Woboditsch test

The Woboditsch test (named after the inventor Walter Woboditsch ) is a physical analysis method for the simple determination of the flexibility of strand-shaped bodies.

theory

The basis for the Woboditsch test is provided by the phenomenon of the resonance frequency . The value for the flexibility of a strand-shaped body is obtained:

{\ displaystyle F = {\ frac {1} {fl ^ {2}}} = {\ frac {2 \ pi} {\ sqrt {8}}} {\ sqrt {\ frac {m '} {EJ}} }}

in which:

${\ displaystyle f}$ the resonance frequency
${\ displaystyle m '}$ the specific mass (mass per unit length)
${\ displaystyle E}$ the modulus of elasticity (modulus of elasticity) and
${\ displaystyle J}$ the area moment of inertia

is.

In general, one can say: the greater its mass and the smaller the modulus of elasticity and the geometrical moment of inertia, the more flexible a test object is.

Suitable test items

The test is based on string-shaped bodies as test objects. These are especially cables , lines and ropes .

Test device

A device for a test according to Woboditsch must at least consist of a one-sided clamping device, which is excited by a crank and thus made to vibrate. The slider crank itself must be driven by a variable-speed motor so that different, defined excitation frequencies can be implemented. According to the current state of the art, a frequency converter is recommended for this.

application

There is no test device on the market that works according to the Woboditsch principle. The procedure is used in isolated companies - due to the lack of a standard , however, comparative measurements between trading partners are not easily possible.

swell

Patent US3610027 : Method of determining flexibility of elongate bodies. Published on October 5, 1971 , applicant: Oberspree Kabelwerke VEB, inventor: Walter Woboditsch. ‌