. There is also a mixture of the two called mixed hardening.http://www.engin.brown.edu/courses/en222/Notes/plasticity/plasticity.htm

http://www.google.com/url?sa=t&source=web&ct=res&cd=2&url=http%3A%2F%2Fecow.engr.wisc.edu%2Fcgi-bin%2Fget%2Fmsae%2F441%2Fstone%2Fnotes%2Fmse441lectureno.20kinematicvsisotropichardening.ppt&ei=Tbu2SZmIEaGbtwfen-yyCQ&usg=AFQjCNG2Y5QXYXcNcVUWdNuihF2pr0ktKA&sig2=FsGt4XflMFcQsytLBtsr9w

http://www.google.com/url?sa=t&source=web&ct=res&cd=5&url=http%3A%2F%2Fpersonalwebs.oakland.edu%2F~l8smith%2Fjunk3%2FNewMetalFormingNotes%2Fch%25204%2520hardening.pdf&ei=Tbu2SZmIEaGbtwfen-yyCQ&usg=AFQjCNGgVfgHikwcz07S9rkZskt5ShRncg&sig2=iX2hshd2ALJx82aMysbBYQ

http://books.google.com/books?id=P2...X&oi=book_result&resnum=7&ct=result#PPA217,M1
 
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What is kinematic hardening?

Kinematic hardening is a type of material behavior in which the yield stress of a material increases as it is subjected to repeated loading and unloading cycles. This is due to the accumulation of permanent deformations in the material.

What is isotropic hardening?

Isotropic hardening is a type of material behavior in which the yield stress of a material increases uniformly in all directions as it is subjected to repeated loading and unloading cycles. This is different from kinematic hardening, where the increase in yield stress is only in one direction.

What are the main differences between kinematic and isotropic hardening?

The main difference between kinematic and isotropic hardening is the direction in which the yield stress increases. In kinematic hardening, the increase is only in one direction, while in isotropic hardening, it is uniform in all directions. Additionally, kinematic hardening is associated with permanent deformations, while isotropic hardening is not.

How do kinematic and isotropic hardening affect the behavior of materials?

Kinematic and isotropic hardening can both lead to an increase in the yield stress of materials, making them more resistant to deformation and failure. However, they can also cause the material to become more brittle and prone to fracture due to the accumulation of permanent deformations.

What are some real-world applications of kinematic and isotropic hardening?

Kinematic and isotropic hardening are commonly observed in materials used in structural and mechanical engineering, such as metal alloys and polymers. They are also important considerations in the design of structures and components that are subjected to repeated loading and unloading, such as bridges, buildings, and machines.

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