Numerical-experimental method for the identification of plastic properties of polymers from microhardness tests

An inversion method for identification of elastoplastic properties for engineering materials from limited spherical indentation measurements

“…Furthermore, in conventional physical model of spherical indentation [4,17,18,22], the friction between the indenter and the indented material has a negligible effect on the indentation curve and for this reason the contact on the common surface between the indenter and the sample can be assumed frictionless. Since an indentation test is nondestructive one (shallow indentation) and can be applied both to small samples or to fabricated machine and structural elements, the above physical model is used for large class of pure and alloyed engineering materials [2][3][4]17,19,20].…”

“…As it follows from the general theory of variational inequalities for monotone potential operators [6,15], the variational inequality (19) has a unique solution u 2 V, if conditions (9) hold.…”

“…Use this iteration in (III) and find the next iteration u ð1Þ n . Repeat this process for the iteration u ðmÞ n , until the fulfillment of the conditions (19) and (20). (V) Continue the steps (III)-(IV) for the next values p ¼ pÀ1 þ Á, p ¼ 2, 3, .…”

“…The results obtained here show that the identification/inverse problems related to determination of the elastoplastic properties of materials based on indentation tests, have ill-conditioned nature. For near linear hardening materials, numerical relationships between material properties and indentation responses have been obtained in [18][19]. A utilization of connection between the indentation curve P ¼ PðÞ and other mechanical properties, in particular Brinell Hardness, were given in [1,16].…”

Applications of synchrotron radiation micro-focus techniques to the study of polymer and biopolymer fibers

“…Finite element analysis of such processes [43] can be complimented by ex situ or in situ indentation experiments using a dedicated Vickers microindenter setup [31,44,45]. Thus, the indentation of a single UHMW-PE fiber normal to the fiber axis with 30 mN force results in irreversible domain rotation around the fiber axis due to plastic deformation [31].…”