Abstract: The technology of wide-space bench blasting has been more and more applied to blasting engineerings of conservancy, hydropower, mining, highway and railway, but at the stage the design of hole distance of wide-space bench blasting is mainly used analogy method and site testing method, there is no precise calculation formula for reference. According to this situation, this paper puts forward the calculation formula of hole distance, which is based on the analysis of the physical process of rock destroyed by blasting, and combined with engineering examples of wide-space blasting at home and abroad, compares the hole distance that is calculated by formula with the hole distance adopted by practical engineerings that have received good blasting results ,the degree of match between the two is over 95%, remedying the defects of the study how to calculat hole distance of wide-space blasting.
Abstract: Molecular dynamics simulation was used to simulate the tension process of purity and containing impurity metal aluminum. Elastic constants of purity and containing impurity metal aluminum were calculated, and the effects of impurity on the elastic constants were also studied. The results show that O-Al bond and Al-Al bond near oxygen atoms could be the sites of crack nucleation or growth under tensile load, the method can be extended to research mechanical properties of other metals and alloys structures.
Abstract: Shock diffraction over geometric obstacles is performed on two-dimensional cartesian grid using the TVD WAF method in conjunction with the HLLC approximate Riemann solver and dimensional splitting. Present cartesian grid results for popular and challenging two-dimensional shock diffraction problems are presented and compared to experimental photographs. Benchmark and example test cases were chosen to cover a wide variety of Mach numbers for weak and strong shock waves, and for square and circular geometries. The results show that the comparisons between experimental and simulated images are consistent.
Abstract: In this paper, a ring shaped numerical specimen is used to studying the failure process in brittle materials. The ring specimen is subjected to a compressive diametral load and contains two angled central cracks. Numerical modeling in this study is performed. It is shown that the obtained numerical results are in a very good agreement with the experiments. Effect of the crack orientation angle on the failure modes and loading-displace responses is discussed. In the range of 0°~40°, the fracture paths are curvilinear forms starting from the tip of pre-existing cracks and grow towards the loading points. For the crack orientation angle 90°, vertical fractures will split the specimen and the horizontal cracks do not influence the fracture process.
Abstract: In this paper, the quasi-static axial compression of the pseudo-elastic phase transformation cylindrical shells (PTCS) is systematically investigated experimentally and numerically. Some interesting phenomena and regularities are found and in-depth understanding is gained: (i) static buckling instability properties of the PTCS with different sizes; (ⅱ) the formation and development regularities of the phase transformation hinges (PTHs). The length-diameter ratio (L/D) of the PTCS is closely related to its buckling modes.
Abstract: Passive ductile protective system is widely used because of its better performance than buttress wall. This paper intends to determine the sliding fall rock impact force against a steel column at first. Then the rigid protective structure and ductile protective structure were compared. At last the hidden principle that passive ductile protective system can reduce the impact force was revealed. Results indicate that rings for energy dissipation in passive ductile protective system can significantly decrease the bending stiffness EI and decrease the impact force. Buttress wall encounters a lot more impact force than passive ductile protective system because of its bulkiness. Thus to ensure the buttress wall non-destructive, the thickness of buttress wall increases and it is not economic.
Abstract: Based on a hybrid transfer-matrix method, a new standing wave-duct system with four microphones for acoustical property prediction of multi-layered noise control materials is developed in this paper. In this system, the two-load method (TLM) and two-cavity method (TCM) are used for computing the transfer matrix of each material sample. The transfer matrices saved in a database in the system hardisk may be selected for predicting both the absorption ratio and transmission loss of a multi-layered treatment of materials. Verification results suggest that the newly designed standing wave-duct system is effective for acoustical prediction of multilayer material configurations.
Abstract: In order to calculate the combined deformations of an Euler-Bernoulli cantilever beam subjected to bending moment, twisting moment, transverse load and axial load, particle flow code in 3 dimensions (PFC3D) is used with parallel bonds model. The computed deformations, including transverse deflections, rotations about axis, maximum normal and shear stresses, were compared with the analytical beam-theory solution in terms of axial tension, axial compression and none axial load, respectively. Between computed results and analytical beam-theory solution, the error bands are greater than 99.7% at the beam tip, while the error of the transverse deflection of the whole beam is less than 0.6%. So, the PFC3D is able to precisely simulate the combined deformation of cantilever beam, and this work has special reference to engineering calculations and designs when PFC is applied to model the mechanical behaviors of continuum materials.
Abstract: Hourglass is obviously aroused in cold ring rolling simulation with reduced integration element because of ring vibrating violently and small contact area of ring and rollers. In the developed numerical simulation code named RingForm, two methods are used to control the hourglass. The first method is combination of artificial damping and artificial stiffness. The second is one-point quadrature element with hourglass control, which need not user-defined control parameters. Hourglass energy can be reduced to 3 percent of the internal energy. Using the latter, good elements are acquired, while computational efficiency is obviously lower than the former.