Computational Design Of Composite Microstructures

Along with the development of science and technology, in the engineering applications of the material the requirement of material performance becomes much higher, the service conditions for material become more and more harsh, and the service life estimates for the engineering component are increasingly strict. Some traditional materials have been unable to meet a variety of extreme conditions demand, which requires us to design the advanced material to be applicable to various engineering environment by expanding thinking and improving methods, effectively to predict the material property and to evaluate the failure behavior for the advanced material.In recent years, with the rapid development of computational science, computer technology has been used to a wide range of applications in various fields. At present, many scholars at home and abroad make computer technology to apply to material science successfully by means of computer simulation and numerical calculation, to make up for deficiency of the design and manufacture of the traditional material. Digital simulation and numerical simulation of material microstructures is achieved by using various algorithms, and material science is researched by using computer technology, which has become the major study trends. Finally a new subject that is the Material Microstructures calculation is formed gradually. "Digital Materials" technology is a key to computerize the design of microstructure, the prediction of performance and the evaluation of material service. It is used to support visualizing expression,characterization,simulation and virtual failure of interscale/intertemporal material microstructures and the process evolution, thus the design,deducing and prediction of the status of material microstructure is achieved. At the same time, along with the digitizing process of the material microstructure, the numerical technology of material microstructure is also very important. Digitization process is a translation process of a status, while numerical process is a treatment process of a status. "Numerical material" technology is the basic premise of "Digital Materials" technology going into the field of materials science successfully, and is basis of "material microstructure calculation". Its role is to make effective numerical calculation based on the geometric,component and phase structure of material microstructure. "Numerical Materials" technology has laid a foundation for the quantitative analysis of material microstructure. After numerical calculation of material microstructures is implemented, you can achieve virtual failure analysis of material microstructures, which systematically set up the scientific method of deducing virtual failure process of multi-phase heterogeneous material microstructure and assessing the virtual failure state of the microstructure, develop the more useful computer software. Eventually a set of database platform of" the component geometric structure of microstructure-the component material properties of microstructure-the identification of material microstructure weaknesses-propagation behavior of microcrack-material performance after damage-virtual failure status of microstructure "is created.Around the above problem, this paper finally achieves the design of the different composites microstructure and the study of numerical simulation, respectively, combining with metal matrix composites, resin-based composites and carbon-carbon braided composites applied widely in the field of aerospace. As the guide of "Digital Materials" technology, composite microstructure with a variety of complex geometric morphology is characterized. As the core of "Numerical Materials" technology, numerical simulation and virtual failure analysis of material microstructure is achieved in a variety of working conditions.Titanium matrix composites (TMCs) become select materials of ultra-high speed aerospace vehicle and the advanced of aero-engine next generation, because of its higher specific strength, specific stiffness and resistance of high-temperature. With the rapid development of aviation industry, the conventional titanium and titanium alloy can not meet the requirements.so it is necessary to develop new high-performance titanium alloys to meet higher requirements, therefore the focus of research is shifted from conventional titanium to intermetallic compounds,from the solid Solubilization enhanced titanium to titanium matrix composites. Titanium matrix composites include fiber reinforced and particle reinforced 2 major categories. When the low-density,high-modulus,high-strength reinforcement is added to titanium matrix alloy, the composite performance such as strength, modulus and creep strength has been greatly improved, and be able to meet the needs of the aviation industry. Based on the developed material microstructure simulation software ProDesign, the "representative volume element" of a titanium matrix composite microstructure is constructed, and combined with C++ programming and Python scripting language, the secondary development of pre-/post-processing for the commercial finite element software ABAQUS is carried out. We can achieve the finite element mesh and mesomechanics calculation of titanium matrix composite microstructure, and according to numerical value of the material microstructure mechanical response calculation, predict material performance of titanium matrix composite microstructure, identify "material structural weaknesses", assess the crack initiation,expansion of the micro cracks, deduce "microstructure virtual failure" behavior.Advanced polymer matrix composites have found widespread application in the field of aviation and aerospace, because of its higher specific strength and specific stiffness, good design, good anti-fatigue fracture properties, corrosion resistance, good dimensional stability, as well as facilitating to form the overall shape. Advanced polymer matrix composits are the major components of the polymer, usually including thermoplastic resin and thermosetting resin two categories. Epoxy resin is one of the most common thermosetting resins, and there is a series of excellent material properties such as structure multiplicity, convenient solidification, strong adhesion, low shrinkage, good mechanical and electrical properties, and good chemical stability. But the biggest weakness of epoxy resin is poor toughness, impact resistance is bad, and easy to crack, hence epoxy resin need to be toughening modification when it is used to an high-performance composites of aviation. For epoxy resin-based composite microstructure of different phase structure manufactured with different ratio of TP/TS (Thermoplastic/Thermoset), We have characterized the phase structure of the toughened epoxy system according to experimental observation, by using of computer simulation methods, combined with experimental data that was provided by Beijing Institute of Aeronautical Materials, have studied the relationship between the composition ratio and particle size distribution,particle spacing, and have predicted the mechanical properties of resin-based composite materials such as elastic modulus, shear modulus, Poisson's ratio, impact toughness and fracture toughness by using of numerical simulation of finite element method.Three-dimensional carbon-carbon braided composites, using a whole pieces of knitting as reinforcing material, without suture and mechanical processing, have good design of high material properties and good comprehensive performance indicators, such as higher strength, stiffness and better impact resistance, ablation resistance, etc. So it has been the general concern of the engineering sector, and become an essential material in the fields of aviation and aerospace. By means of design of three-dimensional carbon-carbon braided composite microstructure of the six-square, the four-square fasciculus. We characterized "repetitive unit cell" (RUC) of the different woven material microstructures, analyzed specific conditions of material microstructure, predicted material properties such as elastic modulus, tensile strength and coefficient of thermal expansion in different direction. On this basis, the impact of elastic modulus on braided composite microstructure including different types of defects which is characterized by material element of zero stiffness is studied.