Jian Xun Zhang

Resistance of metallic foam-filled trapezoidal plate core sandwich plate to blast loading

Abstract The resistance of metallic foam‐filled sandwich plate with trapezoidal plate core under blast loading is studied. The role of metal foam filling the interstice of metal sandwich plate is investigated to ascertain the effect of foam on the structural performance. The results are compared with those of unfilled trapezoidal plate core sandwich plate having the same weight. Large deflection and resistance of metallic sandwich plate to blast loading is analytically and numerically analysed. The impulsive blast loading is applied to the sandwich plate with infinite length and fully clamped along the sides. Additionally, the normal and longitudinal compressive stresses in the foam‐filled trapezoidal plate core are analytically obtained.

Ag–ZnO composite nanocrystals: synthesis, characterisation and photocatalytic properties

Abstract Ag–ZnO composite nanocrystals were prepared by a simple hydrolysis process of zinc acetate dihydrate together with a reduction of the Ag ions in diethylene glycol. Different contents of sodium hydroxide were added into the initial reaction mixture so as to form an effective contact between Ag and ZnO. X-ray diffraction analysis, ultraviolet–visible spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy and transmission electron microscopy were used to characterise the structural and morphological properties of the derived nanoparticles. The effects of the content of sodium hydroxide on the structural and morphological properties of the derived nanoparticles were discussed in detail. Photocatalytic measurement was also conducted, and the results indicate that the sample derived from 0·2M NaOH has the best ultraviolet photocatalytic activity for the degradation of the methyl orange aqueous solution among all the samples, which should be ascribed to the heterostructure formed between Ag and ZnO as well as a good dispersity of the nanoparticles.

Quasi-Static Crush Behavior of Aluminum Hexagonal Honeycomb with Perforated Cell Walls

The crush behavior of aluminum hexagonal honeycomb with perforated cell walls under out-of-plane quasi-static loadings was experimentally investigated. The honeycomb specimens with different heights were compressed in axial direction under displacement control. There are four sequential deformation stages during compression: linear elasticity, buckling, crushing and densification state. The performances of hexagonal honeycombs with perforated cell walls were compared with those of imperforated hexagonal honeycombs with the same sizes. The results show that the perforated holes weaken the strength of honeycombs markedly and the strength of honeycomb decreases with the specimen height.

Low velocity impact response of lightweight metal sandwich panel with corrugated core

Abstract Low velocity impact resistance of a lightweight metal sandwich panel with a corrugated core struck by a heavy mass is investigated. Face sheets and the corrugated core are made of the same material. Large energy impact is considered that is sufficient to produce lateral deflection. Fracture is not included in analysis and it is assumed that the sandwich panel has sufficient ductility to sustain the large deformation. It is shown that the metal sandwich panel with a corrugated core possesses higher impact resistance compared to monolithic solid plate of the same mass. In addition, analytical predictions are obtained and agree well with finite element results.

The Resistance of Metallic Sandwich Plates to Blast Loading

The resistance of metallic sandwich plates to blast loading is studied in this work. Two typical cores, i.e. trapezoidal plate core and metallic foam core are considered in the analysis. The normal and longitudinal compressive stresses of the trapezoidal plate core are analytically and numerically obtained. Large deflection and resistance of metallic sandwich plates to blast loading are numerically analyzed. The results are compared with that of monolithic solid plates made of the same material and having equivalent weight. It is shown that the well-designed sandwich plates possess higher resistance to blast loading than monolithic solid plates.

Numerical Studies on Damage Evolution of Notched Round-Bar with Welding Mechanical Heterogeneity

The effects of the welding mechanical heterogeneity on the damage evolution of notched round-bar tensile specimens were investigated numerically using a fully coupled elastic-plastic damage finite element method. Some parameters reflecting the welding mechanical heterogeneity such as strength mismatching, rupture strain and weld metal width were taken into account to study their effects on the damage evolution of the weld metal. The calculation results show that the damage evolution of the weld metal is affected strongly by the welding mechanical heterogeneity. The damage evolution of the weld metal becomes larger with the decrease of both the rupture strain and yielding stress of the base metal. The effects of the mechanical properties of the base metal on the damage evolution of the weld metal decreases with the increase of the weld metal width.

Resistance of Metal Sandwich Plates with Polymer Foam-Filled Core to Localized Impulse

This work examines the resistance of metal sandwich plates with corrugated core subjected to impulsive loading over central patch, in which effects of the low-density polymeric foam filling the interstices of the corrugated core on dynamic response of sandwich plate are studied to ascertain the enhancement of sandwich plate under impulsive loading. The face sheets and corrugated core are made of the same metal materials. The resistance of the metal sandwich plates with foam-filled cores is compared to that of the metal sandwich plates with unfilled core with the same weight. The results of comparison show that the foam-filled core does not make the overall deflection decrease compared with empty core, but it can make the sandwich plate achieve multifunctional advantages. The membrane method is employed to predict large deflection response of metal sandwich plates with foam-filled and unfilled cores under impulsive loading over a central patch. The theoretical predictions agree well with FE results of sandwich plates with foam-filled and empty cores.

Large Deflection of a Pin-Supported Slender Geometrically Asymmetric Sandwich Beam under Transverse Loading

The objective of this work is to study the large deflection of a pin-supported slender geometrically asymmetric metal foam core sandwich beam under transverse loading by a flat punch. Based on the yield criterion for geometrically asymmetric metal foam core sandwich structure, analytical solution for the large deflection of a pin-supported slender sandwich beam is obtained, in which the interaction of bending and stretching induced by large deflection is considered. The finite element results confirm the accuracy of the analytical solutions. The effects of asymmetric factor and boundary condition on the structural response of the asymmetric sandwich beam are discussed in detail. It is shown that the axial stretching induced by large deflection plays an important role in the load-carrying and energy absorption capacities of geometrically asymmetric sandwich structure.

Experimental Research on Fracture Toughness of High Grade Line Pipe

Crack tip opening displacement (CTOD) tests were carried out on different positions of X70, X80 and X100 pipe by three-point bend testing method. The results show that the crack propagation resistance and the tear modulus of base metal, heat affected zone (HAZ), and weld of X70 and X80 pipe are larger than that of X100 pipe. At the same time,The initial CTOD values and the CTOD values withmaximum load of X70 and X80 pipe are larger than that of X100 pipe.The test results suggest that the fracture toughness, crack initiation and propagation resistance of theX70 and X80 pipe are greater than that of X100 pipe, and the mechanismis analyzed finally.

Analytical Solution for Pin-Supported Metal Foam Core Sandwich Beam with Local Denting

Structural response of pin-supported metallic foam core sandwich beam is theoretically investigated. Effects of local denting and core strength and interaction of bending and axial stretching are considered in analysis. A rigid-plastic beam-on-foundation is employed to consider local denting deformation. The local denting continues during the overall deformation of sandwich beam. It is shown that upon neglecting the effect of local denting, the load-carrying capacity and energy absorption of sandwich beam may be overestimated, and the normal axial (membrane) force associated with plastic stretching substantially stiffens the sandwich beams.