#PRIMARY DATUM ISO#
#PRIMARY DATUM SERIES#

In regard to the DSCDM, the requirements came from existing GD&T drawing-based standards (e.g., ASME Y14.5M, ISO 1101, and ISO 5459 ). “The first step in data modeling is to define the data requirements”. The model presented in STEP Part 47 will be referred to as “the Part 47 model” throughout the remainder of this paper. Additionally, a portion of the data model presented in STEP Part 47 is reviewed and a comparison is made between it and the DSCDM.

This paper presents this data model, which will be referred to throughout the remainder of the paper as the DSCDM (Datum System Conceptual Data Model). The portion of the semantics that this data model defines encompasses the concepts of datum systems, datums, datum features, and datum targets. As “a data model is an effective technique to define the shareable semantics that are essential to the success of data communication in an integrated environment”, a conceptual data model has been developed that defines a portion of the semantics necessary for the electronic exchange of GD&T data among the design, manufacturing, and inspection divisions of an enterprise. However, with the advent of computer-aided design, manufacturing, and inspection equipment, the ability to exchange these requirements in a computer-sensible manner has become increasingly more desirable. The vessel type conventions do not have any effect on time history data.Traditionally, geometric dimensioning and tolerancing (GD&T) requirements have been exchanged with technical drawings.

Primary time history is always measured relative to global axes, and superimposed time history relative to primary axes. To handle this OrcaFlex uses ramping during the build-up period to smooth the transition from the static state to the position and motion given in the time history. The position and velocity specified by a time history for the start of the simulation will not, in general, match the static state from which OrcaFlex starts the simulation. If you have suitable data for the wave elevation then you can use that to specify the wave by time history. If there is any wave-generated motion present in a vessel's time history motion then the OrcaFlex wave data must match the wave that generated that motion. The time values in a vessel time history need not be equally spaced. That is, if your time history data are defined as the displacement of the datum point away from its initial position you need to add in the offset, of the datum point from the vessel's local origin, into your time history data. These are the positions of the datum point measured relative to the primary position of the vessel, in the primary frame axes directions.įor details of how rotations are applied, see order of application of rotations.īecause the superimposed time history motion defines the position of the datum point, measured in the primary motion frame, your time history data for the surge, sway, and heave motion must be inclusive of the offset of the datum point from the vessel's local origin. For superimposed motion, the degrees of freedom are surge, sway, heave, roll, pitch and yaw.These are the positions of the datum point measured relative to the global axes. For primary motion, the degrees of freedom are X, Y, Z, rotation 1, rotation 2 and rotation 3.

These data define the vessel motion by specifying the six degrees of freedom of the vessel as a function of time. To do so, you set the primary motion or superimposed motion calculation data (or, exceptionally, both) to time history, and then define the time history data on the primary motion or superimposed motion page (or both).

#PRIMARY DATUM SERIES#

Time history data allow you to define the vessel motion as a series of time-dependent positions.

Primary datum