晶體硅的相關(guān)論文.doc

Research on The Explosive Impact Vibration Damage Model of Electronic Equipment Based on ANSYS/LS-DYNASHI Quan，TIAN Qing-wei，WANG Guang-yan，HU Qi-wei(Department of Management Engineering，Shijiazhuang Mechanical Engineering College， Shijiazhuang Hebei 050005，China)Abstract: The thesis designed a basic simulation project on the explosive vibration damage of electronic equipment.Found a two dimensional model including the explosive，the ground，the elastic body and the electronic equipment with ANSYS/LS-DYNA.Acquired a lot of data corresponding to the explosive impact vibration characteristic about the response acceleration，response displacement，effective stress of the electronic equipment. Lastly,the method which found the comprehensive simulation model and analyze on the explosive vibration damage simulation problem with ANSYS/LS-DYNA software is verified the possibility.Key words: Explosive impact vibration；Electronic equipment；Damage；Modeling；Orthogonal experiment18In modern wars, the explosive impact vibration has already become one of the most important reasons of the damage of electronic equipment. according to statistics, the ratio can be up to 50 percent to 60 percent because of the mechanical vibration and the explosive impact vibration. However, the explosive dynamics processes are greatly complicated and affected by external factors (for example, explosive property, distance from the surge, ground medium etc.) It is too difficult to get an accurate analytic model. At the present time，the studies of shock and vibration impacting on the digital products are mainly confined to the test mode of the direct imposing the equivalent load of local sine or square wave on the local of the individual components and neglect the synthesized effect of the factors like the surge property, the transmitting medium and so on, hence it has great limitations.the paper adopts ANSYS/LS-DYNA FSI technology, considers over the environmental factors of explosive impact vibration, studies the electrical device explosive vibration damage model, and provide theoretical basis for emulation studies of electrical device damages in war.1 electrical device explosive impact vibration damage1.1 properties of the explosive impact vibration the explosion is a lot of energy in a limited size and a very short time rapid release or rapid-conversion phenomenon. The roots of doing work outside are:the instantaneous temperature of the reaction of the systemic explosion and the sudden expansion of the high pressure gas make the media around fried points into the sharp pressure-jump. The pressure-jump acts on geotechnical media to generate Overpressure and cause the ground vibration. An explosion experiments get the history chart of acceleration and time of the ground vibration,which is shown in Figure 1.It shows the acceleration of the vertical peak of the ground vibration 11m away from the explosion source varies with the time. 圖1 距爆源11m處爆炸地面豎向振動加速度幅值時程The amplitude duration of the acceleration of the vertical peak of the ground vibration 11m away from the explosion1. It can be seen from the chart, at the beginning the vertical acceleration of the ground vibration is nearly zero, then is the process of sharp rise to reach a certain value, then is the process of rapid decay, which is a very significant characteristics of a peak of the blast shock and vibration . 1.2 Mechanisms of DamageIn short, the damage of explosive vibration to electronic equipment mainly includes two aspects: first, the instantaneous acceleration of the equipment parts in a particular excitation frequency exceeds the limits of the equipment or occurs resonance leading to the damage; Second, long-term effects of stress caused by vibration acceleration make the products effete and destructive. As the time of shock and vibration of the explosion is very short, whose duration lasts from a few to a few milliseconds , the vibration after the main pulse attenuates quickly, so the the equipment damage is mainly caused by the destruction of the vertical peak of the Rayleigh wave, followed by fatigue damage 3. This paper mainly studies the damage to electronic equipment caused by the acceleration of the significant blast vibration peak. 2 the study of the damage model of blast shock and vibration of the electronic equipment2.1 The implementation scheme of the damage simulation.(1)Making a overall analysis of the target equipment by means of a equivalent model of a single degree of freedom. In general,the mechanical structures of the electronic equipment are more complicated and its overlay is also a relatively high degree of freedom, but many products can be equivalent or be decomposed into system models of a single (multi-) degree of freedom linear, which are shown in Figure 2. The model in this paper,which is through the vehicle electronic equipment of the equivalent single degree of freedom ,is a kind of simulation model.圖2 單自由度力學(xué)等效模型The mechanical equivalent model of a single degree of freedom （2）The damage threshold of acceleration sets the criteria. The acceleration value of a given region within the model of the electronic equipment exceeds a predetermined acceleration value, which determines the failure of its subsidiary parts. (3)It proceeds the equivalence of the parameters. According to the actual operating characteristics of the equipment, the use of an equivalent method or a conversion method converts the technical indicators of the constituent elements of into the corresponding system parameters of the ANSYS / LS-DYNA program.2.2 The simulation method Based on LS-DYNA One very powerful feature of the program is to simulate the interaction of the explosive materials and other materials, which includes mainly two methods: First, it is the method of Lagrange,which can make a better description of the deep-fried pits of the soil and the design and analysis of the warhead and the interaction between the explosives and the structure that is achieved by the definition of the contact relationships .The drawbacks of this method are: The explosive units in the explosion will engender the serious distortion and even affect the solution of the process. Second, it is the coupling method of the multi-material fluid-solid, whose algorithm is used to describe the process of the explosion .The explosives and other fluid materials (such as air, water, soil, etc.) use the Euler algorithm while the solid structures use the Lagrange method,whose interaction both are dealt with the coupling approach .This paper will establish simulation model adopting the coupling method of Fluid-solid.2.3 the establishment of the finite element model (1) the analysis of the modelingIn view of this major study of the paper pointing to the threat of blast shock and vibration,therefore the design of multi-material coupling factors only refers to the establishment of explosives models, terrain models, elastic body (shock effect) model and the electronic equipment model (cavity), but part of the establishment of the air model can avoid the additional role of the the target equipment imposed by the explosion shock wave leading to influence the calculation accuracy. In the algorithm, the explosive and the ground grid adopt the Euler modeling while the elastomers and the objective equipments adopt the Lagrange mesh modeling. Ignoring of taking the impact of end conditions into account, it converts the question into a plane strain problem, and uses single-layer grid to carry out the calculating. The model units use the uniform unit cm-g-s ,which simplify the contact of the elastomer and the target equipment with the ground as the coplanar. The specific constitution and size of a model are shown in Figure 3 and Table 1. Model classificationLength cmWidth cmheightcmthe Explosives10.52The air200.518The Ground750.51The Elastomers30.51Target chamber (outer)100.55Target chamber thickness10.51地 面目標(biāo)腔體圖3 仿真模型整體設(shè)計(jì)The overall design of simulation modelsIn order to study the impact of an explosion vibration on the various elements of the simulation model， we select A E test points separately so as to measure and compare the data. A point lies in the midpoint of cavity on the ground, B and C point lie respectively in the midpoint of the cavity and the midpoint of the connnection surface of the Elastomers, D and E lie separately in the midpoint of the ground and in the midpoint of the connnection surface of the Elastomers . The specific case shows in Figure 4.圖4 測量點(diǎn)分布示意圖DECBthe Schematic diagram of the distribution of the measurement points In addition, we still select four points (75cm, 101 cm, 125 cm, 148 cm) from the detonation point at different distances on the ground. For the purpose of the analysis of the spread of the blast vibration waves in the ground medium.(2) cell type selection and meshing All models select the 8-node hexahedral element SOLID164 of the supportive non-linear features and controllable precision,which is shown in Figure 5. 圖5 SOLID164實(shí)體單元幾何圖式The solid element geometry typeOf SOLID164The explosives, the ground,and the elastic body model take the unified body of Hex and Mapped meshing, the length of the cell side sets to 0.5.The electronic equipment uses Tri mesh, the length of the cell side sets to 0.25.(3) The material models and the equation of state explosive model ANSYS / LS-DYNA program provides the numerical model for the role of the simulation of the explosives, namely, “MAT_HIGH_EXPLOSIVE_BURN “with a description of the JWL equation of state model between detonation gas pressure and volume relations. The followings are the specific expressions: ，A, B, R1, R2 and represent separately the parameters of the JWL equation of state, whose value is determined by the tests; P represents a unit pressure, E0 represents internal energy of the explosives, V represents the current relative volume. This paper uses TNT explosives, then the above equations take the values of the following table.Table 2: values of each parameter in the table values of the explosives model .nameValuenameValueRO2.640B0.032D0.693R14.150PCJ0.270R20.950A3.7400.300RO represents the mass density of the explosives, D represents the detonation velocity of the explosives, PCJ represents the detonation pressure of the explosives, A, B, R1, R2 and represent the parameters of the equation of state. Ground Model In view of the characteristics of hard materials and large-strain properties of the surface, this paper uses the John-Cook material model and Gruneisen equation of state to define,and the specific parameters take the values from the following Table 3. namevaluenamevalueRO7.830S30.000G0.770GAMAO2.170C0.457A0.460S11.490E00.000S20.000V01.000Thereinto, RO represents the mass density of the material, G represents the shear modulus, E0 represents the internal energy of the material, V represents the current relative volume, C, S1, S2, S3, GAMAO and A represent the parameters of the equation of state. Elastomers Elastomers are a kind of elastic material,which are similar with the Rubber Body and use the * MAT_ELASTIC material constitutive model to make a definition. Thereinto the density DEN = 3.989, elastic modulus EX = 7.355E-02, Poissons ratio NUXY = 0.330. the materials of target equipmentThe upper chamber is made of the aluminum alloy,which uses thel MAT_PLASTIC_KINEMATIC material constitutive model to make a definition , in which the density DEN = 2.655, elastic modulus EX = 4.000E-01, Poissons ratio NUXY = 0.350. (4) the definition of CouplingFirst, determining the Formula of liquid medium and Solid structures.l Formula for calculating the four substances are all options * SECTION_SOLID. Which, elastomers and objectives of the equipment, use of Lagrange algorithm, explosives and surface binding by * ALE_MULTI_MATERIAL keyword, use the ALE algorithm. Second, the division of PART and the PART Group: explosives, on the ground, elastomers and objectives of the equipment, respectively, PART1, PART2, PART3, PART4; by * SET_PART_LIST the PART1 and PART2 divided into a group (ID numbers set to 1), will PART3 and PART4 is divided into a group (ID numbers set to 2), the latter using the keyword * CONSTRAINED_LAGRANGE_IN_SOLID establish the relationship between fluid-solid coupling. (5) The establishment of boundary conditions In order to ensure the spread of blast vibration direction and precision, this paper consider the model of the boundary conditions, were handled as follows: the border YOZ plane bound for the direction of UX, on the one hand the number of mesh can reduce the model to improve computing speed, a aspects of abnormal cells can avoid termination of the calculation procedure. the soil model, the stress wave propagation direction of an explosion of law to face the conditions imposed NONREF to avoid the stress before the wave after wave reflection superposition, resulting in measurement data are not allowed. the model for all NODE points the direction of the constraints imposed by UZ improve the stress wave propagation direction. (6) Other parameter settings In order to ensure the accuracy of simulation models and the effects of explosives detonation mode is set to the top of a single point of initiation, the process total time set to 240s, the output once every 0.5s results; other parameters to determine, with other finite element analysis method similar to the here will not repeat them.2 the simulation results After establishing the finite element model according to the above methods and modifying the material parameters of the K file and the ID parameters of the PART group ,it is submitted to the solution of the LS-DYNA. Through the post-processing of LS-PREPOST,it obtains Von-Mises equivalent stress cloud, cloud displacements and contrast curve on the ground, the elastomers and the target equipment at different time,which are shown in Figure 5 Figure 10.圖9 t=140.5s時目標(biāo)裝備的應(yīng)力響應(yīng)云圖圖5 t=72.391s時地面的應(yīng)力波傳遞情況table5: the transmission of the ground stress wave圖6 地面模型101節(jié)點(diǎn)加速度曲線圖5 t=72.391s時地面的應(yīng)力波傳遞情況圖9 t=140.5s時目標(biāo)裝備的應(yīng)力響應(yīng)云圖圖10 腔體地面B點(diǎn)瞬時加速度曲線table6: the acceleration curve of the Ground Model 101 nodes 圖7 地面75148測量點(diǎn)加速度對比曲線Table7: the acceleration contrast curve of 75 148 measurement points on the ground 圖8 彈性體的緩沖作用加速度對比曲線Table8: the acceleration contrast curves of the buffering effect of the elastomerTable9: the stress response cloud of the target equipment圖10 腔體地面B點(diǎn)瞬時加速度曲線圖6 地面模型101節(jié)點(diǎn)加速度曲線圖7 地面75148測量點(diǎn)加速度對比曲線a few milliseconds after table10: the instantaneous acceleration curve of the cavity surface-point BAccording to the graphics above, something can be found：（1）Simulation model has a very clear vibration characteristics of the explosion.It can be seen from Figure 5, Figure 6, an explosion caused shocking vibration in the ground, and resulted in a marked feature of the pulsed beam, whats more, the role of time is very short, the main pulse lasts only a few to dozen milliseconds, then the vibration attenuate soon, which is consistent with the vibration waveform of explosion measured actually in the engineering. （2）Distance has a regular impact on the vibration of explosion. Contrast can be seen from Figure 7, In each of four different distances from the burst point on the 75node, 101node, 125node, 148node, get a different acceleration values, And the peak tend to decrease gradually, and is also consistent with the propagation rule measured in the actual engineering.（3）Elastomer has good cushioning effect. Seen from Figure 5, Figure 6, the acceleration reduced drastically from G (349) points to E (946) points, H (342) points to F (974) point.This shows that when the vibrations reach the equipment location, first caused movement of elastic physical point, Elastomer amortizes off some of the vibration energy, but later passed to the upper and equipmentm, then to the upper and equipment（4）The whole Equipment occurred Vibration Response. From Figure 9 and Figure 10 can be seen, the vibration of the blast passed through the elastic body to the target equipment, therefore the upload Part received a transient upward acceleration excitation, Produced in different parts of different stress response. The acceleration of Y direction created within the cavity B-point also has the typical characteristics of blast vibration wave, this is similar to the response of equipment shelter. The conclusions indicate that, Using ANSYS / LS-DYNA established simulation model of blast shocking vibration of electronic equipment, which can better reflect the response characteristics of electronic equipment under the condition of the actual explosion. Further basicly verify the feasibility of the use of the model.4 Analysis of importance of factors The damage of blast vibration of electronic equipment has many environmental impact factors, the main aspects of battlefield-related, including: Vibration source characteristics, the media, an explosion height, the distance between objectives and local oscillator, they have different damage effect on the equipment. This paper will be based on the above model, using the orthogonal experiment to analyze the degree of influence of various factors. According to the equipments working environment, this pa