Experimental research and finite element analysis on mechanical performance of ETFE cushions

The static and dynamic characteristics of a full-scale ETFE cushion were studied on the basis of form-state test, loading test, and free vibration test. The interaction model of ETFE cushion was established and form-state analysis, loading analysis, and modal analysis were performed in order to verify the validity of finite element method. Results show that the internal pressure of ETFE cushion is sensitive to external loads. The variation amplitude of internal pressure decreases nonlinearly with the initial pressure increasing. The loads on the middle or side part of ETFE cushion will cause larger changes of membrane shape and internal pressure. Under the same load, the deformation of cushion also decreases nonlinearly with initial pressure increasing. In the range of common internal pressure, the first frequency of the test cushion locates between 6 Hz and 10 Hz. The interval of the first two frequencies is larger, and the second to fifth frequencies are more concentrated. The natural frequencies of cushion increase nonlinearly with the increase of internal pressure. The two-layer membranes show symmetrical vibration in lower-order modes. The ETFE cushion is a low damping structure, and the damping ratio of each mode declines with internal pressure increasing. The finite element results of form-state analysis, loading analysis, and modal analysis are in good agreement with the test results. It is verified that the interaction finite element model has good accuracy and applicability in static and dynamic analysis of ETFE cushions. ©, 2015, Science Press. All right reserved.