Papers by Keyword: Shock Loading

Abstract: Some recent trends and developments in advanced manufacturing of advanced materials from macro-to nanoscale subjected to shock loading, i.e. the up-to-date very important engineering area from industrial, research and academic points of view, with industrial applications to net-shape manufacturing, bioengineering, energy and safety, an outcome of the very extensive, over 40 years, work on this field performed by the author and his research international team, are briefly outlined.

Abstract: Magnesium alloys can be utilized as potential aerospace materials due to their low density, high specific strength, good vibration and shock absorption ability. This paper deals with the mechanical behavior of hot-rolled AZ31 alloy that was shock-deformed to 2.3 and 3.3 GPa. The post shock microstructure and mechanical response have been determined via full one-dimensional recovery techniques. The microstructure of deformed sample was characterized by the transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD) techniques. All the shock-deformed materials showed shock-strengthening effect that was greater at higher shock pressure. The reload yield stress of the shock-deformed 2.3 GPa sample was determined to be 238 MPa while 264 MPa for the sample which shock-deformed at 3.3 GPa. It was postulated that the shock-strengthening is ascribed to a greater dislocation density and the formation of deformation twins.

Abstract: This research work is investigates the processes of structure formation in the samples were 110Г13Л subjected to shock loads. The processes of structure formation, initiated by shock waves are explained from the terms of new theoretical developments. Analysis of the results can be extended to a wide range of materials.

Abstract: The main types (groups) of models of deformation and the fracture, used for the solution of problems of dynamic and shock wave deformation of materials, are considered. All models are divided into three main groups: macroscopic (models of mechanics of continuous medium), microstructural (based on the description of evolutions of ensemble of defects ) and atomistic (are used in calculations by methods of molecular dynamics and quantum mechanics). The short characteristic of models of the listed groups is given. Some approaches to development of the most perspective multilevel models are described. The simple test for applicability of models for the description of shock and wave processes are offered. Approaches to the description of destruction of materials and used at this criterion are considered. The perspective directions of development of models of dynamic deformation and fracture are suggested.

Abstract: By changing influent COD volume loading and dyestuff volume loading of membrane bio-reactor, the anti-shock capacity of traditional MBR and bio-ferric MBR was analyzed comparatively. The experiment results showed: whatever the influent COD volume loading altered, the supernatant and effluent COD in bio-ferric MBR varied less than that in traditional MBR, and the discreteness was smaller which indicated that the reinforcement of bio-ferric sludge could enhance the system stability, and the anti-shock loading of bio-ferric MBR was much better than traditional MBR. While the influence of the influent dyestuff volume loading on dyestuff concentration in supernatant and dyestuff removal efficiency was smaller. The relationship between influent COD volume loading and dyestuff loading and removal volume loading were linear.

Abstract: The purpose of this work is to study the effect of liquid in double bottom structures subjected to a closely underwater explosion shock loading. The comparative analyses are made by use of a commercial, explicit finite element program. Based on the difference of depth of liquid in double bottom structures and distance between explosive and outer bottom, six cases were simulated in this paper. The results show that liquid in cabins can enhance the resistance of double bottom structures to an underwater explosion.

Abstract: The paper briefly examines the metallurgical effects of shock waves on different metals. Two points are then specifically addressed. The first one regards how X-ray diffraction (XRD) can be usefully employed to get exhaustive information about the microstructure of a shock loaded metal. The second point concerns the mechanisms of martensitic transformation in alloys such as AISI 304 when submitted to repeated explosive deformations.

Abstract: Nanostructured composites inspired by structural biomaterials such as bone and nacre form intriguing design templates for biomimetic materials. Here we use large scale molecular dynamics to study the shock response of nanocomposites with similar nanoscopic structural features as bone, to determine whether bioinspired nanostructures provide an improved shock mitigating performance. The utilization of these nanostructures is motivated by the toughness of bone under tensile load, which is far greater than its constituent phases and greater than most synthetic materials. To facilitate the computational experiments, we develop a modified version of an Embedded Atom Method (EAM) alloy multi-body interatomic potential to model the mechanical and physical properties of dissimilar phases of the biomimetic bone nanostructure. We find that the geometric arrangement and the specific length scales of design elements at nanoscale does not have a significant effect on shock dissipation, in contrast to the case of tensile loading where the nanostructural length scales strongly influence the mechanical properties. We find that interfacial sliding between the composite’s constituents is a major source of plasticity under shock loading. Based on this finding, we conclude that controlling the interfacial strength can be used to design a material with larger shock absorption. These observations provide valuable insight towards improving the design of nanostructures in shock-absorbing applications, and suggest that by tuning the interfacial properties in the nanocomposite may provide a path to design materials with enhanced shock absorbing capability.

Abstract: In this paper, we analyze a RVE of concrete reinforced (RC) with steel reinforcing bar in two vertical directions on basis of the thoughts of composite material and propose that in the ideal case the constitutive equation of reinforce concrete is declared to multiply the viscoelastic constitutive equation of concrete by a reinforcing multiplier G , which is depended on material characters and arrange mode of steel reinforcing bar. In the model, we draw the growing damage law on the assumption that damage only occur in the concrete. Subsequently, we obtain the damage viscoelastic constitutive equation of reinforced concrete. Lastly, the comparison with the plate impact test results of specimens shows that the proposed model can give consistent prediction of the dynamic behavior of SFRC.