Metals

Thin plates are widely used and can be subjected to combined loads that trigger elasto-plastic buckling. Often, these plates are perforated, which significantly changes their mechanical response. This study investigates six perforation geometries (elliptical, longitudinal hexagonal, transverse hexagonal, longitudinal oblong, transverse oblong, and rectangular) and their influence on the ultimate buckling stress of perforated plates under biaxial compression and lateral pressure. Three plates with a distinct width b and length a ratio (b/a) and five unperforated plate volume and perforation volume ratios (ϕ) are analyzed using finite element analysis in ANSYS^®, combined with Constructal Design, Exhaustive Search, and the Technique for Order Preference by Similarity to an Ideal (TOPSIS). Perforation geometry is shown to be a decisive parameter: elliptical perforations are the most efficient, limiting strength loss in rectangular plates with b/a = 1/3 and ϕ = 0.025 to about 6%, while oblong perforations cause reductions of up to 14%. In square plates (b/a = 1), elliptical perforations preserve more than 98% of the original strength for ϕ ≤ 0.05 and over 90% at ϕ = 0.20. TOPSIS results highlight configurations that balance small reductions in ultimate buckling stress with up to 23% lower maximum deflection, providing practical design guidelines.

The liquidus and solidus temperatures, the initial temperature of the solidification of binary eutectics, and the partition ratios of the solid solution at the Al corner of the ternary eutectic-type Al-Si-Cu alloy system were calculated using the thermodynamically based ESTPHAD method. It is shown that these data can be calculated from the liquidus and solidus data of the two binary equilibrium phase diagrams (first estimation), the binary phase diagram and the eutectic valleys in the ternary system (second estimation), as well as the binary phase diagram, the eutectic valleys, and one (third estimation) and more (fourth estimation) liquidus and solidus temperatures of the ternary equilibrium phase diagram with varying precisions. A database calculated with Thermo-Calc software (version 4.1.0.4995), was used for the calculations.

Molecular dynamics simulations were conducted at a cooling rate of 1.0 × 10¹¹ K/s to investigate the solidification mechanism of zirconium (Zr) under high pressure. Three distinct pressure-dependent regimes are identified: crystallization into a body-centered cubic (BCC) phase below 27.5 GPa, vitrification between 27.5 and 65 GPa, and crystallization into an A15 phase above 65 GPa. The volume change during crystallization is found to reverse at critical pressures of 5 and 103 GPa, and anomalous behavior is observed at the phase boundaries: at 27.5 and 65 GPa, the volume varies continuously despite a sharp drop in potential energy, whereas at 65 GPa, the volume decreases abruptly while the energy changes smoothly. Structural analysis indicates that evolution in the low-pressure regime is governed by atomic configurations extending to the second-neighbor shell, while at high pressures, nearest-neighbor interactions become dominant. This work clarifies the microstructure–pressure relationship during metallic solidification, providing insights into controlling phase transitions under extreme conditions.