Research On The Laboratory Tests And Dynamics Strike For Roll Over And Falling Object Protective Structures

Roll Over Protective Structures ( ROPS ) and Falling Obiect ProtectiveStructures(FOPS )are a steel fram system installed on earth moving ma chinery toprevent driver from danger in the crash . In some developed coun tries , theregulations concerning ROPS and FOPS which should attached to some specialvehicles such as loader ,tractor,tractor scraper and grader, come into force , butthere are no perfect tests data and theories for the design of ROPS-FOPS.Requried by construction machinery department of ministry of machinery industry ,the following researches have been made :①.TO verify ZL50G wheel loader's ROPS-FOPS , The laboratory tests havebeen performed according to ISO-3471-1994, ISO-3449 -1956 andISO-3164 -1994.By tests results,the fail behaviour and several key problems which should be paidattentions to in design are acquired . ②.On the basis of tests , a new design method called nonlinear safe energymethod is presented in this dissertation . The maximum lateral load of ROPS-FOPS,the strain energy absorbed by ROPS-FOPS can be calculat -ed conveniently byit ,so the safe performence of ROPS-FOPS could be pre -judged effectively indesign stage . ③.A nonlinear finite element model of ROPS-FOPS and machine fram systemis developed to consider the energy absorbed by the machine fram in the test whichdon't include it . The model not only reduces test cost greatly , but also suppliesdistrbutions of deformation,stress and moment . It makes a complement of the testsand the nonlinear safe energy design method . ④.The structures optimal design is carried out . The optimal results show thatto increase the strength and rigid of the end section of post will improves the abilityof absorbing energy . ⑤ The dynamic character of ROPS-FOPS are studied firstly.The naturalfrequencis and eigenmodes are obtained.For calculating the displacements responseof FOPS when it is impacted by falling object,a nonlinear transient dynamicanalysis method is advanced. The analysis values of ZL50G's FOPS using ANSYSsoftware are conformed to results of mode experiment very well.⑥ This paper has established the limit speed mathematical model of elasticdeformation,plastic deformation and flow deformation of the FOPS shell. We haveresearched for the impacted dynamic response of the thin plate and established themaximal displacement mathematical model of the impact center. Therefore,ithaslaid the theoretical foundation for rational design of FOPS. Further more, wegive a anti-break through capability test of the wheel-loader ZL50G FOPS,andcalculate the exciting force on boththe drop hammer and the crossbeam of theFOPS . We find that the FOPS top surface of wheel loader produce plastic yieldand non-linear response while being impacted by drop hammer.The United States ANSYS application software companies ANSYS9.0 to thestate constitution ZL50G loader ROPS-FOPS various analyses conducted limitedelement.We take use of ANSYS 9.0 to separate the side load, the minimal load, thevertical load and calculate stress and displacement.It takes use of nonlinear energysecurity methods to analyze the failure ROPS-FOPS mechanisms,a situation thatthe risk of danger to a reasonable cross-section and a theoretical foundation fordesign ROPS-FOPS .After a result end up,wo usually take care of the plot results .In Chapter VI, on ROPS-FOPS dynamic impact system performance by theanalysis. And the impact dynamics with the theory of using ANSYS calculatedstress, and in the impact process, the response curve over time. The incentiveequivalent to a simplified derive from the impact of ROPS-FOPS and accepted thetop shell onto the center displacement and stress value, pointed out that thecross-section location danger, provided a reasonable structural design methodologyfor the future ROPS-FOPS. In the module analysis, it give the inherent band of theformer 20-unit, the unit provides the third and fifths inherent type plot. The former20-unit plot didn't display all.It only pick up two typical plot. The other plotshow the roof of the main sources for distortions deformation. Modal analysis toavoid resonance provided data for reference.By understanding the main text of ROPS-FOPS research and the developmentof relevant international standards, ROPS-FOPS will be researched in light ofinternational crganization for standardization. The establishment of the MechanicsROPS-FOPS analysis models derived elasticity or plasticity ROPS-FOPSdeformation stage formula for The establishment of a viable ROPS-FOPS limitedelement nonlinear analysis methodology. It calculated ZL50G ROPS-FOPSdeformation of the type load. To designe ZL50G type loader ROPS-FOPS structureprovided theoretical basis.