Concept

Bauschinger effect — where it appears

The drop in yield stress a metal shows on reversal after it has been taken past yield in the opposite direction. It shortens the elastic range on the second half-cycle, rounds the stress-strain loop, and is the reason a cyclically loaded member dissipates energy long before it reaches its monotonic capacity.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

Also named here as unloading — the same set of essays touches all of them, so they are one junction rather than several.

What is left when the load comes off

Unload a section that has yielded and it does not return to nothing. It returns to a self-equilibrating stress field it did not have before, a permanent set, and an elastic range wider than the one it started with.

materials · Unloading

Yielding one way makes it easier to yield the other. Mild steel taken to a strain of 1.20% and then pushed back the other way. The stress falls by 550 N/mm² before it yields again, against a yield stress of 275 — the elastic range is twice the yield stress and not once it, which is the Bauschinger effect and is a consequence of the yield surface sliding rather than growing.

Yielding one way, and then the other

A material that has yielded in tension yields earlier in compression than it did the first time, and by an amount that is exactly what makes its elastic range twice its yield stress rather than once it. That is a property no monotonic test reports and every reversing structure depends on.

materials · Ductility

Named alongside it

The objects these essays reach for when they reach for this one.

Kinematic hardening Residual stress Unloading Autofrettage Buckling-restrained Cyclic loading Ductility Energy dissipation Free body Hysteresis Low-cycle fatigue Permanent set

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