Papers by Author: Qing Ming Zhang

Abstract: Ab initio electronic structure optimization and total energy calculations for fcc aluminum are used to study the equation of state (EOS).Through fitting to quasi-harmonic Debye model, the thermodynamics properties of different temperatures are calculated. The melting curve at different pressures is presented based on Lindemann measures. The results show that the calculated EOS and the revised melting curve both are in a good agreement with the shock compression and the diamond-anvil-cell (DAC) data. The results illustrate that we can use simple static calculation method which takes less time to gain reasonable melting results. It can be used in the qualitative forecast for materials with difficult experiments.

Abstract: By building up a debugging method about material parameters of concrete impact damage model based on DOE (Design of Experiments) analysis, this paper studies the influence of material parameters of concrete targets on the results of numerical simulation based on quantitative analysis, when the impact velocity is 300m/s and 850m/s respectively. It concludes that when the impact velocity of 300m/s, 5 parameters have considerable effect on the residual velocity of warhead, they are ， ， ， and . Of all 5 parameters, , and can be obtained by calculation therefore it only needs to debug two parameters and according to experiments. Finally, when the impact velocity is 300m/s or so, debug combining the experiments to get a set of concrete impact damage model material parameters to make the results of simulation and experiment anastomosis well.

Abstract: Moiré grating is a basic optical component, and can be used in various moiré methods. The conventional grating fabrication technology is based on photolithography and holographic interferometry, however, it requires complex optical components and is very difficult to put into practice. In this study, nanoimprint lithography (NIL), or rather, hot embossing lithography (HEL), is proposed for producing high frequency grating. Compared with silicon mold, holographic moiré grating mold costs less and is not easy to break, thus is chosen to be the mold in HEL. Using this mold and the hot embossing system, the grating structure can be transferred to the polymer after HEL process. Through a number of experiments, the process parameters were optimized and gratings were successfully fabricated. The multi-scale morphology of the fabricated gratings was then characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and moiré interferometry. The microscale images observed by AFM and SEM show the regulate dots with equal spacing and the macroscale moiré patterns illuminate the excellent qualities of fabricated grating in a large area. The successful experimental results demonstrate the feasibility of the grating fabricated by HEL for the moiré measurement.

Abstract: As a new type of protection design, composite armor structures have good performance in impact resistance, and have been widely used in ship structure protection. Due to its academic value and potential applicability, the dynamic characteristics of ship composite armor structures were studied in this paper. The whole process of the shaped charge’s explosion and penetration, and the ship composite armor structures’ damage response were described. According to the numerical simulation with Ansys-Autodyn, it was found that the ship composite armor structures were damaged not only by the explosively formed projectile but also by the detached shock wave in the conditions of contact underwater explosion and the thickness of composite armor structures was the main factor effecting the impact resistance properties.

Abstract: The spider silk is considered as a new type of biomaterials with its excellent mechanical properties. The mechanical properties of the spider silk are crucial to their applications. In this study the mechanical properties of spider silk were studied with a micro-tensile system driven by magnet-coil force actuator, which is very effective to measure the properties of low dimensional materials. The Young’s modulus of the spider silk is obtained, the relationship between the mechanical properties of spider silk and time is also acquired.

Abstract: Martensitic phase transformation can greatly affect the mechanical behaviors and the stress-strain response of shape memory alloys (SMAs). In this study, the effect of martensitic phase transformation on the deformation of a single-crystal TiNi SMA specimen with a triangle crack was investigated experimentally by means of moiré interferometry method. A typical displacement field and the corresponding strain field in areas both around and far from the tip of the crack were measured in a certain time during the loading process in which the tensile load is coupled with the stress-induced martensitic phase transformation. Some characteristics of the deformation and the martensitic phase transformation of the specimen are revealed. These results may provide a reliable support for revealing the fracture mechanism of single crystal TiNi SMAs, and may enable further development in putting forward the failure criterion of SMAs.

Abstract: With elastic theory and approximate calculation, the dynamic responses of elastic thin plates with four edges simply supported under blast loading is analyzed in this paper , with dimensional analysis , 30 cases are calculated, and a reasonable model of engineering calculation is built up in the end.

Abstract: The experiments of the shielded charge initiated by the high speed half- prefabricated steel fragment has been studied in this paper. The damage way of half- prefabricated steel fragment to the shielded charge is hit, burning or detonation action. And the damage effect is structure damage or function damage. The result shows that toward Comp. B explosive with 1.62g/cm3 dense behind 6mm Q235 steel and of φ 200 mm×100mm size, the fragment’s critical detonation speed is about 2 400~2 600m/s.

Abstract: The variation process of radius and pressure of explosion products in borehole are analyzed in this paper, based on theory of damage and structural mechanics, the formative mechanism of blasting crater in reinforced concrete under internal blast loading is analyzed, the computation method of crater size has been proposed. The calculated results are identical with experimental results on the whole.

Abstract: Results of tests using two kinds of nylon reinforced concrete samples are described . In order to deal with the heterogeneous effects of samples resulted from large particles which range from7mm to10mm in diameters, a SPH bar which is 74mm in diameter is used. There seems something new and difficult in the method of testing the concrete’s dynamic compressive responses. The results show that there are obvious strain rate effects in both the two kinds of samples , and the failure strength increases with the increasing of the strain rate.