Yuan Long

Study on Vibration Characteristics of Natural Gas Pipeline Explosion Based on Improved MP-WVD Algorithm

In order to meet the requirement of precise analysis of nature gas pipeline explosion, authors combined MP algorithm and WVD distribution to improve the time-frequency resolution and to solve the problem of cross-terms interference. The HHT algorithm was applied to the data preprocessing of MP algorithm to reduce the computational complexity of the MP algorithm. It improved the computing efficiency and laid the foundation for big data analysis. In this paper, authors carried out a full-size pipeline explosion experiment at the CNPC pipeline fracture control State Key Laboratory. Advantages of the improved MP-WVD algorithm were taken to obtain the time-frequency distribution characteristics of the pipeline explosion vibration. The research provided a new algorithm for the time-frequency distribution of nonstationary random vibration, and the result provided a reference for the safe operation and construction of natural gas pipeline.

DYNAMIC RESPONSE AND MICROSTRUCTURE EVOLUTION OF OXYGEN-FREE HIGH-CONDUCTIVITY COPPER LINER IN EXPLOSIVELY FORMED PROJECTILE

THE DYNAMIC RESPONSE AND MICROSTRUCTURE EVOLUTION OF OXYGEN-FREE HIGH-CONDUCTIVITY COPPER IN A SHAPED CHARGE LINER OF AN EXPLOSIVELY FORMED PROJECTILE ARE INVESTIGATED THROUGH MICROSTRUCTURAL EXAMINATION OF A SOFT-RECOVERED EFP. THEORETICAL CALCULATION RESULTS INDICATE THAT THE HIGHEST TEMPERATURE INCREASE OF EFP CAUSED BY SHOCK WAVE AND PLASTIC DEFORMATION CAN REACH 673K, WHICH IS 0.5TM (WHERE TM IS THE MELTING TEMPERATURE OF COPPER), AND THE FORMATION PROCESS OF COPPER EFP IS PRIMARILY CAUSED BY EXTREME PLASTIC FLOW, WHICH IS POSSIBLY A TYPE OF SUPERPLASTIC FLOW IN A SOLID STATE. THE MAIN BODY OF THE EFP UNDERGOES COMPLETELY DYNAMIC RECRYSTALLISATION, AND THE AVERAGE SIZE OF THE REFINED GRAINS SIGNIFICANTLY DECREASES TO APPROXIMATELY 10ΜM. A SLIGHT INCREASE IN GRAIN SIZE OCCURS MAINLY AWAY FROM THE CENTER AND EXTENDS TOWARDS THE HEAD AND REAR SECTIONS OF THE EFP. DURING THE DRX PROCESS, THE DISLOCATION MOVEMENTS ARE BELIEVED TO BE THE CONTROLLING MECHANISMS SIGNIFICANTLY REFINING THE MICROSTRUCTURE AND HELPING IN THE FURTHER FLOW OF THE MATERIAL.

EXPERIMENTAL AND NUMERICAL STUDY ON THE DISPERSION PATTERNS AND PENETRATION PROPERTIES OF MEFP WITH SEVEN ARC-CONE LINERS

EXPERIMENTS AND THREE-DIMENSIONAL NUMERICAL SIMULATIONS HAVE BEEN PERFORMED TO STUDY THE SPATIAL DISPERSION PATTERNS AND PENE-TRATION PROPERTIES OF INTEGRAL MULTIPLE EXPLOSIVELY FORMED PENETRA-TORS (MEFP) WARHEAD WITH SEVEN ARC-CONE LINERS. TERMINAL EFFECTS OF MEFP WARHEAD WERE PERFORMED ON FIVE #45 STEEL TARGETS OF DIMEN-SION 160CM X 160CM X 1.5CM AT VARIOUS STANDOFFS (45CM, 60CM, 80CM, 120CM, 170CM). IT FINDS THAT THE NUMBER OF PERFORATIONS PRESENTED IN THE TARGET CHANGES FROM 7(45CM) TO 19(80CM, 120CM, 170CM) WITH THE INCREASE OF STANDOFF. NUMERICAL RESULTS HAD SUCCESSFULLY EXPLAINED DISTRIBUTION PATTERN OF PERFORATIONS ON THE TARGET NAMELY EVERY SURROUNDING LINER WAS FINALLY BROKEN INTO THREE PENETRATORS DURING THE FORMATION PROCESS OF MEFP, FORMING A GROUP OF AIMABLE PENETRATORS CONSISTED A CENTRAL PROJECTILE SURROUNDED BY 18 PENETRATORS. MAXIMUM DIVERGENCE ANGLE OF SURROUNDING PENETRATORS GROUP IS 9.8° AND DAMAGE AREA CAN REACH 0.37M2 AT 1.7M. LAWS OF PERFORATION DISPERSION PATTERNS OF MEFP ARE ALSO OBTAINED BY A NONLINEAR FITTING ABOUT INFORMATION OF PERFORATIONS ON THE TARGET AT DIFFERENT STANDOFFS. IT HAS SHOWN EXCELLENT AGREEMENT BETWEEN SIMULATION AND EXPERIMENT RESULTS. IN ADDITION, WE CONDUCTED EXPERIMENTAL AND NUMERICAL STUDY ON THE POWER OF MEFP REMAINDERS AFTER BREAKDOWN FRONT TARGET. IT REACHED THE CONCLUSION THAT DISTRIBUTION OF REMAINDERS BECAME MORE DISPERSED AND TOTAL ENERGY OF REMAINDERS GOT RELATIVELY SMALLER WITH THE INCREASE OF STANDOFF.