Papers by Keyword: LS-DYNA

Abstract: This publication presents the results of a numerical analysis of the drawing process for tailored blanks. The focus is on the analysis itself of drawing without the connection method of these two sheets. The influence of the drawing tailored blanks on the height each of the halves was analysed. The values of stress and strain in the selected time steps of the process were presented. On the graph, the drawing force for both halves is illustrated as a function the relationship of the punch path. The differences were compared in the thicknesses of the sheets in specific areas. The value was shown of the tensile force of the binding place as a function of the punch path. The displacement was also described of the selected nodes at the binding place relative to the coupling plane.

Abstract: On account of the steadily increasing number of road casualties, the present research study underpins a thorough investigation on the impact issue between the driver’s knee and the vehicle’s dash board. Such type of impacts tends to occur especially in frontal collisions between a vehicle and an obstacle or another vehicle. Thus, aiming at determining the impact force in the coxofemoral joint, we have carried out a series of virtual simulations by means of the LS-DYNA software package. Also, we had to consider the influence the vehicle’s velocity impact displays upon the injury degree in the driver’s lower limbs area. Furthermore, an additional method to determine the impact force in this joint was to implement a mathematical modelling of the impact phenomenon. In the end, after having completed the two processes, we sought compare the results obtained both by the virtual simulation, and mathematical modelling.

Abstract: The effects of strain rate on the changes in material properties are commonly known [2,5]. This phenomena is also the subject of studies related to composite materials due to fact that composites are widely used as an energy absorbers in road safety structures [6]. Those effects are more often considered as required to be included in the design of structures subject to dynamic loads [1,3]. The example structure is the road infrastructure subject to high strain due to the vehicle impact characterized by a high strain rate [1].Various numerical methods are being employed at the design stage to reduce the costs of experiments on actual structures. One of the most important factors in preparation of the analysis is to select a suitable material model to allow for the effects of strain rate on the changes in material properties. One of the material models allowing for the effects of strain rate is the model developed by G.R. Johnson and W.H. Cook.The study aims to verify the FEM modelling capabilities of the effects characterized by the effects of high strain rate on the material properties. Thus, the strength tests required to determine the material constants for Johnson-Cook model were performed and modelled using FEM method and the results including the effects of strain rate on the mechanical properties were compared.

Abstract: The present underpins a computer-assisted investigation regarding the driver’s behavior and the injuries suffered in frontal vehicle collision, more precisely the injuries suffered in the thorax area. Hence, by means of the LS-Dyna software package we have carried out two series of virtual simulations with a dummy positioned on the driver’s place, i.e. belted and unbelted. For the simulation we have selected a Hybrid III 5th percentile female dummy. Aiming at achieving a simulation that would display a high accuracy degree with respect to the driver’s kinematic behaviour at the impact moment, our complete model also included, besides the dummy, the elements in the habitable: the seat, the seat belt, the steering wheel, the airbag and the dash board. Thus, the focus of the undertaken study was to establish the accelerations in the driver’s thorax area as well as the injury degree, expressed by the CSI (Chest Severity Index). The results obtained validated our hypothesis in that passive safety systems, i.e. the seat belt, diminish considerably the driver’s injuries degree in case of a road traffic accident.

Abstract: This paper investigated the damage degree and damage mechanism of aluminum sandwich plate subjected to blast loading by using numerical simulation method. Finite elements models of aluminum foam sandwich plates were established. The distortion and damage pattern of the sandwich plate under different masses of detonator were got by using LS-DYNA to simulate the destructive effect of shock wave and detonation product against sandwich plate. The results showed that the maximal deflection and overloading of the sandwich plates were different because of the changing of mass of detonator. This paper could provide some reference for the designing of sandwich structures.

Abstract: Composite materials that have low weight and high strength properties are currently one of the promising materials for a vehicle’s body. However, the effect of low velocity impact on composite may cause failure through matrix cracking, fibre breakage and delamination which may reduce the structure strength. Low velocity impact can be analysed either by experimentation or numerical simulation. Numerical simulation which is also known as finite element analysis can show the degradation of the composite structure properties after an impact loading condition without doing any experimentation. Thus, in this paper, LS-DYNA is the finite element analysis software that is used to simulate a low velocity impact on composite structures.

Abstract: Sheet hydroforming has gained increasing interest in the automotive and aerospace industries because of its many advantages such as higher forming potentiality, good quality of the formed parts which may have complex geometry. The main advantage is that the uniform pressure can be transferred to any part of the formed blank at the same time. This paper reports numerical and experimental correlation for symmetrical hydroformed component. Experimental tests have been carried out through the hydroforming cell tooling, designed by the authors thanks to a research project, characterized by a variable upper blankholder load of eight different hydraulic actuators. The experimental tests have been carried out following a factorial plane of two factors, with two different levels for each factor and three replicates for each test with a total of 12 tests. In particular two process parameters have been considered: blank holder force, die fluid pressure. Each factor has been varied between an High (H) and Low level (L). The order in which have been conducted the tests has been established through the use of the Minitab software, in order to ensure the data normality and the absence of auto-correlation between the tests. An ANOVA analysis has been performed, in addition, with the aim of evaluating the influence of process parameters on the thickness distribution of the component, its formability and feasibility. Finally, finite element analysis (FEA) was used to understand the formability of a material during the hydroforming process. In this paper, the commercial finite element code LS-Dyna was used to run the simulations. A good numerical – experimental correlation has been obtained.

Abstract: The authors have investigated, in other paper, the problem related to the definition of a “set of shape factors” in order to declare the feasibility of a product through sheet hydroforming. In particular the defined shape factors are three different a-dimensional coefficients by which it is possible to declare the feasibility of a product through the calculation, in different sections, of the three previous shape factors. The robustness of this methodology is related to the correct calculation of the “limit value” of each shape factor. In fact the feasibility is reached if, in any section, the calculated shape factors are higher than their respective limit values. In this paper the authors have performed an extensive numerical and experimental campaign, taking into account a different geometry respect to that of the first paper, in order to: re-calculate the limit value for each shape factor and, then, verify the correctness of the limit values exposed in the previous first paper. The numerical campaign has been used, after the evaluation of the accuracy of the numerical model, in order to study the feasibility of the product without engaging the hydroforming machine. Finite Element Analysis (FEA) has been extensively used in order to investigate and define each shape factor with a proper comparison to the macro feasibility of the chosen component geometry. The limit values that have been calculated by the authors in this paper are slightly different from those calculated in the first paper. From this point of view it is possible that, although the shape factors are a-dimensional coefficients, they are affected by different choices of the users as, for example, the dimensions of the initial blank. Anyway, the small differences in the shape factors limit values do not adversely affect the use of the shape factors in order to predict the feasibility of the product.

Abstract: The setup programme of dry storage of using spent fuel is that transportable storage canister (TSC) packing by using spent fuel placed in vertical concrete cask (VCC), then conveyed VCC from plant to site and put concrete pad. After VCC is in position, place the add-on-shell (AOS).This research analyses and simulate the behavior of VCC and AOC during earthquake by LS-DYNA which is dynamic transient structural analysis of finite element method. The main issue is the shaking response of VCC under earthquake while there is a hump on the bottom floor. From the result, the perturbation of dynamic stability of VCC and AOS have been occurred when the hump existed onto the floor. The construction specification of VCC/AOC bottom flatness should be considered

Abstract: The finite element method was used to analyze the crash simulation of road safety barrel in this paper. According to the road safety barrel standard of China—GB/T 28650-2012, 3D software AUTOCAD was used to establish collision system model. By using the project software ANSYS/LS-DYNA to simulate the different wall thickness of road safety barrel, the stress and strain, energy variation and deformation are analyzed for different number of road safety barrel, the layer of road safety barrel wall and road safety barrel in different circumstances. The simulation results may uncover the reasonability of the current road safety barrel set and provide the basis for further improvement.