Al/Fe bimetals prepared by a compound casting method, combining the excellent properties of both the Al alloy and the ductile cast iron, exhibit great potential for application in achieving engine weight reduction. However, the problem of insufficient interfacial bonding ability because of the difference in thermophysical properties of Al and Fe is particularly prominent. Therefore, in this work, the electrodeposited Cu coating on the surface of the Fe matrix was used as the interlayer of Al/Fe bimetal fabricated by coupling hot-dipping with compound casting to solve the above problem. The effect of Cu interlayer thickness on the interfacial microstructure and shear strength of bimetal was investigated. The experimental results showed that the shear strength up to 77.65 MPa in regard to Al/Fe bimetal with a 5 μm Cu interlayer was obtained. No Cu element was detected at the interface of bimetal regardless of the thickness of the Cu interlayer. The diffusion behavior of the Cu atom at the interface and the influence of the Cu layer at the atomic scale on diffusion reaction and the Al/Fe interface were further revealed by combining first-principle and molecular dynamics calculations. The simulation results revealed that the Cu layer gradually dissolved into an Al alloy at 750 °C, thereby promoting the diffusion reaction of the Al/Fe interface. Meanwhile, the protective role of the Cu layer against oxidation on the surface of the Fe matrix was confirmed. As a result, the interfacial bonding performance was enhanced when the Cu interlayer was introduced.

In this paper, the second harmonic generation (SHG) method, a non-linear ultrasonic technique, is employed to investigate the interface debonding of steel-concrete composites. The quadratic parameter of non-linear constitutive relationship for the steel-concrete composites is adopted as a measure of the debonding between a steel component and a concrete component. The quadratic parameter is calculated based on the amplitude measurements of probing ultrasonic waves and the corresponding second harmonic generated by the non-linear response of the debonded steel-concrete interface. The ultrasonic experiments are conducted on both scaled-down laboratory samples and full-size structures. Results from both experiments show that the defined parameter is highly correlated with the debonding condition of the composite interface, indicating an excellent feasibility for its use in the detection of the variation of interface microstructure. The SHG experimental results are further compared with results from the amplitude attenuation, a conventional ultrasonic method. It is shown that the change in the defined parameter is orders of magnitude larger than the traditional attenuation coefficient. The results of the comparison demonstrate the higher sensitivity of the developed SHG method in terms of the assessment of interface debonding of steel-concrete composites, particularly in the early phase of structural deterioration.

The aim of this work is to design and build a hardware-in-the-loop simulation (HILS) system for a guided bomb. This paper presents a design scheme, based on the guidance and control system of the guided bomb, and the corresponding test flow of a guided bomb control system to provide a support platform to verify its performance. The design HILS test based on actual conditions is also described. Based on the similarity theory, we provide three examples of simulation experiments. The simulation results confirm the effectiveness of the HILS system of the guided bomb.