Papers by Keyword: Impact

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Authors: S. Mohammadi, S. Forouzan-Sepehr
Authors: Min You, Jia Ling Yan, Xiao Ling Zheng, Ding Feng Zhu, Jing Rong Hu
Abstract: The effect of the adhesive thickness and elastic modulus on the stress distribution in the mid-bondline of the adhesively-bonded steel/steel joint under impact loading is analyzed using 3-D finite element method (FEM). The results show that the stress distributed in bondline near the interface was significantly affected by the adhesive thickness and the elastic modulus. When the thickness increased from 1 mm to 2 mm, the values of all the stress components increased evidently along the upper edge of the adhesive but decreased significantly along the lower edge near the loading face. When the elastic modulus of the adhesive was increased, all the stresses increased along either the upper or the lower edge. It is clear that the suitable thickness and the elastic modulus of the adhesive are very important when the adhesively bonded joints subjected to the impacting load.
Authors: Xiao Dong Li, Fan Zhao
Abstract: Development of 3D printing technology brings revolutionary changes to the future of manufacturing. Based on the development of 3D printing technology and application prospects, this paper analyzes the positive effect of 3D printing technology on industrial design process, industrial design concepts and also some negative issues in the development process, such as intellectual property rights arising. What’s more, it discusses the advent of 3D printing technology which is the catalyst of future industrial design development cycle, the generation of "design of the package" model and the development of industrial design from standardization to individuation.
Authors: Konstantin Jonas Schubert, Axel Siegfried Herrmann
Abstract: One of the largest issues remaining on the way to in situ Structural Health Monitoring of composite structures using Lamb waves is the impact that non-damaging factors like temperature changes and humidity absorption have on most measurement strategies. While some of these tasks have been successfully conquered, others, especially related to slowly developing influences like humidity absorption or mechanical ageing, remain challenging. In this paper, a method to approach this problem for a Lamb-wave based passive impact detection system is presented. Passive approaches use the waves generated by the impact event itself to both localize said event and evaluate whether it was large enough to damage the structure. For this, the impacts energy has to be estimated from sensors detecting the Lamb waves. The problem provided by changing conditions within the material is that the locally measurable wave amplitude due to an impact event of a certain energy is altered if the material properties change. This might happen due to temperature changes, mechanical loads, humidity absorption, fluid loads and other factors. The main idea of the presented approach is to mix a passive and an active system. Piezoelectric elements are used to generate Lamb waves to obtain the attenuation coefficients of the material before and after hot/wet-conditioning. These coefficients are then used to estimate the impact energy from passive sensor responses. Both the approach and experimental validation performed with low velocity impacts from an impact hammer are presented to show the ability to correctly calculate impact forces after conditioning.
Authors: Michele Buonsanti, Giovanni Leonardi
Abstract: This paper using finite elements (FE) an approach to determine the contact stresses in a flexible pavement under landing aircraft loads is presented. The proposed 3-Dimensional model simulates the behaviour of flexible runway pavements during the landing phase. A study on the impact of a rubber solid on the free surface of a granular plate is presented, simulating an aircraft gear system landing on with a flexible surface. This study is performed considering two tires on the structural pavement, with the real loads applied directly on the two wheels of the gear system. The application takes in account the frictional phenomena developed between rubber solid and the surface of the pavement during the lockwire.
Authors: Choumad Ould, Emmanuelle Rouhaud, Manuel François, Jean Louis Chaboche
Abstract: Experimental analysis can be very costly and time consuming when searching for the optimal process parameters of a new shot-peening configuration (new material, new geometry of the part…). The prediction of compressive residual stresses in shot-peened parts has been an active field of research for the past fifteen years and several finite elements models have been proposed. These models, although they give interesting qualitative results, over-estimate, most of the time, the level of the maximal compressive stresses. A better comprehension of the phenomena and of the influence of the parameters used in the model can only carry a notable improvement to the prediction of the stresses. The fact that the loading path is cyclic and is not radial led us to think that a model including kinematic hardening would be better adapted for the modelling of shot peening. In this article we present the results of a simulation of a double impact for several constitutive laws. We study the effect of the chosen constitutive law on the level of residual stresses and, in particular, we show that kinematic hardening, even identified on the same tensile curve than isotropic hardening, leads to lower stress levels as compared with isotropic hardening. Furthermore, the overall shape of the stress distribution within the depth is significantly different for the two types of hardening behaviour. Further, in order to check the modelisations, local measurements were carried on with X-ray diffraction on a large size impact and correlated with the topography of the impact.
Authors: Hong Wei Guo, Zhong Jie Li, Zong Quan Deng, Chuang Shi, Rong Qiang Liu
Abstract: A novel intermittent mechanism and low-impact deployment hinge based on intermittent mechanism are presented in this paper. This application is contemplated to lower the impact dramatically at the end of hinge deployment. The overall deployment process is described and the maximum impact force and angular velocity are derived. The effect of the intermittent motion mechanism on free spring deployable hinges is evaluated by indexes of maximum angular velocity and impact force. Cases are simulated to verify the mechanism design, and results show that the maximum angular velocity and impact force can be decreased by more than 90%.
Authors: Ya Ping Ding, Xiao Yan Tong, Yong Tao Liu, Yong Liao
Abstract: To simulate the impact response of the moving body in the permanent magnetic actuator, this paper takes the magnetic force of the moving body at different positions as one of the input loads for the impact simulation, which avoids the coupling calculation of the magnetic and impact problem. The static and transient analysis of the magnetic field in the permanent magnetic actuator are implemented respectively to compute the magnetic flux density and their relative errors, results show the moving body in this magnetic field exerts little influence on the magnetic intensity and the influence can be neglected. The force of the moving body with respect to its position can be calculated in the static analysis and then be imported into the impact calculation to obtain the velocity and displacement. By comparing these results with the ones from the magneto-mechanical coupling transient analysis, the difference is small which proves the feasibility and accuracy of the proposed method.
Authors: Xiao Tian Zhang, Guang Hui Jia, Hai Huang
Abstract: A method for material fragmentation based on Lagrangian FEM with the concept of nodes separation is proposed. This method is consisted of nodes separation mechanism and elements distortion erosion. In the simulation the nodes of failure elements are separated to form crack and distorted elements are detected and eliminated to prevent singularity. Nodes separation method can greatly improve the energy loss disadvantage in the failure erosion method. Based on LS-dyna secondary development the method is implemented. Hypervelocity impact problem of satellite protective structure is simulated and compared to experimental data for calibration. The performance of multi layer aluminum mesh shield under hypervelocity impact is also evaluated. The results show the high efficiency and applicability of nodes separation method in practical problems.
Authors: Jun Wang, Wei Yi Li
Abstract: Abrasive waterjet machining involves the impact of micro-particles at high or ultrahigh velocities. The material removal mechanism for ductile materials has been popularly accepted for over a half century as cutting wear and deformation wear caused by the component of impact force parallel and perpendicular to the target surface respectively. However, this definition of erosion mechanisms does not give an insight into the erosion process, but describes a surface phenomenon of the event. A computational study has been undertaken to reveal the underlying mechanisms of the material removal process. Based on the findings, the impact erosion mechanisms are re-defined as material destruction through (a) failures induced by inertia, (b) failure induced by elongation, and (c) failure induced by adiabatic shear bending. This new definition appears to better represent the physical process of material deformation and removal by loose micro-particle impacts at high and ultrahigh velocities.
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