SU623119A1 - Method of measuring statistic mechanical stresses - Google Patents

Description

The invention relates to a measurement technique, in particular, to magnetic methods for measuring static mechanical stresses in linear ferromagnets, for example, in steel reinforcement of reinforced concrete structures.

Methods are known for measuring static mechanical stresses in linear ferromagnets, for example, in steel reinforcement of reinforced concrete structures that are based on a magnetoelastic effect, i.e., on the dependence of the magnetic properties of ferromagnets on the nature and magnitude of the mechanical stresses in them, caused by external force 1 2j.

The closest in technical essence is the way in which magnetic marks are applied to the reinforcement before the concrete mixture is formed, according to the induced magnetic field of each of which the stresses are determined on a previously scaled scale, for example, an oscilloscope to which the output signal from the magnetic probe is applied

The method is based on a change in the induction of the induced magnetic field of the marks depending on the change in the mechanical stresses in the NW reinforcement.

However, the method provides measurement of increments only in those reinforced concrete structures, the reinforcement of which was subjected to local magnetization in the form of magnetic marks in the process of making the structures. At the same time, the method basically does not allow to measure the value of mechanical stresses in the armature of the exploited, i.e., is already found under the influence of external stress.

tic load of reinforced concrete structures, on whose reinforcement no magnetic marks were applied during their manufacture. The aim of the invention is to provide

Claims (1)

not measuring stresses in ferromagnetic ticks that were not subjected to magnetization before loading, for example, in reinforcement of used reinforced concrete structures, as well as simplifying the process of measuring stresses. The delivered chain is achieved by the fact that magnetic labels are affected by any external, excluding power, stationary demagnetizing factor, and the magnitude of the demagnetization energy is determined, and the magnitude of the mechanical stress in ferromagnets is determined from this value. To simplify the measurement process, it is advisable to find the voltage values by the value of the physical characteristics functionally related to the energy of the demagnetizing factor and unambiguously determining its value, for example; according to the affective power of the alternating electric current passed through ferro magnetics with applied magnetic marks, the physical justification of the proposed method should be considered the experimentally proportional dependence of the external scattering energy on the value of the mechanical stresses acting in ferromagnetic bodies. . An example; . Measurement of static mechanical stresses in the reinforcement of precast concrete slabs of an operated multi-storey, industrial building is carried out. Immediately prior to the production of voltage measurements, using a laid-on electromagnet fed from a generator of single electric pulses, magnetic labels are applied to the reinforcement of the structures through a protective layer of concrete. Then, the polymer induction probe measures the initial induction of the induced magnetic field of the marks. Next, the tags are exposed to an external stationary demagnetizing factor, which reduces the induction of the induced magnetic field of the tags. For this purpose, ultrasound-wave transducer emitters powered by a powerful source of ultrasonic vibrations are installed on the surface of the structures at the locations of the marks. The magnitude of the energy, ultrasound, reduction of induction of the induced magnetic field of the mark is found in two, and the magnitude of this energy is used to determine the values of mechanical stresses in the reinforcement using the dependence of the ultrasonic energy, the magnitude of the stresses in the laboratory. x As a demagnetizing factor, an alternating electric current is also used, which is passed through the armature with printed magnetic marks. There is no need to determine the magnitude of the alternating current energy, which reduces the induction of the induced magnetic field by two times, but the purpose is: this should be limited only to the corresponding effective power, physical characteristic, functionally related to energy and unambiguously determining its value by law Joel Lenz. In this case, the calibration dependence is expressed as the effective alternating current strength — the magnitude of the voltages in the reinforcement. The use of the proposed method for measuring static mechanical stresses provides the possibility of measuring stresses in ferromagnets that are at the time of measurement at any level of an elastic stress-strain state; differentiation of stresses, acting in welded insulated steel pipelines for residual (temperature) and increments under load. Furthermore, the method provides non-destructive quality control of prestressed iron-concrete structures, which greatly simplifies the method and technique of studying the work of a number of engineering structures under load, and also increases the reliability and efficiency of quality control of precast concrete products while reducing labor costs for its organization. Claims The method of measuring static mechanical stresses in linear ferromagnets, such as steel reinforcement of reinforced concrete structures, includes localized magnetization of ferromagnets to produce magnetic marks and detecting the magnetic field of these marks, characterized in that, in order to measure voltages in ferromagnets that are not exposed, in order to measure voltages in ferromagnets that are not subject to stress, ferromagnets are not subject to measurement of ferromagnets. magnetization before loading, the magnetic marks are affected by any external, excluding power, stationary demagnetizing factor, and determine The magnitude of the demagnetization energy and by this value determine the value of mechanical stresses in ferromagnets. Sources of information taken into account in the examination. 1. USSR author's certificate NO 372465, cl. G OIL 1/12, 1973. 5b, 2, Chilin KS Magnetometric manufacture of reinforced concrete structures, Cascades method of location and stress L., LDTPP, 1963. of the state of reinforcement and the possibility of its Copyright certificate №i 255820 application in process automation G O1 L 1/12, 1968. 623119