SU789716A1 - Dilatometer for investigation of construction materials - Google Patents

Description

The device contains a rack 1 with a sample 2 mounted on it, a displacement indicator 3 and a sensor 4, which are placed in an insulated temperature sensor 5, the temperature in which is changed by means of the temperature controller 6 according to a signal from a linear unit 7. Node 8 is connected to sensor 4 automatic registration of the magnitude of the strain.

The temperature measurement error is due to the deformation of the stand of the sample fastening elements to the rack, the mechanism of the movement indicator 3 and the thermal drift of the electrical parameters of the sensor 4.

In a fairly wide range of temperatures at which building materials are tested, the listed error components depend linearly on temperature, and the error due to the stand deformation is opposite to the sign of the other components of the error. To eliminate the temperature error of the dilatometer, the rack is assembled in two parts with different temperature expansion coefficients oi and. In this case, the absolute value of the temperature error of the registration DE is approximately determined by the expression

. u & - aci2 + () c,

where O is the adjustable distance from the base of the stand to the joint between its parts; U - rack length | - the total temperature coefficient of dilatometer error;

At - temperature change. From the expression (1), the position of the boundary between the parts of the rack is determined at which the temperature error of the dilatometer is zero.

 with |

Such a constructive solution of the device thus ensures the elimination of the temperature error of the dilatometer.

The linear temperature adjuster provides a monotonic change in temperature in chamber 5 by means of controller 6 (heating, cooling is proportional to the movement of the chart tape of the automatic registration unit. The rate of temperature change is chosen low enough to eliminate the dynamic temperature difference between sample 2 and temperature maintained in chamber 5. Temperature change The sample length is converted by sensor 4 into an electrical signal recorded on the chart tape of the automatic recording unit 8.

The movement indicator serves to adjust the dilatometer, which, in order to improve the accuracy of recording, is carried out immediately before each measurement.

Claims (2)

1.Dilatometer for the study of building materials, containing a rack with a sample, a sensor and a movement indicator placed in a heat-insulated chamber, a temperature controller in the chamber, a linear setpoint temperature gauge and an automatic deformation recording unit, in order to improve the accuracy registration of deformation, the dilatometer rack is made of two parts with different temperature expansion coefficients, and the border between them is removed from the base of the rack for a distance where K is the temperature coefficient dilatometer errors J L - rack length, - temperature coefficients Expansion of parts of the rack. 2. The dilatometer is pop.1, which is also distinguished by the fact that, in order to facilitate the adjustment of the dilatometer when the dimensions of the test samples are changed, it additionally contains a node to change the distance of the stand to the border between its parts. Sources of information taken into account in the examination 1. USSR author's certificate number 354333, cl. G 01 N 25/16, 1972. 2. The author's certificate of the USSR W 545909, cl. G 01 N 25/16, 1977 (prototype).