【作者】 胡孔刚；

【导师】 程和法；

【作者基本信息】 合肥工业大学 ， 材料加工工程， 2005， 硕士

【摘要】 由于泡沫铝的力学性能是由其基体的力学性能、泡孔结构和相对密度所共同决定的,因此,深入研究和了解它的力学行为和性能随这些参数的变化对于优化泡沫铝的结构、进一步提高其力学性能和吸能性具有非常重要的意义。本文主要研究了泡沫铝基体的合金化、泡孔结构的变化以及所含填充物对其准静态和动态下的压缩应力-应变行为、力学性能及吸能性的影响。 采用加压渗流法制备了开孔泡沫纯Al、泡沫AlSi12合金、泡沫AlSi12Mg0.4合金和泡沫AlSi8Cu1.6Mg0.4合金,研究了Si、Mg和Cu元素的合金化对泡沫铝准静态压缩性能和吸能性的影响。实验结果表明,多元合金化显著地提高了泡沫铝的屈服强度、弹性模量和流动应力,但是,多元合金化使泡沫铝的塑性下降,其应力-应变行为显示出脆性泡沫的特征,并且在压缩载荷下没有出现类似于泡沫纯铝的致密化过程,从而使压缩平台段大幅度延长;另外,由于采用Si、Mg及Cu元素复合合会化大幅度提高了泡沫铝的屈服强度和流动应力,因此,使其具有更加优异的吸能性。 通过向开孔泡沫AlSi12合金的泡孔中渗流液念硅橡胶的方法制备了含硅橡胶填充物的泡沫铝合金,并且对这种含硅橡胶的泡沫铝合金进行了准静态和动态压缩试验,研究了硅橡胶对泡沫铝合金力学行为的影响。由于硅橡胶体积的不可压缩性,改变了泡沫铝的微观变形机制和应力-应变响应,与不含硅橡胶泡沫AlSi12合金的三阶段变形特征显著不同,含硅橡胶的泡沫AlSi12合金在准静态压缩下表现出类似致密材料的变形特征,而在动态压缩条件下,含硅橡胶泡沫AlSi12合金的应力-应变行为却具有泡沫材料的变形的特征,具有弹性段和塑性平台段。含硅橡胶的泡沫铝具有较强的应变率效应,随着应变率的提高,其屈服强度和流动应力均显著提高、吸能性上升。实验结果还发现:随着泡沫铝孔径的增大,填充硅橡胶后的屈服强度和流变应力均升高。 本文还用有限元模拟和实验方法相结合,研究了泡沫铝中大、小孔径的泡孔按不同比例相混合的结构对力学性能的影响。首先,用有限元法建立不同的孔结构模型,模拟孔结构的变化对泡沫铝力学性能的影响,取得相应的参数,然后,用渗流法制备出泡沫铝进行压缩实验验证。模拟和实验结果均表明,当泡沫铝的孔结构是由大孔和小孔按一定的尺寸比和体积比组成时,相同的密度下,泡沫铝的强度和刚度显著提高,小孔与大孔的尺寸比和体积比分别在0.40～0.45和0.07～0.12之间是最优的。更多还原

【Abstract】 The mechanical behavior of aluminum foams is determined by mechanical properties of the matrix material, pore structure and relative density. So, it is very important to study the variation of the mechanical behavior and properties of the aluminum foams with the factors above for the purpose of optimizing the pore structure, further increasing the mechanical properties and energy absorbing capacity of the materials. The main purpose of this paper is to investigate the influence of alloying of matrix, pore structure and fillers on the compressive behavior and energy absorbing capacity of aluminum foams with quasi-static and dynamic compressive experiments.The open cell foamed commercial pure Al, AlSi12, AlSil2Mg0.4 and AlSi8Cul.6Mg0.4 alloy were prepared by the infiltrating process respectively. The influence of alloying elements such as Si, Mg and Cu on the compressive properties and energy absorbing capacity of the aluminum foams was studied by the quasi-static compressive experiments. The experimental results indicate that the yield strength, elastic modulus and flow stress of the aluminum foams are increased greatly through multiply alloying of the matrix. However, the plasticity of the aluminum foams is decreased by multiply alloying, and the strain-stress behavior of the multiply alloyed aluminum foam is characterized by the feature of a brittle foam in the compression. Without densification, the multiply alloyed aluminum foam exhibits a prolonged plateau region in its strain-stress response to the compression. In addition, the yield strength and flow stress of the aluminum foam are increased by addition of the alloying elements such as Si, Mg and Cu, more excellent absorbing capacity are obtained in the aluminum alloy foams, as a result.A kind of AlSi12 foams with silicate rubber filler was fabricated through infiltrating the liquid silicate rubber into the open-cell aluminum foam. And the quasi-static as well as dynamic compressive experiments have been conducted to investigate the influence of the silicate rubber on the mechanical behavior of the AlSi12 foam. Due to the incompressibility of the filled silicate rubber, the deforming mechanisms of micro-structure and stress-strain response of the aluminum foam are altered. Unlike the AlSi 12 foam without filler exhibiting three regions in compression, the AlSi 12 foam filled with silicate rubber behaves like a dense matter in the static compression. However, the AlSi 12 foam with silicaterubber filler exhibits the stress-strain response of a foamed material during dynamic compression, for a linear elastic region and a plateau region are observed in its strain-stress curve. Furthermore, the AlSi12 foam with silicate rubber filler has a more distinct strain rate sensitivity compared with the foam without filler. The yield strength, flow stress as well as energy absorbing capacity of the AlSi 12 foam with silicate rubber filler increase with increasing in strain rate. It is also indicated that with increase of the cell size, more increase in the dynamic yield strength and the flow stress take place in the AlSi12 foam filled with silicate rubber.The effects of mixing a big cell size with a small cell size in different size and volume proportion on mechanical properties of the open-cell aluminum were investigated by experimental research and using finite element simulation. Firstly, the models of the aluminum foams with different pore structure were established by the finite element method. The influence of the variation in pore structure on the mechanical properties of the aluminum foams was simulated and corresponding parameters were obtained. Then, the aluminum foams with the corresponding pore parameters were prepared by the infiltration process. And the quasi-static compressive experiments were conducted on the materials in order to check the FEA simulative results. The experimental and the FEA simulative results both indicate that the strength and stiffness of the open-cell aluminum foams are increased obviously by the pore structure consisting of the big cell更多还原