Vehicle rear axle housing road test fatigue test load spectrum acquisition method

A vehicle rear axle housing road test fatigue test load spectrum acquisition method comprises the following steps: 1) road test acquisition: installing a displacement sensor at a suspension spring position of a road test vehicle, and acquiring a spring displacement signal during a no-load road test through the displacement sensor to obtain a road test time-displacement map; 2) curve fitting: parking a road test vehicle on a weighing instrument, gradually adding the same counter weight to each seat in the vehicle at the same time until a spring displacement signal acquired by a displacement sensor reaches the maximum value of the road test displacement in the step 1), gradually and uniformly reducing the counter weight, and fitting a displacement-wheel load curve; and (3) converting a load spectrum: substituting the spring position displacement data of the displacement-wheel load curve in the step (2) into the time-displacement spectrum in the step (1), and converting the spring position displacement data into