首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 125 毫秒
1.
基于ABAQUS软件建立三种支持跨度的层压板三维有限元模型,分别计算在两种质量冲头冲击下的响应和损伤。结果表明,在判断支持跨度对冲击结果的影响时,要考虑冲头质量与板质量的比;在大质量冲头冲击的情况下,层压板的响应呈现准静态特征,层压板支持跨度的变化对,最大接触力、冲击持续时间、分层损伤面积等参数的影响较为简单明确;对于中等质量冲头情况,冲击接触时间减小,层压板振动明显,导致冲头与层压板在冲击过程中会脱离接触。在这种情况下不同跨度下板的响应差异也较为明显,冲击力的大小和损伤情况要依据具体的分析。从冲击接触时间和层压板固有振动周期的角度分析了冲头质量水平对冲击响应的影响。  相似文献   

2.
低速冲击下复合材料合板的响应过程模拟   总被引:4,自引:0,他引:4  
彭俊  刘元镛 《力学季刊》2001,22(1):138-142
运用一种精度较高的高阶位移模型分析了复合材料层合板在低速击下的响应过程,该位移模型能够同时考虑层间正应力和横向剪应力,另外,采用修正的Hertz接触定律与Newmark积分方法相结合,建立了冲击接触的有限元模型,本文的数值模拟计算结果与解析结果相比较证明了该方法的有效和精确性。  相似文献   

3.
采用实验方法研究了低速冲击下泡沫金属填充薄壁圆管的弯曲行为,详细说明了实验方法和原 理。通过与准静态实验结果的比较发现,冲击加载使泡沫金属填充圆管跨中截面的局部压入变形增大,跨中 截面高度变小,结构下缘拉裂破坏延迟。由于结构的惯性效应,锤头总冲击力高于准静态加载时的对应值。  相似文献   

4.
无约束修正Timoshenko梁的冲击问题   总被引:3,自引:0,他引:3  
介绍了修正后的Timoshenko梁运动方程,并比较了修正Timoshenko梁与经 典Timoshenko梁的运动方程. 推导了考虑剪切变形引起的转动惯量的修正Timoshenko 梁的正交条件,推导了集中质量对无约束修正Timoshenko梁的正碰撞对梁所引起的瞬态冲 击响应公式,并用算例进行了分析,且与集中质量对经典的无约束Timoshenko梁的正碰撞 对梁所引起的冲击响应进行了比较,另外还用算例分析了梁的刚度的变化和冲击质量比对其 冲击响应产生的影响.  相似文献   

5.
李志斌 《实验力学》2016,31(2):277-282
利用材料试验机(MTS)实验研究了复合材料面板、闭孔泡沫铝芯层夹芯板结构在准静态压入时的变形和破坏特征。实验结果表明,夹芯板的破坏主要集中在压头作用的局部区域内;同时,根据最小势能原理建立了泡沫铝夹芯板在半球形压头作用下的压入力学响应理论预测模型。通过引入无量纲参数分析了夹芯板压入载荷-位移响应,并在不同面板厚度、芯层厚度和芯层相对密度情况下,对夹芯板压入响应理论解的有效性和适用性进行了讨论。  相似文献   

6.
通过落锤冲击实验研究高孔隙率闭孔泡沫铝的动态压缩性能及抗低速冲击特性,同时通过高速摄影仪观察试件的动态压缩行为,并记录落锤冲击速度的衰减过程.结果表明,高孔隙率闭孔泡沫铝的抗冲击缓冲效果明显,且在低速冲击条件下其变形特征与准静态变形类似.采用有限元方法分析了落锤和泡沫中应力的分布特点以及表面摩擦系数对应力分布的影响.由于摩擦力阻碍了接触面处泡沫的横向位移,致使其压缩外形呈"鼓形";在低速冲击时,应力在泡沫铝试件内部的传播周期远小于冲击的缓冲时间,应力波现象并不明显,应力的变化与准静态压缩时相似.在考虑接触面上摩擦力的基础上,通过第2类 Lagrange方程建立了落锤-泡沫材料的碰撞解析模型,将预测的落锤冲击速度的衰减过程分别与实验和有限元结果进行比较,取得了较为一致的结论,并进一步讨论了不同冲击速度和材料参数对冲击过程的影响.  相似文献   

7.
采用嵌锁组装工艺制备了碳纤维/树脂基复合材料方形蜂窝夹芯梁,实验研究了低速冲击载荷下简支和固支夹芯梁的动态响应及失效机理,获得了不同冲击速度下夹芯梁的失效模式,分析了其损伤演化过程和失效机理,探讨了冲击速度、边界条件、面板质量分布以及槽口方向等因素对夹芯梁破坏模式及承载能力的影响。研究结果表明,芯材长肋板槽口方向对夹芯梁的失效模式有较大影响,槽口向上的芯材跨中部分产生了挤压变形,而槽口向下的芯材跨中部分槽口在拉伸作用下出现了沿槽口开裂失效,继而引起面板脱粘和肋板断裂;同等质量下,较厚的上面板设计可以提高夹芯梁的抗冲击能力,冲击速度越大,夹芯梁的峰值载荷和承载能力越高;固支边界使得夹芯梁的后失效行为呈现出明显的强化效应,在夹芯梁跨中部分发生初始失效后出现了后继的固支端芯材和面板断裂失效模式。  相似文献   

8.
建立了颗粒流子弹发射有限元模型,利用离散元和有限元的联合模拟方法,研究了高速颗粒流冲击负泊松比内凹蜂窝夹芯梁的动态响应及缓冲吸能机理。分析了加载冲量、冲击角、芯材强度以及颗粒流子弹与面板间的摩擦力等因素对夹芯梁动态响应的影响。研究结果表明:夹芯梁在正向颗粒流子弹冲击载荷作用下表现为局部凹陷和整体弯曲的耦合变形模式,面内设计芯材因胞壁弯曲呈现局部内凹的变形模式,面外设计芯材因胞壁屈曲呈现局部褶皱的变形模式。在等面密度的条件下,采用面外设计的硬芯夹芯梁面板的跨中最大挠度比采用面内设计的软芯夹芯梁小,但初始冲击力峰值和冲击力整体水平较高,冲击力响应时间较短。夹芯梁前后面板的跨中最大挠度与冲击载荷近似呈对数线性递增关系。与正向冲击相比,斜冲击下夹芯梁的变形模式具有非对称性,局部凹陷程度减小;在颗粒流子弹不同冲击角度作用下,夹芯梁前后面板的跨中最大挠度、初始冲击力峰值以及传递到夹芯梁的动能和动量占比随冲击角度的增大而减小,而颗粒流子弹与夹芯梁面板间的摩擦因数对夹芯梁的动态响应无显著影响。  相似文献   

9.
余先锋  全涌  顾明 《力学学报》2012,44(4):727-734
基于合理假定, 推导了迎风面单开孔两空间结构在其屋 盖以动力和准静态两种方式响应时的内压控制方程组. 通过数值算 例, 分析了各种屋盖柔度下由动力模型与准静态模型计算得到的两子空间内压增益函数、内压系数功率谱以及内压系数均方根值. 结果表明: 当屋盖较柔时, 须采用动力模型来计算内压响应, 反之, 可采用简化的准静态模型. 随着屋盖自振频率的增大, “内压-屋盖”系统的三阶共振频率都增大, 前二阶共振频率处的峰值内压响应也随之增大, 但第三阶共振频率处的峰值内压响应却越来越小, 由两模型计算得到的内压系数均方根值均随之增大, 但它们的差值却越来越小.  相似文献   

10.
软弱顺倾岩体爆破层裂的准静态力学模型应用研究   总被引:1,自引:0,他引:1  
针对顺倾岩质边坡爆破引起软弱夹层冲刷、压密而影响边坡稳定的问题,应用爆轰气体等熵绝热膨胀理论,建立深孔爆破过程中软弱顺倾边坡的准静态力学模型,导出了爆炸作用在软弱夹层内形成爆腔后的准静态压力和软弱层临界层裂长度计算公式。通过分析爆轰气体楔入层面内对边坡岩体产生的抬动作用,推得了边坡潜在滑体的稳定系数与装药参数、岩体力学参数和边坡几何尺寸的定量关系。将提出的准静态力学模型应用于两个典型顺倾岩质边坡的爆破动力稳定分析,得到了与工程实际相符合的计算结果。  相似文献   

11.
双层夹芯复合材料结构横向冲击响应实验   总被引:1,自引:0,他引:1  
采用玻璃纤维增强环氧树脂复合材料层合板作为内、外面板,以PVC泡沫作为芯材,构造了双层夹芯复合材料结构。采用落锤冲击实验,得到了冲击过程的撞击力历史;研究了在不同的冲击能量下,双层夹芯结构的冲击响应及内面板位置对双层夹芯结构冲击响应的影响。实验结果表明,内面板的引入及内面板的位置显著影响双层夹芯结构的撞击力历史,根据该撞击力历史可以优化设计出抗冲击性能优异的新型双层夹芯复合材料结构。  相似文献   

12.
Usually when analyzing the mechanical response of foam-cored fiber-reinforced composite sandwich structures to localized static loading, the face sheets are treated as a linear-elastic material and no damage initiation and growth is considered. However, practice shows that at higher indentation magnitudes damage develops in the face sheet in the area of contact with the indentor, which could lead to local failure of the face laminate due to the loss of bending stiffness and strength. Therefore, the main objective of the present study is to develop a damage model for predicting the local failure in the composite face sheet and its influence on the load–displacement behavior of sandwich structures under local loading. For this purpose, the Hoffman failure criterion is incorporated into a finite element modeling procedure using the ABAQUS program system. Results deducted from the modeling procedure are compared with experimental data obtained in the case of static indentation tests performed on sandwich beam specimens using steel cylindrical indentors. It is shown that taking into account the damage in the face sheet leads to a substantial improvement in the performance of the model when simulating the mechanical behavior of the sandwich structures at higher indentation values.  相似文献   

13.
Abstract

In the present study, the high-order free vibration analysis of rotating fully-bonded and delaminated sandwich beams; with and without vertical contact; containing AL-foam flexible core and carbon nanotubes reinforced composite (CNTRC) face sheets subjected to thermal and moisture field are investigated by using generalized differential quadrature method (GDQM). The compressible core and face sheets of sandwich beam, respectively, are composed of Aluminum alloy foam with variable mechanical properties in the thickness direction and CNTRC with temperature dependent material properties. In this study, the high-order sandwich panel theory (HSAPT) for AL-foam flexible core and Euler-Bernoulli beam theory for CNTRC face sheets are considered. By employing Hamilton’s principle, the governing partial differential equations of motion and associated boundary and continuity conditions for various types of regions (fully-bonded, delaminated with contact, delaminated without contact) are derived and then discretized by using GDQM. The final formulations lead to 14 partial differential equations for the entire structure including five equations for fully-bonded two-headed parts of AL-foam cored sandwich beam (AL-FCSB) and four equations for delaminated middle part of AL-FCSB beam which are combined in axial and transverse deformations. A parametric study is performed to investigate the influence of some important parameters such as existence of delaminated region, type of delaminated region (with or without contact), longitudinal position of delaminated region, slenderness ratio, face sheet thickness ratio, CNT volume fraction, temperature rise, moisture concentration, rotating speed, and hub radius. The obtained results reveal that the 1st frequency of delaminated AL-FCSB beam, whether with or without vertical contact, is less remarkably than ones of fully-bonded AL-FCSB beam which its value for the case of delaminated ‘with contact’ is larger than that of ‘without contact’. Moreover, the 1st frequency variation of the delaminated AL-FCSB beam is symmetrical with regard to the longitudinal position of the debonded region such that the 1st natural frequency declines with moving the debonded region toward the center of the beam. The study of vibration behavior of rotating sandwich beams is very important in design of rotating structural systems, specially damaged ones, such as airplanes, helicopter rotor blades, and robot arms. One of the most important types of damage encountered in mentioned cases is the decomposition of two layers or delamination. Working these rotating structures in the media, are always along with variations of temperature and humidity and hence their mechanical properties may be changed due to the environment conditions.

Communicated by S. Velinsky  相似文献   

14.
《力学快报》2022,12(5):100379
Carbon fiber reinforced polymer (CFRP) and CFRP-based composite honeycomb sandwich structures are particularly sensitive to impact. The mechanical characteristics of composite honeycomb sandwich structures under oblique impact are studied by numerical simulation and experiment. The oblique impact model is established, and the reliability of the model is verified by the oblique impact test. To further analyze the influence of structural parameters on energy absorption under oblique impact, the influence of impact angle, face sheet thickness and wall thickness of the honeycomb is numerically studied. The results show that the impact angle has an important effect on energy distribution. The structural parameters also have an effect on the peak contact force, contact time, and energy absorption, and the effect is different from normal impact due to the presence of frictional dissipation energy. Compared with normal impact, the debonding of oblique impact will be reduced, but the buckling range of the honeycomb core will be expanded.  相似文献   

15.
冰雹撞击下泡沫铝夹芯板的动态响应   总被引:2,自引:0,他引:2  
在传统单层泡沫夹芯结构的上、下面板之间插入中面板,通过移动中面板的位置,获得了外形尺寸相同、质量相等的5种构型夹芯结构,其上层芯材与芯材总厚度比分别为0:30、10:30、15:30、20:30和30:30。在量纲分析的基础上,应用非线性动力有限元程序LS-DYNA对5种构型夹芯结构进行了冰雹撞击数值分析,研究了中面板位置对夹芯板的能量吸收、能量耗散和动态响应的影响。结果表明:中面板的存在对下层芯材能形成有效的保护;随着中面板位置由上向下移动,夹芯板的抗撞击性能呈现由大到小再增大的态势。数值计算结果对抗冰雹撞击夹芯结构的优化设计具有一定的参考价值。  相似文献   

16.
The finite element (FE) method is employed to analyse the response of clamped sandwich beams subject to shock loadings. Pressure versus time histories representative of shock loadings are applied uniformly to the outer face of the sandwich beam; an impulse applied uniformly to the outer face of the sandwich beam is shown to model adequately shock loadings. Material elasticity and strain hardening representative of structural steels have only a minor effect upon the beam response. Further, the magnitude of the compressive strength of the core has only a limited influence upon the dynamic response of the sandwich beam for the representative range of core strengths considered. The FE results for the deflections and structural response time agree well with the rigid ideally-plastic analytical predictions of Fleck and Deshpande (J. Appl. Mech. (2003), in press).  相似文献   

17.
The problem of low-speed impact of a one-dimensional sandwich panel by a rigid cylindrical projectile is considered. The core of the sandwich panel is functionally graded such that the density, and hence its stiffness, vary through the thickness. The problem is a combination of static contact problem and dynamic response of the sandwich panel obtained via a simple nonlinear spring-mass model (quasi-static approximation). The variation of core Young’s modulus is represented by a polynomial in the thickness coordinate, but the Poisson’s ratio is kept constant. The two-dimensional elasticity equations for the plane sandwich structure are solved using a combination of Fourier series and Galerkin method. The contact problem is solved using the assumed contact stress distribution method. For the impact problem we used a simple dynamic model based on quasi-static behavior of the panel—the sandwich beam was modeled as a combination of two springs, a linear spring to account for the global deflection and a nonlinear spring to represent the local indentation effects. Results indicate that the contact stiffness of the beam with graded core increases causing the contact stresses and other stress components in the vicinity of contact to increase. However, the values of maximum strains corresponding to the maximum impact load are reduced considerably due to grading of the core properties. For a better comparison, the thickness of the functionally graded cores was chosen such that the flexural stiffness was equal to that of a beam with homogeneous core. The results indicate that functionally graded cores can be used effectively to mitigate or completely prevent impact damage in sandwich composites.  相似文献   

18.
采用有限元方法研究爆炸载荷下四边固支孔结构金属复合夹芯板的动力响应及吸能特性,给出了孔结构金属复合夹芯板的动力响应过程,得到夹芯板的变形模式,比较了孔结构金属复合夹芯板与非孔结构金属复合夹芯板的抗爆炸冲击性能,同时讨论了孔大小、间距、排布方式和面板质量分布等因素对孔结构金属复合夹芯板抗爆炸冲击性能的影响。研究结果表明,迎爆面外面板的孔设计使爆炸冲击波穿过孔洞直接作用在芯材上,增强了芯材的压缩,从而提高了夹芯板的能量吸收能力。同等面密度情况下,内外面板厚度比大于1的孔结构金属复合夹芯板变形挠度小于内外面板厚度比小于1的孔结构金属复合夹芯板。进一步研究发现,通过合理设计内外面板的质量分布,可以使孔结构金属复合夹芯板的抗爆炸冲击性能最优。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号