Analysis Functions (pybow.analysis)

Beckhoff 1964

pybow.analysis.beckhoff1964(data, MoE, MoR[, name=None[, shape=halfround[, G=None[, braceheight=None[, strict=False]]]]])

Calculate bow properties from artefact measurements after the method described in Beckhoff 1964. [kb1964] See Beckhoff 1964 for a description of the method.

Parameters:
  • data (pandas.DataFrame) – A dataframe containing a sequence of measurements as described in Limb Measurement Conventions.
  • MoE (float) – The artefact material’s modulus of elasticity. (in Pa)
  • MoR (float) – The artefact material’s modulus of rupture. (in Pa)
  • name (str) – The artefact name. If given, the result pandas.Series’ name attribute will be set to its value.
  • shape (function) – A bundle function (see Beam Theory Properties) describing the cross-section shape to assume for the artefact.
  • G (float) – A Beckhoff-G (see Beckhoff 1964) for the artefact. If no value is given, a rough approximation will be estimated. (default behaviour)
  • braceheight (float) – A brace height for the artefact. (in cm) If no value is given, a rough approximation will be estimated. (default behaviour)
  • strict (bool) – Indicated whether to calculate bending force strictly by maximum permissible stress or apply an approximation of Beckhoff’s rounding up beyond that level. (default behaviour)
Return type:

tuple(pandas.Series, pandas.DataFrame):
Returns:

A tuple:

  • A pandas.Series containing the calculated bow properties.
  • A pandas.DataFrame based on data, but with all additionally calculated properties.

Calculated Properties

beckhoff1964() calculates the following properties:

  • Draw weight (Series key: drawweight, in N)
  • Draw length (Series key: drawlength, in cm)
  • Brace height (Series key: braceheight, in cm)
  • Effective length (Series key: ntnlength, in cm)
  • Set taken (Series key: stringfollow, in cm)
  • Energy stored (Series key: energy, in J)

Data Requirements

beckhoff1964() computes on the following properties:

  • Second moment of area (data['I'])
  • Neutral plane distance to belly (data['e_belly'])
  • Section modulus towards belly (data['W_belly'])

Any of these columns not present in data will be calculated from data['width'] and data['thickness'] via shape.

Junkmanns 2013

pybow.analysis.junkmanns2013(data, correlationfactor[, spread=None[, name=None]])

Calculate bow properties from artefact measurements after the method described in Junkmanns 2013. [jj2013] See Junkmanns 2013 for a description of the method.

Parameters:
  • data (pandas.DataFrame) – A dataframe containing a sequence of measurements as described in Limb Measurement Conventions.
  • correlationfactor (float) – A Junkmanns correlation factor for the artefact material. (See Junkmanns 2013)
  • spread (float) – Percentage of spread in correlation factors for artefacts of this material. If supplied, low and high boundaries of draw weight get calculated. They are NaN otherwise.
  • name (str) – The artefact name. If given, the result pandas.Series’ name attribute will be set to its value.
Return type:

tuple(pandas.Series, pandas.DataFrame):
Returns:

A tuple:

  • A pandas.Series containing the calculated bow properties.
  • A pandas.DataFrame based on data, but with all additionally calculated properties.

Calculated Properties

junkmanns2013() calculates the following properties:

  • Draw weight (Series key: drawweight, in N)
  • Low end of draw weight spectrum (Series key: drawweight_low, in N)
  • High end of draw weight spectrum (Series key: drawweight_high, in N)
  • Draw length (Series key: drawlength, in cm)
  • Effective length (Series key: ntnlength, in cm)

Data Requirements

junkmanns2013() computes on the following properties:

  • Junkmanns ‘Querschnittsstärke’ (data['Qs'])
  • Junkmanns ‘Biegewiderstand’ (data['Bw'])

If these columns are not present in data, they will get calculated from data['width'] and data['thickness'] after Junkmanns’ formula.

[kb1964]Beckhoff, K 1964, ‘Der Eigenbogen von Vrees‘, Die Kunde N.F. 15, pp. 113–125.
[jj2013]Junkmanns, J 2013, Pfeil und Bogen, Verlag Angelika Hörnig, Ludwigshafen.