Elastomers with embedded carbonyl iron particles, anisotropically arranged during the material curing in magnetic field form smart magnetorheological elastomers (MREs). They are capable of significant (here: up to nine-fold) changes of their mechanical properties under external magnetic field. These novel materials are becoming of utmost importance for industry. We have already studied relaxation properties of MRE based on polyurethane (PU) by SAXS (speckle analysis, XPCS). The latter yielded plausible, yet qualitative and ambiguous description. In view of a number of open questions still remaining unanswered, the proposed experiment is aimed at complementing XPCS with the study of elastomer matrix through SANS analysis. Morphology and arrangement of PU hard domains (310 nm in size), considered embedded nanoobjects, will be studied in relaxed MRE and under internal strain. The latter is caused by the action of organised structures of iron particles, responding to external magnetic field. By including samples long pretreated with alternating magnetic field the effect of material wear will be seen. The results will facilitate further improvement of the performance of these MREs.