Papers by Keyword: Triaxial Stress

Abstract: Workability is a degree of the amount of deformation that a powder metallurgy bits and pieces can survive prior to fracture occurred in the forming or upsetting processes. Ductile fracture is the most general mode of breakdown in bulk forming process. The formability is a complicated happening, dependent upon the method as well as the material parameters. An investigational research work was performed for the kind of the working behavior of Al–SiC-Y2O3 hybrid composite under triaxial stress state circumstance. Upsetting of Al–SiC-Y2O3 powder metallurgy compacts with various aspect ratios and initial preform densities were carried out and the working behavior of the powder compacts at various state conditions was computed. In the powder metallurgy technique cold pressing can be used for compaction of the reinforcement of SiC and Y2O3 with Aluminum hybrid composites (Al+SiC+Y2O3). The bottle green compacts can be sintered and workability characteristics can be studied. In the hybrid composites, SiC content has been different from 0% to 20% with different particle sizes namely 60 and 80μm. Y2O3 nanoparticles of size 30-50nm and reinforced with 1wt% , 2wt% and 3wt%. The experimental Results can be analyzed for workability and frictional stress state conditions during upsetting as a role of relative density. The formability stress index values obtained for various addition of SiC and Y2O3.

Abstract: Better understanding of concrete behavior is beneficial to the determination of concrete strength and detection of cracking using nondestructive testing techniques such as ultrasonic and acoustic emission. For advanced nondestructive evaluation of high early strength concrete under triaxial compression loading, stress-strain relationship in axial as well as in radial directions needs to be described in explicit form. This paper presents empirical models developed for high early strength concrete under active confinement to explore the effect of confining pressure. Empirical model for axial stress-strain relationship is determined first. Transverse deformation model is automatically generated from the given axial stress-strain model using plastic strain rate. Parameters used in the model are identified and their recommended values are provided. Compressive strength of 24 MPa and 45 MPa concretes are considered along with four different levels of confining pressures.

Abstract: The strain rate sensitivity of a A6061-T6 aluminum is examined as a function of triaxial stress. The triaxial stress state is changed by changing the notch acuity of notched specimens. Under the high strain rate conditions, increasing triaxiality increases flow stress. Plastic constraint factor decreases in notched specimens under high strain rate conditions. Reduction-of-area in notched specimen increases with increasing strain rate. The relaxation of plastic constraint takes place under high strain rate in the notched specimens. The effects of triaxial stress and strain rate on the fracture surfaces are discussed.