In case of elasto-plastic problem it is mentioned that unloading of an integration point should be started along the elastic moduli when the solution gives a negetive increment of the plastic strain at the integration point. If anyone could elaborate it a little more, it will be really helpful.

Thanks 

Dear Esteemed Researcher,

It is my pleasure to invite you to submit your recent work as a contribution to the special issue on “Bridging of Material Length Scales” for the journal “International Journal of Materials and Structural Integrity” [http://www.inderscience.com/browse/index.php?journalID=162].