Single crystal deformation vis slip and twinning

Single crystals can deform via slip or twinning. When slip occurs we need to calculate the stress necessary to activate slip. We do this by using the critical resolved shear stress and the equations for resolved stress as a function of loading direction, slip plane, and slip direction. We can use the dot product to calculate the angle between these directions.
Twinning occurs when large groups of atoms cooperatively shift in the same direction to create a grain boundary that preserves mirror symmetry.

[@Ryan-vc8dk]

Thank you for explaining the twin so easily to be understood!

[@TaylorSparks]

Happy to help!

[@피아뉴김]

hi i'm korean student
when my professor exprain this in korea languague
i didn't understand about "tenslie stress" even if my native language
so i have to find ather lecture
surching surching....
now i find this grate lecture
i understanding all of this thank you

[@TaylorSparks]

💪🏻💪🏻💪🏻

[@kevinpham7085]

this was so much simpler than how my prof explained it, thank you so much!

[@josephfulford2770]

You made somethingn that made no sense make sense, thank you!

[@TaylorSparks]

Very glad to do it

[@pegaferno4429]

At 2:20 is there a way to calculate what that extension would be, given the material has a metallic FCC lattice?

[@alvinlee9619]

why cos(45) x cos(45) is maximum value?

[@TaylorSparks]

well, the resolved shear stress gets minimized, not maximized. cos(90)=1 and it gets lower as we go towards cos(45). So mathematically it makes sense that we want to minimize that term. Recall that slip normal and slip direction are always going to be normal to one another so they have a fixed 90degree relationship one to another.

[@kylecrooymans2762]

@@TaylorSparks How does cos(90)=1?

[@user-rr1rs3my3o]

​@@kylecrooymans2762 you have to go elementary school again 😄

[@mamosimo3804]

اين الطرجمة باللغة العربية 😭

[@mamosimo3804]

اين الطرجمة باللغة العربية 😭