Improvement of compressive testing instrument with wide range of speed for examining agricultural materials

• PC controlled electro-mechanical testing machine with PC-based data logger.
• Static and dynamic compressive tester for investigate of biological materials.
• Loading with constant, linear slope and cosine force–time functions.
• Operating in single or cyclic mode.

Since the construction of a static and dynamic compressive testing instrument for examining biological materials, particularly fruits and tubercular roots, the need has arisen for the construction of a computer-controlled instrument that can bridge the gap between static and dynamic investigations in this field. The main utilisation possibilities of this instrument are demonstrated some measurement results with apple. The recently developed, easy-to-use instrument presented herein is suitable for serial measurements. In its present implementation, this instrument is capable of performing compressive testing with loading sticks of typical size with constant, linear slope and cosine force–time functions in single or cyclic mode. The force is generated by a PC-controlled servo system, and the deformation is measured by a laser sensor. The excitation force is 0–15 N within 1% FS accuracy in 0–300 Hz frequency range. Deformation measuring range is 10 mm with 12 μm resolution. The system contains a PC-based data logger.