Abstract:
The evaluation of residual stress after winding and curing process is the basement for the optimization design of winding process scheme and the achievement of pre-service stressing design. In this paper, three kinds of winding tension strategies, e.g. constant tension (40 N), loose inside and tight outside tension (20 N-40 N-60 N), and tight inside and loose outside tension (60 N-40 N-20 N), were used to prepare the composite winding cylinders on the steel mould and polyamide 6 (PA6) mould by the dry winding process, respectively. The internal residual stresses were analyzed by measuring the released strain and spring-in angle during cutting process. With the aid of element birth and death technique, numerical model of the layer-by-layer winding process were created and the distributions of residual stress during winding were calculated. Subsquently, the curing process was simulated based on the constitutive model of CHILE (Tg). The after-curing residual stress and after-cutting spring-in deformation were predicted. It is shown that both the curing stress and the winding tension stress contribute to the total residual stresses. However, due to the further releasing of winding residual tension during the curing process, the total residual stresses are lower than the sum of the winding residual stresses and curing residual stresses. The impact of the winding tension strategies on total residual stresses is not affected by curing operation. The contribution of winding tension to the total residual stress is affected by the mould material used. The larger thermal deformation of the mould, the weaker the influence of winding tension strategy. For the situations with same mould, the winding cylinder with loose inside and tight outside (20 N-40 N-60 N) tension strategy shows the smallest after-cutting spring-in angle and the one with tight inside and loose outside (60 N-40 N-20 N) tension strategy shows the largest after-cutting spring-in angle. For the cases with same tension strategy, the winding cylinders made on PA6 mould give much larger after-cutting spring-in angle than that made on steel mould.