Tag Archives: damage accumulation
The paper deals with the assessment of the residual life of shell structures, operated under long-term static loading. Existing techniques of an estimation of the residual life in the capacity of parameters of a technical condition of vessels and apparatuses use the measured magnitudes of the originated faults, the data about change of physical and chemical characteristics of materials, and also number of cycles of a loading. Thus the irreversible structural changes of the material which has originated while in service are not considered. For an estimation of a technical condition of the equipment of a shell-type construction it is offered to develop integrated criterion for evaluating the accumulated damage in the material, applicable for conditions of static loading. Experimental researches showed that in a material under the influence of long static loading there are the changes of an internal structure related with adaptation to external impact when the material exhausting one adaptation mechanism passes to another and thus there is the accumulation of damages. Found that the velocity of ultrasonic waves, magnetic field strength, voltage of the electric signal response and the surface energy are the parameters that are sensitive to the accumulation of damage in the material. The establishment of threshold values for these parameters that characterize the level of accumulated damage will measure the time of the limit state and to determine the residual life the structure.
Assessment of equipment material damage by using the degree of attenuation the response of the electrical signal
The article describes the method for assessing the degree of damage to equipment material, maintained in the conditions of fatigue loading, by using the degree of attenuation of transition process the response of electrical signal. As a result of research, optimal settings of eddy current probe were identified and experimental dependencies allowing to monitor the condition of equipment material were obtained.
Two-parameter control of various stages of elastic-plastic loading of specimens produced from steel 09G2S
This article focuses on the general mechanisms of material properties changing using electromagnetic and ultrasonic methods of nondestructive testing. As a research results experimental dependences of the response duration variation of the ultrasonic and electromagnetic signals occurring in the specimen’s material under the influence of static tensile loading were obtained.
In this article it is offered to realize identification of limit state of the metal equipment which is operated in the conditions of fatigue loading according to parameters of electromagnetic signal response and middle and active voltages were used as the parameters. As test results it was received the experimental dependencies of these voltages on the level of the accumulated fatigue damages having the extremum which characterize the limit state of the material of the test object.