Papers by Keyword: LS-DYNA

Abstract: By using nonlinear finite element analysis software-ANSYS/LS-DYNA, a numerical model was carried out to simulate the explosive stress wave generated from a single-hole coupling continuous charge blasting which varies with time at different levels of rock. Meanwhile, the propagation and attenuation law of the explosive stress wave at different rock levels was analyzed to gain an in-depth knowledge of rock explosion. The result shows that the explosive stress wave in rock is in the trend of exponential decay and presents three forms: shock wave, stess wave and seismic wave. It illustrates that numerical simulation can objectively reflect the failure law of rock blasting and provide theoretical and technical guidance for the corresponding practical engineering.

Abstract: The impact responses and ballistic resistance of the metal encapsulating ceramic composite armors with same area density and two hybrid cores are investigated. The hybrid cores include square metallic lattice with ceramic block insertions, and square metallic lattice with ceramic ball insertions and void-filling epoxy resin. Three-dimensional (3D) finite element (FE) simulations are carried out for each composite armors impacted by bullet with 12.7mm diameter. The focus is placed on the energy absorption capabilities and ballistic limit velocity of different composite armors. Results indicate that two kind of armors can improve the ballistic resistance properties and save mass of 22% and 25% compared to the homogeneous 4340 steel, respectively.

Abstract: The new broken-explosive warhead for back deep underground target and airport runway hard target has a unique advantage. Through analyzing hard target characteristics of the concrete , process using ANSYS/LS-DYNA software to break-explosive warhead of a warhead forming process and penetration into concrete target is studied by numerical simulation. Experiments show: the simulation results are accurate. A warhead on concrete penetration and expanding role better, open a channel for level two warhead implement efficient damage. To counter this deep underground and airport target road of hard target penetration has a certain application prospect. .

Abstract: Karagozian & Case Concrete (KCC) model in LS-DYNA is a parameter automatically generated material model for simulation of concrete. By giving the unconfined compressive strength of the concrete material, all other constitutive material parameters will be generated by the model. It is a valuable concrete model for users who have no laboratory data or conduct tentative simulations. However, the automatically generated parameters will induce error when the concrete material behavior deviates from the regular behavior. In this research, a calibration method is introduced to show a simple way for generating input material parameters of ultra-high performance concrete (UHPC). Empirical equations for triaxial compressive tests are used here for the calibration. The calibrated model is firstly checked by the simulation of uniaxial compression test with one element and the results reveal that the calibrated model shows a better agreement with the test data than the parameter automatically generated KCC model.

Abstract: In order to improve the collision characteristics of energy-absorbing box and realize the optimization design, the collision simulation on energy-absorbing box is analyzed by LS-DYNA software. The collision characteristics including stress; strain; energy variation and deformation are analyzed for two kinds of main material; three different cross-sectional shapes and three different thicknesses in contrasts. Furthermore, energy-absorbing box has a smooth compression process effect through the improvement of structure. The simulation results may uncover the reasonability of the current design of energy-absorbing box and provide the basis for further improvement.

Abstract: Based on the code LS-DYNA, the simulation strategy on the quasi-static crushing process of composite tubes is studied by conducting two series of comparison simulations: one is at different virtual loading speeds with the real material density and the other is with different virtual material densities at the given loading speed. The simulation results are summarized as three types, namely mode-varying type (MVT), unstable type (UT) and stable type (ST), depending on the change of the structural failure mode and the occurrence of the load-fluctuating stage in the load-displacement curve. Analysis has shown that the steady load possesses the stability, the peak load has the convergence zone, and the thresholds of energy ratio can be adopted to evaluate the simulation results. In the end, the simulation strategy is proposed to makes it possible to acquire the simulation results with a higher query precision at a lower computing cost.

Abstract: The hereby paper presents comparison of numerically modelled Charpy test in LS-Dyna environment with an experiment on accredited Charpy impact test machine. The comparison was applied to dimensions of a strained sample at selected points and energy consumed for the sample fracture and strains during the test.

Abstract: This paper presents procedures to be used for development of an experiment plan which is supposed to provide the tested structure with operating conditions most similar to those in real life. The research object is an air handling unit subjected to random loading such as earthquakes.

Abstract: The article presents experimental validation of the numerical model of a testing platform impact on a support structure mast. Numerical analysis of explicit type was performed in LS-Dyna environment. Experimental tests of crash test type were conducted on testing track. Comparison of values of deformations measured at selected mast characteristic points with the values of deformations specified during numerical analyses was performed.

Abstract: In this study, the energy absorption capacity and crush strength of cylindrical thin-walled structures is investigated using nonlinear Finite Elements code LS-DYNA. For the thin-walled structure, Aluminum A6063 is used and its behaviour is modeled using power-law equation. In order to better investigate the performance of tubes, the simulation was also carried out on structures with other types of cross-sections such as triangle, square, rectangle, and hexagonal, and their results, namely, energy absorption, crush strength, peak load, and the displacement at the end of tubes was compared to each other. It was seen that the circular cross-section has the highest energy absorption capacity and crush strength, while they are the lowest for the triangular cross-section. It was concluded that increasing the number of sides increases the energy absorption capacity and the crush strength. On the other hand, by comparing the results between the square and rectangular cross-sections, it can be found out that eliminating the symmetry of the cross-section decreases the energy absorption capacity and the crush strength. The crush behaviour of the structure was also studied by changing the mass and the velocity of the striker, simultaneously while its total kinetic energy is kept constant. It was seen that the energy absorption of the structure is more sensitive to the striker velocity than its mass.