Dynamic reliability analysis method for derrick under action of multiple random loads

Abstract

The invention discloses a dynamic reliability analysis method for a derrick under the action of multiple random loads, and belongs to the technical field of petroleum drilling machinery reliability. The method comprises the following steps of (1) determining a load mainly born by the derrick and analyzing a probability distribution situation of each load stress; (2) combining load stresses into two combination forms; (3) obtaining laws of change, with time, of a mean value and a variance of each load stress combination; (4) establishing a limit state equation of the derrick; (5) building derrick dynamic reliability models under the conditions of not considering and considering strength degradation respectively; and (6) calculating a dynamic reliability index of the derrick and drawing a curve of change, with the time, of the reliability index of the derrick. According to the method, in combination with a practical loaded condition of the derrick, the derrick reliability is regarded as a dynamic function, and the uncertainty of the law of change, with the time, of the load and the dynamic influence of the strength degradation characteristic of the derrick on the derrick reliability are considered, so that the accuracy of derrick reliability analysis is improved.

Description

Technical field [0001] The invention relates to a dynamic reliability analysis method of a derrick under multiple random loads. It is a method for dynamic reliability analysis of a derrick under multiple random loads based on the first-order second moment method and structural strength degradation theory. Reliability technology field of petroleum drilling machinery. Background technique [0002] In the drilling process, the rig derrick is used to place the crane, suspend the traveling crane system, rely on the drill pipe and deal with underground accidents and other operations. It is the key equipment of the rig lifting system. The drilling rig not only bears the drilling load directly, but also bears additional dynamic loads caused by wind, earthquake, and dead weight. However, most derricks have a long service life of 30 years or even longer. As the service time increases, the derrick structure will inevitably suffer from corrosion, fatigue, material aging, overload, disassemb...

AI Technical Summary

Problems solved by technology

None of the above methods considers the uncertainty of the change of the load on the derrick over time and the dynamic influence of the derrick strength degradation over time on the reliability of the derrick. The reliability of the derrick is still regarded as a static value, and the The derrick has only been analyzed for static reliability, which is not consistent with the actual situation

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