On the Feasibility of a Transient Dynamic Design Analysis Method

1992 ◽  
Author(s):  
George J. O'Hara ◽  
Patrick F. Cunniff
Keyword(s):  
Design Analysis ◽  
Analysis Method ◽  
Dynamic Design ◽  
Transient Dynamic

scholarly journals Feasibility of a Transient Dynamic Design Analysis Method

1994 ◽  
Vol 1 (3) ◽  
pp. 241-251
Author(s):  
Patrick F. Cunniff ◽  
George J. O’Hara
Keyword(s):  
Degrees Of Freedom ◽  
Time History ◽  
Design Analysis ◽  
Analysis Method ◽  
Dynamic Design ◽  
Fixed Base ◽  
Design Values ◽  
Rigid Mass ◽  
Comparison Of The Results ◽  
Three Degrees Of Freedom

This article addresses the degree of success that may be achieved by using simple equipment–vehicle models that produce time history responses whose equipment fixed base modal maximum response values are equivalent to those found in the U.S. Navy's dynamic design analysis method. The criteria of success is measured by a comparison of the results with typical interim shock design values. The equipment models reported are limited to two- degree and three degrees of freedom systems; the model of the vehicle to which the equipment is attached consists solely of a rigid mass and an elastic spring; and the shock excitation is produced by an ideal impulse that is applied to the vehicle mass.

Shock Analysis of a Stern Ramp Using Dynamic Design Analysis Method

2017 ◽  
Author(s):  
Jonas W. Ringsberg ◽  
Erland Johnson ◽  
Meng Zhang ◽  
Yunbo Yu
Keyword(s):  
Response Spectrum ◽  
Underwater Explosion ◽  
Structural Response ◽  
Vertical Direction ◽  
Design Analysis ◽  
Shock Load ◽  
Analysis Method ◽  
Dynamic Design ◽  
Loading Direction ◽  
Design Changes

Shock load caused by underwater explosion in naval battles can lead to malfunction of the equipment on-board naval vessels. It makes the ships vulnerable and they can lose the ability to accomplish their missions. This study presents a shock analysis, using the dynamic design analysis method (DDAM), of a naval ship stern ramp subjected to a non-contact underwater explosion. The objective is to evaluate the performance of the ramp subjected to a shock load, identify areas for structural improvements and recommend design changes. The DDAM in the commercial software ANSYS is used in the evaluation of the ramp. The structural response to the shock load is estimated by combined modal and response spectrum analyses. The shock load is applied in three directions (vertical, fore and aft, athwart ships) and the results show that the vertical direction is the most severe loading direction and critical to the functionality of the ramp. A parametric study is presented which shows which parameters that influence the most the structural response. The results from this study are used to suggest improvements of the ramp structure to make it more resistant to shock loads.

scholarly journals Dynamic Design Analysis Method DDAM

1996 ◽  
Vol 3 (6) ◽  
pp. 461-476 ◽  
Author(s):  
Gene M. Remmers ◽  
George J. O’Hara ◽  
Patrick F. Cunniff
Keyword(s):  
Earthquake Engineering ◽  
Large Scale ◽  
Field Testing ◽  
Design Analysis ◽  
Current Status ◽  
Response Analysis ◽  
Engineering Practice ◽  
Analysis Method ◽  
Dynamic Design ◽  
Basic Physics

This article describes the evolution of the dynamic design analysis method (DDAM) by assimilating information from references spanning more than three decades. This evolution began with attempts to use earthquake engineering practice, circa 1950, in dealing with hostile environments created by modern weaponry. It became necessary to develop new theories that went beyond the then current status. This led to research programs that went back to basic physics and engineering principles that resulted in a sound technique for naval applications. The elements of the technique were theoretically based and confirmed by laboratory and large scale field testing. One important example is the structural interaction effects between a vehicle and large equipment structures by means of a newly defined quantity called modal effective mass. Another example led to the discovery that attaching a vibration generator to a structure in an effort to find the frequencies useful for foundation motion response analysis was guaranteed to produce failure. DDAM continues to be used after its introduction 36 years ago. Although familiar in US and international naval circles, it is not well known by persons other than naval engineers. Many myths and misconceptions have grown during this period, so some of the major ones are addressed.

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