Abstract: A test apparatus for torsional testing of a wind turbine blade is provided. The apparatus includes a test stand for rigidly supporting the wind turbine blade; a load frame for mounting on the wind turbine blade at a testing position along the length of the blade; and an actuator connected to the load frame for twisting the blade via the load frame. The load frame includes an outer frame to which the actuator is connected and a profiled insert held within the outer frame and defining a profiled aperture corresponding to the profile of the blade at the testing position. The profiled insert encloses and is in direct contact with the outer surface of the blade over substantially the entire profile of the blade. A system and method of torsional testing of a wind turbine blade and a load frame for the test apparatus are also provided.

Abstract: A vibrator-mounted holder is attached to a casing of a vibration generator which moves a vibrator to generate a vibration when used. The vibrator-mounted holder includes a vibrator, a vibrator retention unit retaining the vibrator, a fixing unit fixed to a casing, and an arm. The vibrator includes a magnet having a plate shape parallel to a horizontal surface and a yoke arranged on the magnet. The arm connects the fixing unit to the vibrator retention unit, and supports the vibrator retention unit in a manner that the vibrator retention unit is displaceable with respect to the fixing unit. The yoke has a projecting portion which is projected downward and fixed to the vibrator retention unit. The arm is connected to a portion, at which the projecting portion is arranged, within the vibrator retention units.

Abstract: A linear vibrator that transmits tactile signals to a user of a mobile phone, PDA, or a portable game console. The linear vibrator uses rubber or silicone rubber having lower elasticity as a material of an elastic body secured to a casing or a base for supporting an oscillator horizontally moving by an electromagnetic force relative to a facing stator, thereby lowering the frequency sensitivity due to a characteristic frequency; reducing various errors of parts and errors in part assembly, thus resulting in smaller deviations of characteristic frequencies between products from mass production; and significantly reducing production cost by using an elastic body made of rubber or silicon rubber instead of steel plate or wire, thereby efficiently producing a structure through a simple assembly process and reducing the manufacture facility cost and labor cost resulting in improved productivity.

Abstract: In operating a vibration testing system, a table is provided with a plurality of distinct regions, and each of the plurality of distinct regions is provided with at least one vibrator of the plurality of vibrators and at least one accelerometer of the plurality of accelerometers. Target vibration strengths are set for each region, and the vibrators are operated. Local vibration strength is measured at each distinct region with the corresponding accelerometer(s) of the plurality of accelerometers. A signal corresponding to each of the measured local vibration strengths is provided to a controller. An individual vibrator control signal is calculated for each distinct region based on the corresponding measured local vibration strength and the corresponding target vibration strength. The individual control signals are provided from the controller to control the vibrator(s) of each distinct region to achieve the target vibration strength at each of the distinct table regions.

Abstract: Testing method for determining the distribution of a physical property along a wind turbine blade comprising the following steps: a) installing inside the blade a first optical fiber cable (13) along the leading and trailing edges and a second and third centered optical fiber cables (14, 15) at both sides of the blade (9), leaving in them a free end; b) applying one load to the blade (9) in a test bench (10) placed at the blade factory; c) obtaining the strain distribution produced by said load along the blade (9) using a suitable external equipment connected to said free end for measuring the strain using Rayleigh scattered light; d) determining the distribution of said physical property from said strain distribution; e) comparing the distribution of said physical property with its design distribution. The invention also comprises a method of installation of said cables.

Abstract: A vibrator-mounted holder is attached to a casing of a vibration generator which moves a vibrator to generate a vibration when used. The vibrator-mounted holder includes a vibrator, a vibrator retention unit retaining the vibrator, a fixing unit fixed to a casing, and an arm. The vibrator includes a magnet having a plate shape parallel to a horizontal surface and a yoke arranged on the magnet. The arm connects the fixing unit to the vibrator retention unit, and supports the vibrator retention unit in a manner that the vibrator retention unit is displaceable with respect to the fixing unit. The yoke has a projecting portion which is projected downward and fixed to the vibrator retention unit. The arm is connected to a portion, at which the projecting portion is arranged, within the vibrator retention units.

Abstract: Sensors for monitoring shock or vibration of an object are provided. The sensors include a proof mass, at least piezoelectric device, and an electronic circuit connected to the piezoelectric device. The piezoelectric device generates a current when the proof mass imparts a force on the piezoelectric device in response to the proof mass being subjected to a transient acceleration when the object is subjected to a shock or vibration. The electronic circuit is at least partially controlled in response to the current generated from the piezoelectric device due to the shock or vibration. Embodiments of the sensor provide multi-axis sensing capabilities. Methods of making the sensors and flexible circuits are also provided.

Abstract: Focusing on the criterion of “Energy save” or “Quiet noise” or other suitable operating parameter and considering the existing limitation of the operation of the electro-dynamic shaker system, apparatus for optimizing the operating condition of the vibration test system is proposed. The apparatus 100 measures the field current and drive current under the state that the desired vibration is fed to the specimen 20, and calculates the necessary force the shaker 1 should supply. Field current is supposed to be varied, and the necessary drive current is calculated based on the necessary force data. Further, the blower rotation is supposed to be varied, and the total power consumption at the coils and the blower is calculated. Also the temperatures of the field coil 4 and of the drive coil 10 is estimated and checked whether within the limitation. Then the optimal operating condition for the focused criterion is selected.

Abstract: Some embodiments of the present invention provide a system that generates a simulated vibration pattern in a computer subsystem. During operation, a vibration pattern is monitored at a location in the computer subsystem, wherein the vibration pattern is monitored while the computer subsystem is incorporated into the computer system and the computer system is operating. Then, the vibrations of the computer subsystem are mimicked by generating the simulated vibration pattern at the same location in the computer subsystem based on the monitored vibration pattern.

Abstract: Horizontal vibration shakers 21a and 21b are disposed opposite to each other on both sides of a vibration table 4, and either of the horizontal vibration shakers, e.g. 21a is arranged vertically movable so as to produce a positional difference (offset) with respect to a horizontal vibration axis 63 of the other horizontal vibration shaker 21b. When it is supposed that an accelerated velocity appears upwards on the left side of the vibration table 4, while another accelerated velocity appears downwards on the right side of the vibration table 4 as a result of generation of a rotational mode M, one of the horizontal vibration shakers, e.g. 21a, is elevated to produce the positional difference (offset) with respect to the horizontal vibration axis 63 of the other opposed horizontal vibration shaker 21b.

Abstract: A vibration information transmission apparatus for improving efficiency of field wiring of a vibration monitoring/analyzing system includes transmitters (11-1 to n) for converting vibration information from vibration sensors (2-1 to n) for detecting vibration of an object to be measured, into an electric signal and outputting the electric signal to a digital network (DN). The transmitters (11-1 to n) includes in the same casing, a transducer circuit (18) for converting the vibration information from the vibration sensors (2-1 to n) into an analog electric signal, an A/D conversion circuit (19) for converting the analog electric signal from the transducer circuit (18) into a digital signal, and a network interface (20) for outputting the digital signal from the A/D conversion circuit (19) to the digital network (DN).

Abstract: An adaptive control method is provided with particular relevance in methods which use a varying input frequency for analysis of an oscillatory response of a system, such as sine sweep testing. In one aspect the method includes the steps of applying a drive force having at least one sinusoidal component to said system, the frequency of the sinusoidal component being changed with time; and measuring an oscillatory response of said system; the method further including the step of providing a control signal based on at least a comparison between the frequencies of the sinusoidal component and the oscillatory response, wherein the rate at which the frequency of the sinusoidal component is changed is adjusted according to the control signal, so as to adapt the rate of frequency change to the region of the response spectrum being analyzed. A test apparatus capable of carrying out the methods of the invention is also provided.

Abstract: A vibration test system for structures comprises a vibration exciter that vibrates a real model portion, a load meter that measures a load, and a computer that receives a numerical model representing a numerical model portion. The computer includes a block that calculates a displacement, which is made in a predetermined time after completion of measurement, according to a load value and an external force value. A signal production block produces a command signal using as a target value the displacement calculated by the displacement calculation block. A step control block controls the displacement calculation block and signal production block so that they will act cyclically. The displacement calculation block uses an ?OS method to time integrate a solution of a vibrational equation.

Abstract: A method for the diagnosis of natural vibrations in a mechatronic system, includes at least one rigid body (WT1, WT2), which is moved relative to another rigid body (S) by means of at least one numerically-controlled drive, whereby the natural vibrations are caused by the drive (A1, A2) and are detected by sensors (WM1, WM2, N1, N2, BA1, BA2,) internal or external to the system. The drives (A1, A2) can be used as a system-internal, vibration-generator, so-called rotatory shakers, by superimposing white noise on a constant speed for the drive, or by wobbling the frequencies.

Abstract: An apparatus for controlling motion of an object includes a first actuator for moving the object, an elastic-motion measuring unit for measuring elastic motion of the object, and a control unit for controlling the first actuator based on a result of measurement of the elastic-motion measuring unit. Another apparatus for controlling motion of an object includes a first actuator for moving the object, a second actuator for suppressing elastic motion of the object, and a control unit for controlling the second actuator based on a result of predicting the elastic motion of the object caused by the first actuator.

Abstract: A nondestructive method of and apparatus for detecting degradation of reinforcing members embedded within a structure is disclosed. Degradation can arise from many sources, such as corrosion, fracture, cracking, fatigue, chemical reaction, etc. The device includes an inducing instrument(210) to induce a vibration of the reinforcing members (110)and a measuring device (220) to detect the vibration of the reinforcing members. The measurement is analyzed to detect the presence of reinforcing member degradation or reinforcing member-to-concrete bonding. The device may include a controller (230) to enhance the detection. The device may also include an amplifier (240) to further increase the energy in the waves imparted to the structure and the acoustic waves detected by the measuring instrument.

Abstract: In a hybrid vibration experiment of the structure, while shaking an actual model simulating a portion of the structure, vibration response analysis of a numerical model simulates the remaining portions of the structure using a computer. Loading members are provided neighboring the actual model. A plurality of vibrators vibrates the actual model through the loading members. The vibrators are controlled so that, not a point displacement but, a distributed displacement is loaded on the actual model.

Abstract: A surrogate component for shock testing is disclosed that includes a housing with exterior dimensions, mass, and a center of gravity approximately the same as the exterior dimensions, mass, and center of gravity of a counterpart component. The housing also has a stiffness greater than the counterpart component and has an interface for securing a sensor. In particular, the counterpart component may be hard drive and the housing may be constructed from a molybdenum material.

Abstract: A capacitance probe measures and tracks frequency and amplitude changes of a component during a high cycle fatigue portion of a life test. The probe includes an internal oscillator, an adjustable receiver circuit, a product detector, and a pair of gain amplifiers. The oscillator generates a single controlled frequency output. The receiver circuit receives the frequency and creates a DC voltage shift that nulls the capacitance bridge. The product detector detects an amplitude modulated product of the oscillator and rejects undesirable frequencies. The gain amplifiers detect a DC voltage shift and permit the capacitance effect to be easily nulled.

Abstract: The vibration damping properties of brake rotors and drums can be represented accurately and repeatably by a single factor obtained from a curve fitting based on an eighth order sine function. A series of test points taken only around one or more vibrational antinodes is used to measure resonant frequencies and vibration decay times around the periphery of a part. This data is then used to determine Q-factors, which are found to vary sinusoidally around an annular brake part.

Abstract: The vibration damping properties of a brake rotor (or other vibration-prone component) can be measured by vibrating the component part at its resonant frequency, using a magnetic coil that is excited by an A.C. signal having a frequency that is one half the frequency of the vibrating wave generated in the component. The A.C. signal crosses the zero current axis twice per current cycle, so that the magnetic flux in the coil core reverses polarity at the frequency selected for vibrating the part.

Abstract: A shaking table has a control unit for controlling the shaking table so that a target waveform signal is reproduced with at least an acceleration measuring signal as a feedback signal. The control unit is adapted for effecting control by employing the force applied to the shaking table from a specimen under test loaded on the shaking table as the feedback signal. As a control error deriving from the force is canceled, highly accurate acceleration reproducibility is attainable even in the case of a non-linear specimen under test whose dynamic characteristics fluctuate with time.

Abstract: A method for measuring damping characteristics of a friction member include: relatively pressing a first member as a friction member to be measured against a second member, for relatively sliding with respect to a second member and vibrating, measuring vibration states of the pressed first and second members, and measuring variations in the vibration states of the pressed first and second members and measuring damping characteristics of the friction member to be measured against vibrations by comparing damped amounts based on the variations in the vibration states of the first and second members. The above method and an apparatus therefor enable detailed evaluations of friction member having high performance.

Abstract: The invention disclosed is an elliptical vibratory apparatus including a first controller which includes at least a first phase shifter, a first high-gain amplifier and a first saturating element; a first power amplifier for amplifying an output of the first controller; a first vibratory exciter receiving an output of the first power amplifier for generating a horizontal vibrational force in a horizontal direction; a horizontal vibrational system of an elliptical vibratory machine receiving said horizontal vibrational force; a vibrational displacement detector for detecting a horizontal displacement of a movable part of the elliptical vibratory machine in the horizontal direction, the output of the vibrational detector being supplied to both the input of the first controller and the input of a second controller; the second controller including at least a second phase shifter, a second high-gain amplifier and a second saturating element; a second power amplifier for amplifying an output of the second controlle

Abstract: The vibration damping properties of brake rotors and drums can be represented accurately and repeatably by a single factor obtained from a curve fitting based on an eighth order sine function. A series of test points is used to measure resonant frequencies and vibration decay times around the periphery of a part. This data is then used to determine Q-factors which are found to vary sinusoidally around an annular brake part.

Abstract: A stage feeding device has a movable guide which is guided on a reference surface of a platen to be movable in the Y-direction, a Y-linear motor for moving the movable guide in the Y-direction, a movable stage which is supported by the movable guide to be movable in the X-direction, and carries an object, and an X-linear motor for moving the movable stage in the X-direction. The stator of the X-linear motor is supported by a second stationary guide to be movable in only the Y-direction independently of the movable guide, and is moved in the Y-direction by a driving mechanism. The stator of the Y-linear motor and the second stationary guide are fixed to the base, and mount members for removing vibrations are arranged between the base and the platen.

Abstract: An elliptical vibratory apparatus includes first and second controllers; first and second power amplifiers for amplifying outputs of the first and second controllers; first and second vibratory exciters receiving outputs of the first and second power amplifiers for generating first and second vibrational forces in first and second directions; first and second vibrational systems of an elliptical vibratory machine receiving the first and second vibrational forces; and detectors of first and second vibrational displacements for detecting vibrational displacements of a movable part of the elliptical vibratory machine in the first and second direction. A closed loop is formed by the first and second controllers, the first and second power amplifiers, the first and second vibratory exciters, the first and second vibrational systems, and the detectors of the first and second vibrational displacements.

Abstract: In a vibratory apparatus including vibratory speed detector for detecting a vibratory speed of a vibratory machine, a self-excited oscillation controller for amplifying the output of the vibratory speed detector at a feed-back gain K, receiving the output of the vibratory speed detector as a positive feed-back signal, a power amplifier for power-amplifying the output of the self-excited oscillation controller and a vibratory exciter receiving the output of the power amplifier for vibrating the vibratory machine, the feed back gain K is changed in accordance with the equation; K=K.sub.1 .DELTA.r+K.sub.3 (.DELTA.r).sup.3 +Kcr, where .DELTA.r represents the amplitude difference between a predetermined amplitude and the present amplitude, K.sub.1, K.sub.3 constants, and Kcr critical stability gain.

Abstract: In a plating apparatus 10, a known control signal for detection is supplied from a computer 50 to a motor 13 in advance; the motor 13 is rotated at a variable speed within a predetermined range; and the displacement of a basket 18 is detected by a displacement sensor 30 to obtain displacement characteristics data. Next, the computer 50 controls the rotating operation of the motor 13 through a motor controller 60 to put the basket 18 in a desired optimum state of vibration using the obtained displacement characteristics data and data of an optimum amplitude for the plating process obtained in advance.

Abstract: A computer-implemented apparatus and method for operating vibrational testing equipment which conducts vibrational testing upon automobile components. Raw engine acceleration data is gathered from a running car so that a sine on random calculation may be performed upon that data. The sine on random calculation uses peak hold envelope data and sin tone data as determined from the acceleration data. Thereupon, an iterative equalization technique operates upon the peak hold envelope data and sine tone data to generate a vibrational testing specification. The vibrational testing specification defines how the vibrational testing equipment should operate by specifying such parameters as the gain, the sweep duration, and the time to run the vibrational test in order to achieve a particular reliability and confidence level.

Abstract: A vibration testing system is economical and has high precision in realizing an equivalent test condition for testing for an entire structure, by employing a partial model by coupling testing of a partial structure and analysis of a numerical model with respect to a large structure or a structure having a portion that is difficult to establish the numerical model. In the vibration test using an actuator, a reaction of the member of the structure is detected to derive a vibration response after a given period of time at a boundary between the numerical model and the member. Excitation is performed so that the response of the actuator after the given period becomes consistent with a calculated value to make it possible to apply the response calculated with respect to the numerical model to the member by the actuator at the same timing to the actually occurring timing.

Abstract: A multiexciter digitally swept-sinewave vibration test controller employing an adaptive control method which compensates for nonlinear and time variant physical characteristics of a system under test and for instrumentation errors. A system under test (12) is stimulated using an exciter array (26) and response is measured using a sensor array (28). The exciter array (26) is driven by signals produced by a digital vector swept oscillator (18). A control loop (14) is used to modify signals to the exciter array (26) based upon input from the sensor array (28). A digital processing system (24) processes signals in the control loop (14). Within the digital processing system (24), a system impedance matrix (44) containing values representing the inverse of response characteristics of the system under test (12) is updated to approximate an "actual" system impedance matrix. A drive signal matrix (52) is modified to cause the digital vector swept oscillator (18) to produce updated drive signals.

Abstract: An active control precision damping table supported by air springs. Level displacement and vibrations of the table are detected by a sensor or sensors, and sensor outputs are fed to a variation adder which carries out an adding operation on one of the sensor outputs and an inversion signal produced by inverting the other sensor output 180 degrees. The adder outputs results of the operation to a drive circuit, which in turn outputs a drive signal to a control valve. The control valve is operable in response to the drive signal to adjust air pressure in pressure vessels of the air springs.

Abstract: A waveform tracking clipper circuit for limiting the instantaneous amplitude of a processed vibration test signal at the input to a shaker amplifier to the instantaneous amplitude of an unprocessed vibration test signal, the unprocessed vibration test signal having been processed to develop the processed vibration test signal. Included is clamper circuitry connected to the input of the amplifier. Numerous variations are disclosed, including the use of precision rectifiers and a variety of redundancy configurations to guard against the potentially-devastating consequences of a component failure or control misadjustment.

Abstract: The invention provides a friability testing apparatus which has an electrically excitable vibrator (10, 12) for vibrating a capsule (14) containing material to be tested. The apparatus includes a microprocssor (20) which proivdes an output waveform with a frequency which is determined by an oscillator (22). The output of the microprocssor drives a power amplifier (18) which controls the vibrator. An accelerometer (16) supplies signal to the microprocessor, so that the operation of the vibrator is maintained within predetermined limits.

Abstract: An active control precision damping table supported by air springs. Level displacement and vibrations of the table are detected by a sensor or sensors, and sensor outputs are fed to a variation adder which carries out an adding operation on one of the sensor outputs and an inversion signal produced by inverting the other sensor output 180 degrees. The adder outputs results of the operation to a drive circuit, which in turn outputs a drive signal to a control valve. The control valve is operable in response to the drive signal to adjust air pressure in pressure vessels of the air springs.

Abstract: A randomization unit for use in a vibrational control system for generating a series of randomized drive terms where the magnitude of each randomized drive term is the convolution of a psuedo-random sequence of bistable signals and a drive data sequence characterized by a drive power spectral density (PSD). The randomization unit does not required multipliers to perform the convolution operation.

Abstract: A randomization unit for use in a vibrational control system for generating a series of randomized drive terms where the magnitude of each randomized drive term is the convolution of a psuedo-random sequence of bistable signals and a drive data sequence characterized by a drive power spectral density (PSD). The randomization unit does not require multipliers to perform the convolution operation.

Abstract: A load support servomechanism circuit controls the armature of a shaker apparatus. The circuit includes a position sensor, peak detectors connected to outputs of the position sensor, an A/D converter connected to outputs of the peak detectors through a switching bank, a power supply and a microprocessor which provides clock, read, write and ready signals and which automatically controls the position of the armature through solenoids operating on an exhaust valve and a pressure valve. Manual operation of the shaker armature is also provided.

Abstract: A method and apparatus for driving a seismic hydraulic vibrator in which a conventional sinusoidal drive signal in modified in such a manner as to improve vibrator response parameters. The sinusoidal drive signal is modified such that in the regions of the signal proximate the reference axis, the signal will abruptly pass from one side of the reference axis to the other side of the reference axis. This modification is accomplished by summing a square wave signal with the sinusoidal signal to form a composite drive signal.

Abstract: A solid state amplifier for driving a shaker is described. The amplifier is comprised of a circuit which generates a pulse-width modulated drive signal for driving an armature of a shaker. The circuit includes an oscillator, power supply, wave-shaping generator, error detection network, comparator modulator and drive amplifiers. The oscillator generates a base waveform which is shaped by the wave-shaping generator. This signal is compared with error signals and the resulting signal is used to provide the pulse-width modulated driving signal to the shaker.

Abstract: A load signal representing the load between a mold and an oscillating mechanism is separated into its static offset and dynamic components. The static offset signal is compared with a free-running static offset to obtain a substantially DC signal representing the DC component of mold friction. A DC voltage is generated corresponding to the RMS value of the dynamic load signal component, and a reference voltage corresponding to the RMS value of the dynamic signal component of a free-running load signal is subtracted in order to obtain a substantially DC signal representing the dynamic component of mold friction.

Abstract: In order to ensure that the vibrations of a system under test are in accordance with a reference spectral density Z(w), the system is driven by a signal x.sub.n (t) provided by an inverse discrete Fourier transform (IDFT) with random phases introduced by a function R.sub.n (w) and the response spectral density Y.sub.n (w) provided by a DFT is brought into agreement with Z(w) by a feedback loop. Moreover, in order to ensure that this is done in one iteration, X'.sub.n (w) is derived from x.sub.n (t) by a DFT and divided by Y.sub.n (w) and the quotient is multiplied with Z(w) to provide the new input x.sub.n (w) for the IDFT. The division cancels out the random factor which is present in both X'.sub.n (w) and Y.sub.n (w).The system thus equalizes both rapidly and stably.

Abstract: A load indication system monitors not only the total frictional load on the mold oscillator in a continuous casting apparatus, but also monitors the difference in the oscillator load at various locations around the mold to detect mold wobble and load imbalance. In addition, both the total frictional load and the mold wobble are monitored by detecting their peak-to-peak values.

Abstract: In accordance with an embodiment of this invention, voltages are received from the pilot valve torque motor, the main servo valve and the actuator indicating the value of the torque motor current, spool position and actuator displacement. The received voltages are compared to a preselected threshold value. When one or more of the voltages exceed a threshold value, an attenuator control voltage is generated. An attenuator circuit is coupled between the reference driver signal generator and the DC servo amplifier. The attenuator control voltage, if present, is applied to the attenuator circuit and scales down the reference driver signal as a function of the error signal level thereby to limit the torque motor current and consequently the displacements of the main servo valve spool and actuator shaft.

Abstract: A system for testing articles with random and harmonic vibrations comprises a multichannel random signal shaper, a tuneable rejection filter connected to the output of the shaper, a vibrator connected to the output of the filter through an adder and a power amplifier which are placed in series, first and second tuneable filters and a signal spectrum analyzer connected to the first tuneable filter. The system according to the invention includes a variable-frequency harmonic signal generator, the signal spectrum analyzer representing a harmonic signal analyzer and comprising a harmonic signal control loop and a random signal control loop coupled thereto.

Abstract: A method of forming a desired vibration spectrum comprising the steps of preliminarily causing vibration of an article in a predetermined frequency range by the use of harmonic variable-frequency oscillations and using a multichannel signal shaper to produce specific values of spectral vibration acceleration density at each chosen check point on the article under test in each band of the predetermined frequency range, a random output signal level K in each channel being computed by solving a set of linear equations. A device for accomplishing the proposed method comprises the multichannel shaper connected to a vibrator mounting the article under test; vibration pick-ups secured at the chosen check points and connected through a switch to the input of a signal analyzer; a unit for setting parameters of a desired random vibration spectrum; and a control unit. The device forming the subject of the invention also comprises a variable-frequency harmonic oscillator and a memory unit connected thereto.

Abstract: A random vibrations testing device comprising a noise generator the output whereof is connected to an input of a wide-band filter. An output of the wide-band filter is connected directly and through paralleled narrow-band in-phase signal shaping channels to a means for shaping dips and spikes in the spectrum of a signal being shaped, which is electrically coupled with narrow-band opposite-phase signal shaping channels. The means for shaping the spikes and dips in the shaped signal spectrum is devised in the form of an adder series-connected to the wide-band filter, used commonly by all the narrow-band in-phase signal shaping channels and serving to form spikes in the shaped signal spectrum, and adders also series-connected to said wide-band filter, used individually by each opposite-phase narrow-band signal shaping channel and serving to form dips in the shaped signal spectrum.

Abstract: A stability control system for a vibration test device having an acceleration control system and using an electro-hydraulic servo-system is disclosed. The stability control system comprises a model operation circuit which simulates a model response corresponding to value representing the states of a vibration table in response to command signals produced from a signal generator and associated with the displacement, velocity and acceleration of the table, and a gain-adjusting circuit which produces gain-adjusting signals to gain-adjusting sections in response to model response signals produced from the model operation circuit, state-representing signals produced from a feedback circuit and the command signals produced from the signal generator. The gain of each gain-adjusting section is automatically controlled in such a manner that the state-representing values of the parts of the control system coincide with the corresponding state-representing values in the model operation circuit.

Abstract: The vibration motor comprises a concentrator of torsional vibrations, whose end face is in close contact with a rotor, and a piezoelectric cell unit adjoining the concentrator of torsional vibrations. Besides, the vibration motor is provided with a magnetic field source arranged under the rotor at the side of the concentrator of torsional vibrations and having a power sufficient to hold the rotor firmly against the concentrator end face, and with magnetic circuit. One part of the latter is movable, being fashioned as a disk with circumferentially spaced slots and rigidly connected to the rotor. The other part of the magnetic circuit separated from the first one by an air gap is stationary. It surrounds the magnetic field source and has peripheral slots identical to those of the movable disk and arranged opposite to them.