HCM rainflow counter relies on node_id being the assessment point #153
Description
Problem description
The current HCM rainflow counter treats multi indexed load signal differently if one node level is named node_id. That means that load signals that are defined per element and thus have only element_id in their index levels, are not properly processed.
The HCM rainflow counter mus be agnostic to the index level of the assessment points.
Requirements
If the load signal is multi indexed, the HCM rainflow module must insist that one level is load_step. All the others are considered to define the assessment point.