Abstract
In order to effectively use the vehicle road test load spectrum data and adjust road test specifications, a net map method on vehicle structural fatigue damage analysis is proposed, by taking the vehicle subframe as a study objective. This article consists of three parts. First part discusses that, the finite element analysis model of the vehicle subframe was built in ANSYS software, and its construction stress was calculated and analyzed under the action of lateral and longitudinal forces, respectively. The hot points on the control arm were determined, which could bring about fatigue damage. The location was identified as load testing point P, where strain rosette was pasted. Second part discusses that, the strain load of the subframe was measured under the condition of proving ground, eight kinds of roads that fall under combination roads were chosen in the proving ground and the vehicle speed was found to be different on each road. After finishing the data processing, and the pure signal of vehicle subframe was acquired. Using rain flow counting method, the load spectrum of the subframe was worked out, and load distribution histogram on the testing point was obtained. On this basis, according to local stress-life method and Miner standard and stress concentration correction factor, the fatigue damage analysis was completed for the subframe under the combination road and each of the enforced roads. Third part discusses that, the fatigue damage density and weight of each road conditions were calculated under the condition of each enforced road about subframe structure, and a net map that represented its closed area fatigue damage was drawn. In the net map, the central angle represents the damage weights on different road conditions and the radius length represents the damage density on each road. The results show that the network diagram can easily express the vehicle structural damage under the conditions of all the different combination of roads when the size of the central angle and length of radius were changed, vehicle structure damage relative to the change would be obtained by drawing a new net map. This method provided a convenient and effective way to analyze vehicle fatigue damage.
Highlights
In the reliability design of the vehicle product development stage, the fatigue durability of the road needs to be tested according to the road specifications, the fatigue strength of vehicle and its important components, and estimate the fatigue life
To obtain the accurate load of the subframe received in the vehicle operation accurately, according to the results of finite element analysis, the strain gauge should be welded at 10 mm and considering the convenience of the test and patch arrangement, the strain measurement in the sub frame should be the left position as shown in Fig. (4)
This article addresses the vehicle fatigue damage analysis using structural damage representation method, and through research the following conclusion has been reached: 1) The method of finite element analysis can be used to determine the exact location of fatigue damage on the vehicle structure
Summary
In the reliability design of the vehicle product development stage, the fatigue durability of the road needs to be tested according to the road specifications, the fatigue strength of vehicle and its important components, and estimate the fatigue life. Research is being conducted on the fatigue durability of the vehicle structure, in the process of product development. In the evaluation of fatigue damage process of vehicle components, method applied in the tests are used for production or verification. In order to realize comparison analysis of vehicle structure fatigue injury under different conditions, the vehicle structure and load spectrum data is repeatedly used effectively, and adjustments are made to the fatigue durability road test specification according to the objective. Provides direct reference for the fatigue damage analysis of vehicle structure, and provides a new experience for the research on fatigue and other important structures
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