WO2022078532A1 - A method and equipment for vibration testing of large and pliable components for their resilience to vibrations - Google Patents

A method and equipment for vibration testing of large and pliable components for their resilience to vibrations Download PDF

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Publication number
WO2022078532A1
WO2022078532A1 PCT/CZ2021/000035 CZ2021000035W WO2022078532A1 WO 2022078532 A1 WO2022078532 A1 WO 2022078532A1 CZ 2021000035 W CZ2021000035 W CZ 2021000035W WO 2022078532 A1 WO2022078532 A1 WO 2022078532A1
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WIPO (PCT)
Prior art keywords
testing
vibration
tested component
sources
frame
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PCT/CZ2021/000035
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French (fr)
Inventor
Pavel Steinbauer
Petr Denk
Vít Pawlik
Karek KRAUS
Jindřich Karlíček
Aleš Dočkal
Oldřich Štajner
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České vysoké učení technické v Praze
Robert Bosch Spol. S R.O.
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Application filed by České vysoké učení technické v Praze, Robert Bosch Spol. S R.O. filed Critical České vysoké učení technické v Praze
Publication of WO2022078532A1 publication Critical patent/WO2022078532A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M7/00—Vibration-testing of structures; Shock-testing of structures
    • G01M7/02—Vibration-testing by means of a shake table
    • G01M7/022—Vibration control arrangements, e.g. for generating random vibrations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M7/00—Vibration-testing of structures; Shock-testing of structures
    • G01M7/02—Vibration-testing by means of a shake table
    • G01M7/06—Multidirectional test stands

Definitions

  • the invention concerns a method and equipment for vibration testing of large and pliable components for their resilience to vibrations using equipment comprising a mounting testing frame, which is connected to a foundation through force sources and to which a tested component fitted with vibration sensors is attached, whereas force sources and vibration sensors are connected to a control system.
  • Vibration tests are an integral part of development of the most of products in the field of mechanical engineering or electronics.
  • the most frequently used device for vibration testing is a structure with a vibration generator (a shaker) transferring force through a shaker table to an attached tested component.
  • the shaker can be in the form of electrodynamic, hydraulic, pneumatic equipment or equipment with a rotating unbalance.
  • a character of the exciting signal can be harmonic (sweep, chirp), random with a proportion of demanded frequencies (uniform spectrum random noise), or a short impulse of force can be used.
  • An assessment of a tested sample motion is usually performed through measuring by accelerometers in one or more spots.
  • the tested sample loading is affected by modal properties of the shaker table, the mounting testing frame and the tested component itself.
  • the actual vibration exposure of the tested component changes in dependence on the exciting frequency and modal properties of the system.
  • An increase in mechanical stiffness of the table and mounting testing frame, in typical structures leading to an increase in weight, is one of possibilities to minimize an influence of their modal properties.
  • this procedure results in a need to use a shaker with a higher output even for a tested sample of smaller dimensions.
  • Another disadvantage of the above described principle is a method of assessment of the tested component motion.
  • Complex data of the tested sample motion cannot be gained by measuring of one spot on the sample or shaker table. The result is that some parts of the sample are not subjected to the demanded loading.
  • WO1998029723A1 patent presents a modular system for vibration testing, the basic parts of which are three modules: an exciting module, an interconnecting module and a mounting one. Actuators for generating vibrations in more directions can be connected to the exciting module.
  • the mounting module is intended for clamping of tested components.
  • the interconnecting module serves for interconnecting of the two other modules. Interconnecting of modules can be performed in various ways: by creating vacuum between contact surfaces, through bolts, through flexible or dampening members. Using the above mentioned elements a system can be adjusted for testing particular samples in required conditions. This approach is not practical as well because adjustment of mechanical parameters of respective modules for a particular system is time consuming and, moreover, a modal readjustment of the mechanical system occurs during the test.
  • DE102016002188A1 patent describes a structure for vibration testing of lightweight components particularly, the main attribute of which is a low weight of a shaker table made e.g. of composite materials.
  • a frame for attaching of tested components In the centre of the table there is a frame for attaching of tested components.
  • the frame is moveable in the vertical direction and it is connected to a vibration generator through a sliding shoe. Thanks to a low weight of the whole structure the requirements for input forces of the vibration generator are reduced and, at the same time, the component loading is less affected by the structure weight.
  • the proposed solution is not suitable for large and highly pliable tested components and, moreover, is not flexible. Subject Matter of the Invention
  • a subject matter of the invention concerning a method for vibration testing of large and pliable components for their resilience to vibrations is described in Claims 1 to 7
  • a subject matter of the invention concerning equipment for vibration testing of large and pliable components for their resilience to vibrations is described in Claims 8 to 10.
  • An advantage of this invention is a compensation of dynamic pliability of a mounting testing frame and a tested component using active secondary sources for particular frequency components of the testing spectrum.
  • An active secondary force source can be preferably arranged as a controlled dynamic absorber.
  • vibration testing of a pliable component can be carried out without overloading the tested component in antinode loops of particular forms of a mode of vibration at/near resonant frequency.
  • Another advantage is ad-hoc optimization of connecting of secondary force sources using a device for measuring of the particular forms of a mode of vibration of the system based on a scanning vibrometer. These data are used to control the primary force source in a form of an inversion mathematical model of the system and an original model of the system for controlling the secondary force sources.
  • Another advantage is that tested components are subjected to the vibration exposure uniformly throughout the whole volume and through the entire testing spectrum.
  • Fig. 1 depicts a scheme of the equipment with a primary force source and secondary force sources connected through a connecting rod between a mounting testing frame and a bearing frame,
  • Fig. 2 depicts a scheme of the equipment with a primary force source and secondary force sources connected through a connecting string between a mounting testing frame and a bearing frame,
  • Fig. 3 depicts a scheme of the equipment, where secondary force sources consist of active absorbers
  • Fig. 4 depicts a scheme of the equipment, where secondary force sources consist of spring-loaded electromechanical exciters connected through a connecting string between a mounting testing frame and a bearing frame
  • Fig. 5 depicts a scheme of the equipment, where secondary force sources consist of spring-loaded electromechanical exciters connected through a connecting rod between a mounting testing frame and a bearing frame,
  • Fig. 6 depicts a scheme of the equipment with a scanning vibrometer built-in prior to building-in secondary force sources
  • Fig. 7 depicts a tolerance field according to a required motion of a tested component within the frequency domain
  • Fig. 8 depicts a scheme of the equipment with more primary force sources.
  • Fig. 1 shows the equipment for vibration testing of large and pliable components using more sources of action of force, where primary force source 1 is arranged on foundation 18 through vibroizolators 2.
  • Primary force source 1 is connected to shaker table 3, to which mounting testing frame 4 is connected.
  • Tested component 5 is attached to testing frame 4 through mounting attachments 7.
  • bearing frame 15 for secondary force sources 11 is connected to foundation 18.
  • Secondary force sources 11 are connected to mounting testing frame 4 and to supporting frame 15 through connecting rods 12.
  • Points of connection of secondary force sources 11 to mounting testing frame 4 are determined using an analysis of the particular forms of a mode of vibration, which are obtained by laser scanning vibrometer 14 shown in Fig. 6.
  • Vibration sensors 8, which are connected to control system 6, are arranged on tested component 5 or mounting testing frame 4.
  • Points of location of vibration sensors 8 are also determined using an analysis of the particular forms of a mode of vibration, which are obtained by laser scanning vibrometer 14 shown in Fig. 6.
  • primary force source 1 and secondary force sources 11 are also connected to control system 6.
  • Fig. 2 shows similar equipment as depicted in Fig. 1, wherein secondary force sources 11 are connected to mounting testing frame 4 and to bearing frame 15 through connecting strings 13.
  • Fig. 3 shows an alternative embodiment of the equipment for vibration testing of large and pliable components using more sources of action of force, where secondary force sources consist of active absorbers 9 connected to control system 6.
  • Absorbers 9 include a seismic mass connected through an absorber or another force element with a controlled stiffness to mounting testing frame 4.
  • Control system 6 in a coordination with a control of primary force source 1 controls force elements in particular active absorbers 9, in a feedback with signals from vibration sensors 8.
  • Figs. 4 and 5 show the equipment as depicted in Fig. 1, wherein secondary force sources are electromechanical exciters 10 connected to bearing frame 15 and to mounting testing frame 4 through connecting rods 12 - Fig. 5 or connecting strings 13 - Fig. 4.
  • Figure 6 depicts a scheme of the equipment for vibration testing at the moment prior to installing secondary force sources 11, wherein bearing frame 15 is connected to scanning vibrometer 14 intended for determination of the particular forms of a mode of vibration and other modal properties for the actual arrangement of the whole mounting testing frame 4 including attached tested component 5 and primary force source 1, especially for determination of a position of connecting points of secondary force sources 11 and vibration sensors 8.
  • Fig. 7 shows the required frequency characteristic of loading of a tested component. This means - what amplitude of acceleration of the tested component has control system 6 to ensure through acting of primary force source 1_ and secondary force sources 11 for each frequency component of the tested frequency range.
  • Fig. 8 shows an alternative embodiment, where the equipment is arranged with more primary force sources 1. with the common control.
  • limits of the required prescribed testing frequency spectrum 17 of a motion of tested component 5 are defined, a computational or experimental modal analysis of the system consisting of one or more primary force sources 1, shaker table 3, mounting testing frame 4 and tested component 5 is performed through laser scanning vibrometer 14 or accelerometers, connecting points on mounting testing frame 4 for at least two vibration sensors 8 are determined so that amplitudes of the particular forms of a mode of vibration of the system in the selected points and through the entire prescribed testing frequency spectrum of loading are maximized and secondary force sources 11 are connected to the connecting points using connecting rods 12 or strings 13.
  • a motion of primary force sources 1 is controlled by control system 6 in a computer on the basis of an inversion of a model of the system comprising primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5.
  • the system model is obtained using an experimental modal analysis carried out contactlessly by laser scanning vibrometer 14.
  • Primary force source 1 acts against the centre of weight of tested component 5 along with mounting testing frame 4 and secondary force source 11.
  • Secondary force source 11 acts upon tested component 5 and mounting testing frame 4 in a direction of acting of primary force source 1 in points with the highest amplitude of the most of particular forms of a mode of vibration of the system comprising primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5, within defined frequency spectrum 17 of loading for all points of a surface of tested component
  • a motion of secondary force sources 11 is coordinated by computer control system 6 so that a relative motion of a point of activity of primary force source 1 and secondary force sources 11 is minimized.
  • Secondary force sources 11 are connected to connecting points 16, a position of which is determined according to antinode loops of particular forms of a mode of vibration in required frequency spectrum 17 of loading.
  • the particular forms of a mode of vibration of the system comprising primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5 are obtained using an experimental modal analysis by scanning vibrometer 14, for each system of tested component 5, mounting testing frame 4, shaker table 3 and primary force source 1 ad-hoc, as depicted in Figure
  • Sources 1. and 11 of action of force are controlled in a coordinated way by control system 6 working in a feedback with vibration sensors 8 attached on a surface of tested component 5.
  • Vibration sensors 8 can be preferably collocated with connecting points 16 of secondary force sources 11.
  • Interventions of control system 6 are set according to the whole system model obtained using an experimental modal analysis by scanning vibrometer 14 and updated in accordance with changes of the whole system response and a course of the long- lasting test, which runs in cycles.
  • Secondary force source 11 can consist of electromechanical exciter 10 connected to fixed frame 15 and connected to connecting points 16 on mounting testing frame 4 using connecting rod 12 or connecting string 13 with a high stiffness, preferably a carbon fiber.
  • a trajectory of a motion of tested component 5, which is determined in accordance with prescribed testing spectrum, is performed in cycles by control system 6 and courses of action interventions of primary force source 1 as well as secondary force sources 11 are modified after each cycle by control system 6 so that prescribed testing spectrum 17 can be adhered to with an increasing accuracy.
  • the mass and stiffness of secondary force sources 11 in the form of absorbers 9 is set for approximation of their resulting passive own frequency to the own frequency of the whole system consisting of primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5 obtained using an experimental modal analysis.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)

Abstract

The invention concerns a method for vibration testing of large and pliable components for their resilience to vibrations using equipment comprising a mounting testing frame, which is connected to a foundation through force sources and to which a tested component fitted with vibration sensors is attached, whereas force sources and vibration sensors are connected to a control system, characterized in that limits of the required prescribed testing frequency spectrum of the tested component motion are defined, a computational or experimental modal analysis of a system consisting of at least one primary force source, a shaker table, a mounting testing frame and a tested component is performed, connecting points for at least two vibration sensors on the mounting testing frame are defined so that amplitudes of particular forms of a mode of vibration of the system in the selected points and through the entire prescribed testing frequency spectrum of loading are maximized, secondary force sources are connected to connecting points through connecting rods or strings, the secondary force sources are controlled in a coordinate way with the primary force source by the control system to minimize a deviation of the relative motion of connecting points of the secondary force sources towards a motion of the primary force source and, simultaneously, a motion of the whole tested component within the prescribed testing frequency spectrum. Equipment for vibration testing of large and pliable components for their resilience to vibrations according to the method described above, comprising a mounting testing frame, which is connected to a foundation through at least one primary force source and to which a tested component fitted with vibration sensors is attached, whereas the primary force source and vibration sensors are connected to a control system in a computer, whereas the equipment comprises at least one secondary force source (11) arranged on tested component (5) or connected to mounting testing frame (4) and bearing frame (15) fixed to foundation (18).

Description

A Method and Equipment for Vibration Testing of Large and Pliable Components for Their Resilience to Vibrations
Technical Field of the Invention
The invention concerns a method and equipment for vibration testing of large and pliable components for their resilience to vibrations using equipment comprising a mounting testing frame, which is connected to a foundation through force sources and to which a tested component fitted with vibration sensors is attached, whereas force sources and vibration sensors are connected to a control system.
State-of-the-art
Vibration tests are an integral part of development of the most of products in the field of mechanical engineering or electronics. In industrial practice the most frequently used device for vibration testing is a structure with a vibration generator (a shaker) transferring force through a shaker table to an attached tested component. Depending on a weight of the tested component and the whole structure, the chosen frequency range and other parameters, the shaker can be in the form of electrodynamic, hydraulic, pneumatic equipment or equipment with a rotating unbalance. There are also industrial solutions allowing subjecting a product to temperature or humidity changes. A character of the exciting signal can be harmonic (sweep, chirp), random with a proportion of demanded frequencies (uniform spectrum random noise), or a short impulse of force can be used. An assessment of a tested sample motion is usually performed through measuring by accelerometers in one or more spots.
In the above described vibration testing the tested sample loading is affected by modal properties of the shaker table, the mounting testing frame and the tested component itself. The actual vibration exposure of the tested component changes in dependence on the exciting frequency and modal properties of the system. An increase in mechanical stiffness of the table and mounting testing frame, in typical structures leading to an increase in weight, is one of possibilities to minimize an influence of their modal properties. However, this procedure results in a need to use a shaker with a higher output even for a tested sample of smaller dimensions.
Another disadvantage of the above described principle is a method of assessment of the tested component motion. Complex data of the tested sample motion cannot be gained by measuring of one spot on the sample or shaker table. The result is that some parts of the sample are not subjected to the demanded loading. There are procedures using measuring of acceleration in more spots. For the need to control the primary exciting force the average value of the performed measurements is used, possibly a point with the highest acceleration value is selected. These procedures do not work as required because usually one or more of the measured points go through the loading outside the specified interval.
US5979242A patent (Gregg K. Hobbs) describes a system for vibration testing in which a combination of exciting and interconnecting modules allows adjusting modal properties of the whole system according to the vibration test requirements. Interconnected modules can include various types of passive and active elements enabling to form frequency characteristics of the system. This system uses a concept where each of the used exciting modules has to generate only a part of the specified frequency spectrum. However, such a procedure is not practical, as the testing equipment is intended for testing of different components and projected modules need to be arranged and adjusted every time for each new arrangement again.
WO1998029723A1 patent (Gregg K. Hobbs) presents a modular system for vibration testing, the basic parts of which are three modules: an exciting module, an interconnecting module and a mounting one. Actuators for generating vibrations in more directions can be connected to the exciting module. The mounting module is intended for clamping of tested components. The interconnecting module serves for interconnecting of the two other modules. Interconnecting of modules can be performed in various ways: by creating vacuum between contact surfaces, through bolts, through flexible or dampening members. Using the above mentioned elements a system can be adjusted for testing particular samples in required conditions. This approach is not practical as well because adjustment of mechanical parameters of respective modules for a particular system is time consuming and, moreover, a modal readjustment of the mechanical system occurs during the test.
DE102016002188A1 patent describes a structure for vibration testing of lightweight components particularly, the main attribute of which is a low weight of a shaker table made e.g. of composite materials. In the centre of the table there is a frame for attaching of tested components. The frame is moveable in the vertical direction and it is connected to a vibration generator through a sliding shoe. Thanks to a low weight of the whole structure the requirements for input forces of the vibration generator are reduced and, at the same time, the component loading is less affected by the structure weight. However, the proposed solution is not suitable for large and highly pliable tested components and, moreover, is not flexible. Subject Matter of the Invention
A subject matter of the invention concerning a method for vibration testing of large and pliable components for their resilience to vibrations is described in Claims 1 to 7, a subject matter of the invention concerning equipment for vibration testing of large and pliable components for their resilience to vibrations is described in Claims 8 to 10.
An advantage of this invention is a compensation of dynamic pliability of a mounting testing frame and a tested component using active secondary sources for particular frequency components of the testing spectrum. An active secondary force source can be preferably arranged as a controlled dynamic absorber. Thus, vibration testing of a pliable component can be carried out without overloading the tested component in antinode loops of particular forms of a mode of vibration at/near resonant frequency. Another advantage is ad-hoc optimization of connecting of secondary force sources using a device for measuring of the particular forms of a mode of vibration of the system based on a scanning vibrometer. These data are used to control the primary force source in a form of an inversion mathematical model of the system and an original model of the system for controlling the secondary force sources. Another advantage is that tested components are subjected to the vibration exposure uniformly throughout the whole volume and through the entire testing spectrum.
Overview of Figures in Drawings
The attached Figures illustrate equipment for performing vibration tests of large and/or pliable components as described in the invention, where
Fig. 1 depicts a scheme of the equipment with a primary force source and secondary force sources connected through a connecting rod between a mounting testing frame and a bearing frame,
Fig. 2 depicts a scheme of the equipment with a primary force source and secondary force sources connected through a connecting string between a mounting testing frame and a bearing frame,
Fig. 3 depicts a scheme of the equipment, where secondary force sources consist of active absorbers, Fig. 4 depicts a scheme of the equipment, where secondary force sources consist of spring-loaded electromechanical exciters connected through a connecting string between a mounting testing frame and a bearing frame,
Fig. 5 depicts a scheme of the equipment, where secondary force sources consist of spring-loaded electromechanical exciters connected through a connecting rod between a mounting testing frame and a bearing frame,
Fig. 6 depicts a scheme of the equipment with a scanning vibrometer built-in prior to building-in secondary force sources,
Fig. 7 depicts a tolerance field according to a required motion of a tested component within the frequency domain and
Fig. 8 depicts a scheme of the equipment with more primary force sources.
Examples of Embodiments of the Invention
Fig. 1 shows the equipment for vibration testing of large and pliable components using more sources of action of force, where primary force source 1 is arranged on foundation 18 through vibroizolators 2. Primary force source 1 is connected to shaker table 3, to which mounting testing frame 4 is connected. Tested component 5 is attached to testing frame 4 through mounting attachments 7. In addition to mounting testing frame 4, bearing frame 15 for secondary force sources 11 is connected to foundation 18. Secondary force sources 11 are connected to mounting testing frame 4 and to supporting frame 15 through connecting rods 12.
Points of connection of secondary force sources 11 to mounting testing frame 4 are determined using an analysis of the particular forms of a mode of vibration, which are obtained by laser scanning vibrometer 14 shown in Fig. 6. Vibration sensors 8, which are connected to control system 6, are arranged on tested component 5 or mounting testing frame 4. Points of location of vibration sensors 8 are also determined using an analysis of the particular forms of a mode of vibration, which are obtained by laser scanning vibrometer 14 shown in Fig. 6. Further, primary force source 1 and secondary force sources 11 are also connected to control system 6.
Fig. 2 shows similar equipment as depicted in Fig. 1, wherein secondary force sources 11 are connected to mounting testing frame 4 and to bearing frame 15 through connecting strings 13. Fig. 3 shows an alternative embodiment of the equipment for vibration testing of large and pliable components using more sources of action of force, where secondary force sources consist of active absorbers 9 connected to control system 6. Absorbers 9 include a seismic mass connected through an absorber or another force element with a controlled stiffness to mounting testing frame 4. Control system 6 in a coordination with a control of primary force source 1 controls force elements in particular active absorbers 9, in a feedback with signals from vibration sensors 8.
Figs. 4 and 5 show the equipment as depicted in Fig. 1, wherein secondary force sources are electromechanical exciters 10 connected to bearing frame 15 and to mounting testing frame 4 through connecting rods 12 - Fig. 5 or connecting strings 13 - Fig. 4.
Figure 6 depicts a scheme of the equipment for vibration testing at the moment prior to installing secondary force sources 11, wherein bearing frame 15 is connected to scanning vibrometer 14 intended for determination of the particular forms of a mode of vibration and other modal properties for the actual arrangement of the whole mounting testing frame 4 including attached tested component 5 and primary force source 1, especially for determination of a position of connecting points of secondary force sources 11 and vibration sensors 8.
Fig. 7 shows the required frequency characteristic of loading of a tested component. This means - what amplitude of acceleration of the tested component has control system 6 to ensure through acting of primary force source 1_ and secondary force sources 11 for each frequency component of the tested frequency range.
Fig. 8 shows an alternative embodiment, where the equipment is arranged with more primary force sources 1. with the common control.
Prior to the very vibration testing of tested components 5: limits of the required prescribed testing frequency spectrum 17 of a motion of tested component 5 are defined, a computational or experimental modal analysis of the system consisting of one or more primary force sources 1, shaker table 3, mounting testing frame 4 and tested component 5 is performed through laser scanning vibrometer 14 or accelerometers, connecting points on mounting testing frame 4 for at least two vibration sensors 8 are determined so that amplitudes of the particular forms of a mode of vibration of the system in the selected points and through the entire prescribed testing frequency spectrum of loading are maximized and secondary force sources 11 are connected to the connecting points using connecting rods 12 or strings 13.
A motion of primary force sources 1 is controlled by control system 6 in a computer on the basis of an inversion of a model of the system comprising primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5. The system model is obtained using an experimental modal analysis carried out contactlessly by laser scanning vibrometer 14. Primary force source 1 acts against the centre of weight of tested component 5 along with mounting testing frame 4 and secondary force source 11. Secondary force source 11 acts upon tested component 5 and mounting testing frame 4 in a direction of acting of primary force source 1 in points with the highest amplitude of the most of particular forms of a mode of vibration of the system comprising primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5, within defined frequency spectrum 17 of loading for all points of a surface of tested component
5.
A motion of secondary force sources 11 is coordinated by computer control system 6 so that a relative motion of a point of activity of primary force source 1 and secondary force sources 11 is minimized. Secondary force sources 11 are connected to connecting points 16, a position of which is determined according to antinode loops of particular forms of a mode of vibration in required frequency spectrum 17 of loading. The particular forms of a mode of vibration of the system comprising primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5 are obtained using an experimental modal analysis by scanning vibrometer 14, for each system of tested component 5, mounting testing frame 4, shaker table 3 and primary force source 1 ad-hoc, as depicted in Figure
6.
Sources 1. and 11 of action of force are controlled in a coordinated way by control system 6 working in a feedback with vibration sensors 8 attached on a surface of tested component 5. Vibration sensors 8 can be preferably collocated with connecting points 16 of secondary force sources 11. Interventions of control system 6 are set according to the whole system model obtained using an experimental modal analysis by scanning vibrometer 14 and updated in accordance with changes of the whole system response and a course of the long- lasting test, which runs in cycles. Secondary force source 11 can consist of electromechanical exciter 10 connected to fixed frame 15 and connected to connecting points 16 on mounting testing frame 4 using connecting rod 12 or connecting string 13 with a high stiffness, preferably a carbon fiber.
A trajectory of a motion of tested component 5, which is determined in accordance with prescribed testing spectrum, is performed in cycles by control system 6 and courses of action interventions of primary force source 1 as well as secondary force sources 11 are modified after each cycle by control system 6 so that prescribed testing spectrum 17 can be adhered to with an increasing accuracy.
The mass and stiffness of secondary force sources 11 in the form of absorbers 9 is set for approximation of their resulting passive own frequency to the own frequency of the whole system consisting of primary force source 1, shaker table 3, mounting testing frame 4 and tested component 5 obtained using an experimental modal analysis.
When connecting secondary force sources 11 to a connecting point through strings 13, a motion of secondary force sources 11 is controlled so that strings 13 can be permanently loaded exclusively by the tensile force.

Claims

Patent Claims
1. A method for vibration testing of large and pliable components for their resilience to vibrations using equipment comprising a mounting testing frame, which is connected to a foundation through force sources, and to which a tested component fitted with vibration sensors is connected, whereas force sources and vibration sensors are connected to a control system, characterized in that limits of the required prescribed testing frequency spectrum of the tested component motion are defined, a computational or experimental modal analysis is performed through accelerometers or a laser sensor of a system consisting of a primary force source, a shaker table, a mounting testing frame and a tested component, connecting points for at least two vibration sensors on the mounting testing frame are defined so that amplitudes of particular forms of a mode of vibration of the system in the selected points and through the entire prescribed testing frequency spectrum of loading are maximized, secondary force sources are connected to connecting points through connecting rods or strings, the secondary force sources are controlled in a coordinate way with one or more primary force sources by the control system to minimize a deviation of the relative motion of connecting points of the secondary force sources towards a motion of the primary force source and, simultaneously, a motion of the whole tested component within the prescribed testing frequency spectrum.
2. A method for vibration testing of large and pliable components for their resilience to vibrations as described in Claim 1, characterized in that time courses of action interventions of the primary force source and secondary force sources are derived by the control system using an inversion of a model of the system comprising a shaker table, a mounting testing frame and a tested component obtained with the aid of an experimental modal analysis.
3. A method for vibration testing of large and pliable components for their resilience to vibrations as described in Claim 2, characterized in that a trajectory of a motion of a tested component, determined in accordance with a prescribed testing spectrum, is performed in cycles and time courses of action interventions of the primary force source and secondary force sources are modified by the control system so that the prescribed testing spectrum can be adhered to with an increasing accuracy.
8
4. A method for vibration testing of large and pliable components for their resilience to vibrations as described in Claim 1, characterized in that secondary force sources are connected to connecting points through strings and a motion of the secondary force sources is controlled so that the strings are permanently loaded by the tensile force.
5. A method for vibration testing of large and pliable components for their resilience to vibrations as described in Claim 1 , characterized in that some or all secondary force sources can consist of an active dynamic absorber, a mass and stiffness of which are set so that the resulting passive own frequency of the active absorber is near the selected own frequency of the whole system obtained using an experimental modal analysis, whereas a force member in the active dynamic absorber is controlled by the control system within a feedback from vibration sensors.
6. A method as described in Claim 3, characterized in that all force sources are controlled by common control system (6) synchronizing and coordinating their actions of force for minimization of a relative motion of a point of activity of a primary force source and secondary force sources.
7. A method as described in some of the Claims mentioned above, characterized in that points of activity of secondary force sources (11) are collocated with vibration sensors (8).
8. Equipment for vibration testing of large and pliable components for their resilience to vibrations pursuant to a method described in Claim 1, comprising a mounting testing frame, which is connected to a foundation through at least one primary force source and to which a tested component fitted with vibration sensors is attached, whereas the primary force source and vibration sensors are connected to a control system in a computer, characterized in that the equipment includes at least one secondary force source (11) arranged on tested component (5) or connected to mounting testing frame (4) and bearing frame (15) fixed to foundation (18).
9. Equipment for vibration testing of large and pliable components as described in Claim 8, characterized in that the secondary force source consists of active absorber (9) arranged on tested component (5).
10. Equipment for vibration testing of large and pliable components as described in Claim 8, characterized in that the secondary force source consists of electromagnetic exciter (10) connected to mounting testing frame (4) and bearing frame (15).
9
PCT/CZ2021/000035 2020-10-12 2021-07-12 A method and equipment for vibration testing of large and pliable components for their resilience to vibrations WO2022078532A1 (en)

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Citations (10)

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