Simulation And Experiment Research Of The Door Stiffness On Automotive

Automobile plays a more and more important role in the highly civilized modern social lives. The safety and comfort features of vehicles are increasingly highlighted by both customers and car manufactures.Doors are critical and independent assemblies attached to body which constitutes a major part of vehicles, exhibiting a significant impacts on the safety and comfort performance of a vehicle.Rigidity is an important performance requirement for a door. Insufficient rigidity will result in door drooping down, air leakage, rain leakage and thus lower the comfort. A lower door rigidity will also cause an increase of the shutting force or even the failure of door lock. Excessive door deformation in a crash is also harmful to the passive safety performance.Performances for parts on door such as lock, window regulator, door hinge and door stopper have been defined by vary kinds of regulations or standards, however, the performances of their carrier, the door, are usually defined in the in-house specs of OEMs and not disclosed to outside world. Few Chinese OEMs got their in-house door specs. Only CAE verification is required for a new door development in a Chinese OEM whereas both CAE and physical evaluation are mandatorily carried out in foreign countries. Test evaluation data should be taken as the final judgments. CAE could be carried out in parallel with testing activities with the benefits of reducing developing cost and shortening validation cycle, but assumed CAE boundary conditions still have to be correlated with the testing setups in order to make the simulation results be more closer to the reality. Researches relating to the correlation between CAE and test, door rigidity testing methodology and procedure and the setups thereof are rarely published in China. The domestic practices for developing a door usually involves no testing validations.Doors are large and multi-layer combinations of some assemblies bounding pieces of thin plates welded together featured with container like intricate structure and large mass, which are subject to deformation under loads. Dimension deviations of stamped parts, exigent assembling process and misalignments of welding spots are usual causes of poor assembly qualities. Not only the numerical simulation but also physical testing loads should be applied to the door rigidity evaluation or even to the whole body design. A set of unified and correlated criterion for CAE and testing evaluation are put forward in this paper. This in-house door rigidity specification brings the experiences of product developing and international joint works.Research activities are as follows:1. Definition of door rigidity: Door rigidity involves vertical rigidity, lateral rigidity, belt line rigidity and surface rigidity. Definition of each is given in this paper.2. Certain restrains and loads are defined according to different operation modes, and are used to generate CAE analysis boundary inputs.3. Lab testing procedures are defined based upon real working loads and constrains, including test setup, loading sequence and tested part condition description.4. Design factors for rigidity and evaluation procedures are considered in this paper.5. A conclusion is reached that thought large amount loading conditions could be analyzed by simulation and design iteration cycles could be reduced to a great extent by CAE, the final judgments have to be made based on physical evaluations due to the deviation between simulation and reality.This door rigidity evaluation procedure can find extensive use in new design approval, database generating and providing an effective support for product development.