# Upgrade of the Universal Testing Machine for the Possibilities of Fatigue Tests in a Limited Mode
## 5 FPZ 100/1 Test Equipment  
The HECKERT FPZ 100/1 test device, which is the object of the upgrade, is a universal testing machine with a maximum load of 100 kN with a typical design according to Figure 2. The force is exerted by a mechanical transmission with an electric drive. The drive train includes a thyristor rectifier with a control device, a DC motor and a four-speed control gearbox, guaranteeing a large range of test speeds with high stability. The measurement of load force and elongation is realized by electrical sensors of physical quantities-transducers. These have the character of a dynamometer for measuring forces and an extensometer for measuring absolute elongation. There is a set of interchangeable force transducers (dynamometers) with force levels of 40 N, 400 N, 10 kN and 100 kN for the tension modes and one 100 kN force transducer for the pressure mode. The measurement of tensile and pressure forces, respectively, is performed by an interchangeable electronic transducer using the principle of inductive path measurement. The measured values are displayed analogue on a circular scale and can be additionally registered by means of a registration device or peripheral devices can be connected. Changes in length may be measured by deployable extensometers with a transducer character in the range from 50 \(\upmu\)m to 50 mm, or by resistive sensors, which sense the traverse displacement in the range from 10 mm to 935 mm. The measured values are displayed on a flat scale and can be recorded on a recording device, again with peripheral devices [19]. On the left side at the top is the main control unit, at the bottom is the electromechanical drive. On the right side is the load frame itself with two working areas separated by a movable traverse on which the clamping and force measuring elements are installed. The work space at the top is for tension mode tests and the lower work space is for compression mode tests. Clamping and force measurement elements are then installed in the upper bracket in the upper section and the lower bracket in the lower section, paired with the clamping and force measurement elements of the movable bracket. When loading the test specimen in both tension and compression, the traverse always moves downwards. Its maximum stroke is 935 mm. An integrated recording device allows changes in load and specimen elongation to be recorded in force vs. strain, force vs. time and strain vs. time diagrams. In the case of the FPZ 100/1 device, it is not a pulsator with an electrohydraulic drive, directly designed for fatigue tests, but a universal testing machine on an electromechanical basis. Therefore, it is preferably intended for static tensile or compression tests and thus for obtaining strength and deformation characteristics. The possibilities of the pulsation function as a pulsator, i.e., for cyclic loading, is only supplementary, with limited possibilities. These are mainly related to the possibility of loading either only in tension or only in compression mode, i.e., without the possibility of simultaneous alternating tension and compression loading for an alternately symmetrical or asymmetrical cycle. There are two separate working spaces for tension and compression tests. Another limiting factor for the functionality of the pulsator is the loading frequency. This is listed in the datasheet of the device as the so-called switchable frequency, continuously variable up to the maximum value at the level of only 0.1 Hz. The speed of movement of the clamping jaws is given in the range of 0.00035-10 mm/s. This device, based on a 1980s design, is in its basic configuration with purely analogue drive, control and indication of variables. A 10 V, 5 mA analogue output indication voltage signal is provided for peripheral connection, storage and further data processing. The AC component of the analogue signal \(U_{\Delta I}\) corresponds to the measured deformation and the DC component of the analogue signal \(U_{F}\) corresponds to the measured load force.