计及接触非线性的钢丝编织增强软管精细化有限元建模方法

Fine Finite Element Modeling Method of Steel Wire Braided Reinforced Hose Considering Contact Nonlinearity

聚四氟乙烯软管是一种用于航空发动机管路中的钢丝编织复合柔性软管,为了较为准确预测其疲劳寿命,需要建立有效的力学模型。针对以往研究未考虑编织层间接触状态影响软管力学性能等不足,提出根据软管多层结构参数建立钢丝尺度精细化有限元模型的方法,该模型可计算编织层间的接触状态、钢丝间的摩擦应力和软管力学性能的非线性变化。通过应变测量实验验证了模型的有效性,在压力载荷下,软管呈径向膨胀轴向缩短变形状态,中间区域应变基本一致,且应变以周向为主,轴向为周向的20%~30%。在0~20MPa工作压力范围内,由于编织层接触状态的改变,软管表现出3种不同的力学性能,压力从3MPa增加到4MPa过程中,编织层逐渐发生接触,编织层应变、应力曲线出现转折点,而内管和橡胶层转折点略迟于编织层。

Polytetrafluoroethylene hose is a kind of steel wire braided composite flexible hose used in aeroengine pipeline.In order to accurately predict its fatigue life,an effective mechanical model needs to be established.To solve the problem that the contact state between braided layer affects the mechanical properties of the hose which was not considered in previous studies,based on the multi-layer structure parameters of hose,a method of establishing refined finite element model of wire scale is proposed.The model can calculate the contact state between braids,the frictional stress among steel wires and the nonlinear changes of mechanical properties of hoses.The effectiveness of the model was verified by strain measurement experiments.Under pressure load,the hose expands radially and shortens axially.The strain in the middle region is basically the same.The strain is mainly circumferential,and the axial strain is 20%~30%of the circumferential.In the range of 0~20MPa working pressure,the hose shows three different mechanical properties due to the change of the contact state of the braided layer.When the pressure increases from 3MPa to 4MPa,the braided wire contacts gradually,and the strain and stress curves of the braided layer turn,while the turning point of the inner tube and rubber layer is a little later than that of the braided layer.