【作者】 段士伟；

【导师】 李永池；

【作者基本信息】 中国科学技术大学 ， 工程力学， 2013， 博士

【摘要】 陶瓷材料因其优异的物理、力学性能,广泛应用在军用防护装甲以及民用发动机部件等方面,在国防及高科技领域起到了极其重要的作用。对陶瓷材料的力学性能、抗冲击特性以及损伤破坏规律的研究,成为国内外防护工程新的发展趋势。总体上来讲,目前对陶瓷材料的研究工作大多是初步且比较分散的,同时国内的研究工作与国外相比还有较大的差距。本文对陶瓷材料的基本静动态力学性能以及损伤破坏特性等方面,通过实验、理论及数值模拟相结合的较为全面的研究工作,较深刻地揭示陶瓷材料的抗侵彻机理。论文利用系列静动态力学性能实验装置(MTS、SHPB、 LGG及侵彻),开展了AD95与AD86/10两种陶瓷材料的静动态力学性能实验。利用MTS实验装置获得了材料在较低应变率下的强度、泊松比、杨氏模量等参数,以及低应变率下的应力应变曲线。利用SHPB实验装置获得了两种陶瓷材料在中高应变率下的屈服强度,并发现材料的应变率硬化效应。利用极高应变率下的LGG实验装置,获得了材料的自由面速度时程曲线以及层裂强度。开展了两种陶瓷材料抗杆弹侵彻实验,得到了材料的厚度防护系数及质量防护系数,为工程应用提供了依据。以实验研究所获得的基本材料参数及实验数据为基础,得到了陶瓷材料的JH-2本构模型参数。经过理论分析建立了既包含材料应变率效应也包含材料压力相关屈服效应和损伤软化效应的陶瓷材料的含损伤动态屈服准则。分析对比了本构计算的半径回归法与严格增量算法的计算流程及优缺点,以所建立的屈服准则为算例,推导了严格增量算法的计算公式。工程分析方法研究方面,通过同时考虑弹体和靶体材料的应变率效应,严格地以各分区的质量、动量守恒定律为基础,进一步改进了基于流体动力比拟的工程分析方法。应用改进的工程分析方法数值模拟了陶瓷材料的抗侵彻过程,模拟结果与实验结果符合良好。应用量纲分析方法得到了无量纲形式的侵彻相似律模型,并建立了考虑应变率效应时相似律模型的修正公式。数值模拟了SHPB实验中高强度碳化钨垫块所引起的试件轴向应力不均匀现象,并提出了一种合理的添加垫块形式,数值模拟结果显示,新型组合垫块下试件中轴向应力不均匀现象被基本清除；同时应用一维应力波理论得到了修正实验数据的处理方法。这些工作为陶瓷及其它高硬度、高强度材料的动态性能实验数据的准确获取奠定了基础。以细观分析和物理统计思想为基础,建立了陶瓷材料的拉伸型损伤演化方程以及压剪耦合型损伤演化方程,所建立的演化方程物理概念清晰,待定参数少。应用所得到的JH-2本构模型及参数、拉伸型损伤演化方程、半径回归算法,对LGG实验过程中平板撞击下陶瓷靶板材料的自由面速度时程曲线进行了数值模拟,通过优选得到了损伤演化方程参数；应用所得到的损伤演化方程及参数、所建立的陶瓷材料的双幂次屈服准则、本构计算的严格增量算法对同一问题进行了数值模拟,模拟结果与实验结果符合良好,证明了所建立的屈服准则、所应用的本构增量算法和所采用的损伤演化方程及参数的合理性。更多还原

【Abstract】 Ceramic materials have excellent physical, mechanical properties, widely used in military armor protection and civil engine et al, and had played an extremely important role in defense and high-tech sector. Study of the mechanical properties, impact properties as well as the damage and failure of ceramic materials become a new trend for protective works at home and abroad. Generally speaking, the study of the ceramic materials is mostly preliminary and scattered, and there is a large gap between domestic research and foreign countries. This article by means of more comprehensive study of the combination of experimental, theoretical and numerical simulation work, study the basic static and dynamic mechanical properties of ceramic materials, as well as damage and failure characteristics, profoundly reveals the mechanism of resistance to penetration of the ceramic material.Thesis carry out the static and dynamic behaviors of the the AD95and AD86/10two kinds of ceramic materials experiments using experimental apparatus (MTS, SHPB, LGG and penetration). Using MTS experimental apparatus obtained the parameters of the strength, Poisson’s ratio, Young’s modulus and the stress-strain curve of the material in the lower strain rate. Using the SHPB experimental apparatus obtained the yield strength of the two kinds of ceramic materials under medium-high strain rate, and found that the strain rate hardening effect. Using the LGG experimental device obtained the free surface velocity-time curve and the spall strength under high strain rates. Using anti-rod penetrated experimental device obtained the thickness protection factor and quality protection factor of the two kinds of materials.Making use of the basic material parameters and the experimental data obtained the ceramic materials’JH-2constitutive model parameters. Two yield criterions were established through theoretical analysis which contain both material strain rate effect and pressure related effects about ceramic materials. Compared the calculation process and the advantages and disadvantages of the radius regression with strict incremental algorithm through analysis. Take the established yield criterion for example, the strict calculation formula of incremental algorithm was deduced in details.Through taking into account the strain rate effect of the projectile and target materials, further improved the engineering analysis method based on the hydrodynamic analogy. The improved engineering analysis method was applied to numerical simulation of the resistance to penetration process of ceramic materials, the simulation results were in good agreement with the experimental results. Dimensional analysis method was applied to get no dimensional form similarity law of model, and established the correction law of similarity when considering the strain rate effect.Numerical simulated axial stress uneven phenomenon of ceramic specimen under SHPB experiment with high strength tungsten carbide inserts, and put forward a reasonable inserts form. The numerical simulation results showed that under the new combination inserts form the axial stress uneven phenomenon of specimen is basically eliminated. Application of one-dimensional stress wave theory got the correction method of experiment data.The tensile damage evolution equation and the compression-shear coupling damage evolution equation of ceramic materials were established. The physical concept of the evolution equations is clear and the undetermined parameters are few. We simulated the free surface velocity time history curve of ceramic materials under plate impact experimentation, using the above-mentioned JH-2constitutive model and parameters, the tensile damage evolution equation and the radius regression algorithm. The parameters in damage evolution equation are obtained by optimization. Application of the damage evolution equation and the parameters, the double exponential yield criterion and the strict incremental algorithm, we simulated the same LGG experiment. The simulation results were good agree with the experimental results, proved that the yield criterion, the strict incremental algorithm and the damage evolution equation are reasonable.更多还原