SU590698A1 - Device for determining dynamic characteristics of oscillating systems - Google Patents

Description

one

The invention relates to instrumentation and can be used in vibration testing and the study of nonlinear oscillatory systems.

Devices are known for determining the dynamic characteristics of oscillating systems, in which the characteristics of the restoring and damping forces are determined from stationary oscillations by reproducing the laws of the distribution of the oscillatory displacement and velocity and their central moments, followed by processing them in the functional converter 1, 2.

Of the known devices, the closest in technical essence to the invention is a device for determining the dynamic characteristics of oscillating systems, comprising a first and second voltage source, a switch, the first output of which is connected to the control inputs of the first and second keys through a pulse shaper, and a two-coordinate recorder 3 .

The disadvantages of such a device include its functional complexity, which reduces the accuracy of the results obtained, and the impossibility of obtaining the characteristics of the system under study only from the temporal characteristics of the vibration process. The specified device involves the preliminary determination and introduction of functions of an equivalent parameter stiffness coefficient, equivalent damping and damping coefficient. It also reduces the accuracy and significantly increases the complexity of the process of determining the dynamic characteristics.

The purpose of the invention is to increase the accuracy of the device.

To do this, the device has two inverters, an adder and two memory blocks, the first and second outputs of the second voltage source being connected directly and through inverters to the corresponding inputs of the switch, the second output of which is connected to the same key through the serially connected first switch from the inputs of the two-coordinate recorder, the output of the first voltage source and the third output of the second voltage source are connected to the inputs of the adder, the output of which is connected in series via volts swarm key and the second block memory is connected to the other input dvuhkoordnnatnogo registrar.

The block diagram of the device is shown in the drawing.

It contains the first 1 and second 2 voltage sources, the adder 3, the first 4 and second 5 inverters, the switch 6, the functional converter 7, which includes a shaper of 8 pulses, the first 9 and second 10 keys, the first 11 and the second 12 memory blocks , and two-coordinate recorder 13.

The device works as follows.

When entering the inputs of the adder 3 from the outputs of the first 1 and second 2 voltage sources, proportional to the acceleration and disturbing force of signals, whose different-dimension scales are matched, a signal proportional to the sum of potential and damping forces is obtained at its output, since this sum is balanced in the oscillating system the sum of the disturbing force and the force of inertia proportional to the acceleration. This signal is fed to the input of the second key 10, at the output of which a signal equal to the output signal of the adder 3 face occurs in those short periods of time when a pulse is output from the output of the imaging unit 8 to the control input of the key 10, namely, at the moments of changing the sign of the input signal signal of the pulse generator in one direction (in the described case - from positive to negative).

The output signal of the key 10 passes to the input of the memory unit 12 at the same time as the pulse arriving at its control input from the output of the driver 8. As a result, the output of the memory unit 12 is equal to the voltage of the output pulse of the key 10. This voltage is kept constant until the next pulses from the outputs of the key 10 and the driver 8 arrive at its inputs.

Thus, at the output of the memory unit 12, a step signal appears, the level of which steps is proportional to the values of the potential or damping force at the instants of time when one of them is equal to zero. This signal is fed to the first input of the two-coordinate recorder 13, to the second input of which, from the output of the memory block 11, a similar stepped sweep signal is supplied, the level of which is proportional to the corresponding fixed values of the oscillatory displacement (if a potential characteristic is determined) or speed (if the damping signal is determined) characteristic).

The device has four possible modes of operation; And - definition of a positive branch of the potential characteristic; B - the definition of its negative branch; B - definition of the positive branch of the damping characteristic; G - the definition of its negative branch.

In operating mode A, switch 6 provides the connection of the input of the pulse shaper 8 to the first output of the voltage source 2, and the input of the switch 9 to the second output of the same source. Similarly, in operating mode B, the above inputs are connected respectively to the outputs of inverters 4 and 5, in operating mode B to the first and second outputs of the voltage source 1, and in operating mode G to the outputs of inverters 5 and

4. In the case of a slow change in the amplitude of oscillations, the recorder 13 fixes the corresponding branch of one of the characteristics in the form of a broken curve, the length of which uniform sections can be adjusted by changing the oscillation frequency and the rate of increase (or decrease) in amplitude. The device is also suitable for determining the characteristics of free damped oscillations (the signal of the voltage source 1 is zero), but in this case it is not possible to adjust the length of the uniform portions of the characteristic to be fixed. If the oscillation process rapidly decays, the process repeats several times under different initial conditions, and the points of all the curves obtained are joined by a smooth curve.

As a source of voltages proportional to the temporal characteristics of the oscillatory process, a vibration measuring device consisting of an acceleration sensor, an amplifier and two integrating amplifiers, a recording signal reproducing device together with the corresponding amplifiers, a recording device of all three temporal characteristics can be used. and etc.

The application of the proposed device makes it possible to obtain graphics characteristics

restoring and damping forces with minimal faults and with minimum labor-intensiveness, without preliminary determination and introduction into the device of auxiliary functions, only by temporal characteristics and by the process of initiating the oscillatory motion, i.e., the invention gives both technical and economic effect.

Claims (3)

1. USSR author's certificate No. 417771, cl. G 05В 23/02, 1972.5 2. USSR author's certificate No. 483654, cl. G 05В 23/02, 1973. 3. USSR author's certificate №450139, cl. G 05В 23/02, 1973.