Effect non linear material properties Clause Samples

Effect non linear material properties. Materials such as duplex stainless steels have non linear stress-strain properties in the range of operational stress levels. This shall be taken into account where it has an impact on performance. If the material stress- strain curve is not determined from tests the curve shown below may be adopted. The curve shall be linear from zero to a point where 0,1 % strain corresponds to a stress of 200 MPa. From there on it shall be parabolic through a point corresponding to 0,2 % permanent strain and the specified 0,2 % proof stress. σy 200 MPa 0.2% The limits on stress and strain imposed for HISC design ensure that the effect of non-linearities will only be significant in localised areas. Structural analysis to determine load distribution and cross sectional forces may therefore be performed as conventional linear elastic pipe stress analysis using a Young’s modulus of 200 000 MPa. To determine the distribution of stress and strain across a cross section allowance shall be made for non- linearity.