RU49254U1 - CONSOLE STRENGTH TEST STAND - Google Patents

Abstract

The utility model relates to the field of testing equipment, in particular, to the design of stands, which are designed for unidirectional endurance tests in a dynamic way of cantilever beam-type structures: wings of large elongation, blades of wind turbines and their spars. The proposed utility model solves the technical problem of conducting fatigue tests in a resonant manner without loading the building or structure with significant dynamic loads, which reduces the strength requirements of the building or structure. In order to achieve the named technical effect in the proposed endurance test bench for predominantly full-scale cantilever structures in a dynamic way, comprising a portal, a device for connecting the test structure to the portal, a vibration exciter for exciting forced oscillations, a system for determining resonant frequencies, a system for automatically maintaining the frequency and amplitude of the driving force and load measurement and regulation system, device for connecting the test structure to the portal It executes a soft suspension system.

Description

The utility model relates to the field of testing equipment, in particular, to the design of stands, which are designed for unidirectional endurance tests in a dynamic way of cantilever beam-type structures: wings of large elongation, blades of wind turbines and their spars.

Closest to the proposed model is a repetitive fatigue test facility used as a prototype, used in testing the wings of the S-46 transport aircraft (V. Haston, “Comparison of test results of full-scale structures for constant amplitude loads and for random step loads to identify critical components ", Sat." Fatigue strength and durability of aircraft structures ", Moscow, Engineering, 1965, pp. 251-253). The installation contains a power portal with a power support for cre Lenia test structure, the forced vibration exciter for exciting vibrations of the structure at the resonance frequency, the system automatically maintain a constant frequency and amplitude of the exciting force measuring system and load regulation. All the mentioned features, except for the power portal and the power support for fastening the test structure, are present in this technical solution.

The disadvantage of the stand adopted as a prototype is that when testing a cantilevered large structure, for example, a spar or blade of a powerful wind power installation, the dynamic forces of a significant magnitude (bending moment, etc.) created in its closure are transmitted to the stand and, further, to a building that undergoes an unacceptably large dynamic

loading. Therefore, to conduct dynamic tests of large structures, unique testing facilities are required.

The proposed utility model solves the technical problem of conducting fatigue tests in a resonant manner without loading the building or structure with significant dynamic loads, which reduces the strength requirements of the building or structure.

In order to achieve the named technical effect in the proposed endurance test bench for predominantly full-scale cantilever structures in a dynamic way, comprising a portal, a device for connecting the test structure to the portal, a vibration exciter for exciting forced oscillations, a system for determining resonant frequencies, a system for automatically maintaining the frequency and amplitude of the driving force and a system for measuring and regulating loading, a device for connecting the test structure to the portal in It is satisfied in the form of a soft suspension system. As a suspension, for example, rubber cords, pneumatic shock absorbers, springs, etc. can be used. The attachment points of the shock absorbers to the structure are selected in at least two sections, in the region of the vibration nodes, where the amplitude is minimal and the suspension stiffness is selected sufficiently small so that when the structure vibrates, the amplitudes of the efforts in the suspension are within acceptable limits, and "zero" tones. " This occurs when the vibration frequency of the structure on the suspension as a rigid body is less than 0.10-0.25 the frequency of bending vibrations at which the structure is tested. Such fastening of the structure is not power, and it can make almost free bending vibrations. As a result, dynamic loads on the building or test frame

buildings are reduced to almost zero; only the weight of the structure is transferred.

In addition, in addition, an inertial counterweight is provided for loading the root portion of the structure and the joint. The counterweight fits into the test structure into a single object. The dimensions, moment of inertia, mass and rigidity of the counterweight are selected from the conditions for obtaining the required value of the loads at the joint during testing. The counterweight is not rigidly connected to the stand, the loads coming to it from the structure are balanced by inertia and are not transferred to the stand.

Two counterbalance suspension options can be used. In the first embodiment, the soft suspension is associated only with the tested design. In the second version, the counterweight is directly suspended on a soft suspension that meets the previous requirements.

A distinctive feature of the proposed stand for endurance testing of cantilever structures is that the device for connecting the test structure to the portal is made in the form of a soft suspension (rubber cords, pneumatic shock absorbers, soft springs), which perceives the weight of the structure and practically does not transmit variable dynamic loads. To load the joint and the root section of the structure with variable loads at the operating mode, an inertial counterweight is provided in the stand with which the structure is joined. The counterweight may have its own soft suspension, similar to the suspension design.

Thanks to the soft suspension, dynamic loads on the building or power frame of the test structure are reduced to almost zero; only the weight of the structure is transferred. The inertial counterweight, not rigidly connected to the stand, allows testing the joint and the root section of the structure with variable loads without testing them

transfers to the portal and the building. Therefore, the portal may not be power. It is not required to design and manufacture a powerful structure for fixing the console. Tests can be performed in existing halls for static strength tests.

As a result of a search by sources of patent and scientific and technical information, no solutions containing such a feature were found. Therefore, we can conclude that the proposed solution is unknown for the current level of technology and meets the eligibility criterion - “new”.

The proposed solution can find application in mechanical engineering, wind energy, construction, etc., where it is necessary to determine experimentally the resource of an elongated cantilever structure such as a wing, a blade or a spar, which allows us to conclude that the criterion of "industrial applicability" is met.

The proposed technical solution is illustrated by the figures of Fig.1,2.

Figure 1 shows the stand for endurance testing of cantilever structures on a soft suspension.

Figure 2 shows the stand for endurance testing of cantilever structures on a soft suspension with an inertial counterweight.

The stand depicted in FIGS. 1 and 2 contains a portal 1, a soft suspension system 2, on which the test structure 3 is suspended in selected sections, a power vibration exciter 4, a control unit 5 connected to the control panel 6. The control unit 5 through the search and hold resonance system frequency 7 and a system for measuring and regulating the level of loading 8 controls the exciter 4 in order to create a predetermined load of the structure 3. The primary sources of information are accelerometers 9 and strain gauges 10 installed on the structure 3, and the accelerometer 11 mounted on the moving part of the vibration exciter 4.

The loading program (loading level, number of cycles, 'frequency) is set automatically or by the operator using the remote control 6.

The work of the stand is as follows. Accelerometers 9 and strain gauges 10 are installed on the tested structure 3 in the selected sections. The strain gauges 10 are connected to the load measuring and regulation system 8 and statically calibrated according to the value of internal force factors (bending moments, shear forces, stresses). The structure 3 thus prepared by means of a soft suspension 2 is suspended on the unloading beam, vibration exciter 4 is connected with a power amplifier and control systems 7, 8 and an operator panel 6. Accelerometers 9 are connected to the search and maintenance system of mode 7. Connect the load measurement and regulation system 8 In Fig. 2, an inertial counterweight 12 is connected to the structure 3.

Depicted in figure 1, the stand works as follows. The forced vibrations of the structure 3 are excited by harmonic force from the vibration exciter 4 with an arbitrarily chosen constant amplitude and a changing frequency. Determine the natural (resonant) frequencies and the corresponding diagrams of internal force factors (measured by the readings of strain gauges 10). Based on a given value of internal force factors, the amplitude of the driving force at the resonant frequency is selected and endurance tests are carried out up to a given number of loading cycles or until failure.

Before testing the structure 3 with an inertial counterweight (Fig. 2), by calculating the dynamic loading, the mass, moment of inertia and dimensions of the inertial counterweight 12 are selected to obtain the required forces (bending moment, etc.) in the root part of the structure and its junction with the counterweight 12. Test structure 3 with the inertial counterweight 12 installed on it, is fixed in the stand on the suspension 2. The tests are carried out as in FIG. 1.

Claims (3)

1. Stand for testing the endurance of cantilever structures in a dynamic way, comprising a portal, a device for connecting the test structure to the portal, a vibration exciter for exciting forced oscillations, a system for determining resonant frequencies, a system for automatically maintaining the frequency and amplitude of the driving force, a measurement and regulation system for loading, characterized the fact that the device for connecting the test structure to the portal is made in the form of a soft suspension connecting the structure to the portal not less than in two sections, and the stiffness of the suspension is selected from the condition of the absence of “zero tones” of the structural vibrations on the suspension. 2. The stand according to claim 1, characterized in that it further comprises an inertial counterweight rigidly connected to the root section of the test structure. 3. The stand according to claim 2, characterized in that the inertial counterweight as well as the test structure is connected to the portal with a soft suspension.