Affiliations: Professor of Mechanical Engineering Emeritus, The
University of Akron, Akron, OH, USA | Alion Science and Technology, 4300 King St., Suite
101, Alexandria, VA, USA
Abstract: In this paper, a detailed model of a ship deck and attached dynamic
systems was developed and subjected to dynamic studies using two different
shock inputs: a triangular shaped velocity pulse and the vertical motion of the
innerbottom of the standard Floating Shock Platform (FSP). Two studies were
conducted, one considering four single degree-of-freedom systems attached at
various deck locations and another considering a three-mass system attached at
one location. The two shock inputs were used only for the multi-mass system
study. The triangular pulse was used for the four single degree-of-freedom
systems study. For the single degree-of-freedom systems study, shock spectra
were first calculated at the four mounting locations assuming the oscillators
were not present. Then the oscillator systems were added to these grid points
to determine the change in the shock spectra. First, the oscillators were added
one at a time, and then all the oscillators were added to the deck. The
multi-mass system was analyzed using both shock inputs. First, the fixed-base
modal masses and frequencies were determined. Then, the system as a whole was
attached to the deck and the spectrum values at the base point were determined
and compared to those for the free deck case. In the last step each mode of the
multi-mass system, represented by a single degree-of-freedom system with the
modal mass and appropriate spring stiffness, was considered individually to
determine the spectrum responses. Results of the free deck, the entire system
and individual modal responses are compared.
