PSD Random Vibration Strength and Fatigue Analysis of a CNG Tube Trailer

Tube trailer is a kind of gas transportation equipment, which is widely used in transportation of various industrial gases including compressed natural gas (CNG). However, due to its particularity of carrying high-pressure gas and operating and parking on urban roads, the requirements for its safety performance are especially concerned. In this paper, finite element random vibration analysis on a tube trailer was performed according to the standard GB/T 4857.23-2012, random vibration analysis under the “ISTA 3A vehicle power spectral density (PSD) curve”. The first 9 orders natural frequencies are obtained from modal analysis and it is found that only the first natural frequency is covered in the speed limitation of 80 km/h for the tube trailer. The maximum deformations in the first 3 orders all occur in the middle of the frame of the tube trailer; Stress analysis under random vibration excited by the specified PSD found that the maximum stresses corresponding the probability values at 1σ, 2σ and 3σ are all less than the yield stress of the material, meaning that the structure meets the strength requirements. Within the fatigue life under PSD random vibration, the trailer’s fatigue damage cycle ratio D is less than 1, meaning the structure meets the fatigue design requirements.