You can do this by creating a new report based on the work item traceability to the Iteration object and then edit the query in advanced mode to remove the dependency to the work item.

1) create a query, datasource DWH, select your project, select work item
2) add traceability from work item to Iteration
3) remove any condition
4) In format add attribute start/end date of iteration
5) In format remove all attribute from workitem
6) in advanced mode remove the iteration test in the on clause

Before:

SELECT DISTINCT T2.NAME,       T2.END_DATE,       T2.START_DATE,       T2.PARENT_ITERATION_NAMEFROM RIDW.VW_REQUEST T1INNER JOIN RIDW.VW_ITERATION T2ON (T2.ITERATION_ID = T1.ITERATION_ID) AND T2.PROJECT_ID = 433 WHERE T1.PROJECT_ID = 433  AND(T1.ISSOFTDELETED = 0 AND T2.ISSOFTDELETED = 0) AND(T1.REQUEST_ID <> -1 AND T1.REQUEST_ID IS NOT NULL) AND(T2.ITERATION_ID <> -1 AND T2.ITERATION_ID IS NOT NULL)

SELECT DISTINCT T2.NAME AS NAME1,       T2.END_DATE,       T2.START_DATE,       T2.PARENT_ITERATION_NAMEFROM RIDW.VW_REQUEST T1INNER JOIN RIDW.VW_ITERATION T2ON T2.PROJECT_ID = 433 WHERE T1.PROJECT_ID = 433  AND(T1.ISSOFTDELETED = 0 AND T2.ISSOFTDELETED = 0) AND(T1.REQUEST_ID <> -1 AND T1.REQUEST_ID IS NOT NULL) AND(T2.ITERATION_ID <> -1 AND T2.ITERATION_ID IS NOT NULL)