CZ34689U1 - Mechatronic test frame for vibration tests - Google Patents

Description

The technical solution relates to a mechatronic test frame for vibration tests, in particular large and flexible parts for their vibration resistance, comprising a clamping test frame which is connected to the base via force sources and to which a test part provided with vibration sensors is connected, the force sources and vibration sensors they are connected to the control system.

Prior art

Vibration tests are an integral part of the development of most products in the field of engineering or electronics. For vibration testing, a construction is most often used in industrial practice, where a vibration generator (shaker) transmits force via a vibration table to a clamped test part. Depending on the weight of the tested part and the whole structure, the selected frequency range and other parameters, it is possible to choose a shaker in the form of an electrodynamic, hydraulic, pneumatic device or a device with a rotating unbalance. There are also industrial solutions that allow the product to be exposed to changes in temperature or humidity. The character of the excitation signal can be harmonic (sweep, chirp), random with the representation of the required frequencies (white noise), or it is possible to use a short pulse of force. The evaluation of the movement of the test sample is usually performed by measuring the accelerometer at one or more places.

In the vibration testing described above, the load of the test specimen is affected by the modal properties of the vibrating table, the clamping test frame and the test piece itself. Thus, the actual vibration exposure of the test piece varies depending on the excitation frequency and modal properties of the assembly. Increasing the mechanical rigidity of the table and the clamping test frame, which in conventional constructions leads to an increase in weight, is one of the ways to minimize the influence of their modal properties. However, this procedure results in the need to use a higher performance shaker even for a test sample of smaller dimensions.

Another disadvantage of the described principle is the method of evaluating the movement of the tested component. By measuring one place on the sample or vibrating table, we do not get a complete overview of the movement of the tested sample. As a result, some parts of the sample do not undergo the required load. There are procedures that use acceleration measurement at multiple points. For the needs of the control of the primary excitation force, the average value from the performed measurements is used, or the point with the highest acceleration value is selected. These procedures do not work as required because, as a rule, one or more of the measured points passes through the load outside the specified interval.

U.S. Pat. No. 5,976,242 A (Gregg K. Hobbs) discloses a vibration testing system in which a combination of excitation and interconnect modules allows the modal properties of the entire system to be adjusted according to the requirements of the vibration test. The interconnected modules may contain different types of passive and active elements enabling the shaping of the frequency response of the system. This system uses the concept that each excitation module used has the task of generating only a part of the specified frequency spectrum. However, such a procedure is impractical because the test equipment is designed to test disparate parts and the proposed modules must be designed and reassembled for each new arrangement.

WO 1998029723 A1 (Gregg K. Hobbs) discloses a modular vibration testing system, the basic components of which are three modules. Excitation, connection and clamping module. Actuators for generating vibrations in multiple directions can be connected to the excitation module. The clamping module is used to clamp the tested components. The connection module is used to connect the other two modules. The connection of the modules can be realized in various ways: by creating a vacuum between the contact surfaces, screws, flexible or damping elements. It is therefore possible with the above-mentioned means

-1 CZ 34689 UI tune system for testing specific samples in required conditions. This approach is also impractical, as the tuning of the mechanical parameters of the individual modules for a particular assembly is lengthy, and in addition, a modal retuning of the mechanical assembly occurs during the test.

DE 102016002188 A1 describes a construction for vibration testing, in particular of lighter components, the main attribute of which is the low weight of a vibrating table made, for example, of composite materials. In the middle of the table there is a frame for mounting the tested component. The frame is movable in the vertical direction and is connected to the primary vibration generator by means of a slider. Thanks to the low weight of the entire structure, the requirements for the input forces of the vibration generator are reduced and at the same time the load on the component is less affected by the weight of the structure. However, the proposed solution is not suitable for large and highly flexible tested parts, and it is not flexible.

The essence of the technical solution

The essence of the technical solution concerning a mechatronic test frame for vibration tests of particularly large and flexible parts for their vibration resistance, comprising a clamping test frame connected via a primary force source to the base and to which a test part provided with vibration sensors is connected, the primary force source and the vibration sensors are connected to the control system, in that it comprises at least one secondary force source arranged on the test piece or connected to a clamping test frame and to a support frame fixed to the base. The secondary source of force is optionally an active damper mounted on the test piece or an electromagnetic exciter connected to the clamping test frame and to the supporting frame.

The advantage of this technical solution is the compensation of the dynamic flexibility of the clamping test frame and the tested part by means of active secondary sources or for individual frequency components of the test spectrum. The active secondary force source can advantageously be arranged as a controlled dynamic damper. Thus, it is possible to perform a vibration test of a flexible test piece without overloading the test piece in the oscillations of the individual oscillation shapes at or near the resonant frequency. Another advantage is the ad-hoc optimization of the connection of the secondary force sources by means of a device for measuring the actual oscillation shapes of the assembly on the basis of a scanning vibrometer. This data is used to control the primary force source in the form of an inverse mathematical model of the system and the original system model to control the secondary force sources. Another advantage is that the tested parts are subjected to vibration exposure evenly throughout the volume and throughout the test spectrum.

Explanation of drawings

The attached figures show a device for performing vibration tests of large and / or flexible parts according to the technical solution, where it shows:

Fig. 1 is a diagram of a device with a primary force source and secondary force sources fixed by a connecting rod between the clamping test frame and the supporting frame;

Fig. 2 is a diagram of a device with a primary force source and secondary force sources fixed by a connecting thread between the clamping test frame and the support frame;

Fig. 3 is a diagram of a device where the secondary power sources are formed by active absorbers;

Fig. 4 is a diagram of the device, where the secondary power sources are formed by spring-loaded electromechanical exciters fixed by a connecting thread between the clamping test frame and the supporting frame;

Fig. 5 is a diagram of the device, where the secondary power sources are formed by spring-loaded electromechanical exciters fixed by a connecting rod between the clamping test frame and the supporting frame;

Fig. 6 is a diagram of a device with a built-in scanning vibrometer before the installation of secondary power sources; and FIG. 7 shows a tolerance field according to the required movement of the test part in the frequency domain.

Examples of technical solution

Fig. 1 shows a device in the form of a mechatronic test frame for vibration tests of e.g. large and flexible parts by means of several sources of force, where a primary force source 1 is arranged on the base 18 by means of vibration isolators 2. Attached to the primary force source 1 is a vibrating table 3 on which a clamping test frame 4 is mounted. The test frame 4 is connected to the test piece 5 by means of clamps 7. Outside the clamping test frame 4, a supporting frame 15 of secondary sources is attached to the base 18. 11 forces. The secondary force sources 11 are connected to the clamping test frame 4 and to the supporting frame 15 by means of connecting rods 12.

The points of connection of the secondary force sources 11 to the clamping test frame 4 are determined by analyzing the actual oscillation shapes obtained by the laser scanning vibrometer 14 shown in Fig. 6. Vibration sensors 8 are arranged on the test part 5 or on the clamping test frame 4. which are connected to the control system 6. The locations of the vibration sensors 8 are also determined by analyzing the proper oscillation shapes, which are obtained by the laser scanning vibrometer 14 shown in Fig. 6. The primary power source 1 and the secondary sources are further connected to the control system 6. 11 forces.

Fig. 2 shows a device similar to Fig. 1, with the secondary force sources 11 being connected to the clamping test frame 4 and to the supporting frame 15 by means of connecting fibers 13.

Fig. 3 shows an alternative arrangement of a device for vibration testing of large and flexible parts by means of several force sources, where the secondary force sources are formed by active dampers 9 connected to the control system 6. The dampers 9 comprise seismic mass connected by a damper or other force element with controlled stiffness to the clamping test frame 4. The control system 6, in coordination with the control of the primary force source 1, controls the force members in the individual active dampers 9, in feedback with the signals from the vibration sensors 8.

Figures 4 and 5 show a device similar to Figure 1, with the secondary source of force being electromechanical exciters 10 connected to the support frame 15 and to the clamping test frame 4 by means of connecting rods 12 - Fig. 5 or connecting fibers 13 - Figs. 4.

Figure 6 shows a diagram of the vibration testing device at the moment before the installation of the secondary force sources 11, when a scanning vibrometer 14 is attached to the support frame 15 to determine the eigenmodes and other modal properties for the current assembly of the whole clamping frame 4 including the fixed test piece 5. and a primary force source 1, in particular for determining the position of the connection points of the secondary force sources 11 and the vibration sensors 8.

Fig. 7 shows the desired frequency characteristic of the load of the tested part, i.e. what acceleration amplitude of the tested part the control system 6 must provide for each frequency component of the tested frequency range by the action of the primary force source 1 and the secondary force sources 11.

Before the actual vibration testing of the tested parts 5, the limits of the required prescribed test frequency spectrum 17 of the movement of the tested part 5 are defined,

Experimental modal analysis of the system of primary force source 1, vibrating table 3, clamping test frame 4 and test part 5, the connection points of at least two vibration sensors 8 on the clamping test frame 4 are determined so that the amplitudes of their own The oscillation shapes of the assembly at selected locations and in the entire prescribed test frequency spectrum of loads have been maximized and secondary force sources 11 are connected to the connection points by means of connecting rods 12 or fibers 13.

The movement of the primary force source 1 is controlled by the control system 6 based on the inversion of the system model consisting of the primary force source 1, vibrating table 3, clamping test frame 4 and test part 5. The system model is obtained by experimental modal analysis performed by non-contact laser scanning vibrometer 14 The primary force source j acts against the center of mass of the test part 5 together with the clamping test frame 4 and the secondary force source 11. The secondary force source 11 acts on the test piece 5 and the clamping test frame 4 in the direction of the primary force source 1 at the largest amplitude of most natural oscillation shapes of the primary force source system 1, vibrating table 3, clamping test frame 4 and test piece 5. in the defined frequency spectrum 17 of loading for all points of the surface of the tested part 5.

The movement of the secondary force sources 11 is coordinated by the control system 6 so as to minimize the relative movement of the primary force source 1 and the secondary force sources 11. The secondary power sources 11 are connected to the connection points 16, the position of which is determined according to the oscillations of the natural oscillation shapes in the desired frequency spectrum 17 of the load. The actual oscillation shapes of the primary force source system 1, vibrating table 3, clamping test frame 4 and test piece 5 are obtained by experimental modal analysis with a scanning vibrometer 14, for each assembly of test piece 5, clamping test frame 4, vibrating table 3 and primary source 1. ad-hoc forces as shown in Figure 6.

The force sources 1 and 11 are controlled in a coordinated manner by a control system 6 operating in feedback with vibration sensors 8 mounted on the surface of the test piece 5. The vibration sensors 8 can advantageously be collocated with connection points 16 of secondary force sources 11. Interventions of the control system 6 are set according to the whole set model, obtained by experimental modal analysis with a scanning vibrometer 14 and updated according to changes in the response of the whole set and the course of the long-term test, which takes place in cycles.

The secondary power source 11 may be formed by an electromechanical exciter 10 attached to the fixed frame 15 and connected to the connection points 16 on the clamping test frame 4 by means of a connecting rod 12 or a high stiffness connecting fiber 13, preferably a carbon fiber.

The trajectory of the test part 5, determined according to the prescribed test spectrum, is performed cyclically by the control system 6 and the action sequences of the primary source 1 and secondary force sources 11 are modified by the control system 6 after each cycle so that the prescribed test spectrum 17 is observed with increasing accuracy. .

The mass and stiffness of the secondary force sources 11 in the form of absorbers 9 are adjusted to approximate their resulting passive natural frequency to the natural frequency of the whole system of primary force source 1, vibrating table 3, clamping test frame 4 and test piece 5 obtained by experimental modal analysis.

When connecting the secondary force sources 11 to the connection point of the fibers 13, the movement of the secondary force sources 11 is controlled so that the fibers 13 are permanently stressed exclusively by the tensile force.

Claims (3)

CLAIMS FOR PROTECTION A mechatronic test frame for vibration tests of particularly large and flexible parts for their vibration resistance, comprising a clamping test frame (4) which is connected via a primary force source (1) to a base (18) and to which a test part (5) provided with sensors is connected. (8) vibrations, the primary force source (1) and the vibration sensors (8) being connected to a control system (6), characterized in that it comprises at least one secondary force source (11) arranged on the test part (5) or connected to a clamping test frame (4) and a supporting frame (15) fixed to the base (18). Mechatronic test frame for vibration tests according to claim 1, characterized in that the secondary source of force is an active baffle (9) mounted on the test part (5). Mechatronic vibration test frame according to Claim 1, characterized in that the secondary source of force is an electromagnetic exciter (10) connected to the clamping test frame (4) and to the support frame (15).