SU1320702A1 - Method of determining material modulus of elasticity at elevated temperatures - Google Patents

Abstract

The invention relates to the study of the strength properties of materials, and in particular to methods for determining the elastic modulus at elevated temperatures. The aim of the invention is to reduce the labor intensity. This is achieved due to the fact that on one sample both the natural frequency of the flexural vibrations and the coefficient of temperature expansion are measured. The coefficient of temperature expansion is determined by measuring the change in the distance between the vibration nodes of the sample. For this, two rods bent at a right angle are attached to the sample in the vibration nodes. The end of one section of each rod is connected to the sample at two diametrically opposite points lying in the neutral plane of the sample. The second sections of the rods are placed outside the heating device towards each other and the change in the distance between their ends when the sample is heated is measured. When using the invention, labor costs for the manufacture of special samples are excluded to determine the temperature expansion coefficient on the dilatometer. 1 hp f-ly, 2 ill. W (L S

Description

The invention relates to the study of the strength properties of materials, in particular, to methods for determining the elastic modulus of materials at elevated temperatures.

The aim of the invention is to reduce the labor intensity.

The essence of the invention is to determine the coefficient of temperature expansion directly on the sample to be tested by measuring and changing the distance between the nodes of the flexural vibrations of the sample. Due to this, labor costs for the manufacture of special samples are excluded to determine the coefficient of temperature expansion on the dilatometer. The coefficient of temperature expansion is determined simultaneously with the measurement of the natural frequency of oscillation of the sample under examination, as a result of which additional labor and time costs for performing dilatometric measurements are excluded.

Figure 1 shows the test scheme for the proposed method; figure 2 - view And figure 1.

The determination of the elastic modulus by the proposed method is carried out by the resonant method using the natural frequency of the flexural vibrations, taking into account the coefficient of thermal expansion of the sample. The rod sample 1 is suspended on thin threads to a vibration sensor exciter (not shown).

On sample 1, in the nodes 2, its bending- Hfcpix oscillations fix the ends of one sections of two rods 3 bent at a right angle, the second sections of which are directed towards each other. The plane of the axis of the rods coincides with the plane in which the bending vibrations of sample 1 are excited. The latter with rods 3 is placed in the heating device 5 so that the second sections 4 rods 3 are removed from the heating device 5. The end of the section 3 of the rods connect with the sample in two diametrically opposite points lying in the neutral plane of the sample.

The determination of the elastic modulus of the proposed method is made. in the following way.

The sample is heated to a predetermined temperature. After that, bending vibrations of sample 1 are excited and the natural frequency of bending vibrations is measured. At the same time, a change in the distance between the ends of the sections of the 4 rods is measured with a microscope, and the coefficient of thermal expansion is determined from it. For the specified measurement, the marks can be the risks caused near the ends of the rods, or the ends themselves.

Example. The elastic modulus of brass was determined in the temperature range of lT 20–720 0. A cylindrical specimen with a diameter of d 8 mm and a length of 1,200 mm was used for this. At the vibration nodes located at a distance of 0.2241 from the ends of the specimen, two bent rods with a diameter of 1 mm were attached to the sample by a check-box. The ends of the rods were labeled, the distance between which was measured on the scale of the microscope MPV-1 with a division of 2.5 µm. The coefficient d of the temperature expansion was determined from the change in this distance when the sample was heated. According to the measured frequency f of natural flexural vibrations and the coefficient d, the elastic modulus E was calculated using the formula

35

40

E 1,6388 .lo- "f: ™ | -J y-f

one-, .

where P is the weight of the sample

and the remaining designations are given

above.

Claims (2)

1. A method for determining the modulus of elasticity of a material at elevated temperatures, namely, that The sample under study is suspended in the vibration nodes at NITs inside the heating device, the sample is heated, bending vibrations are excited in it, the natural frequency of the bending oscillations of the sample is measured, and the elastic modulus of the material is calculated using the coefficient of thermal expansion of the sample, characterized in that, in order to reduce labor intensity, the coefficient of temperature expansion of the material is determined on the sample under test simultaneously with the measurement of the specific frequency by measuring the change in the distance between the oscillation nodes. 2. Method POP.1, characterized in that for measuring the change in the distance between the vibration nodes to the sample in the vibration nodes attach two bent at a right angle angle, which are located in the plane of the bending kolefi. J View A 207024 The sample bay, at the same time the end of one section of each of the rods is connected to the sample at two diametrically opposite points lying in the neutral plane of the sample, and the second sections of rods are placed outside the heating device towards each other and the change in the distance between the ends of the second sections 10 rods. VNIIPI Order 2652/46 Circulation 776 Subscription Random polygons pr-tie, Uzhgorod, st. Project, 4 04 / 8.2