RU2715895C1 - Device for determining elastic-viscous and viscous medium - Google Patents

Abstract

FIELD: physics.SUBSTANCE: invention relates to the field of control and measuring equipment for determination of viscoelastic medium and viscous medium, in particular, polymer media. Device for determining elastic-viscous and viscous medium of polymer resin consists of two coaxial cylinders, having rotation, between which there is polymer resin, outer cylinder has a device which sets rotary oscillatory motion with a certain amplitude and a defined frequency, inner cylinder is suspended on a cylindrical tube, one end of which is connected to the cylinder, and the other end is connected to the fixed housing of the device, the inner cylinder has a device which records the cylinder oscillation process, amplitude and frequency.EFFECT: technical result is determination of elastic viscous medium and viscous medium.1 cl, 1 dwg

Description

This device relates to the field of control and measuring equipment for determining an visco-elastic medium and a viscous medium, in particular polymeric media.

Design description

In the manufacture of polymer composite materials, polymer resins are used. These resins are impregnated with fabrics of high-strength glass fibers, boron, carbon and other high-strength fibers. The polymeric materials used may be viscoelastic or viscous media. In elastic-viscous media, the dependence of shear stresses on strains is determined by the relation:

where G is the elastic shear modulus of the resin, γ is shear deformation,

η is the dynamic coefficient of viscosity of the resin,

- скорость сдвиговой деформации.

- shear strain rate.

For viscous media, dependence (1) has the form:

The components of elastic deformation in relation (1) may be insignificant in magnitude. However, they affect the parameters of the technological process of forming parts from polymer composite materials. Therefore, when calculating the technological parameters, control is necessary: the elastic-viscous or viscous medium is resin.

There are various types of viscometers for measuring the viscosity of liquid media - rotational (ASTM D 5293-CCS), capillary (ASTM D 445) [1].

In rotational viscometers, viscosity studies are carried out using a measuring cylinder or a disk (spindle) immersed in the analyzed material, which, in turn, are previously placed in an external reservoir cylinder. Further, at a certain speed of rotation of the spindle (cylinder), viscosity is determined by measuring the resistance of the substance. Viscosity can be determined by using different types of spindles (cylinders) and their rotation speed.

The disadvantages of the known devices include the complexity of the design and maintenance, as well as the high cost of their manufacture.

In rotational viscometers of the ST-2001 L-H series from AWTech, the spindle principle of measuring resistance in the range from 20 cP to 1060,000 P (poise) is implemented [2]. The disadvantage of the AWTech ST-2001 L-H viscometers is the large volume of the test fluid, as well as the insufficiently low lower limit of viscosity measurements.

Viscosity can be determined by using different types of coaxially arranged cylinders and different speeds of rotation. In rotational viscometers with coaxially arranged cylinders, the outer cylinder is either stationary or rotates at a given angular velocity. In the latter case, the inner cylinder is connected to a dynamometer sensing the torque transmitted by the test fluid, the magnitude of which is directly proportional to the effective viscosity.

Of the viscometers of this type, a rotational viscometer deserves attention, including a coaxial outer cylinder and a measuring inner cylinder concentrically located in it, connected to a synchronous electric motor using a hollow shaft [3]. A rod is placed inside the hollow shaft, which is rigidly connected to the measuring inner cylinder. The rod is simultaneously rigidly connected through torsion bars at one end to the motor shaft, and the other to the lower base of the genital shaft. When the motor shaft rotates, the torsions transmit torque to the internal measuring cylinder. The magnitude of the angular displacement of the torsion is fixed by a collector-type dynamometer, which supplies an electrical signal to the recording device, which is directly proportional to the viscosity of the investigated fluid.

Inside this device, outside the measuring (inner) cylinder, a protrusion is installed over its entire height with a minimum gap between it and the inner surface of the stationary outer cylinder. A through slot-like groove is made in the annular channel between the cylinders along the entire height of the outer stationary cylinder, through which the test fluid enters, and a protrusion extends and retracts into the annular channel. The extension of the protrusion on the inner surface of the fixed cylinder is controlled by a cam mechanism rigidly fixed to the hollow shaft of the engine.

The disadvantages of this device include: the need for research of a sufficiently large volume of resin samples, which makes it unsuitable for research in the presence of small volumes of polymer resin.

Closest to the claimed invention is a method for determining an elastic-viscous medium and a viscous medium (patent RU 2390758) [4], which consists in improving the reproducibility of shear stresses due to structural changes in coaxial cylinders and recording the number of revolutions of the measuring cylinder for a fixed 10-second time interval .

The disadvantage of this method is that during the measurement process is not fixed resonant oscillation of the inner cylinder, which is an indicator of an elastic-viscous medium.

The aim of the invention is to expand the range, increase accuracy and improve the diagnostic capabilities of viscometric measurements.

The technical problem, which this method is aimed at, is the determination of an elastic-viscous medium and a viscous medium.

The technical result of the proposed method is to determine the elastic-viscous medium and a viscous medium.

The technical result is achieved by recording the presence or absence of resonance oscillations of the inner cylinder.

The application proposes a design consisting also of two cylinders, inner 1 and outer 2, between which test resin 3 is placed (Fig. 1). The outer and inner cylinders can rotate about a common axis. The inner cylinder is suspended on a tubular element 4, the end of which is attached to the fixed body 5 of the device. This element acts as a torsion spring. The outer cylinder on the outside has a device that can create rotational vibrational movements of its cylinder with a certain amplitude of oscillations and a certain frequency. The inner cylinder has where the device is located, which allows to record the amplitude and frequency of oscillations arising from the exciting oscillations of the outer cylinder, which are transmitted through the test medium. By changing the oscillation frequency of the outer cylinder, we seek to create the maximum amplitude of the oscillations of the inner cylinder. The oscillations of the inner cylinder are caused by vibrations of the outer cylinder, which transfers the vibrations to the inner cylinder through the test polymer resin. If the inner cylinder enters into resonance with the vibrations of the outer cylinder, then this indicates that the liquid under test at small amplitude vibrations is an elastic medium and is an elastic-viscous body. If the inner cylinder does not have pronounced resonant vibrations, then this is evidence that the test material is a viscous medium.

Claims (1)

A device for determining the elastic-viscous and viscous medium of a polymer resin, consisting of two coaxial cylinders having rotation, between which there is a polymer resin, characterized in that the outer cylinder has a device that specifies rotational vibrational motion with a certain amplitude and a certain frequency, the inner cylinder is suspended on a cylindrical tube, one end of which is connected to the cylinder, and the other end is connected to the stationary case of the device, the inner cylinder has a device that records the process cylinder with oscillation amplitude and frequency.

Images