Key Engineering Materials Vol. 831

Abstract: A die to estimate the thickness of the thinnest fin of a heat sink made by die casting aluminum alloys is proposed. The die consists of a taper-off thin fin and a cooling area. It was shown that this die can be used to estimate the smallest fin thickness of different aluminum alloys.

Abstract: The article solves the problem of rapid design of optimal stacking of a polymer laminated composite material of the traditional scheme. The existing engineering technique for laying design is based on constructive-force decomposition. However, this approach does not take into account the joint work of the layers. A solution is proposed that is based on the search for phenomenological dependencies for designing optimal styling parameters. The problem is solved by calculating the carrying capacity of a large number of styling options, searching among them for optimal solutions.

Abstract: Finite strain plastic deformation effects of SMAs are simulated based on finite strain elastoplastic J₂-flow equations, in a direct sense with no reference to any additional variables for phase transition mechanisms. Uniaxial loading-unloading curves of any given shape may be exactly reproduced as uniaxial stress-strain responses of these equations in each loading-unloading cycle. A new technique for combining linear spline functions into a unified, smooth interpolating function is proposed toward the purpose of explicitly, accurately fitting any given test data for both loading and unloading cases.

Abstract: Finite strain elastoplastic J₂-flow equations are established toward the purpose of automatically, accurately simulating pseudo-elastic effects of SMAs. The uniaxial responses derived from these equations in each loading-unloading cycle exactly produce a closed stress-strain curve of any given shape. Then, any given test data for pseudo-elastic hysteresis loops of SMAs may be accurately fitted by means of a new technique for combining linear spline functions into a unified, smooth interpolating function, in a sense with no need to identify any unknown parameters.

Abstract: In order to obtain the high temperature flow behavior of as-cast SA508-3 low alloy steel, the stress-strain curves of steel are obtained by Gleeble thermal simulation compression test at deformation temperature 800°C-1200°C and strain rate 0.001s^-1-1s^-1. Based on Laasraoui two-stage flow stress model, a high temperature flow stress model is established by multiple linear regression method. The results show that the peak stress characteristics are not obvious at low temperature and high strain rate, which is a typical dynamic recovery characteristic. Meanwhile, the peak stress characteristics are obvious at high temperature and low strain rate, which is a typical dynamic recrystallization characteristic. By means of the comparisons between experiments and calculations, the Laasraoui two-stage flow stress model can truly reflect flow behavior of steel at high temperature, which provides theoretical guidance for the hot deformation of the steel.

Abstract: In metal cutting, surface roughness plays an important role in assessing the quality of processed products. The roughness depends greatly on the selection of machining parameters such as cooling conditions and cutting parameters. For this purpose, cooling conditions including dry, MQL, and Silica-based nanofluid MQL as well as cutting parameters including cutting speed, depth-of-cut and feed-rate were investigated to determine their influence on machining roughness during hard milling of AISI H13 steel. The DOE method developed by G. Taguchi was used to design the experiments. An analysis of the signal-to-noise response and ANOVA were carried to obtain the optimal values of cutting parameters for minimizing surface roughness. The results of the present study show that Silica-based nanofluid MQL, minimum feed-rate, minimum depth-of-cut, and maximum cutting speed is an optimal cutting condition for reducing machining roughness.

Abstract: The factors affecting the shape and size of burrs that form at the edges of strips cast by a vertical type twin roll caster were investigated in this study. The size of the burr was found to be affected by the Si content of the strip. When the Si content was larger than 7 mass%, the burrs became larger. The position of the lower edge of the side dam plate also affected the shape of the burr. The burrs that formed were generally perpendicular to the strip surface but changed to being parallel to the strip surface as the position of the lower edge of the side dam plate was displaced upward from the center of the rolls.

Abstract: A simple twin-wheel caster is proposed for casting thin bars. The lower wheel of this caster has a trapezoidal groove with an area of 25 mm2. A 1070 pure aluminum bar with a convex, not concave and trapezoidal, cross section could be cast at speeds ranging from 3 to 4 m/min. The area of the bar was 38 mm2 when the wheel speed was 3 m/min. The area decreased with increasing wheel speed.

Abstract: Since abrasive gels with single direction motion are very difficulty to achieve the smooth surfaces in the complex holes finishing during abrasive flow machining (AFM), therefore, the helical cores were proposed here to create the multiple motions of abrasive gels to get the even surface of the complex holes in AFM. The results showed that helical core with 5 spiral grooves and narrow gap between the core tip and the hole could obtain the even surface and fine surface roughness after AMF.