Research On NVH Evaluation Of Automobile Based On Four-column Test Bench

During the driving process of the car,various structures and components in the car generate various noises due to problems such as assembly processes and materials.These noises have a great impact on the comfort of the vehicle,which will lead consumers to doubt the quality and workmanship of the vehicle.Therefore,it is an important part of the car development process to eliminate the abnormal noise of a car’s structure and interior in advance.In this paper,the NVH evaluation of the vehicle is carried out by driving in the virtual test field,collecting the acceleration signal of the four-wheel center,and conducting road simulation on the four-column test bench.It can solve the NVH problem in the automobile structure and interior decoration in the automobile development stage.In this paper,the phenomenon of abnormal sound in the sunroof of a car collecting road spectrum in the test field was studied.Firstly,the multi-body dynamics theory used in the construction of the whole vehicle model and the RPC theory used in the road simulation test of the four-column test bed are introduced.The multi-body dynamics analysis of the test vehicle was carried out,and the vehicle model was established according to the front and rear suspension forms of the vehicle,the vehicle parameters and the hard point information.The two-wheel co-directional running test was carried out on the front and rear suspension frame systems respectively.The relationship between the curve of the toe angle of the wheel,the camber angle and the wheel running and the curve of the suspension K&C test were compared to verify the accuracy of the model.The vehicle model is simulated in the virtual test field,and the acceleration time domain signals of the vehicle center on various road surfaces at different vehicle speeds are output to provide target signals for road simulation.Secondly,the acceleration sensor is placed on the wheel center of the test vehicle and installed on the four-column test bench,and the polarity of the acceleration and the PID parameters of the four-column test bench are adjusted.The transfer function of displacement and acceleration of actuating cylinder is obtained by white noise excitation.The wheel center acceleration signal of the vehicle in the virtual test field is taken as the target signal,and the driving signal of the four-column test rig is obtained by iterating according to the target signal,and the road simulation test is conducted.Then,the NVH evaluation test was carried out on the four-column test bench,and compared with the test field evaluation.The comparison method was divided into subjective evaluation and objective evaluation.Subjective evaluation is based on the combination of semantics subdivision method and grading method.When the vehicle conducts road simulation test on the four-column test bench,the evaluators will evaluate whether the skylight has abnormal sound under different road conditions.By comparing the evaluation results with the test results of the test field,it is found that the test field and the four-column bench scoring results are relatively consistent.The objective evaluation is to install an acceleration sensor on the sunroof of the test vehicle to collect the acceleration signal of the sunroof under different road conditions,and compare it with the acceleration signal of the sunroof of the test field.It is found that the skylight acceleration frequency domain curve fits well.The subjective and objective evaluation results verify the feasibility of the evaluation method.Finally,according to the left rear door abnormal sound of another vehicle,the suspension form and the vehicle parameters were modified for evaluation,which verified the universality of the NVH method proposed in this paper.