铝合金材料中锯齿形屈服现象的初步时序分析-固体力学专业毕业论文.docxVIP

维数进行了估计。求解出了应力涨落曲线中隐含的最大Lyapunov指数，对其动力学稳定性进行了定量刻画。 维数进行了估计。求解出了应力涨落曲线中隐含的最大Lyapunov指数，对其动 力学稳定性进行了定量刻画。 关键词： 塑性失稳，动态应变时效，Portevin．Le Chatelier(PLC)效应，铝合 金，自组织临界性，非线性时序分析。 AbstractIn Abstract In a particular range of strain rate and temperature，several alloys，when subjected in tension tests witll a constant pulling speed．will exhibit repeated yielding of serrations in stress··time series and stepwise bursts in strain-time series as the plastic strain develops．Meanwhile，bands of localized deformation，where most of the plastic strain concentrate，will OCCur along the sample once and again．This fascinating phenomenon of plastic instability is referred serrated yielding or jerky flow．Due to Portevin and Le Chatelier’S early and systematic research work into the serrated yielding of AI alloys under room temperature，it is also called as Portevin—Le ChL,-telier(PLC)effect． For its association with many important subjects in material science，such as dynamic strain ageing(DSA)，solute hardening and SO on，PLC effect has always been attracting growing attention from researchers of metallurgy after its discovery．Furthermore，with the weight-reduction demands for the automotive industry from both of the environmental protection and the product performance perspectives，the proportion of light weight alumina in the required material for automotive parts including engines kept rising in recent years．However，the deduced ductile properties due to the PLC effect result in the non ideal slllface quality in the drawing process of alumina alloys，which greatly restricts the potential application of alumina alloys for industry purpose．In this way,the research into PLC effect makes great sense to industries of metallurgy and fabrication． Various serrated yielding stress series together with the mechanism behind it， which is always an important part of the PLC research，is also the vital object of this paper． In this paper，a reliable method，through which abundant macro characteristic informati