Torsional Vibration Analysis Of High Power Diesel Engine High Elastic Coupling In Fracturing Truck And Optimization

With the rapid development of my country’s energy extraction technology,high-power,high-speed diesel engines have been widely used in fracturing vehicles and other energy extraction equipment.This type of diesel engine has the characteristics of high speed and high power,which also makes this type of diesel engine have the defects of high vibration and noise when outputting torque.Therefore,how to overcome or reduce these defects is an important direction of future research.Because highly flexible couplings have better displacement compensation capabilities and damping properties,high-elastic couplings have been widely used in fracturing vehicles with high-power diesel engines.But so far,there is still no high-elastic coupling series dedicated to high-power fracturing vehicles in my country.At this stage,the high-elastic couplings used in fracturing vehicles are basically imported from abroad.In recent years,due to the key technology blockade of my country by foreign countries,it is difficult to obtain the key data of the high-elastic coupling,which also makes the repair or replacement cost of the high-elastic coupling high,which is completely led by foreign companies.This makes my country’s oil,shale gas and other energy equipment heavily dependent on foreign sources,which is not conducive to the healthy development of my country’s future energy exploitation.In this paper,by studying how torsional vibration reduction of high-elastic coupling,the rubber elastic body,the main component that determines the vibration damping performance has been tested and simulated.Multi-objective optimization of the parameters that mainly affect its damping performance was carried out,and a high-elastic coupling was re-optimized on the original basis.The optimized high-elastic coupling can not only avoid resonance with the diesel engine of the fracturing vehicle,but also has a good vibration reduction effect.The main research contents and results are as follows:（1）Based on the existing researches on torsional vibration of high-elastic couplings at home and abroad,a tensile test was carried out on the rubber elastic body that mainly affects the vibration reduction performance of high-elastic couplings.Taking the rubber element used in the AC11 model produced by Reich in Germany as the research object,the rubber elastic element is made into I-type dumbbell specimens and square rubber specimens.Under the premise of eliminating the Mullins effect,the specimens were subjected to uniaxial tensile and plane tensile tests.Then,after processing the obtained tensile data results,they are imported into ANSYS software to fit the eight commonly used constitutive models in the software.Finally,the Mooney-Rivilin-5 constitutive model that is well-fitted in ANSYS is selected for subsequent simulation analysis.（2）Carry out the selection calculation of the high-elastic coupling,and then conduct the static and dynamic simulation analysis on the selected AC11 type high-elastic coupling.Based on the known constitutive model of the elastic element of the high-elastic coupling,according to the theoretical calculation and selection,the high-elastic coupling model AC11 that matches the MTU-16V4000S83 model of the diesel engine of the fracturing vehicle is selected.The statics simulation of the AC11 high-elastic coupling shows that the AC11 high-elastic coupling meets the requirements of static strength.Then through the modal analysis in ANSYS,its natural frequency and main vibration shape are obtained.Finally,the harmonic response analysis is carried out on the basis of the modal analysis,and it is concluded that the AC11 type high-elastic coupling not only meets the strength requirements of the MTU-16V4000S83 output torsional load of the diesel engine of the fracturing vehicle,but also can effectively avoid the diesel engine（253.3 Hz）resonance occurs,and the dangerous frequencies of the AC11 high-elastic coupling are determined to be 21 Hz and 39 Hz.（3）Calculation of key parameters of high-elastic coupling and calculation of damping capacity,using Simulink software in Matlab for digital simulation analysis.The basic parameters of torsional vibration affecting the high-elastic coupling are calculated theoretically,and the equivalent strength of AC11 high-elastic couplingσ_P=1.16N/mm2,torsional static stiffness K _static=7.805×106 N?mm/rad,dynamic stiffness K _dynamic=10.742×106 N?mm/rad.Then through the theoretical calculation of the damping performance,the dynamic amplification factor K_d=0.142 is obtained.It can be seen that the high-elastic coupling has better damping performance,and the K_d value can be used as the evaluation standard of the damping capacity.Establish the dynamic model of the high-elastic coupling to obtain its mathematical differential equation,and then use the Matlab-Simulink module to numerically simulate the linear differential equation in the mathematical model,and the force response curve will reach a relatively stable value at t=0.25 s.（4）Determine the value range of the parameters that affect the vibration performance of the high-elastic coupling,and perform multi-objective optimization of the high-elastic coupling.Determine the key dimensions that affect the mechanical properties of the high-elastic coupling and its change trend and range.Use ANSYS-Workbench software to optimize the AC11 high-elastic coupling with multiple objectives.During the optimization process,the central composite design（CCD）is selected.Methods The test data table was calculated and generated,and three sets of optimal solutions were obtained by using the multi-objective genetic algorithm（MOGA）,and the second set of optimal solutions was selected as the result of the multi-objective structural optimization according to the actual situation.Comparing the performance of the high-elastic coupling before and after the multi-objective optimization,it is concluded that the natural frequency of the optimized high-elastic coupling is reduced by 10.9%,the damping performance coefficient is reduced by 14.8%,and the mass is reduced by 7%.