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The cavitation process of high-performance IIDPE/UHMWPE blends with a uniform dispersion of UHMWPE during cold stretching was investigated. It was observed that incorporating a small amount of UHMWPE into the HDPE matrix resin can serve as a nucleating agent, increasing the number of contact sites and accelerating the crystallization rate. This leads to the formation of thicker lamellar crystals and tethered molecules, ultimately enhancing the mechanical properties of the HDPE matrix. Furthermore, the relationship between the natural tensile ratio and strain-hardening modulus was confirmed. Microstructural changes within the blends were also explored. As the drawing tangles in the middle, the cavities subsequently evolve by collapsing and merging to align parallel to the tensile direction, culminating in tensile damage forming a large crack in the final macroscopic form. As a result, the presence of more tethered molecules in the later stages of stretching inhibits further cavity growth. Highlights * The HDPE/UHMWPE blends were prepared by solution blending and ultrasound-assisted twin-screw extrusion. * The mechanisms underlying the formation and evolution of cavities in HDPE/UHMWPE blends, which lead to stress whitening during tensile damage, were examined by using DSC and SAXS/WAXD. * The relationship between microstructure and mechanical properties was analyzed by cold-drawing the molded blended sheets at room temperature. KEYWORDS cavitation, cold drawing, HDPE, solution blending, UHMWPE, 1 | INTRODUCTION High-density polyethylene (HDPE) has outstanding heat and corrosion resistance, and simple processing performance, usually applied to the production of gas pipelines, but the comprehensive mechanical properties of [...]

As a type of shallow foundation, a mudmat serves as the seabed support structure for subsea wells, pipeline manifolds, and pipeline terminations. The shallow foundations are usually designed with perforations to facilitate installation and removal, but the influence of these perforations has not been fully understood. This paper presents a method to analyze the bearing capacities of both two-dimensional (2D) and three-dimensional (3D) perforated shallow foundations using finite element analysis. The soil was idealized as a Tresca material, with the undrained strength increasing linearly with depth. The outcome indicates that perforations have nonnegligible effects on the bearing capacity of shallow foundations. The bearing capacity decreases with increasing perforation ratio, R, and the degree of reduction increases with the increase of the dimensionless ratio kB/[S.sub.uo], where k is the shear strength gradient, B is the width of the foundation, and [S.sub.uo] is the shear strength at the mudline. For 2D shallow foundations, there exists a critical perforation ratio, [R.sub.c]; when the perforation ratio is lower than the critical perforation ratio, the perforated foundation does not lose its bearing capacity. For 3D shallow foundations, the bearing capacity decreases directly with the increase of perforation ratio, R. Key words: shallow foundation, clay, finite element analysis, perforation, bearing capacity. Comme une sorte de fondation superficielle, les patins servent de structure de support du fond marin pour les puits sous-marins, les collecteurs de pipeline et les terminaisons de pipeline. Les fondations peu profondes sont habituellement concues avec des perforations pour faciliter l'installation et l'enlevement, mais l'influence de ces perforations n'a pas ete entierement comprise. Cet article presente une methode pour analyser les capacites portantes des fondations peu profondes perforees en deux dimensions (2D) et trois dimensions (3D) en utilisant l'analyse par elements finis. Le sol a ete idealise en tant que materiau Tresca, avec la resistance non drainee augmentant lineairement avec la profondeur. Le resultat indique que la perforation a des effets non negligeables sur la capacite portante des fondations peu profondes. La capacite portante diminue avec l'augmentation du taux de perforation R, et le degre de reduction augmente avec l'augmentation du rapport sans dimension kB/[S.sub.uo]. Pour les fondations superficielles 2D, il existe un taux de perforation critique R, lorsque le taux de perforation est inferieur au taux de perforation critique, les fondations perforees ne perdent pas la capacite portante. Pour les fondations superficielles 3D, la capacite portante diminue immediatement avec l'augmentation du taux de perforation R. Mots-cles : fondation superficielle, argile, analyse des elements finis, perforation, capacite portante., 1. Introduction A mudmat is a type of shallow foundation that is usually designed with perforations to facilitate installation and removal. Many existing studies have concentrated on the bearing capacity [...]

Discharge coefficients for water flow through a vertical, circular orifice at the bottom of a conical hopper were experimentally studied in the present paper. The conical hopper consists of a cylindrical hopper of inside diameter of 48 cm and a bottom cone of side slope of 45[degrees]. Experiments were carried out under different orifice diameters and water heads. The dependence of the discharge coefficient on the orifice diameter and water head was analyzed, and then an empirical relation was developed by using a dimensional analysis and a regression analysis. The results show that the larger orifice diameter or higher water head have a smaller discharge coefficient and the orifice diameter plays more significant influence on the discharge coefficient than the water head does. The discharge coefficient of water flow through a bottom orifice is larger than that through a sidewall orifice under the similar conditions of the water head, orifice diameter, and hopper size. DOI: 10.1061/(ASCE)IR.1943-4774.0000213 CE Database subject headings: Water flow; Coefficients; Dimensional analysis. Author keywords: Discharge coefficient; Hopper; Orifice; Dimensional analysis.

In 1946, L. A. Galin proposed an ingenious solution to the problem of analytically determining the plastic region completely surrounding a circular hole in a thin initially elastic plate subject to tensile stress at infinity. The results of Galin's analysis are recovered by a simple collocation, provided an elliptical elastic-plastic boundary is assumed. This elementary procedure is then applied to treat the case, unresolvable by Galin's method, in which the plastic domain does not completely surround the hole. DOI: 10.1061/(ASCE)EM.1943-7889.0000062 CE Database subject headings: Plastics; Holes; Elastoplasticity.

Study on supersonic flow over wall-mounted cavities with different ramp angles is carried out experimentally. Experiments include instantaneous shadowgraph visualization and unsteady pressure measurements. In the case of cavities with ramp angles of 90, 75, and 60 degrees, four different types of waves were observed in the supersonic flow above the cavity. The shear layer appeared predominantly wavy in nature. The wave system observed in the case of cavities of 90, 75 and 60 degrees is distinctly different from that in cavities of 45, 30, and 15 degrees. In the case of cavities with higher ramp angles, high-amplitude tones were observed and the presence of an upstream-traveling acoustic wave could be confirmed. A cavity with a ramp angle of 45 degrees was found to reduce the amplitude of oscillations. An increase in amplitude of oscillations at various locations inside the cavity has been observed for cavities with ramp angles of 30 and 15 degrees. This is in contrast to the cavity with a ramp angle of 45 degrees. The reasons for this ambiguous behavior could not be ascertained. The presence of a forward-moving acoustic wave could not be identified in the cavities with ramp angles of 45, 30, and 15 degrees. Temporal mode switching occurring in cavities with higher ramp angles was confirmed by spectrogram studies. DOI: 10.2514/1.43068

Making beams shorter may not stave off buckling. Making beams shorter may not stave off buckling., Author Affiliations: Size and spacing of holes in beams key to avoiding failure Engineers often make structures such as buildings and bridges lighter by incorporating beams containing holes. But over [...]