Papers by Keyword: Technological Defects

Abstract: The effect of the quantitative and qualitative composition of mixed binders on the physical and mechanical properties of cement compositions has been experimentally established. A cement stone with a different amount and dispersion of mineral fillers was considered. The research results showed that the plastic strength of the hardening system depends on its initial composition. The defects embedded in the material during its technological processing into the product determine the local stress-strain state of the structure, the nature of cracking and the fracture surface. The effect of technological damage on the mechanical characteristics and the nature of cracking of cement compositions are shown. The possibility of reducing the material consumption of construction materials by 15-21 wt.% due to the use of fillers that are optimal in appearance and quality composition has been proved.

Abstract: Hollow multilayered structures are increasingly used in various fields of engineering and technology. One of the most important applications is шт aircraft engine construction and power-plant engineering. In recent years, the methods of superplastic forming have started to be used to obtain hollow parts specified for different areas. However, despite significant advances in this field, these technologies have several drawbacks, leading to the emergence of technological defects, particularly those associated with the the effect of Baushinger. In this regard, this article discusses the development and study of a technology for production of multilayer hollow constructions by superplastic forming, in particular, degradation process of adhesive bonds in areas, forming cavities in a constructional workpiece. It is shown that the use of more delicate effects to create the breaking away of the load enables the reduction of process defects in the part.

Abstract: This paper identifies and investigates the influence of technological defects of manufacturing process on the dynamic behavior of thin chromium microbeam. The analytical models will be analyzed and corrected using finite element method (FEM) to determine their validity under influence of technological defects. A semi-analytical model will be proposed for the extraction of corrective factors from 3D FEM simulation of dynamic behavior of microbeam. Final results indicate that the correction of technological defects is very significant for Cr microbeam 80x2x0.95μm³. In other hand, the corrected value of Young’s modulus is very close to the experimental results and it is about 279.1GPa.

Abstract: Four-point bending strength and Weibull distribution of the strength values of a carbon derived Si3N4-SiC nanocomposite have been investigated. The fracture origins were identified and characterized and a “labeled Weibull plot” was constructed. The fracture origins are surface, subsurface and volume located technological defects with a dimension from 10 µm to 180 µm, mainly in the form of cluster of pores and large SiC grains.