Dynamic Simulation Of Rubber Transmission Belt And Energy Dissipation Mechanism Investigation

As one of the most important rubber industry product,transmission belt is mainly used in mechanical power transmission.However,the domestic analysis and design level of transmission belt is still falling behind at present.Manufactures don’t have core technology and lack market competitiveness,mostly counterfeiting belt structure refer to foreign standard or product structure.Finite element simulation technology as a modern product design and analysis technology has been widely applied to various rubber product,such as tire and shock absorber,studying and predicting dynamic properties when product operating and assisting product design.However,the application and report related rubber transmission belt is few.Only some foreign companies hold the belt simulation design technology.Therefore,it has significant scientific study and engineering value for studying finite element simulation method of belt transmission.Transmission efficiency and energy dissipation are key factors of evaluating transmission belt design and the temperature rise can also affect usability.However,the complicated viscoelastic hysteresis behavior and nonlinear slip friction of rubber transmission belt under dynamic working condition bring difficulties in investigating belt heat generation and transmission,to deeply analysis the transmission mechanism of transmission belt,predicting transmission efficiency.This paper has studied the dynamic mechanical behavior,energy dissipation and temperature rise,comprehensively relating to friction type V-belt transmission and meshing type synchronous belt transmission,meanwhile the structure characteristic,loading form,contact slippage of two kind of transmission belt are analyzed,proposing different modeling method.In this paper,V-belt and synchronous belt transmission have been separately modeled which consider rubber material properties and composite structure,calculating rubber stress and stain,shear slip,contact pressure and loading on framework layer,further optimizing structure of belt.Meanwhile,two kinds of belt transmission thermal coupling model are built,designing different computing method based on model characteristics,consequently analyzing the dynamic energy dissipation,transmission efficiency,temperature distribution of whole belt transmission system.The detail working content as follows:(1)To obtain precise rubber material parameter,we conduct the uniaxial cyclic stretch and compress measurement,dynamic frequency sweep measurement,comprehensively analyzing the stretch,compress,creep,relax and hysteresis properties.Meanwhile on the basis of considering the stress soften effect,we use hyper-elastic constitutive model and viscoelastic constitutive model fitting out the material parameters.And compare the time domain and frequency domain characteristics when fitting viscoelastic parameters.Hence,we both considerate the hyper-elastic and viscoelastic property of rubber when building the simple rubber cylinder dynamic compress FEA model to analysis the distribution stress and strain.To further study the dynamic heat generation property of rubber material,we not only use compression heat generation instrument to test the dynamic heat generation property of rubber cylinder sample,but also use static and dynamic stiffness instrument to study the dynamic modulus variation changed by dynamic stress softening.Using the least square method,we obtain the variation curve which can describe the loss modulus changed over dynamic compression time,and it is used to calculate the hysteresis heat generation rate.To further built thermal coupling FEA model,we test the thermal physical parameter,the hysteresis heat generation is applied on model as inner flux by subroutine,and consider the heat generation rate changing with time,calculating the temperature changing of rubber cylinder during the total course,and compared with actual measurement.The result shows that when the rubber cylinder sample is compressed,the contact edge appear stress concentration,however the overall distribution of tress is uniform.The loss modulus presents a parabolic decline trend over time by dual affect factor of temperature and creep.The predict temperature change tendency on upside and flank side are both approximate to actual test results,the error is little.(2)On the basis of obtaining rubber material parameter,take the SPB V-belt transmission system for example,we build the friction type belt transmission thermal coupling FEA model.We consider the rubber-skeleton complex structure on V-belt transmission mechanical model,which is simulated by REBAR element.The total course of V-belt tension and V-belt transmission are modeled by combining standard solver and explicit solver.The bending stress,contact pressure,contact area,and force on cord are analyzed during the V-belt go through the pulley,and further calculating the nonlinear circumference slippage which aroused by elastic deformation and radial slippage when enter in or leave from pulley.To further analyze the dynamic heat generation and transfer behavior,we both considerate the effect of hysteresis heat generation and friction heat generation.Hysteresis heat generation rate can be obtained by integrating the stress and strain curve which is extracted during going across pulley.The friction heat generation rate is obtained by calculating contact pressure and slippage.At the same time,to considerate the phenomenon of hysteresis heat generation rate changing affected by temperature rise,we also study the viscoelastic dependency on time-temperature,using WLF function fitting test data and modifying.When building V-belt heat transmission model,due to the insufficient of technology,we can’t use direct coupling method,so we propose a multiple dynamic contact heat transfer modeling method.Namely,through equivalent conversion of convection heat transfer coefficient,contact heat transfer coefficient,apply them at static heat transfer model,meanwhile considering contact state between belt and various pulleys.The heat source and thermal physical property in model will change with temperature updating,thereby realizing the prediction of energy dissipation and temperature distribution of V-belt transmission systerm.The actual test result shows that compare the temperature rise under different working conditions,the predicted temperature result is reliable.The friction heat generation rate is larger than hysteresis heat generation rate.(3)Meanwhile,we also study the meshing transmission type 8M arc tooth synchronous belt transmission property and optimize the belt structure.Synchronous belt meshing transmission FEA model is built,and analyzing the poly edge effect when belt under tension,which lead to obvious interference phenomenon.The loading character of belt cord is calculated,and the relationship between loading variation and contact interference are analyzed.The flexure stress at complete meshing region,clearance between belt tooth and pulley tooth under tension state are also investigeted.Variation of meshing contact stress,contact pressure,contact shear stress,at uncomplete region are computed.The different torque loadings are applied on driven pulley to analyze the effect of different torque on transmission,discussing meshing contact state,belt tooth deformation,reaction force on pulley,as well as the variation of poly edge effect under different torque.To further optimize synchronous belt structure to alleviate the stress concentration phenomenon aroused by meshing interference,we propose two aspect optimizing the 8M arc tooth synchronous belt combine theory and practice,containing pitch and tooth profile.Meanwhile,building new FEA model according to new structure.Comparing calculating stress distribution and interference state of different structure.The calculating result shows that when the pitch is 7.98 mm,the meshing interference phenomenon is obviously improved,the contact pressure and strain at uncomplete meshing region decreased,the whole stress distribution is more uniform.And further optimizing the tooth profile based on pitch being optimized,the meshing interference phenomenon is almost eliminate,reducing the stress concentration,improving the product property and transmission stability.(4)Build thermal mechanical coupling FEA model of synchronous belt to analyze the the heat generation and transfer property of meshing transmission.Since the synchronous belt model using standard solver,we can’t directly output viscoelastic hysteresis energy dissipation.When calculating hysteresis heat generation rate,on the basis of mechanical model,we abstract stress curve and strain curve in one cycle on every node of each belt tooth element.Use Fourier transform theory translating random stress and strain spectrum into superposition of many equivalent sinusoid spectrum,then calculate it with hysteresis energy dissipation function.When compute frictional heat generation rate,the meshing between belt tooth and pulley tooth is continuously,a thermo-mechanical model which comprehensively considered hysteresis heat and frictional heat was developed to predict temperature distributions under various operating conditions.An integral-summation methodology used for calculating nonlinear meshing frictional heat generation was proposed.Meanwhile,heat flux partition coefficient was obtained by frictional heat partition equation.In addition,temperature distributions of synchronous belt transmission system changed with various revolving speeds and loads were also predicted and verified respectively.Temperature change tendencies and the ratios of energy dissipation in two forms was also analyzed.The total energy consumption is 31.17J/s,and the prediction transmission efficiency is about 98%.The temperature of belt tooth is 34 ℃,which is well accordance with test data.