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This paper evaluates and modifies the direct strength method (DSM) in AS/NZS 4600:2018 for cold- formed channel purlins based on the nonlinear analysis of Strand7 software. Initially, the original DSM curves from the THIN-WALL program are investigated for each buckling mode. Then the nonlinear analysis is performed using the finite element method (FEM). Next, the accuracy and reliability of the original and modified DSM curves are examined and analyzed based on the FEM results. In analyzing the results, the differences, mean and standard deviation between DSM and FEM results are compared. The percentage error ε is reasonable with the width-to-thickness ratios of 40 ≤ b/t ≤ 75, while in the distortional buckling mode, the acceptable range of the width-to-thickness ratio would be 32 ≤ b/t ≤ 63. Most sections have reasonable error values for different slenderness ratios λl (or λd). The results show that the modified DSM results are more accurate and reliable than the original ones, and the dispersion and calculation error of the test data will be smaller after the modification. However, the study’s limitations would be the interference of the buckling modes and the sample size. The results of this research will provide structural engineers with a more comprehensive analysis of design methods and can be used as a reference for engineering design. [ABSTRACT FROM AUTHOR]

Underwater vehicles have a great deal of tactical significance in the future sea warfare, and their structural forms are mostly cylindrical shells: underwater vehicles. It may be attacked by underwater weapons. Its payload forms include hydrostatic pressure and localized impact. This article uses finite element analysis software ABAQUS to study the dynamic response of thin-walled cylindrical shells under local impact loading and circumferential pressure effect of cylindrical shell under coupling effect of pressure and local shock. Study shows that under impact load alone, the time of action, the maximum deflection at the point of application of the timing is linear with the peak value of the impact load. When the impact load peak is less than 40MPa, the coupling 30% reduction in critical collapse pressure of columnar crucibles due to cooperative use than cumulative ones, and impact load crest satisfy a certain function form and fit the results of this study to get the functional relationship. [ABSTRACT FROM AUTHOR]

Hybrid plasma-arc welding with a consumable electrode (PAW-MIG) of sheet aluminum alloy blanks exposed to a fast-moving heat source is involved in the formation of residual stresses and strains that can lead to changes in size and shape, buckling distortion, fatigue strength reduction, and deterioration of other operational properties of the welded product. This necessitates to introduce additional arrangements for reducing welding strains, stresses, and displacements, such as rigid outfits. Finite-element analysis of residual stress-strain state parameters of PAW-MIG welded 1561 aluminum alloy butt joints 5 mm thick with two different process modes: in the free state and in the outfit followed by its removal after cooling, was performed. The PAW-MIG welding after the second alternative compared to the first one was established to reduce the total displacements by 15 times and equivalent stresses by more than 30%, it also provides a decrease in displacements on the weld axis: longitudinal by 1.5 times and buckling distortion by 16.7 times. [ABSTRACT FROM AUTHOR]

A snake-bone flexible drill pipe was designed based on bionics to relieve the overlarge deflecting curvature radius of the sidetrack horizontal well. Specifically, flexible design is carried out for coiled tubing in combination with morphology and mechanism bionics. The ball head+external casing+torque pin structure was used to decompose the drill pipe, and the torque pin was used to transfer torque. Each section can reach a torsion angle of 4.1°, which can alleviate the buckling of the drill pipe in the casing pipe. A maximum bending angle of 5.12° can be generated between sections, and the deflection curvature radius is shortened to 1.8 m. To overcome the directional uncertainty between flexible drill pipe sections of small curvature radius during dispersion, a highly flexible pipe was added at the angle in the flexible drill pipe, which guaranteed a high discharging rate. Based on the multi-body dynamics finite element analysis software ADAMS and the statics simulation software ANSYS, the multi-body linkage dynamics and statics simulation analysis were carried out for the flexible drill pipe as a whole, which confirmed the effectiveness of the described deflecting method. Field experiments were carried out in Well PU 2-365, and the borehole trajectory was calculated based on the data derived from the inclinometer. The deflection section curvature radius could reach 1.8 m, which completed the design expectation. [ABSTRACT FROM AUTHOR]

This paper uses the Split Hopkinson Pressure Bar (SHPB) test to analyze the aluminum honeycomb's dynamic and failure behavior under different strain rates. At the same time, we propose a modeling method. The representative volume element (RVE) models the complex materials. On this basis, the equivalent material parameters of complex materials are calculated. Taking the aluminum honeycomb material as an example, we use the equivalent material parameters calculated by the representative volume element of aluminum honeycomb to construct the macro-model of the aluminum honeycomb and compare it with the refined model of aluminum honeycomb. According to the SHPB test of aluminum honeycomb, the finite element models are compared and calibrated, and the accuracy of the finite element model is verified. It is expected to provide a reference for applying aluminum honeycomb materials in various fields, the dynamic behavior of aluminum honeycomb, and the combined use of multi-scale finite element modeling. [ABSTRACT FROM AUTHOR]

This study is focused on designing and manufacturing punches and dies of cylindrical and polygon shapes to produce a polygon shape with eight edges via two methods: drawing and redrawing operations. In the first method, a polygon cup was formed from the nondeformed circular blank of 1008-AISI low-carbon steel. In the second method, a polygon cup was redrawn from the cylindrical shape formed from the nondeformed circular blank. In addition, finite element method was utilized by adding ANSYS software for modeling and analysis of drawing and redrawing processes. The aim of this research is to produce polygon shapes from nondeformed circular blanks and cups of cylinder shapes and to draw a comparison between the experimental work results and the finite element analysis. The comparison revealed that in the drawing process, the maximum punch load required to produce a polygon shape was recorded as 40.250 and 35.165 kN with the redrawing process. The maximum effective strain recorded was 0.4185 with the polygon shape produced by the redrawing process. The redrawing process is a convenient process to form intricate shapes (polygons). [ABSTRACT FROM AUTHOR]

The paper deals with the dynamics of asymmetric three-layer hemispherical shells with the discretely symmetric lightweight, rib-reinforced filler under pulsed loads. Since the distances between the ribs are much larger than the dimensions of the rib cross-sections, the theory of independent static and kinematic hypotheses for each layer is applied. In asymmetric shells, the load-bearing layers are made of different materials and have various thicknesses. The equations of motion of asymmetric three-layer spherical shells and natural boundary conditions are obtained using the Hamilton– Ostrogradsky variational principle for the Timoshenko-type shell and rod theory model. This makes it possible to develop an adequate finite element model for asymmetric three-layer shells composed of several materials and obtain numerical results on the dynamic behavior of an asymmetric three-layer elastic structure using the finite element method. The influence of physical and mechanical parameters of asymmetric layers of hemispherical shells on the stress-strain state under axisymmetric internal pulse loading is investigated. New mechanical effects are revealed. [ABSTRACT FROM AUTHOR]