# BORE

Bulk Data Entry Defines the surface, coordinate system, and parameters required to request Bore Deformation output for Static Analysis Subcases.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
BORE BID CID USID ORDER MIDPNT

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
BORE 6 2 4 3

## Definitions

Field Contents SI Unit Example
BID Bore identification number.

No default (Integer > 0)

CID Identification number of a user-defined Cylindrical Coordinate System with the Z-axis aligned with the central axis of the Bore.

No default (Integer > 0)

USID Identification number of a Bore Surface (SURF Bulk Data Entry) which defines the internal surface of the Bore.

No default (Integer > 0)

ORDER Defines the order of the Fourier series until which the Bore distortion is calculated.

No default (100 > Integer > 0)

MIDPNT Controls the inclusion of mid-nodes of second order elements on the bore surface.
YES
The mid-nodes of second order elements on the Bore surface are included.
NO (Default)
The mid-nodes of second order elements are not included. Only the corner nodes are used.

1. All “displacement” used in the context of bore distortion analysis is the displacement in radial direction of cylindrical system defined in the CID field in this Bulk Entry.
2. The BORE Bulk Data Entry determines the various orders of Bore Distortion from Displacement results associated with the grid points of the Bore surface. The Distortion Orders are determined by representing the Bore Deformation profile by means of a Fourier series and evaluating the Fourier series using the Fast Fourier Transform (FFT).(1)
${R}_{L}={r}_{0}+\sum _{k=1}^{N}\left({A}_{k}\text{cos}\left(k\theta \right)+{B}_{k}\text{sin}\left(k\theta \right)\right)$
(2)
${M}_{k}=\sqrt{{A}_{k}^{2}+{B}_{k}^{2}}$
Where,
${R}_{L}$
Bore Deformation of the Layer $L$ until the order $N$ (defined via ORDER field)
$\theta$
Polar angle
${A}_{k}$ and ${B}_{k}$
Fourier series coefficients of the ${k}_{\prime }$ th order
${r}_{0}$
Zero order deformation
${M}_{k}$
Magnitude of the ${k}_{\prime }$ -th order deformation

Circularity is also output if BORE entry is present in the model. Circularity is:

Circularity (at each Z-depth) = Max(True Distortion) – Min(True Distortion)

Where,

True Distortion = Displacement of the grid – (0th order deformation + 1st order deformation)

At a particular Z-depth, each grid of the bore at this depth will have a corresponding value of True Distortion. The Circularity value is the difference between maximum and minimum true distortions of grids at a particular Z-depth.

3. If BORE Bulk Data Entries are present in the input deck, two output files, <filename>_bdst.mvw and <filename>.bdst are generated. The magnitude of bore distortion for each order is plotted versus the depth of the Bore (Z-depth), where Bore Deformation is calculated (Layer $L$ ). Additionally, circularity is also plotted versus the depth of the Bore (Z-depth).
4. Bore deformation output is currently only available for Static Subcases.