Papers by Keyword: Complex Materials

Abstract: Geotechnical materials are complex materials with very strong structures, but their structural problems have always been difficult problems in this field. In this paper, by studying the structural problems of geotechnical materials, we understand and master this kind of structural materials. Methods for describing complex materials, as well as the nature, characteristics, and changes of the material after being affected by the environment, especially the influence of the structure of the material on the macroscopic properties of the material. Starting from the basis of the material-material particles, fully consider the particle Geometry, surface characteristics and material characteristics, further analysis of the mechanical and geometric characteristics of structural materials composed of particles, a porosity model describing the pore size distribution is proposed, and the two-dimensional and three-dimensional The experimental data of pores in the space shows that the predicted value of the porosity model agrees well with the measured value in the three-dimensional space.In two-dimensional space, the validity of the model is closely related to the corresponding number of pores and the fractal dimension of the pore size distribution.

Abstract: The analysis of structural materials, especially the theoretical research, is always a challenge. Starting from the structural characteristics of the material, the theory of full state function about the strength - stiffness - strain that reflects the properties of structural material is established on the basis of the structural state of the material. The full state function is an important method to solve this problem. In order to further analyze the characteristics of the full state function, the full state function, strength theory of the material and the constitutive relation found are first studied. It is found that the full state function can more comprehensively reflect the properties of the structural material. The full state function accommodates the strength theory in the classical elastic-plastic theory. The full constitutive relation of the materials can be derived from the full state function. That is to say, the full state function can unify the strength theory and constitutive relation in the classical theory and can be used for the analysis of the structural materials. The full state function is more than a mere form, because it has explicit physical and mechanical meanings.

Abstract: Strength criteria for materials in the classical elastoplastic theory are formed mostly based on experiments and some assumptions [1, . However, no concensus has been achieved though many strength models were put forward to explore the applicable material strength criteria previously. Even the influence of material structures on strength has not been realized. In this article, the tensile failure strength criterion, shear strength criterion and strength criterion of friction materials are explored on the basis of the model of material with a structure of uniformly random distribution. Through analysis, it can be discovered that the strength criteria in the classical elastoplastic theory can be derived from the complex material theory based on the concept of material structure. However, as the theoretical basis, conditions of derivation and assumptions of concepts are totally different, it is proved that the complex material theory used for studying the material structures can fully cover the contents and conclusions obtained in classical elastoplastic theory.

Abstract: The structural problem of materials, belonging to the field of material mechanics, is one of the most challenging problems for geotechnical materials. The theory of full state function for materials is a feasible method to describe the structural property of materials. Based on the analysis of structural parameters and its number in the geometric - mechanical material model, the concept of full state function for materials was introduced in this study. The full state function of structural parameters for the materials was obtained. It was found that, in the specific material analysis model, the number of the structural parameters of materials was known. The physical meaning of the corresponding material parameters was essentially the reflection of the degree of mutual influence among the directions of the structure of the material. The number of independent structural parameters represented the number of combinations which could produce influence independently among the direction of structured materials. The magnitude of the structural parameter reflected the degree of mutual influence among the structured directions. It could also be thought that the inconsistency of geometric - mechanical properties along the direction of the structured materials was reflected by the number of structural parameters, while the inconsistency degree was reflected by the magnitude of the structural parameters.

Abstract: Direct at the anticorrosive problem of the pipeline, especially inner wall of the small-caliber pipe, we conceived and designed a new anticorrosion glass fiber powder reinforced plastic (GFRP) coating material. The reinforced material is GFRP powder, but not traditional fiber glass cloth or short glass fiber. This material assures perfect physical and chemical properties of traditional GFRP and ensures good coating fluidity for it at the same time. By experiment, raw materials of GFRP coating, their best formula and the fiber glass’s dispersion technology and parameters were determined. Drying time, thickness, abrasion resistance, adhesion, flexibility, heat resistance, and chemical resistance of coating were tested.

Abstract: A novel method to examine the defect of aerial complex material is presented in this paper. The novel speckle averaging technique for DSPI static measurement is proposed to improve the quality of measurement. A speckle averaging mechanism is designed and fabricated. The measurement result of sandwich structure material of practical aviation engineering is presented. The defect in the final results is clear.