Analysis Of Stress And Fatigue Of Piggyback Transporter Loading And Unloading Mechanism

The Piggyback Transporter is a kind of railway-specific vehicle which designed to transport road cargo.It can combine the advantages of both road and railway transport,thus has a good development prospect.The loading and unloading mechanism is the most important structure of the Piggyback Transporter.When loading and unloading cargo,the loading and unloading mechanism carries the total weight of the cargo,so the components of which may be obviously deformed by force.As a result,Long-term operations of loading and unloading mechanism may cause such kind of phenomenon that each component be fatigue and damaged.Currently,there are few researches on the stress and fatigue of this structure in china.The existing research mainly focuses on the development prospect of piggyback transportation.Therefore,the research on the stress and fatigue of the loading and unloading mechanism has theoretical research significance and practical application value for the design improvement of the Piggyback Transporter.This paper takes loading and unloading mechanism of a kind of piggyback transporter in China as the research object.According to the three-dimensional geometric model of each component of the loading and unloading mechanism,the finite element software HyperMesh and Ansys are used to establish the flexible model of the moving track.Then the multi-body system dynamics simulation software ADAMS/View is used,the module of which defines the simplified constraints and connection relationships between the components,also establishes a complete rigid-flexible coupling dynamics model of the piggyback transporter loading and unloading mechanism,that realizes the simulation with a series of actions such as rolling and lifting.Through model debugging,the result finally achieves the actual movement.Secondly,the kinematics and dynamics analysis of the rigid-flexible coupling model of the loading and unloading mechanism is carried out,and the trend of the constrained internal force between the components is analyzed,and the time history curves including displacement,angle and interaction force are output;The dynamic stress is extracted to analyze the strength of the flexible body of the moving track,and the location of the dangerous area of the flexible body in the simulation process is determined by searching for the high stress region.Finally,based on the main S-N method,the modal structural stress method based on modal superposition method is introduced to evaluate the fatigue life of the moving rail weld.At the same time,based on the BS7608 standard,the fatigue life assessment of the depressed center underframe lifting device and the end chassis support device is performed.The analysis results show that there is no interference during the motion process of the rigid-flexible coupling model of the loading and unloading mechanism.The maximum driving force required to drive the motor is obtained by calculation,which provides a reference for the selection of the motor.The modal of the moving orbit is obtained by rigid-flexible coupling analysis.Based on which,the fatigue life of the moving rail weld is evaluated under the action of the moving load.At the same time,the external load obtained by the kinetic calculation was used to check the strength and fatigue of the critical parts.Research shows that the loading and unloading mechanism meets the structural design requirements.