Microstructure and Texture Evolution during Severe Plastic Deformation at Cryogenic Temperatures in an Al-0.1Mg Alloy

The deformation structures formed in an Al-0.1Mg single-phase aluminium alloy have been studied during plane strain compression (PSC) down to liquid nitrogen temperature, following prior equal channel angular extrusion (ECAE) to a strain of ten. Under constant deformation conditions a steady state was approached irrespective of the temperature, where the rate of grain refinement stagnated and a minimum grain size was reached which could not be further reduced. A 98% reduction at 77 K (−196 °C) only transformed the ECAE processed submicron grain structure into a microstructure with thin ribbon grains, where a nanoscale high angle boundary (HAB) spacing was only approached in the sheet normal direction. It is shown that the minimum grain size achievable in severe deformation processing is controlled by a balance between the rate of compression of the HAB structure and dynamic recovery. The required boundary migration rate to maintain a constant boundary spacing is found far higher than can be justified from conventional diffusion-controlled grain growth and at low temperatures, a constant boundary spacing can only be maintained by invoking an athermal mechanism and is considered to be dominated by the operation of grain boundary dislocations.

Effects of Trailing Edge Deflections Driven by Shape Memory Alloy Actuators on the Transonic Aerodynamic Characteristics of a Super Critical Airfoil

A smart structure to actuate a morphing trailing edge based on the super critical airfoil NASA sc-0714(2) was designed and verified in a transonic wind tunnel. The pressure distribution over the wing was measured to evaluate the structure ability and effects of trailing edge deflections on the aerodynamic characteristics. In the experiment, Mach number was from 0.4 to 0.8, and the angle of attack was from 0° to 6°. The results showed that the smart structure based on shape memory alloy could carry aerodynamic loads under transonic flow and deflect the trailing edge. When the driving force was constant, deformation would be influenced by the Mach number and angle of attack. Increasing the Mach number weakened the actuation capability of the smart structure, which decreased the deflection angle and rate of the trailing edge. The influence of the angle of attack is more complex, and couples with the influence of the Mach number. The higher the Mach number, the stronger the influence of the angles of attack. Additionally, the trailing edge deflection would dramatically change the flow structure over the airfoil, such as the shock wave position and strength. If separation was caused by the trailing edge deflection, the limitation of the smart structure would be further found.

Geological Analysis and Model Test of Bedding Rock Cutting Landslide

To explore the staged catastrophic evolution mechanism and failure process of bedding rock landslides under construction disturbance and rainfall conditions, we selected water content, displacement, strain, and soil stress as the study objects and carried out a model test. Combining the test phenomena, the following conclusions are drawn: first, bedding rock landslides have experienced three different stages of initial, constant velocity, and accelerated deformation affected by construction and rainfall factors. Then, the mode of bedding rock landslides is both sliding and traction sliding compound sliding mode. Finally, in the initial and constant deformation stages, the stress and strain values in the soil both increase slightly. In the accelerated deformation stage, the horizontal and vertical deformation at the slope foot increases sharply. Meanwhile, the strain value increases greatly, the stress decreases, and the stress in the slope increases significantly. Therefore, stress, strain, and displacement can be used as early warning indicators for staged disasters of bedding rock landslides.

Effect of Pre-Tension on the Springback Behavior of the Yellow Brass

Springback forecasting of sheet formation is constantly remarkable problem in the métier, due to their influence the great in the definitive shape of the product. Study presents effects of pretension in tow rolling direction (0, 45 degree) on the springback behavior of the (Brass 65-35) sheet under V-die bending by an experimental. The pretension ranges from five different pretensions levels starting from 11% to 55% from total strain in each rolling direction by increment of 11%. used in punching that was performed at a constant deformation velocity of (5 mm/min) then bent on a 90° V-shaped die for the springback evaluation. The results from experiment indicate that the springback increase with pretension ratio and the springback in 45 degree is higher in rolling direction.

Topologies of Organization: Space in Continuous Deformation

This paper offers to extend existing discussions about the socio-material production of organizational space through the concept of topology. It does so by: (1) connecting the concept of topology to existing approaches to spatial organization that emphasize its socio-material and open-ended emergence; (2) theorizing organizational space as being in constant deformation across different topological shapes; and (3) exploring this in an empirical example that juxtaposes a management meeting with its interruption. The empirical material is collected through the method of shadowing managers at a Danish school. Theoretically, the paper argues that the shaping of space is contingent upon dis/continuities between (non)human agencies. The topological deformation of space testifies to the continuous but under-acknowledged work provided by (non)human agencies to both achieve and challenge the stability of organizational space. It further situates the boundary between inside and outside as a transient condition. This renders spatial matters such as scale and size situational achievements. Topology thus implies that we cannot in advance scale organization into micro and macro spatialities, and further, foregrounds the inherent dis/organization of space.

ЕЛЕКТРОХІМІЧНІ ТА КОРОЗІЙНО-МЕХАНІЧНІ ВЛАСТИВОСТІ ТРУБНОЇ СТАЛІ РІЗНОЇ КАТЕГОРІЇ МІЦНОСТІ В МОДЕЛЬНОМУ ГРУНТОВОМУ ЕЛЕКТРОЛІТІ

Determine the influence of the strength category of the pipe steel on the electrochemical and corrosion-mechanical properties under the conditions of the combined effect of constant deformation and protective potential in a weakly alkaline environment. The standard methods were used: the massometry method, the potentiometry, the polarization curves, the method for investigating the resistance to corrosion cracking under constant deformation at the cathode potential.

Assessment of Gilsonite and Trinidad Epuré natural asphaltmodified binders ability to relaxation at low temperature

The paper presents the results of the tests conducted on asphalt binders modified with additives of natural Gilsonite and Trinidad Epuré asphalts, as well as the 20/30, 35/50 and 50/70 penetration grade bitumens by use of an original observation method of the relaxation phenomenon in low temperature. In the tests the authors used a ductilometer equipped with a dynamometer and a bath filled up with a liquid with the temperature of-16°C. Relaxation of the asphalt binder was observed in the period of 20 minutes in the conditions of constant deformation of the sample caused by its prior extension with the constant speed of 1 mm/min. The value of the normal stress occurring in the asphalt binder is calculated on the basis of the measured value of the normal (tensile) force. It has been noted that asphalt binders with higher penetration values are characterised by a better relaxation ability at low temperature, that is relaxation takes place faster and has higher values of sample stress reduction in the domain of time, at constant strain. With approximate penetration values (the maximum penetration difference at 25°C amounting to ±2 mm/10), modified binders comprising Gilsonite are characterised by better relaxation abilities in comparison to binders containing the Trinidad Epuré additive.

Механизм пластического коллапса наноразмерных кристаллов с ОЦК-решеткой при одноосном сжатии

Within the dislocation–kinetic approach, based on the nonlinear kinetic equation for dislocation density, an attempt is made to consider the problem of a catastrophic plastic collapse of defect-free nanocrystals of metals with bcc lattice under their uniaxial compression with a constant deformation rate. Solutions of this equation were found in the form of moving waves, describing the dislocation multiplication process as the wave moves along the crystal from a local dislocation source. Comparison of the theory with the results of experiments on defect-free Mo nanocrystals showed that their ultrahigh strength at the initial stage of deformation is associated with a low rate of rise of crystal plastic deformation in comparison with the growth of its elastic component. The subsequent plastic collapse of crystal is caused by a sharp increasing the plastic component, ending with reaching the equality of elastic and plastic deformation rates.

TECHNOLOGICAL ASPECTS OF PRODUCTION AND RESEARCH OF POLYMERS COMPOSITE MATERIALS WITH INCREASED STRENGTH

The work is devoted to the search for new effective modifying additives that allow to purposefully regulate the technological properties of rubber compounds and physical-mechanical properties of rubbers based on combinations of non-polar rubbers and at the same time being cheaper and more affordable than traditional products, in particular, with resorcinol-urotropin complex (modifier RU -1). It was proposed to use as a modifier of frame rubbers based on a combination of isoprene (SKI-3) and butadiene-styrene (SCS-30ARKM-15) rubbers, chlorinated atactic polypropylene (CHAPP). It is shown that when the RU-1 modifier is replaced with this compound, the conditional stresses and tensile strength, tearing resistance, rebound elasticity, fatigue resistance in the regime of constant deformation amplitude, heat resistance, resistance to thermal aging of rubbers, as well as the strength of rubber bonding with rubber Textile cord, including at elevated temperatures are observed. Comparison of the CHAPP for the effectiveness of the action in the carcass gum with the previously proposed oligoefirmetacrylate epichlorhydrine, from the point of view of the provided complex of properties, showed the advantage of chlorinated atactic polypropylene for a number of priority indicators. From the comparative analysis of the modifying activity of chlorinated atactic polypropylene and oligoether methacrylate epichlorohydrin, it follows that the vulcanizates of rubber compounds containing instead of RU-1 chlorinated atactic polypropylene CHAPP are characterized by more improved parameters of hardness in TM-2, elasticity by rebound, the strength of the rubber-cord connection. It is also revealed that the main advantage of the proposed modifier is the low cost of the modifier used, as well as the use of secondary raw materials for its production.Forcitation:Mustafayeva R.E. Technological aspects of production and research of polymers composite materials with increased strength. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 10. P. 82-86