Method and apparatus for testing of shear stiffness in board

An apparatus for testing the torsional stiffness of a sample of corrugated board including:

• means for holding the sample so that one part of the sample carrying an inertial mass may be rotated relative to another part of the sample about an axis of the sample and then allowed to oscillate;
• a detector for detecting when the inertial mass passes through a zero angle region when the sample oscillates;
• and
• electronic processing means arranged to obtain an indication of the shear stiffness of the sample by reference to the time period of one or more oscillations of the sample.

A method for testing the torsional stiffness of corrugated paper board, including:

• holding a sample of corrugated paper board at one part and attaching an inertial mass to another part of the sample;
• initially rotating the inertial mass about an axis of the sample and then;
• allowing the inertial mass to freely oscillate;
• measuring the time period for one or two oscillation(s) of the sample by detecting the inertial mass passing through a zero angle region as the sample oscillates;
• and
• obtaining an indication of the stiffness of the sample by reference to the time period of said one or two oscillations.

An apparatus for testing the torsional stiffness of a sample of corrugated board including:

• means for holding the sample so that one part of the sample carrying an inertial mass may be rotated relative to another part of the sample about an axis of the sample and then allowed to oscillate;
• a detector comprising an optical pickup fixed to the frame and a finger fixed to the inertial mass for detecting when the inertial mass passes through a zero angle region when the sample oscillates;
• and
• electronic processing means arranged to obtain an indication of the shear stiffness of the sample by reference to the time period of one or more oscillations of the sample.