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2022 ◽  
Vol 1049 ◽  
pp. 18-23
Author(s):  
Vladimir F. Korostelev ◽  
M.S. Denisov

The properties of bulk metal products are formed when molten metal transforms from an unstructured liquid into a solid crystal state. We suggest a new approach to the automation of the control over crystallized metal shrinkage compensation based on controlling the law of change in pressure applied to crystallizing metal through a program taking into account the transition process in the hydraulic system of the production equipment. We observed the increase in rigidity, durability, and pliability of В95-alloy samples as compared to cast aluminum alloys. The metal utilization rate can be increased up to 0.90 of the liquid metal volume.


Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 439
Author(s):  
Mingshi Wang ◽  
Jianxun Zhang ◽  
Hui Yuan ◽  
Haoyuan Guo ◽  
Wenbo Zhuang

The plastic behavior in the large deflection response of slender sandwich beams with fiber metal laminate (FML) face sheets and a metal foam core under transverse loading is studied. According to a modified rigid–perfectly plastic material approximation, an analytical model is developed, and simple formulae are obtained for the large deflection response of fully clamped FML sandwich beams, considering the interaction of bending and stretching. Finite element (FE) calculations are conducted, and analytical predictions capture numerical results reasonably in the plastic stage of large deflection. The influences of metal volume fraction, strength ratio of metal to composite layer, core strength, and punch size on the plastic behavior in the large deflection response of FML sandwich beams are discussed. It is suggested that, if the structural behavior of fiber-metal laminate sandwich beams is plasticity dominated, it is similar to that of metal sandwich beams. Moreover, both metal volume fraction and the strength ratio of metal to composite layer are found to be important for the plastic behavior in the large deflection response of fiber metal laminate sandwich beams, while core strength and punch size might have little influence on it.


Author(s):  
Yu.F. Ivanov ◽  
A.A. Yuriev ◽  
V.E. Kormyshev ◽  
X. Chen ◽  
V.B. Kosterev ◽  
...  

The quantitative estimation of strengthening mechanisms of rails’ surface layer is carried out on the basis of regularities and formation mechanisms of structure-phase states revealed by the methods of modern physical materials science. It is performed at different depths of the rail head along the central axis and fillet of differentially quenched 100-meter rails after the extremely long-term operation (gross passed tonnage of 1411 mln tons). A long-term operation of rails is accompanied by the formation of structural constituent gradient consisting of a regular change in the relative content of lamellar pearlite, fractured pearlite, the structure of ferrite-carbide mixture, scalar, and excess dislocation density along the cross-section of the rail head. As the distance to the rail fillet surface decreases, the relative content of metal volume with lamellar pearlite decreases. However, the relative content of metal volume with the presence of the fractured pearlite structure and ferrite-carbide mixture increases. The contributions caused by the matrix lattice friction, intraphase boundaries, dislocation substructure, presence of carbide particles, internal stress fields, solid-solution strengthening, pearlite component of steel structure are estimated. It is shown that the main mechanism of strengthening in the surface layer is due to the interaction of moving dislocations with low-angle boundaries of nanometer dimensional fragments and subgrains. The main dislocation strengthening mechanism in a near-surface layer at a depth of 2-10 mm is due to the interaction of moving dislocations with immobile ones.


2021 ◽  
pp. 29-36
Author(s):  
Vladimir M. Gevorkyan ◽  
Yury A. Kazantsev ◽  
Aleksandr V. Shutov

A simple algorithm for reliably determining the Q-factor of an open dielectric resonator made of a material with a tgδ less than 0.0001 in the shielded region is presented, based on measuring the parameters of an electromagnetically coupled system of bulk metal and open dielectric resonators. The analytical substantiation of the considered method for determining the Q-factor of an open dielectric resonator in electrodynamic and electrotechnical representations is carried out. The variants of the influence of the metal volume on the effective Q-factor of an open dielectric resonator depending on its electrophysical characteristics are considered. The factors affecting the effective Q-factor of an open dielectric resonator obtained using this measurement method are evaluated, and the range of expected measurement errors is shown. The advantage of the method for determining the Q-factor of an open dielectric resonator is the high accuracy of the obtained analytical ratios for determining the Q-factor, the absence of increased requirements for the accuracy of the measurement sections and the quality of the internal surfaces of the metal resonator, the simplicity of the measurement process, based on the use of ordinary equipment and element base.


Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1430
Author(s):  
Maik Trautmann ◽  
Selim Mrzljak ◽  
Frank Walther ◽  
Guntram Wagner

Multi layered lightweight material compounds such as hybrid laminates are composed of different layers of materials like metals and unidirectional fibre-reinforced plastics and offer high specific strength. They can be individually tailored for applications like outer cover panels for aircraft and vehicles. Many characteristics especially layer structure, volume contents of the embedded materials as well as layer surface adhesion determine the performance of a hybrid laminate. In this study, the influence of layer structure and metal volume content are evaluated with regard to the mechanical properties of the recyclable hybrid laminate CAPAAL (carbon fibre-reinforced plastics/aluminium foil laminate), which consists of the aluminium alloy AA6082 and a graded structure of glass and carbon fibre-reinforced polyamide 6. Hybrid laminates with different ratios of the fibre-reinforced plastic and numbers of aluminium layers were manufactured by thermal pressing. The consolidation quality of in total four laminate structure variations, including 2/1 and 3/2 metal-to-fibre-reinforced plastic layer structures with fibre orientation variation, were investigated by light microscopy through cross-sections and further on computed tomography. For determination and evaluation of the mechanical properties metrologically instrumented quasi-static tensile and three-point bending tests, as well as tension-tension fatigue tests for the establishment of S-N curves were performed. The results were correlated to the microstructural observations, revealing significant influence by the consolidation quality. The layer structure proved to have a proportional impact on the increase of quasi-static tensile and flexure strength with a decrease in metal volume content. Orienting some of the fibre-reinforced plastic layers in ±45° leads to a more evenly distributed fibre alignment, which results in a higher consolidation quality and less anisotropic bending properties. Fatigue results showed a more complex behaviour where not only the metal volume content seems to determine the fatigue loading capability, but also the number of metal-fibre-reinforced plastic interfaces, hinting at the importance of stress distribution between layers and its longevity over fatigue life.


Author(s):  
Ayushman Singh ◽  
Srikanth Rangarajan ◽  
Leila Choobineh ◽  
Bahgat Sammakia

Abstract This work presents a simplified approach to optimally designing a heat sink with metallic thermal conductivity enhancers infiltrated with phase change material for electronic cooling. In present study, thermal conductivity enhancers are in the form of a honeycomb structure. A benchmarked two-dimensional computational fluid dynamics model was employed to investigate the thermal performance of the phase change material-metallic thermal conductivity enhancer composite heat sinks. Metallic thermal conductivity enhancers are often used in conjunction with phase change material to enhance the conductivity of the composite heat sink. Under constrained heat sink volume, the higher volume fraction of thermal conductivity enhancers improves the effective thermal conductivity of the composite, while it reduces the amount of latent heat storage simultaneously. The present work arrives at the optimal design of heat sink for electronic cooling by resolving the stated tradeoff. In this study, the total volume of the heat sink and the interfacial heat transfer area between the phase change material and thermal conductivity enhancers are constrained for all design points. Furthermore, assuming conduction-dominated heat transfer, an effective numerical model that solves the single energy equation with the effective properties of the phase change material- metallic thermal conductivity enhancer composite has been developed. The temperature gradient-time history is compared and matched for both the models to arrive at the accurate effective thermal conductivity value. The relationship of effective thermal conductivity as a function of metal volume fraction and thermal conductivity of metallic thermal conductivity enhancer is obtained. The figure of merit (FOM) is used to define the balance between effective thermal conductivity and energy storage capacity. The FOM is maximized to find the optimal volume fraction for the present design. The results from the study reveals that there exists an optimal metal volume fraction that maximizes the thermal performance of the composite.


Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2122 ◽  
Author(s):  
Qingming Hu ◽  
Tianyi Jiang ◽  
Hongyuan Jiang

The gallium-based eutectic liquid metal alloys exhibit unique properties of deformability, excellent electrical conductivity and low vapour pressure. The liquid metal-based circuits’ element or actuator have drawn considerable attention in stretchable electronics and microelectromechanical (MEMS) actuators. Yet, the motion of the liquid metal within the electrolyte needs to be precisely regulated to satisfy application requirements. Herein, we investigated the locomotion of liquid metal within the alkaline aqueous solution under electrostatic actuation. The relationship between the travelling speed of the liquid metal slug and the relative influential parameters, such as the voltage amplitude and frequencies of the applied electric field, electrolyte concentration, electrodes distance and the liquid metal volume, were experimentally characterized. A travelling speed up to 20.33 mm/s was obtained at the applied voltage of 4 Vpp at 150 Hz at 6 V DC offset. Finally, the frequency-dependent liquid metal marble movements were demonstrated, namely oscillation and forward locomotion while oscillating. The oscillation frequency was determined by the frequency of the applied alternate current (AC) signal. The remarkable transportation and oscillating characteristic of the liquid metal marble under the electrostatic actuation may present potentials towards the development of flexible electronics and reconfigurable structures.


2020 ◽  
Vol 989 ◽  
pp. 691-698
Author(s):  
Dmitriy Konstantinov ◽  
Dinara Emaleeva ◽  
Alexander Pesin

Development of modelling method, which allows prediction of the properties distribution in the metal volume with the behavioral features of the microstructure under the influence of the deformation during drawing, was the objective of the paper. Multiscale model of rod drawing process was proposed. To save computing time, statistical representation of the microstructure was applied. Statistically Similar Representative Volume Element (SSRVE), representing ferritic-pearlitic steel microstructure, was developed. Simulations of the drawing process were performed, and local deformation of each structural component was predicted. Selected results, as well as discussion of the effect of microstructure on obtained stress and strain distributions, are presented in the paper.


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