The study of the interfacial and bond behaviour of reinforced cement-based materials is important for understanding the mechanical behaviour of such composites. This paper presents extensive experimental, theoretical and finite element analyses of pull-out tests of galvanised steel strips with different geometries, in lightweight cement-based material blocks with different densities and mechanical properties. The theoretical model proposed here is capable of determining the pull-out strength and bond stress versus the slip relationship between components of reinforced cement-based materials. This bond-slip relationship is then implemented in finite element simulation through the user-defined subroutine of ABAQUS software. Based on the results, a trilinear bond-slip model is suitable for modelling the interface between a steel strip and a cement-based material interface.

OpenSees is a well-recognized open source platform with high compatibility, and it has a well-developed fiber element method to cope with nonlinear structural analysis. Fiber reinforced polymer (FRP) confined concrete can effectively improve the seismic performance of concrete structures. However, sophisticated constitutive models for FRP confined concrete are not available in the current version of OpenSees. In this paper, after reviewing several typical FRP confined concrete constitutive models, a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lam and Teng (2003)’s model with four main modifications including the determination of FRP rupture strain, ultimate condition, envelope shape, and hysteretic rules. To embed the proposed constitutive model into OpenSees is a practical solution for engineering simulation. Hence, the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow chart. Finally, with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases, FRP confinement types and geometric properties, the utility and accuracy of the proposed model compared with Lam and Teng (2003)’s model and new material secondary development in OpenSees were well validated.

A closed-form out-of-plane dynamic displacement response of a curved track subjected to moving loads was proposed. The track structure was modeled as a planar curved Timoshenko beam periodically supported by the double-layer spring-damping elements. The general dynamic displacement response induced by the moving loads along the curve on the elastic semi-infinite space was firstly obtained in the frequency domain, according to the Duhamel integral and the dynamic reciprocity theorem. In the case of the periodic curved track structure subjected to moving loads, the dynamic displacement equation was simplified into a form of summation within the basic track cell instead of the integral. The transfer function for the curved track was expressed in the form of a transfer matrix. Single and series moving loads were involved in the calculation program. For the verification of the analytical model, the mid-span vertical deflection of a simply support curved beam subjected to moving load was recalculated and compared with the same case in the reference. The research results indicate that: under the same moving loads, the displacement response of the curved track decreases slightly with the increasing track radius, and the displacement response of the curved track with the radius greater than or equal to 600 m is almost equivalent to the displacement response of the straight track; the frequency spectrum of the curved track is more abundant than that of the straight track, which may result in more wheel-rail resonance and rail corrugation in the curved lines.

X-joints are one of the fundamental joint configurations used in a wide range of transmission tubular structures. Experimental investigation of four tubular X-joints with bolted connection was conducted in this study, and it was found that the annular plate was the main yielding control member of such X-joints. Moreover, the portion outside the effective width of the chord member still had a restriction effect on the annular plate, which led to reducing the yielding strength of the joint, while the gusset plate could help to improve the yield strength capacity. In the current design code of steel structures, the contribution to the strength capacity of the gusset plate has not been taken into account. Therefore, based on some mechanical assumptions, a general mechanical model was proposed. After the introduction of the gusset plate strength capacity factor, the yield capacity simplified calculation method of such X-joints was derived. Through the analyses of such X-joints with various diameters and thicknesses, it was concluded that a simple mechanical model could predict test results very well and that the contribution of the gusset plate was also taken into account.

This study presents a new design of a piezoelectric-electromagnetic energy harvester to enlarge the frequency bandwidth and obtain a larger energy output. This harvester consists of a primary piezoelectric energy harvesting device, in which a suspension electromagnetic component is added. A coupling mathematical model of the two independent energy harvesting techniques was established. Numerical results show that the piezoelectric-electromagnetic energy harvester has three times the bandwidth and higher power output in comparison with the corresponding stand-alone, single harvesting mode devices. The finite element models of the piezoelectric and electromagnetic systems were developed, respectively. A finite element analysis was performed. Experiments were carried out to verify the validity of the numerical simulation and the finite element results. It shows that the power output and the peak frequency obtained from the numerical analysis and the finite element simulation are in good agreement with the experimental results. This study provides a promising method to broaden the frequency bandwidth and increase the energy harvesting power output for energy harvesters.

Pd₇₇Cu₆Si₁₇ (PCS) thin film metallic glasses (TFMGs) with high glass forming ability and hardness were selected as a hard coating for improving the surface hardness of AZ31 magnesium alloy. Both microindentation and nanoindentation tests were conducted on specimens with various PCS film thicknesses from 30 to 2000 nm. The apparent hardness and the relative indentation depth (β) were integrated using a quantitative model. The interaction parameters involved and relative hardness values were extracted from iterative calculations. According to the results, surface hardness can be enhanced greatly by PCS TFMGs in the shallow region, followed by gradual decrease with increasing β ratio. In addition, specimens with thinner coatings (e.g., 200 nm) showed greater substrate-film interaction and those with thick coatings (e.g., 2000 nm) became prone to film cracking. The optimum TFMG coating thickness in this study was estimated to be around 200 nm.

The effect of solute Cu and Cu precipitates on the wear behavior of ferritic iron under an unlubricated condition was investigated. The specific wear rate of Cu-containing steel abruptly decreased up to 50 N of load, and then gradually decreased with further increased load. The specific wear rate of the as-quenched specimen, in which Cu was in a solid solution, was the lowest among all the specimens at low loads, and all specimens had almost the same specific wear rate at high loads. Subsurface observation showed that the hardness increments of all specimens decreased with increased depth below the worn surface. The as-quenched specimen had a relatively large depth of deformed region than the other specimens even though the increments in hardness were almost the same for all specimens at low loads. With the same hardness at an unworn state, the as-quenched and over-aged specimens exhibited a substantial increase in hardness and large deformed regions below the worn surfaces. This finding indicated that the enhancement in plastic deformation and work hardening led to the decrease in the specific wear rate of the as-quenched specimen at low loads and the improvement in the wear resistance of all specimens at high loads.

A mesoporous sorption complex catalyst was prepared by pore-forming modification and evaluated by the CO₂ reactive sorption enhanced reforming (ReSER) process, which is used to produce hydrogen from methane. Three samples of polyethylene glycol (PEG) with molecular weights between 2000 and 20 000 were added as templates into a mixed slurry to create catalysts with different pore properties by further formation and calcination. The pore characteristics determined by Brunauer- Emmett-Teller (BET) analysis showed that one of the mesoporous catalysts, named M-NiAlCa-6000, had a pore size of 9.2 nm and a surface area of 70.52 m²/g and the CO₂ sorption capacity of this catalyst was 44% higher than that of the catalyst without the PEG 6000 modification. The catalyst was evaluated in the ReSER process in a fixed-bed reactor system at 0.1 MPa and 600 °C with an H₂O/CH₄ molar ratio of 4. An H₂ concentration of 94.2% and a CH₄ conversion of 86.0% were obtained at a carbon space velocity of 1700 h⁻¹, while CO₂ was hardly detected.