Research On The Vibration Characteristics Of The Cab Of Long-head Truck

In recent years,with the widening of the size limit of road vehicles,the long-head vehicle has ushered in a new development opportunity in the domestic market due to its advantages of high safety,good comfort and strong maintainability.This thesis briefly introduces the domestic and international development of long-head truck and the research status of its vibration characteristics.The main content focuses on the study of the phenomenon that the cab shake violently in the idling condition of a long-headed truck and the abnormal vibration and cracking of the cab’s side circumference in the process of driving at 90 km/h.In this article,the abnormal vibration of the cab is analyzed and the fault source is identified.The vibration signals of each measuring point and the evaluation of the occupator’s subjective feeling of the cab under idling and different driving conditions were obtained through the road test.The power spectrum density of the measuring points under each test condition was analyzed,and the cause of abnormal vibration of the cab was basically determined.In order to fully understand and master the vibration characteristics of the long-head cab,this thesis conducted torsion and bending stiffness tests on the white body of the sample cab,analyzed its torsion and bending stiffness characteristics,and mastered the performance characteristics of the cab stiffness.Poly LSCF parameter identification method was used to conduct modal tests on the white body of the cab and the roof glass steel parts,and the corresponding modal parameters were collected to understand the modal characteristics of the cab.On the basis of the vibration performance test of the cab,the finite element model of the cab body-in-white was built based on the CAD model of the sample car,and the accuracy of the finite element model was verified by simulation analysis under torsion and bending conditions and free mode,which laid a foundation for the performance development of subsequent products.Through the comparison of cab vibration performance test and simulation analysis,combined with road test data,the article analyzes the influence of cab structure,engine excitation and wheel excitation on cab vibration,and explains the multiple causes of the abnormal vibration of the cab.The research shows that the long-head cab is different from the flat-head cab in vibration characteristics due to its structural characteristics.The partial stiffness of the cab’s lateral girders is small,and the connection of the horizontal and horizontal beams of the floor is weak.The excitation of the engine under idling speed and the excitation of the wheels in the process of specific speed are just similar to the natural frequency of the cab structure,resulting in abnormal vibration.Finally,this thesis proposes an optimization scheme for the causes of abnormal vibration of the cab,which improves the vibration performance of the cab by adjusting the idle speed,strengthening the connection and optimizing the size,and verifies the effectiveness of the improvement measures based on the calculation and simulation test.