Research On Failure Analysis Of The New Door Lock Latch For Light Trucks

The light truck is widely used in small batch transportation,and its safety performance is the key index to evaluate vehicle quality.As an important part of openclosed system in light trucks,the new door lock latch for light trucks needs to realize multiple functions in a narrow space.As its complex structure,it is easy to apear motion failure;as most of its transmission parts are plastic parts with low strength,it is easy to appear strength failure or fatigue failure,which seriously affects the safety of the vehicle.Therefore,based on the motion link of the new door lock latch for light trucks,combined with graphic method and simulation method,this dissertation analyzes the motion failure of the new door lock latch for light trucks and the failure of the electric drive mechanism,which can effectively improve the reliability of the new door lock latch for light trucks.The main points of this dissertation are as follows:(1)On the basis of analyzing the functional and performance requirements of the new door lock latch for light trucks,the multi-body system analysis method is adopted to establish the kinematic chain of the latch;combined with graphic method and analytic method,kinematic equation of open mechanism of the latch is established;the actuation function of the latch is verified by graphic method and kinematic equation analysis;ADAMS is used to analyze the open actuation process of the latch and verify the correctness of the kinematic chain of the latch.(2)The main factors and main forms of motion failure of the latch are analyzed by using the failure tree theory;combined with geometric method and numerical method,the motion clamping stagnation state of the new door lock latch for light trucks is analyzed,and the fact that there is no clamping stagnation failure is determined during the movement of the latch mechanism.ANSYS and ADAMS are used to compare and analyze the critical state of the ratchet pawl of the new door lock latch for light trucks,and the angular displacement of the pawl was obtained to avoid the failure of the latch movement release.Through the force analysis and calculation,the critical actuation force of each open actuation process of the new door lock latch for light trucks is obtained to ensure that there is no open actuation failure.Compared with the experimental results,the consistency between the experimental results and the theoretical calculated values is verified.(3)The parameters related to the helical gear pair of the electric drive mechanism and the self-locking are calculated,and it is determined that the helical gear pair of the worm has no self-locking phenomenon;based on Hypermesh and ANSYS,the strength simulation model of helical worm gear mechanism is established to verify that the helical worm gear meet the strength requirements under normal working conditions and will not appear strength failure.The fatigue simulation analysis model of worm helical gear is established based on n Code Design Life.The S-N curve is fitted according to the tensile strength of the material,and the fatigue life of worm helical gear is obtained through simulation analysis without fatigue failure.The validity of the fatigue simulation results is verified by the durability test of the new door lock latch for light trucks.In this dissertation,the kinematic chain of the new door lock latch for light trucks is established,and the correctness of the kinematic chain is verified through the open actuation kinematics equation and kinematics simulation,the common failure form of the latch is analyzed,which can provide a reference for top-down design and failure analysis of the door lock latch for light trucks,and has important theoretical significance and engineering application value to improve the security of the door lock.