Numerical Study on the Residual Ultimate Strength of Hull Girder of a Bulk Carrier After Ship-Ship Collision

Abstract

The purpose of the present study is to investigate residual Ultimate Longitudinal Strength (ULS) of bulk carriers after ship-ship collision. A series of a large-scale explicit finite element analysis (FEA) as well as simplified analysis (SA) are carried out using a cape size bulk carrier. In order to accurately investigate collapse mechanism of “damaged ships” under vertical bending moment nonlinear FEA are carried out where two steps analysis is adopted. First step is ship-ship collision analysis; Second step is ULS analysis of the damaged ship. Ship-ship collision analysis is carried out assuming the right angle collision at the midship region of the struck ship, and damage extent of the struck ship is estimated with varying collision speed of 3kt, 6kt, 9kt and 12kt. In the second step of analysis, residual ULS analysis is carried out taking into account residual stress and deformation of the struck ship caused by ship-ship collision. Collapse mechanism of the bulk carrier in damaged condition due to sagging moment as well as combination of longitudinal and horizontal bending moment is investigated and discussed in detail. ULS of hull girder of the bulk carrier in intact condition is also estimated and compared with that in damaged condition. The effect of damaged condition on the reduction of ULS is discussed in detail. Finally some of numerical methodologies are summarized in assessing residual ULS of hull girder after collision.

FPSO collision local damage and ultimate longitudinal bending strength analyses

“…The ultimate longitudinal strength of a Panamax bulk carrier in intact and damaged conditions was investigated by Yamada and Ogawa (2011) and Yamada (2014) using the finite element program LS-DYNA and the simplified Smith's method. The ultimate strength in the damaged condition was estimated assuming a collision on mid-ship where the damage was artificially created.…”

Reduction in ultimate strength capacity of corroded ships involved in collision accidents

“…intact conditions in Table 5) are presented in Section 3.3.1. Yamada (2014) presented a residual strength index, RSI2 = M U /M P , to show the dependence of ultimate strength due to age for intact corroded vessels without collision damage; M U is the ultimate vertical bending moment, M P is the ultimate fully plastic bending moment. In the current study, the residual strengths of the undamaged and damaged hull structures were calculated and assessed with respect to the same reference axis which was in parallel to the water surface.…”

“…The residual ultimate strength in damaged condition was calculated in the cross-section that had the largest damage expansion (see above and Figure 6) in the FE analysis. The residual strength index RSI2 according to Yamada (2014) was used in the assessment which compared all the damaged and the intact cases in Table 5. Figure 12 presents the results in hogging and sagging conditions.…”

“…Considerable research efforts have been spent on the structural response during collision as well as on the residual ultimate strength of struck ships. Examples of such investigations where CONTACT Jonas W. Ringsberg Jonas.Ringsberg@chalmers.se the representation of the material and its characteristics can be found in AbuBakar and Dow (2016), Ehlers (2010), Ehlers and Østby (2012), Hogström and Ringsberg (2012), Hogström et al (2009), Marinatos and Samuelides (2015), Samuelides (2015), Storheim, Amdahl, and Martens (2015), Storheim, Alsos, et al (2015), Yamada (2014), and Zhang and Pedersen (2017). Faisal et al (2016) studied the hull collapse strength of double hull oil tankers after collisions using a statistical approach.…”