Parameter study and multi-objective optimisation of an axisymmetric rectangular tube with diaphragms for subways

Abstract

Abstract This study proposes a new axisymmetric rectangular tube (ART) with diaphragms. Unlike a uniform thickness tube (UTT), the thicknesses of adjacent ART walls are defined to be independent, with the thicknesses of the opposite walls remaining identical. The finite element model of ART with diaphragms was developed and validated by experiments; moreover, we found this structure exhibited acceptable values of crashworthiness indexes with a controllable and stable collapse pattern. To explore coupling influences of the three types of thicknesses on crashworthiness indexes and obtain optimal designs, we conducted a design of experiment (DOE) and employed polynomial response surface method (PRSM) for parameter study and optimisation. It was found that the ART with diaphragms achieved superior crash performance compared with the UTT with diaphragms, because of lower peak force and higher specific energy-absorption. When configurations of the ART wall thickness changed, the sensitivity of the two tube-wall thicknesses on crashworthiness indexes also changed and diaphragm thickness had different influences on crashworthiness indexes. Moreover, the distribution of design parameters of the thicknesses of ART was helpful in developing a crashworthiness design strategy. Therefore, we introduced this ART with diaphragms into crashworthy subways and recommended optimal designs as excellent energy-absorbing structures in practical engineering.