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.
A Net Map Method on Vehicle Structural Fatigue Damage Analysis
