Validation of an inverse model to determine ice load magnitude and load patch on a ship hull

To create safer and more efficient ice-going hull designs, more information about ice loads is needed. Conventional ice load measurements have focused on determining ice loads, e.g., from frames but do not provide information on the load patch. The purpose of this paper is to determine the magnitude of the loading and the load patch. The hull of ropax ferry Aurora Botnia was instrumented with strain gauges during her construction. In the aft shoulder of the ship, eight strain gauges were installed on the plate field and eight shear strain gauges on the ice frames. Also, a set of physical calibration pushes were carried out after the instrumentation. The calibration pushes were done with contact areas of varying size to validate an inverse method, developed to determine ice loads on the aft shoulder based on strain gauge measurements. The inverse method applies an influence coefficient matrix and Tikhonov regularization. The influence coefficient matrix is based on the load-strain relation from a finite element (FE) model of the aft shoulder. An ill-posed inverse problem of determining pressure on the hull is solved using the Tikhonov regularization. The load patch and magnitude agreed well with the loading and load patch applied in the physical calibration pushes.