Incompatibility of Martensite Variant Clusters in Self-accommodation Microstructure in Ti-Ni-Pd High Temperature Shape Memory Alloy

ABSTRACTThe formation frequency of habit plane variant (HPV) clusters in Ni-25Pd-50Ti shape memory alloy was analyzed using electron backscattering diffraction (EBSD) on the basis of the geometrically nonlinear theory of martensite. Two types of cluster, diamond and wedge, were most commonly observed. The ratio of the formation frequency of the diamond to wedge clusters was approximately 1 : 3, whereas the rotation to keep the kinematic compatibility (KC) condition, θ *, was 3.9° and 0.0032°, respectively. The ratio of the formation frequency is quantified by the value of θ * which is an indicator of the incompatibility of the cluster. The origin of the diamond cluster is discussed based on the degree of incompatibility.

Geometrically Nonlinear Analysis Based on the Simple Truss

In modern architecture the bridge span becomes larger and larger, as well as the structure is more and more flexible and complicated, therefore geometrically nonlinear characteristics seem unprecedentedly significant. In this paper, the comparison of four calculation methods on a simple truss shows the limitations of linear theory and the importance of geometrically nonlinear theory, and then points out that in the complex structures such as the suspension bridge, we must consider the geometrically nonlinear problem.