| Forklift play an indispensable role in logistics transportation.The portal frame is the key component to forklift,which is the main part to bear the weight of load.So,fatigue durability of portal frame is one of the main performance indexes for forklift.Because most accidents about forklift are caused by portal frame fatigue unexpectedly,which usually could lead to property damage and death.Therefore,it is necessary to predict the fatigue life and the position of fatigue damage in the design phase of the parts.While,it could shorten the product development cycle and improve the reliability of the product by finding the weakness of the design and making improvement before the testing or manufacture.This paper takes the 3.5T three level portal frame manufactured by a forklift company as the research object to predict fatigue life of the forklift portal frame based on virtual fatigue test combined with static and dynamic stress test.Firstly,this paper adopts the geometric model of the forklift portal frame provided by the manufacturer and use the rigid multi-body dynamic model of the portal frame established by MSC.Adams to acquire the force of each component for the static stress analysis.The finite element model of the forklift portal frame is established by MSC.Patran.The static stress and modal analysis of the portal frame are carried out by MSC.Nastran,then the stress nephogram and modal values of the portal frames are obtained,while verifying the rationality of the finite element model by the static stress test.Furthermore,the required modal neutral files for establishing rigid flexible coupling multi-body dynamics model and the required modal result files for fatigue analysis are exported.Secondly,using the modal neutral file obtained by MSC.Nastran establish the rigid flexible coupling multi-body dynamic model of the forklift portal frame in MSC.Adams.The dynamic simulation is carried out with the fatigue test condition of forklift portal frame.After that,the load-time graph of each component of forklift portal frame are obtained.Finally,the fatigue life analysis software MSC.Fatigue is used to analyze the safety life of the various parts of the forklift portal frame based on the modal result files,the load-time graph and fatigue analysis theory.And then the dynamic stress of fatigue simulation is verified by dynamic stress test of portal frame.The results show that the fatigue life data obtained from each component of the forklift portal frame have significance for reference,and the portal frame meets the fatigue life requirement of the plant.The study on the fatigue life of the forklift portal frame provides theoretical basis and guidance for the design and has some theoretical significance and engineering value. |
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