Research On Mechanical Performance Of Feeding Roller Filling With Honeycomb For Forest Harvester Based On Equivalent Optimization Relationship

During the logging production of forest harvester,the problem that the serious damage of surface and timber caused by steel teeth for steel feeding roller(SFR)due to the lacking of effective contact area and insufficient working friction,was appeared between traditional feeding roller and logs.Aiming at solving the problem,a honeycomb-structure feeding roller based on Double V-Wings Honeycomb(DVWH)was proposed by replacing hard material with flexible honeycomb structure for filling structure of feeding roller.Benefit from the Negative Poisson’s Ratio(NPR)enhancement,the honeycomb-structure feeding roller could improve its elasticity in vertical direction,increase contact area and number of steel teeth,absorb dynamic compression impact and reduce wood damage under the condition of satisfying the working stiffness requirements.According to the engineering parameters of SFR,the geometrical configuration of flexible honeycomb cell and the roller filling honeycomb structure which constituted the honeycomb-structure feeding roller were designed and proposed.The macro constitutive model under dynamic logging compression was derived including mass,elastic modulus,platform stress and compression strain.Based on this model,the equivalent optimization relationship between honeycomb structure performance and size factor n was obtained.The macro constitutive model and equivalent optimization relationship were verified by numerical simulation and dynamic compression experiment.The mechanical properties and energy absorption,compression deformation mode and structure efficiency of roller filling honeycomb were analyzed,and its variation with size factor n was discussed.The results show that the mechanical structure efficiency of Roller Double V-Wings Honeycomb(RDWH)was several times that of Rolled Hexagonal Honeycomb(RHH).Compared with the standard n=1.0 honeycomb,the optimized honeycomb structure obsessed increasing energy absorption by173.9% and decreasing weight by 13.3%.The contact area of honeycomb-structure feeding roller under dynamic compression was measured by numerical simulation with logging condition boundary.The phenomenon of “sequential increment”and “uprush stage” with the change of size factor n were summarized.For pressures of 9000 N,16000 N and 23000 N,the contact area of the roller honeycomb exceeded that of the steel feeding roller with about 1.99,2.02 and 2.13 times in maximum contact area under the corresponding contact force,respectively.The experimental specimen of RDWH with geometric multiple cell size was constructed and its mechanical properties were studied by compression experiment.The displacement nephogram,contact force curve and deformation behavior of the structure in three compression stages were obtained.By comparing the deformation behavior between compression experiment results and finite element numerical simulation,the reasons for difference for RDWH specimens were discussed and which was concluded that the RDWH has the higher logging efficiency in the range of 10%-25% for elastic compression.