Nosing process of empty and foam-filled circular metal tubes on semispherical die by theoretical and experimental investigations

Nosing process of circular metal tubes in empty and polyurethane foam-filled conditions on a semispherical rigid die was analyzed by theoretical and experimental methods.A new theoretical model of plastic deformation of circular metal tubes was demonstrated during the nosing process on a rigid semispherical die.Based on the analytical model,some theoretical relations were calculated to estimate instantaneous forming load and dissipated energy of empty and foam-filled circular metal tubes versus axial displacement.Some circular brazen and aluminum tubes were prepared and shaped into semispherical nosed nozzles to verify the present theory.Comparison of theoretical predictions and the corresponding experimental measurements reveals that predicted load?displacement and dissipated energy?displacement diagrams by theoretical formulas have a good correlation with the corresponding experimental curves and it proves verity of the theory.Also,the present theory shows that dissipated energy and axial load of empty tubes depend on material type,wall thickness and diameter of the tubes and they are independent of tube initial length.Furthermore,the experimental results show that the presence of polyethylene Teflon-constraints increases ultimate axial displacement of the forming process.

预制混凝土叠合梁复合内墙受力与耗能分析

本文以装配式建筑中的一种新型预制混凝土叠合梁复合内填充墙体为研究对象,基于混凝土塑性损伤本构模型,采用有限元分析软件ABAQUS分别建立包括和不包括叠合梁复合内墙的局部结构模型、标准楼层模型和整体结构模型,分析了叠合梁复合内墙对结构抗侧刚度的影响以及在罕遇地震下的耗能能力。分析结果表明,叠合梁复合内墙可显著增加局部结构的刚度,但由于这种墙体在建筑户型布置中数量较少,其对标准楼层的刚度影响较小。叠合梁复合内墙通过自身塑性耗能和损伤耗能较大程度地提高了结构整体抗罕遇地震性能。